Sunflower Production Field Guide - Your "Home Page"

A-1331 (EB-25 Revised) 

Sunfl ower 

Production 

SEPTEMBER 2007

Foreword 

The fi rst edition of “Sunfl ower Production and Marketing 

Extension Bulletin 25” was published in 1975. 

This publication provided general information for 

growers, seedsmen, processors, marketing agencies 

and Extension personnel. Revised editions followed in 

1978, 1985 and 1994. Interest and knowledge about 

sunfl ower production and marketing in the U.S. has 

increased greatly in the past 30 years. Marketing and 

processing channels have stabilized and have become 

fairly familiar to growers since 1985, but pest problems 

have shifted and new research information has 

become available to assist in production decisions. 

This publication is a revision of the “Sunfl ower Production 

and Marketing Bulletin” published in 1994. 

The purpose is to update information and provide a 

production and pest management guide for sunfl ower 

growers. This revised publication is directed primarily 

to the commercial production of sunfl ower, not to marketing 

and processing. It will attempt to give specifi c 

guidelines and recommendations on production practices, 

pest identifi cation and pest management, based 

on current information. 

This publication also is directed primarily toward sunfl 

ower production in the northern Great Plains of the 

U.S. However, much of the information is relevant to 

other production areas. All pesticides recommended 

have a U.S. Environmental Protection Agency label 

unless otherwise specifi ed. This publication contains 

certain recommendations for pesticides that 

are labeled ONLY for North Dakota. The users of 

any pesticide designated for a state label must have 

a copy of the state label in their possession at the 

time of application. State labels can be obtained 

from agricultural chemical dealers or distributors. 

USE PESTICIDES ONLY AS LABELED. 

Acknowledgements 

The editor is indebted to the contributors for writing 

sections of this publication. The editor also appreciates 

the efforts made by previous contributors, as 

these previous sections often were the starting point 

for current sections. 

i

ii 

Contributors 

Roger Ashley, Area Extension Agronomist, Dickinson 

Research Extension Center, Dickinson, ND 58601 

Duane R. Berglund, Professor Emeritus and Former 

Extension Agronomist, NDSU Extension Service, 

North Dakota State University, Fargo, ND 58105 

Carl Bradley, Former Extension Plant Pathologist, 

NDSU Extension Service, North Dakota State 

University, Fargo, ND 58105 

Gary Brewer, Former Department Chair and Professor, 

Department of Entomology, North Dakota State 


Lawrence Charlet, Research Entomologist, 

ARS-USDA, North Dakota State University, 

Fargo, ND 58105 

Greg Endres, Area Extension Agronomist, NDSU 

Research Extension Center, Carrington, ND 58421 

George Flaskerud, Extension Agricultural Economist, 



Dave Franzen, Extension Soils Specialist, NDSU 

Extension Service, North Dakota State University, 


Thomas Gulya, Research Plant Pathologist, 

ARS-USDA, North Dakota State University, 


James Hanzel, Sunfl ower Breeder, Proseed Inc., 

Harvey, ND 58341 

Kenneth Hellevang, Extension Agricultural Engineer, 



Vernon L. Hofman, Professor Emeritus and Former 

Extension Agricultural Engineer, NDSU Extension 

Service, North Dakota State University, Fargo, ND 

58105 

Larry Kleingartner, Executive Director, National 

Sunfl ower Association, Bismarck, ND 58503 

Jan Knodel, Extension Entomologist, NDSU 



Greg Lardy, Extension Beef Cattle Specialist, 

Department of Animal and Range Sciences, 


George Linz, Wildlife Biologist, USDA-APHIS, 

Bismarck, ND 58501 

Sam Markell, Extension Plant Pathologist, NDSU 



Jerry Miller, Retired Sunfl ower Breeder, USDA-ARS, 


John Sandbakken, Marketing Specialist, National 

Sunfl ower Association, Bismarck, ND 58503 

Tom Scherer, Extension Irrigation Engineer, NDSU 



Don Tanaka, Soil Scientist, ARS-USDA, Northern 

Great Plains Research Laboratory, Mandan, ND 

58554 

Richard Zollinger, Extension Weeds Specialist, 



Former Editors: David W. Cobia, David E. Zimmer, 

Marcia McMullen and Duane R. Berglund 

Former Contributors: Ron R. Allen, William S. Ball, 

James Bauder, Al Black, David W. Cobia, William 

Danke, Alan Dexter, Carl Fanning, Gerhardt N. Fick, 

Basil Furgala, Phil Glogoza, James Helm, Harvey 

J. Hirning, Edna T. Holm, David H. Kinard, Arthur 

Lamey, Darnell Lundstrom, Dean McBride, Hugh 

McDonald, John Nalewaja, Berlin Nelson, David M. 

Noetzel, William K. Pfeifer, Lyle Prunty, Charlie E. 

Rogers, LeRoy W. Schaffner, Albert Schneiter, Robert 

and Jay Schuler, John T. Schulz, Tommy E. Thompson, 

Sebastian Vogel, Howard D. Wilkins, David E. 

Zimmer and Joseph C. Zubriski

Sunfl ower 


Edited and Compiled by 

Duane R. Berglund 

Professor Emeritus and 

Former Extension Agronomist 

North Dakota State University 

Extension Service 

Extension Publication A-1331 

(EB-25 revised) 

September 2007 

North Dakota Agricultural 

Experiment Station 

and 


Extension Service 


Fargo, North Dakota 58105 

Contents 

page 

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i 

Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i 

Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii 

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Historical perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Taxonomy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Growth stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Growing degree days . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

II. Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

World production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

U.S. production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Acreage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Seed yields/acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Pounds of seed production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Processing plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Prices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Sunfl ower marketing strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

III. Hybrid Selection and Production Practices . . . . . . . . . . . . . . 10 

Hybrid selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Oilseed (NuSun), traditional and confectionary . . . . . . . . . . . . 11 

Criterial for hybrid selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

Semidwarf sunfl ower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

Sunfl ower branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Production practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Seed quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Soil fertility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Fertilizer recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

Fertilizer application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

Water requirements for sunfl ower . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

Soil water management for dryland sunfl ower . . . . . . . . . . . . . 16 

Irrigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

Tillage, seedbed preparation and planting . . . . . . . . . . . . . . . . . 18 

Crop rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

Pollination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 

IV. Pest Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 

Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 

Weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 

Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 

Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 

V. Hail Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

VI. Herbicide Drift and Chemical Residue . . . . . . . . . . . . . . . . . . . . 95 

VII. Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 

Maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 

Harvesting attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 

Combine adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 

VIII. Drying and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 

IX. Feeding Value of Sunfl ower Products 

in Beef Cattle Diets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 

X. U.S. Grades and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 

XI. Other Information Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 

Appendix 1. Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 

iii

Introduction 

(Duane R. Berglund) 

Two primary types of sunfl ower are grown: (1) oilseed 

for vegetable oil production and (2) nonoilseed for 

human food and bird-food markets (Figure 1). The oilseed 

hybrids may be of three fatty acid types: linoleic, 

mid-oleic (NuSun) or high oleic. They are usually 

black-seeded and have a thin hull that adheres to the 

kernel. Seed of the oilseed varieties contains from 38 

percent to 50 percent oil and about 20 percent protein. 

Some black-seeded oil types go into the hulling market 

for birdseed. Nonoilseed sunfl ower also has been 

referred to as confectionery sunfl ower, and is usually 

white striped and/or comes in large-seeded varieties. 

1 

2 

Nonoilseed sunfl ower generally has a relatively thick 

hull that remains loosely attached to the kernel, permitting 

more complete dehulling. Seed of the nonoilseed 

hybrids generally is larger than that of the oilseed 

types and has a lower oil percentage and test weight. 

Sunfl ower is a major source of vegetable oil in 

the world. Worldwide production of sunfl ower has 

increased since the last revision of this publication 

and peaked during the 1998-1999 period. The former 

Soviet Union remains the highest producer, followed 

by Argentina and then the U.S., which is third in 

production worldwide. Domestic use and exportation 

of nonoilseed sunfl ower also have increased. The majority 

of U.S. production of sunfl ower oil is exported, 

although domestic use is increasing. 

The following chapters provide a historical perspective 

and background of the sunfl ower as a viable 

economic crop and provide the current information 

on worldwide and U.S. production, U.S. production 

practices, current pest identifi cation and pest management 

practices, hail injury, herbicide use and damage, 

harvesting, drying, storing, and U.S. grades and 

standards for market. 

Historical Perspective 

Sunfl ower, native to North America, is the state 

fl ower of Kansas and grows wild in many areas of 

the U.S. Sunfl ower has a long and varied history as 

an economic plant, but the time and place of its fi rst 

cultivation is uncertain. Sunfl ower was used by North 

■ Figure 1. The two classes of sunfl ower based on seed 

characteristics: (1) oilseed hybrids grown as a source 

for oil and meal, and (2) nonoilseed hybrids-grown for 

human and bird food. Wholeseed and kernel types for 

both are shown. (Gerhardt Fick) 

Introduction 

1

2 

American Indians before colonization of the New 

World. Spanish explorers collected sunfl ower in North 

America and by 1580, it was a common garden fl ower 

in Spain (Figure 2). Early English and French explorers, 

fi nding sunfl ower in common use by the American 

Indians, introduced it to their respective lands. It 

spread along the trade routes to Italy, Egypt, Afghanistan, 

India, China and Russia. Sunfl ower developed as 

a premier oilseed crop in Russia and has found wide 

acceptance throughout Europe. Oilseed sunfl ower has 

been an economically important crop in the U.S. since 

1966. Before 1966, sunfl ower acreage in the U.S. was 

devoted primarily to nonoilseed varieties. 

The center of sunfl ower origin has been identifi ed 

as limited to the western Plains of North America, 

but whether the domesticated type originated in the 

Southwest or in the Mississippi or Missouri River 

valleys has not been determined. The wild form of the 

cultivated sunfl ower is well-known, which is not true 

with most of our cultivated crop species today. 

■ Figure 2. A 1586 drawing of sunfl ower. 

(Mattiolus from Heiser) 

The American Indians used sunfl ower as a foodstuff 

before the cultivation of corn. Sunfl ower also was used 

as a medicinal crop, source of dye, oil for ceremonial 

body painting and pottery, and as a hunting calendar. 

When sunfl ower was tall and in bloom, the bison fed 

on it, and according to stories told, the fat and the 

meat were good. 

Cultivation of sunfl ower was undertaken by New 

World settlers as a supplementary food. Later, sunfl 

ower was grown primarily as a garden ornament. It 

also was grown as an ensilage crop in the late 1800s 

and early 1900s. 

Expanded world production of sunfl ower resulted 

primarily from development of high-oil varieties by 

plant scientists and more recently by the development 

of hybrids. Sunfl ower is widely grown in the world 

where the climates are favorable and a high quality oil 

is desired. 

Taxonomy 

The cultivated sunfl ower (Helianthus annuus L.) is 

one of the 67 species in the genus Helianthus. All 

are native to the Americas and most are found in the 

U.S. It is a member of the Compositae family and 

has a typical composite fl ower (Figure 3). Jerusalem 

artichoke (H. tuberosus L.), another species, is grown 

on a limited basis for food and livestock feed in the 

U.S. A few species are grown as ornamentals and the 

rest are weeds, usually found in pastures or disturbed 

areas. 

The basic chromosome number for the Helianthus 

genus is 17. Diploid, tetraploid and hexaploid species 

are known. The majority of the species are perennial, 

with only about a dozen annual species. Plant breeders 

have made interspecifi c crosses within the genus and 

have transferred such useful characteristics as higher 

oil percentage, cytoplasmic male sterility for use in 

production of hybrids, and disease and insect resistance 

to commercial sunfl ower. 

Growth Stages 

The division of growth into vegetative and reproductive 

stages as developed by Schneiter and Miller is 

shown in Figure 4. This scheme is important as it 

gives producers, scientists and the industry a common 

basis to discuss plant development.

ay fl ower 

petal 

disk fl orets 

receptacle 

Table 1. Growing Degree Days: Sunfl ower Growth and Development 

Sunfl ower Plant 

Ave. days and GDD** units 

accum. from planting 

GDD 

Stage Description units Days 

VE Emergence 167 10 

V4 4 True Leaves 349 20 





R1 Miniature Terminal Bud 919 46 

R2 Bud

4 

Vegetative Stages 

True leaf — 4 cm 

V-12 

Reproductive Stages 

R-5.1 

R-7 

V-E 

V-2 

V-4 

R-1 R-2 

R-3 R-3 Top View R-4 Top View 

R-5.5 R-5.9 R-6 

R-8 R-9 

■ Figure 4. Stages of sunfl ower development. 

(A. A. Schneiter and J.F. Miller.) 

Less 

than 

2cm 

R-2 R-3 

More 

than 

2cm

Description of sunfl ower growth stage 

The total time required for development of a sunfl ower plant and the time between the various 

stages of development depends on the genetic background of the plant and growing season environment. 

When determining the growth stage of a sunfl ower fi eld, the average development of a 

large number of plants should be considered. This staging method also can be used for individual 

plants. The same system can be used for classifying either a single head or branched sunfl ower. 

In the case of branched sunfl ower, make determinations using only the main branch or head. In 

stages R-7 through R-9, use healthy, disease-free heads to determine plant development if possible 

because some diseases can cause head discoloration. Also, in a number of recently released and 

grown hybrids, the stay-green characteristic is present, which means the yellowing or browning of 

the bracts may not be a good indicator of plant maturity. 

Stage Description 

V (number) These are determined by counting the number of true leaves at least 

Vegetative Stages 4 cm in length beginning as V-1, V-2, V-3, V-4, etc. If senescence of 

(e.g., V-1, V-2, V-3, etc.) of the lower leaves has occurred, count leaf scars (excluding those 

where the cotyledons were attached) to determine the proper stage. 

R-1 Reproductive Stages The terminal bud forms a miniature fl oral head rather than a cluster of 

leaves. When viewed from directly above, the immature bracts have a 

many-pointed starlike appearance. 

R-2 The immature bud elongates 0.5 to 2.0 cm above the nearest leaf 

attached to the stem. Disregard leaves attached directly to the back of 

the bud. 

R-3 The immature bud elongates more than 2 cm above the nearest leaf. 

R-4 The infl orescence begins to open. When viewed from directly above, 

immature ray fl owers are visible. 

R-5 (decimal) This stage is the beginning of fl owering. The stage can be divided into 

(e.g., R-5.1, R-5.2, R-5.3, etc.) substages dependent upon the percent of the head area (disk fl owers) 

that has completed or is in fl owering. Ex. R-5.3 (30%), R-5.8 (80%), 

etc. 

R-6 Flowering is complete and the ray fl owers are wilting. 

R-7 The back of the head has started to turn a pale yellow. 

R-8 The back of the head is yellow but the bracts remain green. 

R-9 The bracts become yellow and brown. This stage is regarded as 

physiological maturity. 

From Schneiter, A.A., and J.F. Miller. 1981. Description of Sunfl ower Growth Stages. Crop Sci. 21:901-903. 

Growth Stages 

5

6 


World Production 

(John Sandbakken and Larry Kleingartner) 

The sunfl ower is native to North America but commercialization 

of the plant took place in Russia. Sunfl ower 

oil is the preferred oil in most of Europe, Mexico and 

several South American countries. Major producing 

countries or areas are the former Soviet Union, 

Argentina, Eastern Europe, U.S., China, France and 

Spain (Table 2). These seven countries/areas of the 

world produce about 80 percent of the world’s oilseed 

and nonoilseed sunfl ower. Historically, the former Soviet 

Union has been the No. 1 producer of sunfl ower, 

producing about 35 percent of the world’s production 

annually. During much of the 1970s, the U.S. was 

the world’s second largest producer, but in the 1980s, 

Argentina became fi rmly entrenched in second place. 

Table 2. World Production of All Sunfl ower 

U.S. Production 

Acreage 

The fi rst sustained commercial production of oilseed 

sunfl ower in the U.S. occurred in 1966, when about 

6,000 acres were grown. Total combined acreage of 

oilseed and nonoilseed sunfl ower increased gradually 

in the late 1960s and expanded rapidly in the 1970s, 

reaching a peak in 1979 at 5.5 million acres. The U.S. 

share of world production has declined in recent years 

as production in Argentina and other countries has 

increased. During the peak period of U.S. production, 

the U.S. produced about 15 percent of the world’s 

sunfl ower production. In 2005, the U.S. market share 

was only 6 percent. 

The rapid acreage increase in the late 1970s was 

stimulated by a variety of factors. Favorable yields in 

1977 and 1978 brought about by improved hybrids 

and favorable weather conditions were key factors, 

along with excellent prices when compared with competitive 

crops. 

1996- 1997- 1998- 1999- 2000- 2001- 2002- 2003- 2004- 2005- 

2006- 

2007 

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Forecast 

Argentina 5.45 5.68 7.13 5.80 2.94 3.73 3.34 2.98 3.75 3.82 4.20 

Eastern Europe 2.92 2.18 2.59 2.75 1.67 1.86 2.02 2.67 2.27 2.11 2.17 

European Union 3.87 4.08 3.44 3.10 3.27 3.03 3.72 4.07 4.07 3.72 4.06 

China, Peoples 

Republic of 

1.42 1.17 1.46 1.77 1.95 1.75 1.95 1.82 1.70 1.83 1.85 

former USSR 5.37 5.41 5.74 6.89 7.27 4.94 7.19 9.35 8.00 11.32 11.20 

United States 1.60 1.67 2.39 1.97 1.61 1.55 1.11 1.21 .93 1.82 .92 

India 1.30 1.16 1.17 .87 .81 .73 1.06 1.16 1.45 1.50 1.43 

Turkey .67 .67 .85 .82 .63 .53 .83 .56 .64 .80 .90 

Other 1.99 1.87 2.83 2.98 3.01 3.55 2.74 3.07 3.58 3.25 3.77 

World Sunfl ower 24.63 23.89 27.60 26.95 23.16 21.80 23.95 26.88 26.39 30.16 30.49 


(million metric tons)

Changes in the 1990 government farm program, which 

allowed planting fl exibility while providing price support, 

led to an increase in sunfl ower acreage in 1991 

relative to 1990. The government program established 

a marketing loan and a loan defi ciency payment for 

sunfl ower and other oilseed crops. 

The bulk of U.S. sunfl ower production occurs in North 

Dakota, South Dakota, Minnesota, Kansas, Colorado, 

Nebraska and Texas. Small acreages are grown 

in several other states (Table 3). The majority of the 

acreage harvested is for oil production versus nonoil 

uses. In 2005, the USDA reported that 2,032,000 acres 

of oil sunfl ower and 578,000 of nonoil sunfl ower were 

harvested (Table 4). 

Seed Yield/Acre 

Annual average sunfl ower yields from 1996 to 2005 

ranged from 1,140 to 1,564 pounds per acre for 

oilseed and from 997 to 1,455 pounds per acre for 

Table 3. Total Planted Sunfl ower Acreage by States 1994-2006 

nonoilseed sunfl ower. Average yields per acre during 

the 1996-2005 period were 1,349 pounds for oilseeds 

and 1,220 pounds for nonoilseed sunfl ower (Figure 5). 

Pounds of Production 

U.S. production of oilseed sunfl ower ranged from 

1,763 million pounds (799,700 metric tons) in 2004 to 

4,486 million pounds (2,035,000 metric tons) in 1998 

(Table 5). Nonoilseed production ranged from 286 

million pounds (130,000 metric tons) in 2004 to 844 

million pounds (383,000 metric tons) in 1999. 

Processing Plants 

Four oil extraction plants in North Dakota, Minnesota 

and Kansas process oilseed sunfl ower. These 

four plants have a combined crushing capacity of 

1,900,000 metric tons per year, according to industry 

estimates. Several smaller plants are located throughout 

the main sunfl ower production region. 

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

North Dakota 1,590 1,450 1,180 1,470 1,990 1,700 1,330 1,070 1,370 1,210 880 1,140 900 

South Dakota 940 960 700 825 940 920 720 715 640 505 435 550 535 

Kansas 260 300 265 200 180 280 250 335 193 215 171 300 152 

Minnesota 500 440 150 105 130 130 95 60 70 90 60 135 90 

Colorado 100 115 110 85 160 270 220 195 130 130 135 215 100 

Texas 34 44 31 88 47 75 60 108 35 59 41 145 54 

Nebraska 75 90 47 55 70 101 90 82 60 66 56 99 53 

Other States 68 79 53 60 51 77 75 68 60 91 95 125 100 

Total U.S. 

Thousand Acres 

3,567 3,478 2,536 2,888 3,568 3,553 2,840 2,633 2,580 2,344 1,873 2,709 1,984 

Table 4. Harvested USA Sunfl ower Acreage 1994-2006 

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Oilseed 2,943 2,829 1,934 2,212 2,897 2,695 2,116 2,060 1,815 1,874 1,424 2,032 1,587 

Nonoilseed 487 539 545 580 595 746 531 495 365 323 287 578 277 

Total 

Thousand Acres 

3,430 3,368 2,479 2,792 3,492 3,441 2,647 2,555 2,180 2,197 1,711 2,610 1,864 


7

8 

Table 5. U.S. Sunfl ower Production 1994-2006 

■ Figure 5. Average U.S. Sunfl ower Yield 1996-2005 

in Pounds Per Acre. 

Prices 

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Oilseed 

---------------------------------------------------- Million Pounds ---------------------------------------------------- 

4,223 3,398 2,844 2,986 4,486 3,498 2,910 2,804 2,070 2,260 1,763 3,178 1818 

Nonoilseed 612 611 716 691 787 844 635 615 420 406 286 841 295 

Total 4,835 4,009 3,560 3,677 5,273 4,342 3,545 3,419 2,490 2,666 2,049 4,018 2113 

Historically, sunfl ower depended heavily on the 

export market for either seed or oil. With the advent 

of NuSun and high oleic sunfl ower, the market has 

switched almost exclusively to a U.S. and Canadian 

market. Both of these oils are very stable and do not 

require hydrogenation as do competitive oils, such 

as traditional soybean and canola oils, when used in 

a frying application. Sunfl ower prices now are more 

determined by their relationship to corn oil prices. 

Large domestic users tend to buy in advance, thus 

prices are not directly affected by the Chicago soybean 

oil contract and are not as likely to be as volatile. 

More opportunities are available to presell a portion 

of the crop well before planting begins. This ensures 

a domestic user of a supply and allows a producer to 

“lock in” a price for a portion of his production. Storage 

of sunfl ower is necessary. The domestic market 

needs a 12-month supply of oil and crushers will need 

a steady supply of seed. Crushers likely will have to 

provide producers with storage premiums for delivery 

in the out-of-harvest months. Oilseed sunfl ower producers 

have the advantage of multiple market options: 

the hulling market, the crush market or the bird food 

market. Supply and demand drive prices in all three 

markets. These markets are very specifi c and unique, 

with different values associated with them. Farmers 

should have samples of their crop graded to determine 

quality and talk directly to buyers to fi nd out what 

they want in terms of seed specifi cations. 

Nonoilseed (confection) sunfl ower production is 

geared to the “in-shell” markets. Today’s confection 

hybrids produce a signifi cant level of large seeds. 

Growers often are paid on a percentage of large seed. 

Quality standards for confection sunfl ower are high 

and allow little tolerance for off-color and insect 

damage. Most confection sunfl ower is produced on 

a contract basis. The seasonal average price during 

the 1994/95 to 2002/03 period ranged from $5.89 to 

$12.30 per hundredweight for oilseed sunfl ower and 

from $11.90 to $15.20 per hundredweight for nonoilseed 

sunfl ower. During that period, the nonoilseed 

price exceeded the oilseed price by $3.85 per hundredweight 

on average.

Sunfl ower Marketing Strategy 

(George Flaskerud) 

Sunfl ower marketing strategies usually use the cash 

forward contract for locking in a price prior to harvest. 

Use of this contract may be appropriate on a portion 

of the sunfl ower crop, but so may the use of other marketing 

tools, such as hedging with futures or use of 

options (puts or calls). The best marketing alternative 

depends in part on the basis, which is the relationship 

between a cash and futures price. 

Since a sunfl ower futures market does not exist, relationships 

between the sunfl ower cash price and other 

closely related futures markets need to be considered. 

Using the futures market of a different commodity for 

hedging is cross-hedging, while the cash and futures 

price relationship is the cross-basis. Two futures 

contracts are examined: soybean oil futures, which 

are traded on the Chicago Board of Trade, and canola 

futures, which are traded on the Winnipeg Commodity 

Exchange. 

Historic prices were analyzed during 1997 through 

April 2004 to identify patterns and relationships 

useful for developing marketing strategies. Prices 

were standardized in U.S. dollars per hundredweight 

(US$/cwt). 

Correlations indicate that changes in NuSun prices 

(40 percent oil) at Enderlin, N. D., are the most closely 

correlated with canola futures (correlation = .91). Soybean 

oil futures were a distant, second-best correlation 

(.75). These correlations suggest that canola futures 

should provide the most risk reduction for cross-hedging 

cash sunfl ower prices. However, with the current 

situation for sunfl owers, soybean oil and canola need 

to be evaluated to determine which futures contract 

likely is to be the most profi table. 

Price quotations for canola futures are in Canadian 

dollars (C$) per metric ton. The price quotation for 

November canola was C$352 on August 25, 2003, 

and the exchange rate was 1.41 C$/US$. In U.S. 

dollars per hundredweight, this quotation would be 

US$11.32 (C$352 divided by 1.41 divided by 22.046 

= US$11.32). 

Seasonal patterns for Enderlin NuSun prices (Figure 

6) revealed a broad range of price behavior during individual 

marketing years (October-September). Highs 

occurred during August in 2000-01 and 2001-02, 

April in 1999-00, October in 1998-99 and November 

in 2002-03. The distribution of prices reveals that the 

pattern, on average, is to decline to lows in October 

and then increase to a peak in June before declining 

into the next marketing year. 

The range in the monthly average, excluding the low 

and the high, was only $.53 per cwt. The within-year 

variations were considerably greater. The average 

within-year range was $3.07. During 2000-01 and 

2001-02, when prices trended up, the average withinyear 

range was $3.98. During the other years, the 

average within-year range was $2.47. 

The tendency for the Enderlin NuSun cross-basis 

relative to canola futures (Figure 7) was to decline to a 

low in September and to remain nearly as low during 

October and November, and then to increase to a high 

in February-April before generally declining into the 

end of the marketing year. During three of the fi ve 

years, the cross-basis was near its low in October. The 

range of the cross-basis was the narrowest during September 

and the widest during May. During October, 

the average cross-basis per cwt ranged from -$1.64 to 

-$.16 and averaged -$.99. 

Relative to soybean oil futures, the Enderlin average 

cross-basis showed a pattern of marketing year lows 

per cwt in November (-$9.15), April (-$9.25) and September 

(-$9.16) and highs in February (-$8.08) and 

July (-$8.30). During October, the average cross-basis 

ranged from -$14.47 to -$6.59 and averaged -$8.95. 

■ Figure 6. Seasonal Behavior of NuSun Prices at 

Enderlin, ND. 


9

10 

■ Figure 7. NuSun Cross-Basis at Enderlin, ND 

Relative to Nearby WCE Canola Futures. 

Variability, as measured by the standard deviation, was 

greater for the cross-basis relative to soybean oil futures 

than for the cross-basis relative to canola futures. 

This suggests lower basis risk when cross-hedging 

with canola futures than with soybean oil futures. 

From this information, marketing strategies can be 

developed. The seasonal pattern for Enderlin NuSun 

prices suggests that preharvest sales should be considered 

when prices are above the fi ve-year average 

price. Prices declined into harvest during two of three 

years that prices were above the average early in the 

marketing year. 

Use of the cash forward contract or cross-hedge would 

be appropriate on that portion of the sunfl ower crop 

that can be safely produced, i.e., on 20 percent to 40 

percent of the crop. The cash forward contract would 

be preferred if it refl ects an average or better cross-basis 

relative to sunfl ower oil futures or canola futures. 

A greater portion of the crop could be sold on a cash 

forward contract if it includes an act-of-God clause. 

In addition to the cash forward contract or crosshedge, 

a call option could be purchased to preserve 

upside potential. In the case of the cross-hedge, the 

call option would be purchased in the same futures 

contract. In the case of the cash forward contract, the 

call option could be purchased in either the soybean 

oil futures or canola futures. The put option is an alternative 

to using a cash forward contract or cross-hedge 

in combination with a call option. 

For sunfl owers that are not cash forward contracted, 

storage is an alternative. On average, storage was profitable 

during the 1998-99 to 2002-03 marketing years. 

However, the most profi table period of storage varied 

considerably. The most profi table sell or store strategy 

was to sell the 1998 crop at harvest, store the 1999 

crop until January, store the 2000 and 2001 crops until 

August and store the 2002 crop for one month. Sell or 

store decisions are diffi cult and require frequent evaluation 

of fundamentals, cash prices, futures prices, 

basis and storage costs. 

Additional marketing alternatives are available but beyond 

the scope of this article. Further information can 

be found in NDSU Extension publication EC-1270, 

“Managing Sunfl ower Price Risk.”

Hybrid Selection and 

Production Practices 

Hybrid Selection 

(Jerry Miller) 

Selection of sunfl ower hybrids to plant is one of the 

most important decisions a producer must make 

each season (Figure 8). First, three classes of hybrids 

- NuSun oilseed, traditional oilseed and confection 

hybrids are available,. Second, variables such as yield, 

quality factors, maturity, dry down, standability, and 

pest and disease tolerance, should be considered. 

NuSun Sunfl ower 

NuSun oilseed sunfl ower hybrids will produce an oil 

quality with more than 55 percent oleic fatty acid. 

This oil is in wide demand by the frying food industry 

and potentially could be a bottled oil. Some hybrid 

seed companies are providing a grower guarantee that 

their hybrids will make the minimum oleic grade. 

Some processors of NuSun sunfl ower also are providing 

contracts for producing seed of this quality. A 

premium may be paid to producers for planting NuSun 

hybrids. 

Traditional Sunfl ower 

Traditional oilseed sunfl ower hybrids have a high 

linoleic and lower oleic fatty acid quality in contrast 

with the NuSun hybrids. Traditional hybrids have been 

grown for their multipurpose marketability, with large 

export demand and hulling for the kernel market being 

most important. 

Confection Sunfl ower 

Confection sunfl ower hybrids are used primarily for 

in-shell and hulled kernel markets. They are characterized 

by having large seed, with a distinctive color 

striping on the hull. New hybrids with very long, large 

seed are in demand for the export market. Producers 

must be careful to set their combine concave widths 

properly to avoid hull damage on these hybrids. Producers 

generally plant confection hybrids at a lower 

plant population and increase insect scouting and 

control to maintain high kernel quality. Contracts are 

available to producers interested in planting confection 

hybrids. 

Criteria for Hybrid Selection 

Growers should use several criteria in hybrid selection. 

First, they should take an inventory of available hybrids 

being marketed in their area. Seed yield potential 

is an important trait to consider when looking at an 

available hybrid list. Yield trial results from university 

experiment stations, National Sunfl ower Associationsponsored 

trials and commercial companies should 

identify a dozen or so consistently high yielding 

hybrids for a particular area. Results from strip tests or 

demonstration plots on or near growers’ farms should 

■ Figure 8. A hybrid seed production fi eld of 

sunfl ower. Female and male parents are planted in 

alternate strips across the fi eld. (Marcia P. McMullen) 

Hybrid Selection 

11

12 

be evaluated. Yield results from previous years on an 

individual’s farm and information from neighbors also 

are valuable. The best producing hybrids in a region 

may produce approximately 2,300 pounds per acre 

with good soil fertility and favorable soil moisture, or 

more than 3,000 pounds per acre in the most favorable 

growing conditions. 

Oil percentage should be another trait to consider in 

oilseed hybrid selection. Several environmental factors 

infl uence oil percentage, but the hybrid’s genetic 

potential for oil percentage also is important. Current 

hybrids have oil percentages ranging from 38 percent 

to more than 50 percent. Domestic oil processors have 

been paying a premium based on market price for 

more than 40 percent oil (at 10 percent moisture) and 

discounts for oil less than 40 percent. Current recommendations 

are to select a high-oil hybrid instead of a 

low-oil hybrid with the same yield potential, but don’t 

sacrifi ce yield in favor of oil content. 

Maturity and dry down are important characteristics to 

consider when deciding what hybrid to plant. Maturity 

is especially important if planting is delayed, being 

mindful of the average killing frost in your area. Yield, 

oil content and test weight often are reduced when a 

hybrid is damaged by frost before it is fully mature. 

An earlier hybrid likely will be drier at harvest than a 

later hybrid, thus reducing drying costs. Also, consider 

planting hybrids with different maturity dates as a production 

hedge to spread risk and workload at harvest. 

The most economical and effective means to control 

sunfl ower diseases and other pests is planting resistant 

or tolerant hybrids and considering a minimum 

of three to four years’ rotation between successive 

sunfl ower crops. Hybrids are available with resistance 

to rust, Verticillium wilt and certain races of downy 

mildew. New hybrids may be available with tolerance 

to Sclerotinia head and stalk disease. Growers should 

check with their local seed dealer or sunfl ower seed 

company representative to obtain this information. 

Stalk quality, another trait to consider, provides resistance 

to lodging, various diseases and other pests. Hybrids 

with good stalk quality are easier to harvest and 

yield losses generally are reduced, withstanding damages 

from pests and high winds. Uniform stalk height 

at maturity is another important trait to consider. 

Hybrid selection may include selecting a hybrid with 

resistance to certain herbicides not previously available. 

This nontransgenic resistance either was derived 

from the wild species of sunfl ower or from mutagenesis. 

Sunfl ower hybrids can be sprayed with herbicides 

that control various broadleaf and grassy weeds either 

by one chemical or by a tank-mix of two chemicals. 

This technology will allow broad-spectrum weed control 

in minimum-till or no-till sunfl ower production, 

as well as with traditional production. Growers should 

check with their local seed dealer or sunfl ower seed 

company representative to obtain information regarding 

availability of these hybrids. 

The last item to consider is to purchase hybrid seed 

from a reputable seed company and dealer with a good 

technical service record. This is particularly important 

if producers have any questions regarding production 

practices. Companies and seed dealers provide different 

services, policies and purchase incentives, including 

credit, delivery service and returns. 

Semidwarf Sunfl ower 

(Duane Berglund) 

Semidwarf sunfl ower is 25 percent to 35 percent shorter 

than normal height hybrid sunfl ower. Research results 

show seed yield and oil content of semidwarf and 

normal height sunfl ower are similar in some years but 

not always. In drought stress years, seed yield of semidwarf 

sunfl ower was signifi cantly less than normalheight 

hybrids. Most semidwarf sunfl ower have early 

maturity ratings, thus the potential for high yields is 

limited, compared with conventional-height sunfl ower. 

The semidwarf plant types appear to be less susceptible 

to lodging, which could be very important during 

years of optimum plant growth or where sunfl ower 

is grown under irrigation, in high-plant populations. 

Generally, the semidwarf sunfl ower can be planted 

in narrowly spaced rows or solid seeded. University 

research indicates root penetration and water use 

to a depth of 6 feet is similar for normal height and 

semidwarf sunfl ower. Beyond 6 feet, root penetration 

of the semidwarf may not be as great as that of taller 

plant types. Some sunfl ower breeders have observed 

that short-stature plants have demonstrated limitations 

in head size and ability of the plant to fi ll the center of 

the head. Also, slower seedling emergence has been 

reported for semidwarfs.

Sunfl ower Branching 


Sunfl ower branching is an undesirable trait in commercial 

sunfl ower production. It can be caused by the 

genetics of a hybrid, environmental infl uences and 

herbicide injury. 

Branching of various degrees can occur in sunfl ower, 

ranging from a single stem with a large single infl orescence 

in cultivated types to multiple branching 

from axils of most leaves on the main stem in the wild 

species. Branch length varies from a few centimeters 

to a distance longer than the main stem. Branching 

may be concentrated at the base or top of the stem or 

spread throughout the entire plant. Generally, heads 

on branches are smaller than heads on the main stem. 

Occasionally, some fi rst-order branches have a terminal 

head almost as large as the main head. In most 

wild species, the head on the main stem blooms fi rst, 

but generally is no larger than those on the branches. 

Studies on the genetics of top branching have shown 

that it is dominant over nonbranching and is controlled 

by a single gene. Sunfl ower literature reports that top 

branching in cultivated sunfl ower is controlled by a 

single dominant gene, but branching in wild species is 

controlled by duplicate dominant genes. 

Source: Sunfl ower Technology and Production, 

ASA monograph number 35. 

■ Figure 9. Soil Tests are the most reliable means 

for growers to determine fertilizer needs to obtain 

projected yield goals. (Dave Franzen) 


Seed Quality 


High quality, uniform seed with high germination, 

known hybrid varietal purity and freedom from weed 

seeds and disease should be selected to reduce production 

risks. The standard germination test provides an 

indication of performance under ideal conditions but 

is limited in its ability to estimate what will happen 

under stress. Accelerated aging is another method 

used to evaluate seed vigor. Any old or carry-over 

seed should have both types of tests conducted. Seed 

is sold on a bag weight basis or by seed count. Seed 

size designations are fairly uniform across companies. 

Most seed is treated with a fungicide and insecticide 

to protect the germinating seedling. Seed should be 

uniformly sized to allow precision in the planting 

operation. 

Soils 

(David Franzen) 

Sunfl ower is adapted to a variety of soil conditions, 

but grows best on well-drained, high water-holding 

capacity soils with a nearly neutral pH (pH 6.5-7.5). 

Production performance on high-stress soils, such as 

those affected by drought potential, salinity or wetness, 

is not exceptional but compares favorably with 

other commercial crops commonly grown. 

Soil Fertility 


Sunfl ower, like other green plants, requires at least 16 

elements for growth. Some of these, such as oxygen, 

hydrogen and carbon, are obtained from water and the 

air. The other nutrients are obtained from the soil. Nitrogen, 

phosphorus and sulfur are frequently defi cient 

in soils in any climatic zone. Potassium, calcium and 

magnesium are frequently defi cient in high-rainfall 

areas. Defi ciencies of iron, manganese, zinc, copper, 

molybdenum, boron and chlorine are uncommon but 

can appear in many climatic zones. 

A sunfl ower yield of 2,000 pounds per acre requires 

approximately the same amount of nitrogen, phosphorus 

and potassium as 40 bushels per acre of wheat. 

Hybrid Selection and Production Practices 

13

14 

The nutrient content of the soil, as determined by a 

soil test, is the only practical way to predict probability 

of a response to applied nutrients (Figure 9). A soil 

test will evaluate the available nutrients in the soil and 

classify the soil as very low (VL), low (L), medium 

(M), high (H) or very high (VH) in certain nutrients. 

A fi eld classifi ed as very low in a nutrient will give a 

yield response to applied fertilizer 80 percent to 100 

percent of the time. A yield response is not always 

obtained because soil moisture or some other environmental 

factor may become limiting. A fi eld classifi ed 

as low will respond to applied fertilizer 40 percent 

to 60 percent of the time, a medium testing fi eld will 

respond to added fertilizer 10 percent to 20 percent 

of the time and a high-testing fi eld will respond to 

applied fertilizer only occasionally. Fields testing very 

high will not respond because the reserve of nutrients 

in the soil is adequate for optimum plant growth and 

performance. 

Fertilizer Recommendations 


Soil tests have been developed to estimate sunfl ower’s 

potential response to fertilizer amendments. The most 

important factors in the fertilizer recommendations 

are the yield goal and the level of plant-available soil 

nutrients. In most climatic zones, predicting yield 

is impossible. Past yield records are a reasonable 

estimate of potential yield for the coming year. A yield 

goal for sunfl ower should be more optimistic than the 

average yield, and should approach the past maximum 

yield obtained by the grower on the same or a similar 

soil type. Nutrients not used by a crop in a dry growing 

season usually are not lost and can be used by the 

following crop. 

From an economic standpoint, having a yield goal that 

is somewhat high is much more benefi cial for a grower 

than having a goal that is too low. A low yield goal in 

a good growing season easily can mean lost income of 

$30 to $40 per acre. In contrast, a high yield goal in a 

dry growing season will result in a loss of only $1to 

$2 in additional interest on the cost of unused nutrients 

since most of the nutrients will be available to the 

subsequent crop. 

The amounts of nitrogen, phosphorus and potassium 

recommended for various sunfl ower yield goals and 

soil test levels are shown in Table 6. For yield goals 

not shown in the table, use the formulas at the base 

of the table. The data in this table are based on the 

amount of nitrate-nitrogen (NO 3 -N) in pounds per 

acre found in the top 2 feet of soil, the parts per million 

(ppm) of phosphorus (P) extracted from the top 

6 inches of soil by the 0.5N sodium bicarbonate, and 

the ppm of potassium (K) extracted by neutral normal 

ammonium acetate in the top 6 inches of soil 

Other nutrients are not usually defi cient for sunfl ower. 

On sandy slopes and hilltops, sulfur may be a problem; 

however, sulfur would not be expected to be defi - 

cient in higher organic matter, depressional soils. The 

sulfur soil test is a poor indicator of the probability of 

response to sulfur fertilizers. Sunfl ower has not been 

shown to be responsive to the application of other 

nutrients, including micronutrients in the state. 

Table 6. Nitrogen (N), phosphate (P 2 O 5 ) and 

potash (K 2 O) recommendations for sunfl ower in 

North Dakota. 

Yield 

Soil N 

plus 

fertilizer 

Soil Test Phosphorus, ppm 

VL L M H VH 

Goal N 

lb/acre- 

Bray-1 0-5 6-10 11-15 16-20 21+ 

lb/acre 2 ft. Olsen 0-3 4-7 8-11 12-15 16+ 

- - - - - - lb P2O5 /acre - - - - - - 

1,000 50 20 15 9 4 0 

1,500 75 31 22 14 5 0 

2,000 100 41 30 18 7 0 

2,500 125 51 37 23 9 0 

Nitrogen recommendation = 0.05 YG - STN - PCC 

(Bray-1) Phosphate recommendation = (0.0225-0.0011 STP)YG 

(Olsen) Phosphate recommendation = (0.0225-0.0014 STP)YG 

Yield 

Soil Test Potassium, ppm 

Goal 0-40 41-80 81-120 121-160 161+ 

lb/acre VL L M H VH 

1,000 36 25 14 3 0 

1,500 53 37 21 5 0 

2,000 71 50 28 6 0 

2,500 89 62 35 8 0 

(K, ammonium acetate extractant) Potash recommendation = 

(0.04100-0.00027 STK)YG 

YG = Yield Goal 

PCC = Previous Crop Credit 

STN is the amount of NO 3 -N in the top 2 feet of soil 

STP, STK = Soil Test P or K, respectively 

VL,L,M, H,VH = very low, low, medium, high and very high, 

respectively

Fertilizer Application 

(Dave Franzen) 

Germinating sunfl ower seed is similar to corn in its 

reaction to seed-placed fertilizer. Application of more 

than 10 pounds per acre of nitrogen (N) plus potash 

(K 2 O) in a 30-inch row will result in reduced stands 

or injured seedlings. Dry soil conditions can increase 

the severity of injury. In row widths narrower than 

30 inches, rates of N plus K 2 O can be proportionally 

higher. For improved fertilizer rate fl exibility, starter 

fertilizer should be placed in bands at least 2 to 3 

inches from the seed row. 

Producers have several good reasons to apply nitrogen 

in the fall, such as availability of labor, soil conditions, 

etc. However, the general principle with respect 

to nitrogen application is: The longer the time period 

between application and plant use, the greater the 

possibility for N loss. In other words, use judgment 

in making a decision on time of N application. In the 

case of sandy soils, fall application of N is not recommended. 

In many instances, a side-dress application of 

N when the sunfl ower plants are about 12 inches high 

may be preferable. 

Phosphate and potash may be fall or spring applied 

before a tillage operation. These nutrients are not 

readily leached from soil because they form only 

slightly soluble compounds or attach to the soil. The 

phosphate and potash recommendations in Table 6. 

are broadcast amounts. The recommendations for soil 

that tests very low and low in P and K can be reduced 

by one-third the amount in the table when applied in a 

band at seeding. In minimum or no-till systems, phosphate 

and potash may be applied in a deeper band to 

reduce the buildup of nutrients at the soil surface that 

occurs with these systems. However, most comparisons 

among deep, shallow and surface applications 

have shown little difference in crop response. 

Water Requirements for Sunfl ower 


Sunfl ower has deep roots and extracts water from 

depths not reached by most other crops; thus it is 

perceived to be a drought-tolerant crop. Sunfl ower has 

an effective root depth around 4 feet, but can remove 

water from below this depth. Research on side-by-side 

plots has shown that sunfl ower is capable of extracting 

more water than corn from an equal root zone volume. 

With its deep root system, it also can use nitrogen and 

other nutrients that leach below shallow-root crops; 

thus it is a good crop to have in a rotation. 

Seasonal water use by sunfl ower averages about 19 

inches under irrigated conditions. Under dryland 

conditions, sunfl ower will use whatever stored soil 

moisture and rain that it receives during the growing 

season. When access to water is not limited, small 

grains use 2 to 3 inches less total water than sunfl ower 

during the growing season, whereas soybean water use 

is slightly greater. Corn uses 1 to 4 inches, and sugar 

beets use 2 to 6 inches more than sunfl ower, respectively, 

during the growing season. 

These total water use values are typical for nondrought 

conditions in southeastern North Dakota. Small grains 

use the least total water since they have the fewest 

number of days from emergence to maturity. Sunfl ower 

and soybean have an intermediate number of days 

of active growth and corresponding relative water use. 

Corn ranks above sunfl ower in growth days and water 

use, while sugar beets rank highest in both categories. 

However, water use effi ciency does vary among these 

crops. Comparative water use effi ciency measured as 

grain (pounds per acre or lb/A) per inch of water used 

on three dryland sites and two years in eastern North 

Dakota was 119, 222, 307, 41, 218, 138, and 127 for 

sunfl ower, barley, grain corn, fl ax, pinto bean, soybean 

and wheat, respectively. These results indicated that 

corn had the highest water use effi ciency, sunfl ower 

and wheat were intermediate and fl ax the lowest. 

(Source: M. Ennen. 1979. Sunfl ower water use in 

eastern North Dakota, M.S. thesis, North Dakota State 

University). 

Fertility has little infl uence on total water use, but 

as fertility increases, water use effi ciency increases 

because yield increases. Yield performance has been 

shown to be a good indicator of water use effi ciency 

of sunfl ower hybrids; higher yielding hybrids exhibit 

the highest water use effi ciency. 


15

16 

Soil Water Management 

for Dryland Sunfl ower 


Management practices that promote infi ltration of 

water in the soil and limit evaporation from the soil 

generally will be benefi cial for sunfl ower production 

in terms of available soil moisture. Leaving stubble 

during the winter to catch snow and minimum tillage 

are examples. Good weed control also conserves 

moisture for the crop. The use of post-applied and preemergence 

herbicides with no soil incorporation also 

conserves moisture when growing sunfl ower. 

Sunfl ower has the ability to exploit a large rooting 

volume for soil water. Fields for sunfl ower production 

should be selected from those with the greater waterholding 

capacity and soils without layers that may 

restrict roots. Water-holding capacity depends mainly 

on soil texture and soil depth. The loam, silt loam, 

clay loam and silty clay loam textures have the highest 

water-holding capacities. Water-holding capacity of 

the soils in any fi eld can be obtained from county soil 

survey information available from local Natural Resources 

Conservation Service (NRCS) USDA offi ces. 

Sampling or probing for available soil moisture before 

planting also can help select fi elds for sunfl ower 

production. With other factors being equal, fi elds with 

the most stored soil moisture will have potential for 

higher yields. Where surface runoff can be reduced 

or snow entrapment increased by tillage or residue 

management, increases in stored soil moisture should 

occur and be benefi cial to a deep-rooted crop such as 

sunfl ower. 

Irrigation Management 

(Tom Scherer) 

Irrigation of sunfl ower by commercial growers is not 

common, but sunfl ower will respond to irrigation. 

Data collected by the USDA Farm Service Agency 

(FSA) for irrigated crops in North Dakota shows that 

an annual average of about 1,500 acres of sunfl ower 

are irrigated each year. Data for irrigated and dryland 

oil-type variety trials between 1975 and 1994 from the 

Carrington Research Extension Center show an aver- 

age yield differential of about 500 pounds per acre. 

However, some years the irrigated trials yielded more 

than 1,500 pounds per acre more than the dryland 

plots, and some years the dryland plots actually had 

greater yield than the irrigated plots. 

Irrigated sunfl ower seasonal water use averages about 

19 inches. With good water management, average 

water use will increase from about 0.03 inch per day 

soon after emergence to more than 0.27 inch per day 

from head emergence to full seed head development. 

However, during July and August, water use on a hot, 

windy day can exceed 0.32 inch. 

Research by Stegman and Lemert of NDSU has 

demonstrated the yield potential of sunfl ower grown 

under optimum moisture conditions and the effect of 

water stress at different growth stages. Sunfl ower yield 

is most sensitive to moisture stress during the fl owering 

period (R-2 to R-5.9 reproductive stages) and least 

sensitive during the vegetative period (emergence to 

early bud). A 20 percent reduction of irrigation water 

application from plant emergence to the R-2 stage 

resulted in only a 5 percent reduction in yield, but a 

20 percent reduction in irrigation water application 

during the R-2 to R-5.9 period resulted in a 50 percent 

yield reduction. 

If soil water content is near fi eld capacity at planting, 

research indicates that the fi rst irrigation could be 

delayed until the root zone soil moisture is about 70 

percent depleted. However, if pumping capacity is low 

(less than 800 gallons per minute, or gpm, for a 128acre 

center pivot), a lesser depletion is advisable due 

to inadequate “catch-up capacity.” Irrigations during 

the critical bud to ray-petal appearance (R-2 to R-5.0) 

period should be scheduled to maintain a low soil 

moisture stress condition (35 percent to 40 percent 

depletion). Irrigation should be avoided from R-5.1 

to R-5.9 because of the susceptibility of the sunfl ower 

plant to head rot from Sclerotinia (white mold). Irrigate 

just before fl owering in the bud stages R-3 to 

R-4. Soil moisture depletion again can approach 70 

percent during late seed fi ll and beyond with little or 

no depression in yield. 

Yield increases due to irrigation depend on several 

factors. Soil water-holding capacity and precipitation 

are two of the most important. Research indicates that 

the seed yield versus crop water use (ET) exhibits a 

linear relationship with a slope averaging 190 pounds 

per acre-inch. This means every additional inch of

water applied by irrigation will increase seed yield 

by about 190 pounds per acre. Remember that the 

research was performed on the loam and sandy-loam 

soils of Carrington and Oakes, N.D. A yield increase 

of 50 percent or more with irrigation may be expected 

almost every year on coarse-textured soils. However, a 

seed yield increase from irrigation may not always occur 

on soils with higher water-holding capacities and 

with adequate precipitation. Adequate soil fertility is 

very important in achieving the higher yield potential 

under irrigation. 

Management of applied irrigation water requires the 

combination of periodic soil moisture measurement 

with a method of irrigation scheduling. Soil moisture 

can be measured or estimated in a variety of ways. The 

simplest is the traditional “feel” method that is an art 

developed through time with extensive use and experience. 

For most irrigation water management applications, 

either the resistance block type of soil moisture 

measurement or tensiometers should be used. These 

are relatively inexpensive and require little labor to 

use effectively. 

The soil water balance method of irrigation scheduling, 

otherwise known as the checkbook method, is 

popular and well-documented. With this method, 

a continuous account is kept of the water stored in 

the soil. Soil water losses due to crop use and soil 

surface evaporation are estimated each day based on 

the maximum temperature and the days since crop 

emergence. Precipitation and irrigation are measured 

and added to the soil water account each day. Errors in 

estimating water use will accumulate through time, so 

periodically measuring the moisture in the soil profi le 

is necessary. Detailed instructions for using the checkbook 

method are published (North Dakota Extension 

publication AE-792). A computer program using this 

method also is available from the NDSU Agricultural 

and Biosystems Engineering Department. 

Another form of irrigation scheduling is to use estimated 

daily water use values for sunfl ower (Table 7). 

This method, sometimes called the “water use replacement 

method,” is based on obtaining daily estimates 

of sunfl ower water use and accurately measuring the 

amount of rain received on the fi eld. Irrigations are 

scheduled to replace the amount of soil moisture used 

by the sunfl ower minus the amount of rain received 

since the last irrigation. Estimates of daily sunfl ower 

water use can be obtained several ways. AE-792 has 

a table for sunfl ower water use throughout the season 

based on weeks’ past emergence and maximum daily 

air temperature. More accurate sunfl ower water use 

values, based on measured weather variables from 

the North Dakota Agricultural Weather Network 

(NDAWN), are available at the NDAWN Web site: 

http://ndawn.ndsu.nodak.edu/. Click on “Applications” 

on the left side of the home screen. Sunfl ower crop 

water use estimates can be obtained for the current 

growing season (between emergence and harvest) 

or for past growing seasons if you want to do some 

comparisons. 

Table 7. Average daily water use for sunfl ower in inches per day based on maximum daily air 

temperature and weeks past emergence. For example, during the eighth week after emergence, 

if the daily air temperature were 85 degrees on a particular day, sunfl ower water use for that 

day would be 0.25 inch. 

Maximum 

Daily Air 

Temperature 

Week After Emergence 

°F 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

50 to 59 0.01 0.03 0.05 0.06 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.07 0.06 0.04 0.03 

60 to 69 0.02 0.05 0.08 0.10 0.12 0.14 0.14 0.14 0.13 0.13 0.13 0.12 0.10 0.07 0.04 

70 to 79 0.03 0.07 0.11 0.15 0.17 0.19 0.19 0.19 0.19 0.18 0.17 0.16 0.13 0.10 0.06 

80 to 89 0.03 0.09 0.14 0.19 0.22 0.25 0.25 0.25 0.24 0.23 0.22 0.21 0.17 0.13 0.07 

Above 90 0.04 0.11 0.17 0.23 0.27 0.30 0.30 0.30 0.29 0.29 0.27 0.26 0.21 0.15 0.09 

Bud Ray Flower 100% Ray 

Anther Petal 

Drop 


17

18 

Tillage, Seedbed Preparation 

and Planting 

(Roger Ashley and Don Tanaka) 

Sunfl ower, like other crops, requires proper seedbed 

conditions for optimum plant establishment. Errors 

made at planting time may be compounded throughout 

the growing season. Seedbed preparation, soil tilth, 

planting date, planting depth, row width, seed distribution 

and plant population should be nearly correct as 

conditions permit. 

Tillage and Seedbed Preparation 

Tillage traditionally has been used to control weeds 

and incorporate herbicides in preparation for planting. 

When tillage is used in low rainfall areas, producers 

must take care to control weeds while leaving as much 

of the previous crop’s residue intact as possible. Tillage 

never should occur when soils are too wet. Soils 

that are tilled when too wet and then dry will crust, 

turn lumpy and generally provide for poor seedbed 

conditions for germination and establishment. 

Maintaining a moist seedbed is important if producers 

expect to have uniform germination and emergence 

across the fi eld (Figure 10). Poor germination 

and emergence will infl uence the need for and the 

effectiveness of future management practices. Excessive 

tillage should be avoided where tillage is used 

to prepare the seedbed or to incorporate preplant 

herbicides. Excessive tillage will break down soil 

structure, cause compaction and crusting problems, 

reduce aeration, restrict water movement and provide 

■ Figure 10. No-till one pass seeding systems 

preserve soil moisture and ground cover when water 

is limited. (Roger Ashley) 

conditions favorable for infection by downy mildew or 

other soil-borne diseases. Breakdown of soil structure 

also causes reduced nutrient and water uptake and 

reduces yield. 

Tillage and planting equipment is available to provide 

systems with varying levels of surface residue for 

sunfl ower production. Production systems can range 

from conventional-till, where the quantity of surface 

residue covers less than 30 percent of the soil surface, 

to no-till, where the quantity of surface residue covers 

more than 60 percent of the soil surface. 

Conventional-till Production Systems 

Conventional-till production systems usually involve 

two or more tillage operations for weed control, incorporation 

of pre-emergence herbicides and incorporation 

of the previous crops residues. Pre-emergence 

herbicides may be incorporated with a tandem disk, 

chisel or sweep plows, disk harrow, long-tine harrow, 

rolling harrow or air seeders with sweeps in different 

sequences or combinations. Tillage sequences are 

determined by herbicide label requirements by the 

quantity of crop residue present at the beginning of 

the tillage operation, and by the seedbed requirements 

needed to match planting equipment capabilities. 

Conventional tillage systems, with or without preemergence 

or post-emergence herbicide, may include 

the option of row cultivation once or twice during the 

early growing season before the sunfl ower reaches a 

height too tall for cultivation. A rotary hoe or harrow 

can be used just before sunfl ower emergence and/or at 

the V-4 to V-6 development stage. Harrowing or rotary 

hoeing between emergence and the V-4 stage can result 

in injury or death of the sunfl ower plant. Depending 

on planting depth and stage of crop development, 

stand losses are generally less than 5 percent if the 

sunfl ower crop has at least two fully expanded leaves. 

Proper adjustment of the harrow or rotary hoe will 

maximize damage to the weeds and minimize injury 

to the sunfl ower crop. 

Minimum-till Production Systems 

Minimum-till production systems use subsurface 

implements with wide sweeps, such as an undercutter 

(Figure 11), or harrow systems for application 

and incorporation of herbicides. These production 

systems leave between 30 percent and 60 percent of 

the soil surface covered by crop residue after planting. 

Minimum-tillage sunfl ower production systems rely

on a good long-term crop rotation to help control diffi 

cult weeds. These systems rely on two incorporations 

of granular herbicides, such as Trifl uralin 10G and 

Sonalan 10G. Herbicides can be applied in late fall 

(late October) or early spring (mid to late April) and 

incorporated with either an undercutter (at a soil depth 

of 2 inches) or a harrow system. A second incorporation 

just before or at sunfl ower planting is performed 

with an undercutter, harrow or air seeder with sweeps 

(Figure 12). The time between the application/fi rst 

incorporation and the second incorporation should 

be at least three weeks to increase the opportunity for 

precipitation to occur and rewet the treated soil layer. 

Rewetting the treated soil layer dissolves and activates 

the herbicide granules before the second incorporation. 

■ Figure 11. Undercutter sweep machine used to 

prepare seedbed, control small weeds and conserves 

soil moisture. (Al Black) 

■ Figure 12. Air-seeder with sweeps used for 

minimum till sunfl ower planting. (Roger Ashley) 

Air Drill Use 

Solid-seeded sunfl ower has become popular with 

producers in some regions. Air drills commonly are 

used to plant solid-seeded stands. Advantages listed by 

producers include 1) improved utilization of equipment 

already owned and 2) ease of changing between 

crops. 

Suggested adjustments to the air drill when planting 

sunfl ower include: 1) Use the proper metering roller; 

2) Slow the metering roller speed; 3) Calibrate the 

drill. Run through the calibration cycle10 times and 

then three additional times to check for consistently 

metered weights; 4) Recalibrate the drill every time 

variety or seed lot changes; 5) Reduce airfl ow. Provide 

the minimum amount of air to move seed and fertilizer 

to the opener so the seed is not damaged; 6) Don’t 

place all of your seed in the bin after the drill is calibrated. 

Place a couple of bags in the bin and run until 

the low seed light appears. Then place another bag in 

the hopper and run until the low seed light appears. 

Calculate the number of acres seeded. If you appear 

to be planting the correct seeding rate, place one more 

bag of seed in the hopper and run until the low seed 

light appears. If this seeding rate is correct, fi ll the 

seed bin and plant the rest of the fi eld. 

No-till Production Systems 

No-till is a production system without primary or 

secondary tillage prior to, during or after crop establishment. 

No-till systems rely heavily on diverse crop 

rotations and pre- and postemergence herbicides, and 

minimize soil disturbance to control weeds. Crop rotations 

should include cool-season grass and broadleaf 

crops, as well as warm-season grass and broadleaf 

crops. These production systems maintain at least 60 

percent surface covered by crop residue after planting. 

Crop residues protect soils from erosion, control 

weeds, suppress evaporation and improve soil water 

infi ltration. Pre- and postemergence herbicide choices 

provide producers options that were not available just 

a few years ago. Residual herbicides can be applied 

in a timely manner to get adequate precipitation for 

activation. Burn-down applications of glyphosate or 

paraquat are needed before or shortly after planting 

but before emergence of the crop to control emerged 

weeds and volunteer crop. Spartan (sulfentrazone), a 

residual broadleaf weed herbicide, may be tank-mixed 

with glyphosate to control broadleaf weeds for six to 

eight weeks. At the present time, postemergence herbi- 


19

20 

cides such as Poast (sethoxydim) and Clethodim provide 

excellent grassy weed control and Assert (imazamethabenz) 

will control wild mustard. Clearfi eld 

sunfl ower varieties were selected for tolerance of the 

herbicide Beyond (imazamox) and will allow postemergence 

control of both broadleaf and grassy weeds. 

However, ALS (acetolactate synthase)-resistant kochia 

is not controlled with this herbicide. For current information 

on registered sunfl ower herbicides, contact 

your county agent or weed control specialist. 

Planting sunfl ower in a no-till production system may 

require the addition of residue managers to move 

a minimum of crop residue from the seed row so 

double-disc openers can place seed properly for seed 

to soil contact. Poor placement will delay or prevent 

germination, emergence and establishment of the 

crop. This, in turn, may lead to weed, insect and harvest 

management problems. Single-disc openers and 

narrow-point hoe openers have been used successfully 

to seed sunfl ower. Minimizing soil disturbance is important. 

Soil disturbance can bury weed seed, placing 

them in a favorable position to survive, germinate and 

establish. Weed seed left on the soil surface is exposed 

to weather, insects, birds and fungi and rapidly will 

lose viability. Low-disturbance no-till production systems 

provide the best opportunity for adequate seed 

zone soil water at planting. 

No-till and One-pass Seeding 

When low-disturbance openers, such as the single-disc 

style, are used, seed should be placed at least 2 inches 

deep. In undisturbed silt loam soils, the dry/wet inter- 

face usually will be found about 1 inch below the soil 

surface. In coarse-textured soils, this interface will be 

deeper. Planting at or just below this dry/wet interface 

will result in poor and/or uneven germination, resulting 

in either germinating seed running out of water 

and dying before the plant has a chance to establish 

or seed lying in dry soil until adequate rainfall is 

received. 

One-pass seeding operations utilizing high-disturbance 

openers (sweeps, hoes and narrow points) can 

produce uneven stands under dry conditions. Seeding 

depth is more variable with these types of openers, 

compared with the single-disc style, and moisture 

conditions will be more variable. Long, dry periods 

at planting do occur in western North Dakota. Soils 

will dry below acceptable levels for germination to 

the depth of the disturbed soil in the seedbed. Uneven 

germination, emergence, plant stands and plants at 

different stages of maturity will occur unless adequate 

moisture is received shortly after planting to rewet the 

seedbed. 

Anhydrous ammonia (Figure 13) sometimes is applied 

in one-pass seeding operations with openers specifi - 

cally designed for ammonia application at the time of 

seeding. If moisture is suffi cient and application rates 

do not exceed 50 pounds, little damage to germinating 

seed will occur. However, if the seedbed is abnormally 

dry and/or the soil does not seal properly between the 

anhydrous ammonia band and the seed, damage to 

germinating seed will occur. 

More recently, no-till row planters with row cleaners 

ahead of double-disc openers are equipped with either 

■ Figure 13. This one-pass seeding operation is seeding directly into wheat stubble. 

Anhydrous ammonia and seed are banded through special openers. Glyphosate and 

sulfentrazone were applied three days prior to seeding. (Roger Ashley)

a liquid or dry fertilizer attachment. These attachments 

band nitrogen fertilizers separately from the 

seed band, eliminating injury to the germinating seed. 

Planting Dates 

Sunfl ower may be planted during a wide range of 

dates. In the northern Great Plains, planting may 

extend from May 1 until late June. Early maturing 

hybrids should be selected for late planting or replanting 

in northern areas. Planting may be as early as two 

weeks before the last killing frost and as late as 100 

days before the fi rst killing frost in the fall. 

Growing conditions during the season will affect yield, 

oil content and fatty acid composition. High temperatures 

during seed formation have been identifi ed as 

the main environmental factor affecting the ratio of 

linoleic and oleic acid content. Therefore, the optimum 

planting date will be dependent upon the variety 

and location, as well as weather conditions during 

the growing season. Variety genetics also affect oleic 

content, so select adapted varieties for your area. High 

yields may be obtained from very early planting dates, 

but yields may be reduced by increased pest problems. 

If sunfl ower is seeded early in narrow rows and weeds 

are controlled early with preplant and post-plant herbicide 

products, early canopy closure should control 

late-germinating weeds, eliminating the need for herbicides 

or cultivation later in the season. Also, early 

planting provides producers the opportunity to harvest 

high quality seed earlier with less cost required for 

postharvest handling. Late-June plantings often result 

in lower yields and oil content. In addition, when harvest 

is delayed by weather, mechanical drying of seed 

■ Figure 14. Solid seeded sunfl ower stand 

established using an air drill. (Roger Ashley) 

is required, thus adding to production expenses. The 

fatty acid profi le also is affected by planting date. In a 

three-year planting date study in southwestern North 

Dakota, oleic fatty acid content was greatest when 

the planting date occurred around May 23 and lowest 

when the planting date was later than June 10. 

Soil temperature at the 4-inch depth should be at a 

minimum of 45 F for planting. A temperature near 50 

F is required for germination. Periods of soil temperature 

below 50 F delay germination and extend the 

period of susceptibility to seedling diseases, such as 

downy mildew, and to herbicide injury. 

Row Spacing and Plant Population 

Sunfl ower will perform well in a wide range of plant 

populations and plant spacing. When adequate weed 

control exists, no yield differences have been detected 

between sunfl ower seeded in rows and solid seeded. 

Fields with a row spacing of less than 20 inches are 

considered to be solid seeded (Figure 14). In 2003, the 

National Sunfl ower Association fi eld survey found 70 

percent of the sunfl ower fi elds surveyed in southwestern 

North Dakota to have been solid seeded. Equidistant 

spacing of seeds should produce a uniform sunfl 

ower stand, which makes maximum use of resources, 

such as water, nutrients and sunlight. Seed spacing to 

achieve the desired plant population is listed in Table 

8. Table 8 assumes seed germination is 90 percent 

and a 10 percent stand reduction will occur between 

emergence and harvest. The seed spacing must be 

adjusted with lower or higher germination rates, and 

thus spacing between seed. 

Desired seed spacing may be calculated using the following 

formula: 

SS = (6,272,640/RS)/(PP/(GR x SR) 

Where: 

SS = in row seed spacing in inches 

RS = between row spacing in inches 

PP = desired plant population at harvest 

GR = germination rate as a decimal. For example, 

if germination is 95 percent, then germination 

rate = .95. 

SR = stand reduction as a decimal. This reduction 

is a result of other factors between germination 

and fi nal harvest population. For example, 

if a 10 percent reduction is expected, 

then 100 percent - 10 percent = 90 percent, 

or .9. 


21

22 

Sunfl ower plants will compensate for differences in 

plant population by adjusting seed and head size. As 

plant population decreases, seed and head size will 

increase. Oilseed hybrids generally are planted at 

higher populations than confection varieties, as the 

size of harvested seed is less important. Plant populations 

for oilseed sunfl ower should be between 15,000 

and 25,000 plants per acre, with adjustments made 

for soil type, rainfall potential and yield goal. Lower 

populations are recommended for soils with lower 

water-holding capacity and if normal rainfall is inconsistent 

or inadequate. Confection sunfl ower should 

be planted at populations between 14,000 and 20,000 

plants per acre. Preharvest dry down is more rapid in 

higher plant populations because of the smaller head 

size. However, higher plant populations may result in 

increased lodging and stalk breakage. Producers who 

solid seeded sunfl ower use seeding rates of 18,000 to 

23,000 plants per acre. 

Proper planting equipment adjustment and operation 

is one of the most important management tasks in 

sunfl ower production. Plateless and cyclo air planters 

have been used effectively to get good seed distribution. 

Double-seed drops should be avoided and planter 

adjustments should be made. Conventional plate 

planters will provide good seed distribution by using 

correct planter plates, properly sized seed and proper 

seed knockers. Commercial seed companies have plate 

recommendations for all seed sizes. Grain drills and 

air seeders may be used for seeding, although uniform 

depth of planting and seed spacing may be a problem 

unless proper adjustments and modifi cations are made. 

Postharvest Tillage 

After harvest, tillage of sunfl ower stalks is not 

recommended because snow-trapping potential is 

diminished, thereby reducing soil water conservation 

potential during the winter for the following crop. 

Also, because of the nature of sunfl ower residues, a 

late harvest followed by late fall tillage leaves the soil 

extremely susceptible to wind and water erosion. 

Table 8. Seed spacing required for various populations, assuming 

90 percent germination and 10 percent stand loss. 

Plants 

Row Spacing 

per acre 7.5 12 18 22 28 30 36 

- - - - - - - inches between seeds in the row - - - - - - - 

12,000 56.5 35.3 23.5 19.2 15.1 14.1 11.8 

14,000 48.4 30.2 20.2 16.5 13.0 12.1 10.1 

16,000 42.3 26.5 17.6 14.4 11.3 10.6 8.8 

17,000 39.8 24.9 16.6 13.6 10.7 10.0 8.3 

18,000 37.6 23.5 15.7 12.8 10.1 9.4 7.8 

19,000 35.7 22.3 14.9 12.2 9.6 8.9 7.4 

20,000 33.9 21.2 14.1 11.5 9.1 8.5 7.1 

21,000 32.3 20.2 13.4 11.0 8.6 8.1 6.7 

22,000 30.8 19.2 12.8 10.5 8.2 7.7 6.4 

23,000 29.5 18.4 12.3 10.0 7.9 7.4 6.1 

24,000 28.2 17.6 11.8 9.6 7.6 7.1 5.9 

25,000 

Feet per 

27.1 16.9 11.3 9.2 7.3 6.8 5.6 

1/1,000 acre 69.7 43.6 29 23.8 18.7 17.4 14.5 

Highlighted seed spacings provide nearly equal-distant spacing between plants for a given row 

spacing and plant population.

Crop Rotation 

(Greg Endres) 

Having a proper rotation sequence with all crops, 

including sunfl ower, is important. Research shows that 

sunfl ower seed yield is greater following most other 

crops than sunfl ower (Tables 9 and 10). 

Growers who do not rotate sunfl ower fi elds likely will 

be confronted with one or more of the following yieldreducing 

problems: 

1. Disease and disease-infested fi elds 

2. Increased insect risk 

3. Increasing populations of certain types of weeds 

4. Increased populations of volunteer sunfl ower 

5. Soil moisture depletion. 

6. Phytotoxicity or allelopathy of the sunfl ower 

residue to the sunfl ower crop 

Therefore, producers have many valid reasons for 

rotating sunfl ower fi elds. 

Table 9. Seed yield of sunfl ower based on 

previous crop, Crookston, Minn., 1972-78. 

Previous 

Seed yield/acre (pounds) 

4-yr. 

crop 1973 1975 1977 1978 ave. 

Sunfl ower 852 1,338 1,852 1,781 1,456 

Potato 908 1,279 2,348 1,605 1,535 

Sugar beet 770 1,683 2,358 2,168 1,745 

Pinto bean 946 1,410 2,282 1,674 1,578 

Wheat 1,284 1,549 2,339 1,655 1,706 

LSD .05 240 121 292 132 

Table 10. Seed yield of various crops following 

sunfl ower, Mandan, N.D., 1999-2000. 

Previous crop Seed yield 

Sunfl ower 870 lbs/A 

Canola 1,200 lbs/A 

Flax 22.5 bu/A 

Soybean 35.2 bu/A 

Field pea 41.7 bu/A 

HRS wheat 49.2 bu/A 

Barley 70.0 bu/A 

Risks of sunfl ower disease will be greatly magnifi ed 

by short sequencing of sunfl ower in a crop rotation. 

Sclerotinia or white mold (wilt, stem rot and head rot) 

is the primary disease concern with a poor sunfl ower 

rotation. Other disease concerns with improper rotations 

include Verticillium wilt, Phoma and premature 

ripening. Rotations of at least three- or four-year 

spacings between sunfl ower or other Sclerotiniasusceptible 

crops (e.g., canola, dry bean, soybean) 

are recommended to help reduce disease risk. The 

sunfl ower disease section in this publication contains 

specifi cs on the characteristics and methods of control 

for each disease. 

Crop rotation may help reduce but will not prevent 

insect problems in sunfl ower. Proper rotations help 

reduce populations of insects that overwinter in the 

soil or sunfl ower plant residue. Crop rotation will not 

reduce damage from insects that migrate into an area 

from other geographic regions or from fi elds planted 

to sunfl ower the previous year that are in proximity 

to current-season fi elds. Rotations recommended 

for reducing sunfl ower disease risks also will reduce 

insect risks. 

Rotation of other crops with sunfl ower can reduce 

the buildup of many weed species. Also, proper crop 

rotation increases weed management options, including 

cultural, mechanical and chemical weed control. 

Consult records of previous fi eld management to 

determine if long-residual herbicides that would 

adversely affect sunfl ower production were used. 

Volunteer sunfl ower also can become a serious weed 

problem in repeat sunfl ower and other crops. For additional 

details. refer to the weed management section 

of this publication, herbicide labels and NDSU Extension 

Service publication W-253, “North Dakota Weed 

Control Guide.” 

Different patterns of soil moisture utilization are important 

considerations when planning sunfl ower rotations. 

Sunfl ower is a deep-rooted and full-season crop. 

Sunfl ower has intermediate water use requirements, 

compared with other crops (see water requirements 

section in this publication). Sunfl ower is relatively 

tolerant to effects of short water-stress periods, espe- 


23

24 

cially if the moisture stress occurs before the crop is in 

the reproductive stages. In limited-moisture growing 

seasons, sunfl ower following a shallower rooted and 

short-season crop (e.g., small grain, canola, fl ax) will 

allow the sunfl ower to extract residual water from a 

greater depth in the soil profi le. 

Continuous cropping of crops such as corn, wheat and 

soybeans results in yields that are depressed below 

the level obtained when a crop is rotated with other 

crops. The same effect is observed with sunfl ower, 

even when variable factors such as fertility, disease, 

insects and moisture are well-managed. This response 

with continuous cropping is known as allelopathy. 

Toxic materials in the sunfl ower residue, development 

of antibodies and the increase of soil-borne disease 

organisms all have been suggested as causes for 

allelopathy in sunfl ower. This effect has been demonstrated 

repeatedly and emphasizes a need to rotate 

sunfl ower. 

Suggested sunfl ower rotations for North Dakota 

will vary somewhat by geographic region, primarily 

because of different precipitation zones. For practical 

purposes, the state can be divided into east and west 

regions. Suggested rotations for these regions are 

listed in Table 11. Rotations may be varied by substituting 

other crops in the rotation, but the time spacing 

of the sunfl ower crop should be observed strictly or 

increased. See NDSU Extension Service publication 

EB-48, “Crop Rotations for Increased Productivity,” 

for additional details on crop rotation. 

Table 11. Sunfl ower rotation examples for North Dakota. 

Year West East 

Pollination 

(Gary Brewer) 

1 Sunfl ower Sunfl ower Sunfl ower Sunfl ower 

2 Small grain Pulse crop* Soybean* Small grain 

3 Pulse crop* Small grain Small grain Soybean * 

4 Flax or small grain Corn 

*medium susceptibility to Sclerotinia. 

Native sunfl ower and the early varieties of sunfl ower 

were self-incompatible and required insect pollination 

for economic seed set and yields. However, because 

numbers of pollinators were often too low to ensure 

adequate seed set, current hybrids have been selected 

for and possess high levels of self-compatibility. 

Although self-compatible sunfl ower hybrids usually 

outproduce self-incompatible cultivars, modern 

hybrids benefi t from insect pollination. 

The agronomic value of insect pollinating activities to 

current hybrids varies among hybrids, fi elds and years. 

Controlled studies indicate that in most sunfl ower 

hybrids, seed set, seed oil percentage, seed yields and 

oil yields increase when pollinators (primarily bees) 

are present. Literature reports indicate that yield could 

increase as much as 48.8 percent and oil percentage 

could increase 6.4 percent in bee-exposed hybrids. 

However, despite the increases in yield and oil concentration 

that occur, the benefi t of insect pollination 

of sunfl ower often is overlooked (Figure 15). 

Seed companies and growers who produce F1 hybrid 

seed for planting must use bees to transfer pollen from 

the male parent to the female parent. Although native 

wild bees are often better pollinators of sunfl ower 

than honey bees, the honey bee is the only managed 

pollinator of sunfl ower available. However, if pollen 

sources other than sunfl ower are nearby, the honey bee

■ Figure 15. Bees and hives are occasionally placed 

in sunfl ower fi elds to boost the native population to 

assure a better seed set. (Reid Bevis) 

will forage sunfl ower primarily for nectar and will not 

transfer sunfl ower pollen effi ciently. 

Honey bee colonies are placed in seed production 

fi elds at a rate of one hive per one to two acres. A bee 

density of more than 20 bees per 100 heads in bloom 

is needed to transfer suffi cient pollen from the male 

line to the female sterile line. Placement of honey bee 

colonies will depend upon proximity and acreage of 

competing nectar and pollen sources. With no competition, 

all honey bee colonies are placed at one end 

of the target fi eld. With competing nectar and pollen 

sources, placement of honey bee colonies at 800-foot 

intervals may be necessary. 

Sunfl ower genotypes vary in their attractiveness to the 

honey bee. Honey bees prefer short corolla length, 

unpigmented stigmas, many stomata on the nectary 

and high sucrose content of the nectar. Glandular 

trichomes on the anthers and ultraviolet refl ecting and 

adsorbing pigments also may be important in honey 

bee preference. Although some crops, such as oilseed 

rape, have been selected for honey bee preference, this 

has not been done with sunfl ower. 

Maximum seed yields often require the use of 

insecticides to protect the crop from insect competitors. 

Unfortunately, many of the major insect pests of 

sunfl ower attack the crop when it is fl owering. Thus, 

insecticides used to control the pest also harm pollinating 

bees. If pollinator activity is decreased, yield 

and oil percentage may decline. The hazards to honey 

bees can be minimized with adequate communication 

and cooperation among beekeepers, growers and pesticide 

applicators. Beekeepers must inform applicators 

of the location of apiaries and be prepared to move or 

protect colonies. When insecticide spraying is justifi 

ed, applicators must make every attempt to notify 

beekeepers in advance. 


25

26 

Pest Management 

(Janet Knodel and Larry Charlet) 

Integrated Pest Management 

Sunfl ower can be a high-risk crop because of potential 

losses from diseases, insects, birds and weeds. These 

potential risks require that growers follow integrated 

pest management (IPM) practices. IPM is a sustainable 

approach to managing pests by combining 

biological, cultural, physical and chemical tools in a 

way that minimizes economic, health and environmental 

risks to maintain pest populations below levels 

that cause unacceptable losses to crop quality or yield. 

The concept of pest management is based on the fact 

that many factors interact to infl uence the abundance 

of a pest. Control methods vary in effectiveness, but 

integration of these various population-regulating 

factors can minimize the number of pests in sunfl ower 

and reduce the cost of managing pest populations 

without unnecessary crop losses. IPM also recommends 

the judicious use of chemical pesticides when 

needed and suggests ways to maximize effectiveness 

and minimize impact on nontarget organisms and the 

environment. 

Economic Injury Level 

and Economic Threshold Levels 

One major component of a pest management program 

is determining when tactics should be implemented 

to prevent economic loss. Economic loss results when 

pest numbers increase to a point where they cause 

crop losses that are greater than or equal to the cost of 

controlling the pest. An economic injury level (EIL) is 

defi ned as the level of pests that will cause economic 

damage. An EIL recognizes that treatment is justifi ed 

for some pest population levels while others are not of 

economic importance. 

An economic threshold level (ETL) is the level or 

number of pests at which tactics must be applied to 

prevent an increasing pest population from causing 

economic losses. Usually the ETL is lower than the 

EIL. The ETL has been defi ned most extensively for 

insect pests; fewer ETLs have been established for 

other types of pests. The ETL varies signifi cantly 

among different pests and also can vary during different 

developmental stages of the crop. Crop price, yield 

potential, crop density, cost of control and environmental 

conditions infl uence the ETL and EIL. Generally, 

the ETL increases as cost of control increases and 

decreases as the crop value increases. 

Monitoring Pest Population Levels 

In general, fi elds should be evaluated regularly to determine 

pest population levels. A weekly fi eld check is 

usually suffi cient, but fi eld checks should be increased 

to two or three times a week if the number of pests is 

increasing rapidly or if the number is approaching an 

economic threshold level. Pests should be identifi ed 

accurately because economic threshold levels and con-

trol measures vary for different organisms. In addition, 

when insects pests are monitored, many insects are 

benefi cial and may help reduce numbers of injurious 

insects; recognizing which are pests and those that are 

benefi cial is important. 

Tools of Pest Management 

Tools of pest management include many tactics, of 

which pesticides are only one. These tactics can be 

combined to create conditions that are the least conducive 

for pest survival. Chemical or biological pesticides 

are used when pests exceed economic threshold 

levels; sometimes they are necessary when control is 

needed quickly to prevent economic losses. 

Some of the tools or components of pest management 

that can be used to reduce pest populations are: 

Biological Controls 

Benefi cial insects 

Benefi cial pathogens 

Host Resistance 

Cultural Controls 

Planting and harvest dates 

Crop rotation 

Tillage practices 

Mechanical/Physical Controls 

Temperature 

Weather events 

Trapping 

Chemical Controls 

Pesticides 

Attractants 

Repellents 

Pheromones 

Summary 

Growers should examine their operations and 

minimize pest damage by adopting integrated pest 

management practices based on the use of economic 

threshold levels, when available, plus carefully 

monitoring and combining various control methods. 

Signifi cant progress with sunfl ower pest management 

has been made and undoubtedly will continue to be 

made in the future to aid successful sunfl ower production. 

The following sections provide current information 

on management of insects, diseases, weeds, birds 

and other sunfl ower pests. A growing season calendar 

shows the major sunfl ower pest problems and time of 

occurrence in the northern Great Plains production 

area (Figure 16). 

■ Figure 16. A growing season calendar indicating 

time of occurrence of major sunfl ower pests. 

(J. Knodel) 

Pest Management 

27

28 

Quick Reference Guide to Major Sunfl ower Insects 

The information presented on this page is designed to be a quick reference for growers, crop consultants, fi eld scouts and 

others. Since this information is very brief, the user should refer to the following pages for more detailed data on life cycles, 

damage, descriptions, etc. 

Insects Description Occurrence, Injury and Economic Threshold (ET) 

Cutworms Dirty gray to gray brown. ET – 1 per square foot or 25 percent to 30 percent stand 

(several species) Grublike larva, 0.25 to 1.5 inches in length. reduction. Appear in early spring when plants are in the 

seedling stage, chewing them at or slightly above ground. 

Palestriped Adult: 1/8 inch long and shiny black, with two white ET – 20 percent of the seedling stand is injured and at risk 

Flea Beetle stripes on the back. The hind legs are enlarged and to loss due to palestriped fl ea beetle feeding. Scout for 

modifi ed for jumping. fl ea beetles by visually estimating population on seedlings 

or using yellow sticky cards placed close to the ground. 

Sunfl ower Beetle Adult: reddish-brown head, cream back with three ET – 1 to 2/seedling (adults), or 10 to 15/seedling 

dark stripes on each wing cover. Body 0.25 to 0.5 (larvae). Adults appear in early June, larvae shortly 

inch long. Larva: yellowish green, humpbacked in thereafter. Both adults and larvae chew large holes 

appearance, 0.35 inch in length. in leaves. 

Sunfl ower Adult: wingspread 0.63 to 0.75 inch, gray brown ET – none. First generation adults appear in late May to 

Bud Moth with two dark transverse bands on forewings. mid-June. Second generation adults appear in midsummer. 

Larva: Cream-colored body (0.33 to 0.4 inch) with Larvae from fi rst generation damage terminals and stalks, 

a brown head. whereas second generation larvae feed in receptacle area. 

Longhorned Adult: pale gray and 5/8 inch (6 to 11 mm) in No scouting method or ET has been developed. Adults are 

Beetle (Dectes) length, with long gray and black banded antennae. present from late June through August. Larvae tunnel and 

Larvae: yellowish with fl eshy protuberances on the feed in the petioles and stem pith and girdle the base of 

fi rst seven abdominal segments (1/3 to 1/2 inch) plants. Stalks often break at the point of larval girdling. 

Sunfl ower Stem Adult: small (0.19 inch long) weevil with a ET – 1 adult/3 plants in late June to early July. Adults 

Weevil gray-brown background and white dots on the back. appear in mid to late June, with larvae in stalks from 

early July to late summer. 

Thistle Caterpillar Adult: wingspread of 2 inches, upper wing surface brown ET – 25 percent defoliation, provided that most of the 

(Painted Lady with red and orange mottling and white and black spots. larvae still are less than 1.25 inches in length. Adults 

Butterfl y) Larva: brown to black, spiny, with a pale yellow stripe appear in early to mid-June, with larvae appearing 

on each side, 1.25 to 1.5 inches in length. shortly thereafter. Larvae chew holes in leaves. 

Sunfl ower Midge Adult: small (0.07 inch), tan, gnatlike insect. ET – none. Adult emergence begins in early July. Larvae 

Larva: cream or yellowish, 0.09 inch long, tapered at feed around head margin and at the base of the seeds, 

front and rear. causing shrinkage and distortion of heads. 

Sunfl ower Seed Adults: the red sunfl ower seed weevil is about 0.12 ET – generally 8 to 14 adult red sunfl ower weevils per head 

Weevils inch long and rusty in color. The gray sunfl ower seed (oil) and one per head (confectionery). Adults appear in 

weevil is about 0.14 inch long and gray in color. late June to early July. Treat for red sunfl ower seed weevil 

Larvae: both species are cream-colored, legless and at R5.1 to R5.4. Larvae feed in seeds from mid to late 

C-shaped. summer. 

Sunfl ower Moth Adult: body is 0.38 inch long, with 0.75 inch ET – 1 to 2 adults/5 plants at onset of bloom. Adults are 

wingspread. Color is buff to gray. Larva: brown head migratory and usually appear in early to mid-July. Larvae 

capsule with alternate dark and light lines running 

longitudinally, 0.75 inch in length. 

tunnel in seeds from late July to late August. 

Banded Sunfl ower Adult: small 0.25-inch straw-colored moth with brown ET – See banded sunfl ower moth section for egg or adult 

Moth triangular area on forewing. Larva: in early growth sampling methods for determining ET. Sampling should be 

stage, off-white, changing to red and then green color conducted in the late bud stage (R-3), usually during midat 

maturity, 0.44 inch in length. July. Adults appear about mid-July to mid-August. Larvae 

present in heads from mid-July to mid-September. 

Lygus Bug Adult: small (0.2 inch in length), cryptically colored ET - for CONFECTION SUNFLOWERS ONLY – 

insects with a distinctive yellow triangle or “V” on 1 Lygus bug per 9 heads. Two insecticide sprays are 

the wings and vary in color from pale green to dark recommended: one application at the onset of pollen shed 

brown. Nymph (immature stages): usually green and or 10 percent bloom, followed by a second treatment 

similar in appearance to the adults, but lack wings. 7 days later. 

Sunfl ower Adult: metallic, black, 0.25-inch long body with a long ET – none. Adults appear in mid to late July and create 

Headclipping “snout.” Larvae: 0.25 inch in length. feeding punctures around stalk just below the heads. 

Weevil Heads drop off. 

NOTE: The insects discussed above are listed in the order that they likely are to occur throughout the growing season; however, the various insects 

may or may not appear, depending upon overwintering survival and environmental conditions as the season progresses. The table is intended 

simply as a guide to when fi elds should be checked for possible presence of the various insects known to infest sunfl owers.

Insects 

(Janet Knodel and Larry Charlet) 

Sunfl ower plays host to a number of insect pests. In 

the major sunfl ower producing areas of the Dakotas, 

Minnesota and Manitoba, approximately 16 species of 

sunfl ower insects can cause plant injury and economic 

loss, depending on the severity of infestation. However, 

during any one growing season, only a few species 

will be numerous enough to warrant control measures. 

The sunfl ower insects of major importance in the 

northern Great Plains have been sunfl ower midge, 

Contarinia schulzi Gagne'; sunfl ower beetle, Zygogramma 

exclamationis (Fabricius); sunfl ower stem 

weevil, Cylindrocopturus adspersus (LeConte); red 

sunfl ower seed weevil, Smicronyx fulvus LeConte; and 

the banded sunfl ower moth, Cochylis hospes Walsingham. 

Recently, Lygus bugs have been an economic 

problem for the confection and hulling sunfl ower seed 

market. Populations of the long-horned sunfl ower stem 

girdler, Dectes texanus LeConte, have been increasing 

in North and South Dakota. 

Infestation of sunfl ower insects must be monitored 

regularly, usually weekly, to determine the species 

present and if populations are at economic threshold 

levels. Furthermore, proper timing of insecticidal 

treatment is essential to maximize control. 

The following sections provide information on the 

identifi cation, life cycle, damage, scouting methods, 

economic threshold levels and management of some 

of the most common insect pests of sunfl ower in the 

northern Great Plains. A preliminary quick reference 

guide to sunfl ower insects is available. 

Sunfl ower pests are not distributed evenly throughout 

a fi eld, and fi elds should be checked in several locations. 

Some insect pests, such as banded sunfl ower 

moth, are concentrated in areas of a fi eld or are more 

abundant near the edge of a fi eld than in the middle. 

Determining the extent of a pest population on the 

basis of what is found in only one or two small areas 

of a fi eld is impossible. At least fi ve sites per 40-acre 

fi eld should be monitored to collect good information 

on the nature and extent of a pest infestation. 

Sampling sites should be at least 75 feet in from the 

fi eld margin to determine whether an entire fi eld or a 

portion of the fi eld requires treatment. When infestations 

occur primarily along fi eld margins, delineating 

those and treating as little of the fi eld as needed to 

provide economic control may be possible. In most 

cases, 20 plants per sampling site should be examined 

in the Z or X pattern as shown (Figure 17). 

Crop consultants who are trained in pest management 

scouting may be hired. Consultants should be able to 

identify pest and benefi cial insects and provide information 

about pest management. 

■ Figure 17. The X and Z scouting patterns. 

Insects 

29

30 

■ Wireworms 

Species: various 

Description: Wireworm larvae (Figure 18) are hard, 

smooth, slender, wirelike worms varying from 1.5 to 2 

inches (38 to 50 mm) in length when mature. They are 

a yellowish white to a coppery color with three pairs 

of small, thin legs behind the head. The last body segment 

is forked or notched. 

Adult wireworms (Figure 19) are bullet-shaped, hardshelled 

beetles that are brown to black and about ½ 

inch (13 mm) long. The common name “click beetle” 

is derived from the clicking sound that the insect 

makes when attempting to right itself after landing on 

its back. 

■ Figure 18. Wireworm larvae. (Mark Boetel) 

■ Figure 19. Click beetle or adult wireworm. 

(Roger Key, http://www.insectimages.org) 

Life Cycles: Wireworms usually take three to four 

years to develop from the egg to an adult beetle. Most 

of this time is spent as a larva. Generations overlap, so 

larvae of all ages may be in the soil at the same time. 

Wireworm larvae and adults overwinter at least 9 to 

24 inches (23 to 61 cm) deep in the soil. When soil 

temperatures reach 50 to 55 F (10 to 13 C) during the 

spring, larvae and adults move nearer the soil surface. 

Adult females emerge from the soil, attract males 

to mate, then burrow back into the soil to lay eggs. 

Females can re-emerge and move to other sites, where 

they burrow in and lay more eggs. This behavior 

results in spotty infestations throughout a fi eld. Some 

wireworms prefer loose, light and well-drained soils; 

others prefer low spots in fi elds where higher moisture 

and heavier clay soils are present. 

Larvae move up and down in the soil profi le in 

response to temperature and moisture. After soil 

temperatures warm to 50 F (10 C), larvae feed within 

6 inches (15 cm) of the soil surface. When soil temperatures 

become too hot (>80 F, 27 C) or dry, larvae 

will move deeper into the soil to seek more favorable 

conditions. Wireworms infl ict most of their damage in 

the early spring, when they are near the soil surface. 

During the summer months, the larvae move deeper 

into the soil. Later as soils cool, larvae may resume 

feeding nearer the surface, but the amount of injury 

varies with the crop. 

Wireworms pupate and the adult stage is spent within 

cells in the soil during the summer or fall of their fi nal 

year. The adults remain in the soil until the following 

spring. 

Damage: Wireworm infestations are more likely to 

develop where grasses, including grain crops, are 

growing. Wireworms damage crops by feeding on the 

germinating seed or the young seedling. Damaged 

plants soon wilt and die, resulting in thin stands. In a 

heavy infestation, bare spots may appear in the fi eld 

and reseeding is necessary. 

Scouting Method: Decisions to use insecticides for 

wireworm management must be made prior to planting. 

No rescue treatments are available for controlling 

wireworms after planting. Producers have no easy

way to determine the severity of infestation without 

sampling the soil. Infestations vary from year to year. 

Considerable variation may occur both within and 

between fi elds. 

Sometimes the past history of a fi eld is a good indicator, 

especially if wireworms have been a problem in 

previous seasons. Also, crop rotation may impact 

population levels. 

Two sampling procedures are available. One procedure 

relies on the use of a corn-wheat seed mixture used as 

bait, placed in the soil, which attracts the wireworms 

to the site (Figure 20). The other involves digging and 

sifting a soil sample for the presence of wireworms. 

Economic Threshold: If the average density is greater 

than one wireworm per bait station, the risk of crop 

injury is high and a soil insecticide should be used 

at planting to protect the sunfl ower. If no wireworms 

are found in the traps, risk of injury is low; however, 

wireworms still may be present but were not detected 

by the traps. When digging soil samples, 12 or more 

wireworms in 50 3-inch by 3-inch (8 cm by 8 cm) 

samples, is likely to result in damage to sunfl ower. 

Management: Seeds should be treated with an approved 

insecticide for protection of germinating seeds 

and seedlings. 

■ Figure 20. Wireworm bait station. (Extension 

Entomology) 

■ Seedcorn Maggot 

Species: Delia platura (Meigan) 

Description: Seedcorn maggots are larvae of small 

fl ies resembling housefl ies. The adult is a light gray 

fl y about 0.2 inch (5 mm) long. Larvae are white, 

cylindrical, tapered anteriorly and also about 0.2 inch 

(5 mm) long (Figure 21). Larvae can be found inside 

damaged seeds or in the soil nearby. 

Life Cycle: After soil temperatures reach 50 F (10 C) 

in the spring, the fl ies emerge, mate and then deposit 

eggs in soil, especially where high organic matter 

exists. Eggs hatch in a few days and the maggots burrow 

into seeds. Infected seeds often do not emerge, 

resulting in stand loss. Even when infested seeds do 

germinate, plants may be weakened. No effective preplant 

monitoring techniques are available for seedcorn 

maggots. Fields with extensive decaying organic matter, 

such as those that are heavily manured or where 

a cover crop has been turned under, are particularly 

attractive to egg-laying fl ies. 

Damage: The fi rst sign of seedcorn maggot damage is 

areas in the fi eld where seedlings have not emerged. 

Seedcorn maggots hollow out seeds or eat portions of 

seedlings. Damage is most common in early plantings 

while the soil is cool, and if organic matter is high, 

such as when a green plant material is plowed into a 

fi eld before planting. Females are strongly attracted to 

decaying organic matter for laying eggs. 

Scouting Method: Scouting to determine the risk of 

seedcorn maggot infestation has not been developed. 

■ Figure 21. Seed corn maggot larvae. (Ric Bessin, 

University of Kentucky) 

Insects 

31

32 

■ Cutworms 

Species: 

Darksided cutworm Euxoa messoria (Harris) 

Redbacked cutworm Euxoa ochrogaster (Guenee) 

Dingy cutworm Feltia jaculifera (Walker) 

Description: Darksided cutworm — Forewings 

of the adult darksided cutworm are usually light, 

powdery and grayish brown with indistinct markings 

(Figure 22). The larvae are pale brown dorsally and 

white on the ventral areas (Figure 23 ). Sides have numerous 

indistinct stripes. At maturity, they are about 

1.25 to 1.5 inches (32 to 38 mm) long and 0.19 inch (5 

mm) wide. 

Redbacked cutworm — The forewings of the adult 

redbacked cutworm are reddish brown with characteristic 

bean-shaped markings (Figure 24). The larvae are 

dull gray to brown with soft, fl eshy bodies and may be 

1 to 1.25 inches (25 to 32 mm) long when fully grown 

(Figure 25). Larvae can be distinguished by two dull 

reddish stripes along the back. 

Dingy cutworm — Forewings are dark brown with 

bean-shaped markings as in the redbacked cutworm 

adults (Figure 26). Hind wings in the male are whitish 

with a broad, dark border on the outer margin; in the 

female they are uniform dark gray. The larvae have 

a dull, dingy, brown body mottled with cream color. 

The dorsal area is pale with traces of oblique shading 

(Figure 27). 

Life Cycles: The female darksided and redbacked cutworm 

moths deposit eggs in the soil in late July and 

early August. The eggs remain dormant until the onset 

of warm weather the following spring. The larvae of 

both species emerge from late May to early June. They 

continue to feed and grow until about the end of June, 

when fully grown larvae pupate in earthen cells near 

the soil surface. The pupal period lasts about three 

weeks. Both species have one generation per year. 

The adult dingy cutworms emerge in August and are 

active until mid-October, with peak activity in September. 

Eggs are deposited in plants in the Compositae 

family in the fall. The larvae develop to the second 

or third instar in the fall and overwinter in the soil. 

Pupation occurs in the spring to early summer. One 

generation of this species is produced per year. 

■ Figure 22. Adult - Darksided cutworm 

Euxoa messoria. (Extension Entomology) 

■ Figure 23. Larva - Darksided cutworm 

Euxoa messoria. (Extension Entomology) 

■ Figure 24. Adult - Redbacked cutworm 

Euxoa ochrogaster. (Extension Entomology) 

■ Figure 25. Larva - Redbacked cutworm 

Euxoa ochrogaster. (Extension Entomology)

Damage: Cutworm damage normally consists of 

crop plants being cut off from 1 inch (25 mm) below 

the soil surface to as much as 1 to 2 inches (25 to 50 

mm) above the soil surface. Young leaves also may be 

severely chewed as a result of cutworms (notably the 

darksided species) climbing up to feed on the plant 

foliage. 

Most cutworm feeding occurs at night. During the 

daytime, the cutworms usually will be just under the 

soil surface near the base of recently damaged plants. 

Wilted or dead plants frequently indicate the presence 

of cutworms. Cut-off plants may dry and blow 

away, leaving bare patches in the fi eld as evidence of 

cutworm infestations. 

Scouting Method: Sampling should begin as soon as 

sunfl ower plants emerge, and fi elds should be checked 

at least twice per week until approximately mid-June. 

The Z pattern should be used in scouting fi elds for 

cutworms, with sampling points one and two near the 

margin as indicated in Figure 17. 

Stand reduction is determined by examining 100 

plants per fi ve sampling sites for a total of 500 plants. 

■ Figure 26. Adult - Dingy cutworm Feltia jaculifera. 

(Extension Entomology) 

■ Figure 27. Larva - Dingy cutworm Feltia jaculifera. 

(Extension Entomology)) 

A trowel or similar tool should be used to dig around 

damaged plants to determine if cutworms are present, 

since missing plants in a row do not necessarily 

indicate cutworm damage (damage may be caused by 

a defective planter, rodents or birds). 

The Z pattern should be used again to determine 

cutworm infestation level by examining fi ve 1-squarefoot 

(30 by 30 cm) soil samples per site (in the row) 

for a total of 25 samples. 

Economic Threshold: One larva per square foot (30 

by 30 cm) or 25 percent to 30 percent stand reduction. 

Management: Several different insecticides are registered 

for cutworm control in sunfl ower. Postemergent 

treatment with an insecticide provides quick control of 

surface feeding cutworms. 

■ Palestriped Flea Beetle 

Species: Systena blanda (Melsheimer) 

Description: The adult is about 1/8 inch (3.2 mm) 

long and shiny black, with two white stripes on the 

back. The hind legs are enlarged and modifi ed for 

jumping (Figure 28). 

Life Cycle: The life cycle of palestriped fl ea beetles 

on sunfl ower fi elds is poorly understood. However, the 

adult fl ea beetles seem to overwinter in the fi eld under 

soil clods, fi eld debris and crop residues. They become 

active again in the spring, perhaps feeding fi rst on 

alfalfa and weeds before moving to and feeding on 

sunfl ower seedlings in June. They have been observed 

feeding on sunfl ower through July. Palestriped fl ea 

beetles have a wide host range, which includes various 

weeds, potato, tomato, carrot, peanut, corn, oat, 

cotton, pea, beans, strawberry, watermelon, grape and 

■ Figure 28. Adult - Palestriped fl ea beetle. 

(Michael Catangui, SDSU) 

Insects 

33

34 

pumpkin. Palestriped fl ea beetles are considered an 

important pest of commercially grown vegetables in 

some areas of the U.S. Recently, palestriped fl ea beetles 

have been observed delaying regrowth of alfalfa 

and also were observed feeding on soybean seedlings 

in eastern South Dakota. 

Damage: Palestriped fl ea beetles chew on the cotyledons, 

leaves and hypocotyls of sunfl ower seedlings, 

causing them to wilt and die. Injured leaves become 

riddled with holes, giving them a “lacey” appearance 

(Figure 29). The sunfl ower plant is most sensitive to 

palestriped fl ea beetle injury from seedling emergence 

(V-E) through the four-leaf stage (V-4). Signifi cant 

stand losses may result from heavy feeding injury by 

the palestriped fl ea beetles. 

■ Figure 29. Damaged sunfl ower leaves by 

palestriped fl ea beetle. (Michael Catangui, SDSU) 

Scouting Method: Surveys may be accomplished by 

using yellow sticky cards placed close to the ground 

(Figure 30). Sampling seedlings for beetles also can 

aid in estimating populations and feeding injury 

levels. Palestriped fl ea beetles move very fast and are 

hard to count directly on the seedlings or catch with 

an insect net. 

Economic Threshold: Control is recommended when 

20 percent of the seedling stand is injured and at risk 

to loss due to palestriped fl ea beetle feeding. This economic 

threshold is a guideline based on published hail 

injury data that predicts potential yield loss relative to 

seedling stand loss. 

Management: Palestriped fl ea beetles are hard to 

control with chemical insecticides; research has shown 

that treatments may provide up to 75 percent control 

of adults. 

■ Figure 30. Yellow sticky trap for monitoring 

palestriped fl ea beetles. (Michael Catangui, SDSU)

■ Sunfl ower Beetle 

Species: Zygogramma exclamationis (Fabricius) 

Description: The sunfl ower beetle is associated 

exclusively with sunfl ower. Adults (Figure 31) closely 

resemble adult Colorado potato beetles and may be 

confused with potato beetles. However, sunfl ower 

beetles are smaller and do not feed on potatoes, and 

Colorado potato beetles do not feed on sunfl ower. The 

head of the adult is reddish brown and the thorax (area 

between head and abdomen) is pale cream-colored 

with a reddish-brown patch at the base. Each front 

wing cover is cream-colored and has three dark stripes 

that extend its length. A shorter lateral stripe ends at 

the middle of the wing in a small dot that resembles 

■ Figure 31. Adult - Sunfl ower beetle Zygogramma 

exclamationis. (Extension Entomology) 

■ Figure 32. Larva - Sunfl ower beetle Zygogramma 

exclamationis. (Larry Charlet) 

an exclamation point. The beetle is ¼ to ½ inch (6 to 

12 mm) long and 3/32 to 3/16 inch (2 to 4 mm) wide. 

Eggs are about 1/16 inch (1.5 to 2 mm) long, cigarshaped 

and cream yellow. Sunfl ower beetle larvae 

are yellowish green with a brown head capsule and 

humpbacked in appearance. Newly hatched larvae are 

about 1/16 inch (1.5 to 1.75 mm long), and will reach 

a length of about an inch (8 to 10 mm) when fully 

developed (Figure 32). 

Life Cycle: The sunfl ower beetle has one generation 

per year in North Dakota. The adults overwinter in the 

soil, emerging in late May or early June. Shortly after 

emergence, the beetles begin to feed, mate and lay 

eggs singly on stems and undersides of leaves. Adults 

live for about 8½ weeks and lay eggs for a six- to seven-week 

period. Each female lays approximately 850 

eggs, with a range of 200 to 2,000 eggs. Eggs hatch 

into larvae in about one week (Figure 33). The larvae 

have four instars, which feed and are present in fi elds 

for about six weeks. When mature, the larvae enter the 

soil to pupate in earthen cells. The pupal stage lasts 

from 10 days to two weeks. Adults of the new generation 

emerge and feed for a short period on the bracts 

of the sunfl ower head or on the uppermost leaves of 

the plant before re-entering the soil to overwinter. 

Damage: Adult sunfl ower beetles damage plants soon 

after they emerge from overwintering. Damage to 

cotyledons is generally slight, but the fi rst true leaves 

may be severely damaged or completely consumed. 

Fields may be severely defoliated if beetles are numerous. 

Adults feed predominately on leaf margins while 

■ Figure 33. Eggs - Sunfl ower beetle. (Larry Charlet) 

Insects 

35

36 

larvae feed on the entire leaf surface. When larvae 

are numerous, damaged leaves take on a lacy appearance. 

Most larval feeding occurs at night, and adults 

will feed during the day. During the daytime, larvae 

typically rest in the terminal growth area, where they 

are easily found in leaf axils and fl ower buds. If larval 

feeding is severe, defoliation can reduce yield due to 

poor seed set or fi ll. 

The late summer generation of emerging sunfl ower 

beetle adults and late-maturing larvae rarely causes 

economic damage to the sunfl ower crop. However, in 

some cases, they have been abundant enough to cause 

feeding injury on late-planted sunfl ower. 

Scouting Method: Sampling sites should be at least 

75 to 100 feet (23 to 31 m) from the fi eld’s margins 

when determining if an entire fi eld should be treated. 

Adults and/or larvae should be counted on 20 plants at 

each of fi ve sampling sites along an X pattern for a total 

of 100 plants. The average number of adults and/or 

larvae per plant then should be determined. 

The average percent defoliation of plants is determined 

when damage is evident in the fi eld by examining 

20 plants per fi ve sampling sites for a total of 100 

plants (Figure 34). 

Economic Threshold: As sunfl ower plants develop, 

they can tolerate more feeding damage. In the seedling 

stage, one to two adults per seedling is the recommended 

economic threshold. For larvae, the treatment 

threshold is when populations reach 10 to 15 larvae 

per plant, or when approximately 25 percent defoliation 

occurs on the upper eight to 12 leaves (active 

growing part). Management normally is advised if 

defoliation reaches the 25 percent to 30 percent level 

at the late vegetative and early bud stages and it appears 

(based on larval size of less than ¼ inch or 6 

mm) that more defoliation will occur on the actively 

growing part of sunfl ower plant. However, if defoliation 

is 25 percent and the majority of larvae are about 

1/3 inch (8 mm) long, they have reached maturity and 

soon will stop feeding. Then, management probably is 

not warranted. 

Management: Insecticide seed treatments and foliar 

insecticides are effective in reducing spring populations 

of the adult sunfl ower beetle. Application of a 

foliar insecticide is recommended only when beetle 

populations have reached an economic threshold 

level in a fi eld. Insecticides are effective in prevent- 

ing economic loss when applied to actively feeding 

adults and/or larvae. Adult and larval populations of 

sunfl ower beetle decrease as planting date is delayed. 

Defoliation also is lower at the later planting dates. 

As a result, delayed planting is effective in preventing 

yield reductions caused by sunfl ower beetle feeding, 

but may make fi elds more attractive to later season 

insects, such as red sunfl ower seed weevil. Spring 

or fall cultivation does not reduce the overwintering 

populations of sunfl ower beetle adults or infl uence the 

pattern of emergence from the soil during the spring 

and summer. Sunfl ower hybrids with resistance to the 

sunfl ower beetle are not available. Natural enemies include 

parasites of the eggs, larvae and adults. General 

predators, such as ladybird beetles, carabid beetles, 

lacewings, stink bugs, nabids and anthocorids, destroy 

both eggs and larvae of the sunfl ower beetle. 

■ Figure 34. Percent defoliation of sunfl ower leaves. 

(Extension Entomology)

■ Sunfl ower Bud Moth 

Species: Suleima helianthana (Riley) 

Description: Sunfl ower bud moths have a wingspread 

of about 0.63 inch (16 to 18 mm). Each gray-brown 

forewing has two dark transverse bands (Figure 35). 

One band extends across the middle of the wing and 

the second band is near the wing tip. The larva has 

a dark head capsule with a smooth, cream-colored 

body and is 0.31 to 0.43 inch (8 to 11 mm) at maturity 

(Figure 36). 

Life Cycle: Two generations of sunfl ower bud moth 

are produced per year in North Dakota. Adults emerge 

from overwintering pupae during the last week of May 

to mid-June. 

A few days after adult emergence, eggs are deposited 

on the terminals of immature sunfl ower or on the receptacle 

of mature sunfl ower. Eggs also are deposited 

in leaf axils. The hatched larvae begin tunneling into 

the sunfl ower plant. The initial infestation in mid-June 

is characterized by an entrance hole surrounded by 

black frass, or insect excrement. 

Mature larvae pupate within the sunfl ower plant. Pupae 

move to the opening of the entrance holes formed 

in the stem or head tissue so that adults can emerge 

easily. 

The second-generation adults appear in July and August. 

Infestation by the second-generation larvae is not 

economically important. 

Damage: In early planted sunfl ower, 65 percent to 85 

percent of the infestations occur in the stalks. In lateplanted 

sunfl ower, most infestations occur in the pith 

areas of the head. 

Up to 4,000 larvae per acre have been reported in 

North Dakota and 24,000 larvae per acre have been 

reported in Texas. Despite these high populations, 

economic loss due to this insect has been minimal. 

The only time yield loss is noticeable is when larvae 

burrow into unopened buds, preventing proper head 

development. The larvae normally do not feed on 

developing seeds but confi ne feeding activities to 

the fl eshy part of the head. Yield loss has not been 

economically signifi cant, although injury by the larva 

produces malformations in both the head and stalk. 

■ Figure 35. Adult - Sunfl ower bud moth Suleima 

heliathana. (Extension Entomology) 

■ Figure 36. Larva - Sunfl ower bud moth Suleima 

heliathana. (Extension Entomology) 

Scouting Method: A fi eld monitoring scheme for 

this insect has not been established since it is not of 

economic signifi cance. 

Economic Threshold: None established. 

Management: Insecticide use has not been warranted 

for control of sunfl ower bud moth. 

Insects 

37

38 

■ Long-horned Sunfl ower Stem 

Girdler or Longhorned Beetle 

Species: Dectes texanus LeConte 

Description: The adult is pale gray and 5/8 inch (6 to 

11 mm) in length, with long gray and black banded 

antennae. (Figure 37) Eggs are about 0.1 inch (1.9 

mm) long and elongate, and turn dark yellow prior to 

hatch. Mature larvae are yellowish and 1/3 to 1/2 inch 

(7 to 13 mm) in length. Larvae bear fl eshy protuberances 

on the fi rst seven abdominal segments. (Figure 

38). 

Life Cycle: Adults appear in mid-June to early July in 

the southern Plains. Emergence continues through August, 

with 50 percent emerged by mid-July in Texas. 

Eggs are laid four to eight days after mating and eggs 

are deposited singly in leaf petioles. Approximately 

■ Figure 37. Adult - Longhorned beetle Dectes 

texanus. (Extension Entomology) 

■ Figure 38. Larva - Longhorned beetle Dectes 

texanus. (Extension Entomology) 

50 eggs are laid per female, with about one-third viable. 

Eggs hatch in six to 10 days. Larvae tunnel and 

feed in the petioles and stem pith and fi nally move to 

the base of the plant to overwinter. Larvae develop 

through six instars. In late summer, the mature larvae 

girdle the inside of the lower stalk or root crown, move 

below the girdle and pack frass into the tunnels. Stalks 

often break at the point of girdling, leaving the larva 

protected in its frass-packed tunnel during the winter. 

The larvae are cannibalistic and stalks usually harbor 

only a single larva, even though several may have 

hatched in a stalk. This insect has one generation per 

year. Host plants include sunfl ower, soybean, ragweed 

and cocklebur. 

Damage: Plant damage due to adult feeding appears 

to be insignifi cant since the scars do not penetrate the 

cortex nor encircle the stalk. Larval feeding is apparent 

when stalks lodge at the point of the girdle, about 

2.5 to 3.5 inches (7 to 9 cm) above the soil surface. 

Scouting Method: None has been developed. 


Management: In the southern Plains, later planting 

dates and fall or winter tillage have reduced sunfl ower 

infestations by this pest. Perennial sunfl ower species 

are resistant to stalk infestation, indicating the possibility 

of breeding cultivars resistant to the longhorned 

sunfl ower stem girdler. Chemical treatments on 

soybean and sunfl ower are ineffective against larvae 

and were determined to be impractical against adults 

because of the extended emergence period. When 

larvae are present in the stalks, plants do not always 

lodge. Utilizing lower plant populations that encourage 

thicker stalks may help reduce damage from 

lodging. If fi elds are suspected to be infested, prompt 

harvesting will limit losses from lodging.

■ Sunfl ower Maggots 

Species: 

Sunfl ower receptacle maggot, Gymnocarena diffusa 

(Snow) 

Sunfl ower maggot, Strauzia longipennis (Wiedemann) 

Sunfl ower seed maggot, Neotephritis fi nalis (Loew) 

Description: The adult forms of all three sunfl ower 

maggots (fl ies) have wings with a distinct brown or 

yellowish-brown pattern. The name “picture-wing fl y” 

has been given to fl ies of this type. While all three fl y 

species are similar in appearance, they do have distinguishing 

differences. 

Gymnocarena diffusa - This species is the largest of 

the three, with a body about 0.4 inch (10 mm) long 

and a wing span of approximately 0.75 inch (19 mm) 

(Figure 39). The eyes of this species are bright green 

and the wings have a yellowish-brown and somewhat 

mottled appearance. G. diffusa larvae attain a length of 

nearly 0.31 inch (8 mm) at maturity. The larvae taper 

from the front to rear and are yellowish white (Figure 

40). 

Strauzia longipennis - Adults of this species have a 

wing spread of about 0.5 inch (13 mm) and a body 

0.25 inch (6 mm) long (Figure 41). The wings bear 

broad, dark bands that form a fairly distinct F-shaped 

mark near the tips. The larvae of S. longipennis are 

creamy white, headless and legless, as are the other 

two species (Figure 42). They taper slightly at both 

ends and attain a length of about 0.28 inch (7 mm) at 

maturity. 

Neotephritis fi nalis - This sunfl ower maggot is the 

smallest of the three species, with the adult having 

a body length of about 0.25 inch (6 mm) and a wing 

span of approximately 0.28 inch (7 mm) (Figure 

43). The wings have a brown lacelike appearance. N. 

fi nalis larvae attain a length of 0.19 inch (4.5 mm) at 

maturity. The small, brown pupa of N. fi nalis is found 

in the face of the sunfl ower bud, usually surrounded by 

a small number of damaged fl orets (Figure 44). 

Life Cycles: Adults of G. diffusa emerge in late June 

to early July after sunfl ower buds reach 2 to 4 inches 

(5 to 10 cm) in diameter. Eggs are laid on the bracts 

■ Figure 39. Adult - Sunfl ower receptacle maggot 

Gymnocarena diffusa. (Extension Entomology) 

■ Figure 

40. Larva 

- Sunfl ower 

receptacle 

maggot 

Gymnocarena 

diffusa. 

(Extension 

Entomology) 

■ Figure 41. Adult - Sunfl ower maggot Strauzia 

longipennis. (Extension Entomology) 

■ Figure 42. Larva - Sunfl ower maggot Strauzia 

longipennis. (Extension Entomology) 

Insects 

39

40 

of the developing sunfl ower heads. Egg laying occurs 

from mid-July through August. The hatched larvae 

tunnel into the spongy tissue of the receptacle. Damage 

to the head is negligible. After 30 days, the mature 

larvae cut a small emergence hole on the underside of 

the receptacle and drop into the soil to pupate. Overwintering 

pupae are found about 7.5 inches (19 cm) 

deep in the soil by August or early September. Some 

larvae will pupate in the sunfl ower head. Only one 

generation per year occurs in North Dakota. 

Strauzia longipennis has one generation per year. This 

insect overwinters as a larva in plant debris in the 

soil. Pupation and adult emergence is completed in 

early June. Females lay eggs in stem tissue of young 

sunfl ower, and larvae feed in the pith tissue for much 

of the growing season. 

■ Figure 43. Adult - Sunfl ower seed 

maggot Neotephritis fi nalis. (Extension 

Entomology) 

■ Figure 44. Pupae - Sunfl ower seed maggot 

Neotephritis fi nalis. (Extension Entomology) 

Unlike the other two species of sunfl ower maggots, 

two complete generations per year of N. fi nalis occur 

in North Dakota. Adults of N. fi nalis emerge during 

the fi rst week of July. Egg deposition occurs on the corolla 

of incompletely opened sunfl ower infl orescences. 

The total larval period is 14 days. The fi rst generation 

of N. fi nalis pupates in the head; the second generation 

overwinters in the soil as pupae. 

Damage: Damage by sunfl ower maggots has been 

negligible. 

The maggots of Gymnocarena diffusa feed on the 

spongy receptacle tissue of the sunfl ower head and 

feeding may cause partially deformed heads. Larvae 

do not feed on developing seeds. 

The magnitude of damage to sunfl ower seeds by N. 

fi nalis larvae depends largely on the stage of larval 

and seed development. Seed sterility occurs when 

newly hatched larvae tunnel into the corolla of young 

blooms. Observations indicate that a single larva feeding 

on young fl owers will tunnel through 12 ovaries. 

Mature larvae feeding on older sunfl ower heads will 

destroy only one to three seeds. 

While infestation levels of S. longipennis occasionally 

have reached nearly 100 percent, damage from larval 

feeding is usually light. Part of a commercial sunfl 

ower fi eld next to a grassed waterway or other water 

source sometimes supports a higher than usual infestation. 

Under these conditions, high larval numbers of 

eight to 10 per stalk may be found and stalk breakage 

can occur. Stalk breakage of up to 30 percent of the 

plants has been recorded. 

Scouting Method: A scouting method has not been 

developed for sunfl ower maggots because of the negligible 

injury caused by these insects. 



for control of sunfl ower maggots.

■ Sunfl ower Stem Weevil 

Species: Cylindrocopturus adspersus (LeConte) 

Description: Adult sunfl ower stem weevils are about 

3/16 inch (4 to 5 mm) long and grayish brown, with 

varying-shaped white spots on the wing covers and 

thorax (Figure 45). The snout, eyes and antennae are 

black. The snout is narrow and protrudes down and 

backward from the head. Eggs are deposited inside the 

epidermis of sunfl ower stems and are very small (0.51 

mm long by 0.33 mm wide), oval and yellow, making 

them diffi cult to see. The larvae are ¼ inch (5 to 6 

mm) long at maturity, legless and creamy white with 

a small, brown head capsule (Figure 46). They are 

normally in a curled or C-shaped position within the 

sunfl ower stalk. Pupae are similar to the adult in size 

and creamy white 

Life Cycle: Only one generation occurs per year. Larvae 

overwinter in sunfl ower stalks and crown roots and 

pupate in the spring, and adults emerge in mid to late 

June, feeding on the epidermal tissue of the sunfl ower 

foliage and stem. This feeding does not affect plant 

vigor. Mating occurs soon after emergence of adults. 

Just prior to egg laying, females descend to the lower 

portion of the plant to deposit eggs individually in the 

stem tissue. Approximately 50 percent of oviposition 

occurs by mid-July. Upon hatching in early July, the 

fi rst instar (larval growth stage) larvae feed on subepidermal 

and vascular tissue. Feeding is concentrated in 

the pith tissue as the larvae develop to third and fourth 

instar stages. By the last week in August, the larvae 

descend while feeding to just above the soil surface. 

A chamber is constructed in the stem, and the weevil 

overwinters there as a fi fth instar larva. Pupation of 

the overwintering larva occurs the following year in 

early June. 

Damage: Adult sunfl ower stem weevil feeding causes 

minor damage to the stem and leaf tissue of the plant. 

More importantly, adult weevils have been implicated 

in the epidemiology of the sunfl ower pathogen 

Phoma black stem (Phoma macdonaldii Boerma) and 

charcoal stem rot (Macrophomina phaseolina (Tassi) 

Goid). 

Larval injury can cause the stem to weaken from tunneling, 

pith destruction and especially by construction 

of overwintering chambers at the stalk base. At larval 

infestations of 20 to 25 or more per stalk, the plants 

run a risk of stalk breakage and loss of the entire capitual 

(head). Risk of breakage is greatest when plants 

are under drought stress and/or during periods of high 

winds. The breakage typically occurs at or slightly 

above the soil line, in contrast to breakage attributed 

to a stalk disease, which normally occurs farther up on 

the stalks. 

Scouting Methods: Field monitoring for sunfl ower 

stem weevils to estimate population size is important. 

However, adults are diffi cult to see on the plants 

due to their small size, cryptic color and “play dead” 

behavior. They are inactive on the plant or fall to the 

ground when disturbed and remain motionless. Adults 

can be found on both surfaces of the leaves, the lower 

portions of the stem, in leaf axils, within the dried 

■ Figure 45. Adult - Sunfl ower stem weevil 

Cylindrocopturus adspersus. (Extension Entomology) 

■ Figure 46. Larva - Sunfl ower stem weevil 

Cylindrocopturus adspersus. (Extension Entomology) 

Insects 

41

42 

cotyledons or in soil cracks at the base of the sunfl 

ower plant. Yellow sticky traps were unsuccessful in 

relating captured adult numbers to larval infestations. 

Sampling for the larval stage is diffi cult since they 

develop totally within the sunfl ower plant. The only 

method for detecting the presence of larvae is to split 

the sunfl ower stem, a time-consuming process. 

Field scouting for adults should begin when plants 

are in the eight- to 10-leaf stage, developmental stage 

V-8 to V-10, or late June to early July, and continue 

until mid-July. Select sampling sites 70 to 100 feet in 

from the fi eld margin. Count the number of adults on 

fi ve plants at fi ve randomly selected sampling sites 

throughout the fi eld for a total of 25 plants. Calculate 

the average number of weevils per plant. Use an X 

pattern (or W pattern) to space sample sites throughout 

the entire fi eld. When scouting for stem weevils, 

approach plants carefully and slowly to avoid disturbing 

the adults. 

Economic Threshold: Average fi eld counts of one 

adult sunfl ower stem weevil per three plants can result 

in damaging larval densities of more than 40 larvae 

per stalk at the end of the season. 

Management: Insecticidal treatment, if needed based 

on fi eld counts, should be initiated in late June or 

early July before signifi cant egg laying has occurred. 

Cultural control tactics, including delayed planting, 

altered plant population and tillage, are useful for 

managing the sunfl ower stem weevil. Delayed planting 

of sunfl owers until late May or early June has been 

effective in reducing densities of larvae in the stem. 

Reducing plant population results in an increased 

stalk diameter and, as a result, decreases damage from 

lodging. Combinations of disking to break up stalks 

and moldboard plowing to bury them at a depth of 6 

inches (15 cm) can increase larval/pupal mortality and 

severely impact the emergence of adult stem weevils. 

Otherwise, larvae/pupae are physically protected in 

the woody stalks. Survival is affected only by performing 

both operations. Greenhouse and fi eld experiments 

have shown resistance to feeding, oviposition 

and larval development in many native species of 

sunfl ower. Field research for resistant sunfl ower germplasm 

is under way. Natural enemies of the sunfl ower 

stem weevil include parasitic wasps that attack both 

the egg and larval stages. 

■ Black Sunfl ower Stem Weevil 

Species: Apion occidentale (Fall) 

Description: Adults are black and only 0.1 inch (2.5 

mm) long from the tip of the snout to the tip of the 

abdomen (Figure 47). The snout is very narrow and 

protrudes forward from the head, which is small in relation 

to the rather large, almost globose body. Larvae 

of A. occidentale are very similar in appearance to C. 

adspersus, except they are only 0.1 to 0.12 inch (2.5 to 

3 mm) long at maturity and yellowish (Figure 48). 

Life Cycle: Apion occidentale overwinters as an adult 

in soil, plant residue, sod and weed clusters and begins 

to emerge and feed on volunteer sunfl ower as soon 

as the plants reach the early seedling stage. Females 

deposit eggs under the epidermis of the stem or leaf 

petioles. Larvae emerging from these eggs tunnel in 

the pith area of the stem, pupate and emerge as adults 

in early August. Little or no adult activity is observed 

■ Figure 47. Adult - Black sunfl ower stem weevil 

Apion occidentale. (Extension Entomology) 

■ Figure 48. Larva - Black sunfl ower stem weevil 

Apion occidentale. (Extension Entomology)

for about two weeks in late July and early August. 

Black sunfl ower stem weevil adults emerging in August 

also feed on the leaves and stems of the plant, but 

as the plant matures and the leaves begin to die, the 

adults move under the bracts of the sunfl ower head, 

where they can be observed feeding until the plants 

are harvested. 

Damage: Adult feeding generally is considered as insignifi 

cant mechanical injury. Like the sunfl ower stem 

weevil, the black sunfl ower stem weevil is suspected 

of vectoring Phoma black stem disease in sunfl ower 

fi elds. In situations of extremely high populations 

feeding on seedling sunfl owers, stand loss has occurred. 

However, in most cases, populations are too 

low to cause economic damage and stalk tunneling 

only results in minor injury to the plant. 


developed for the black sunfl ower stem weevil. 


Management: Recommendations for insecticidal control 

of this insect have not been developed. 

■ Figure 49. Adult - Sunfl ower root weevil Baris 

strenua. (Extension Entomology) 

■ Sunfl ower Root Weevil 

Species: Baris strenua (LeConte) 

Description: Adults are rather robust-looking weevils, 

with a somewhat oval-shaped body (Figure 49). They 

are 0.25 inch (6 mm) long and have a short, almost 

blunt, downward projecting snout. Their coloration is 

dull black in contrast to the shiny, black appearance 

of A. occidentale. Baris strenua larvae are similar in 

appearance to C. adspersus larvae but much larger and 

are not located in the sunfl ower stalk (Figure 50). 

Life Cycle: Adult root weevils emerge during the latter 

part of June. They feed on sunfl ower foliage in early 

morning and late afternoon. About two weeks after 

emergence, the adults begin to congregate around the 

root zone near the soil surface. Continued feeding and 

copulation occur during this period. Feeding activity 

during this period produces callus tissue, under 

which the bright yellow eggs are deposited two or 

three at a time. Hatching of the larvae normally occurs 

during the second week in July. Baris strenua larvae 

are not very mobile. Most of the feeding (consisting 

of circular tunnels) and development to fourth instar 

takes place in the same area where hatching occurs. At 

about the time that the fourth larval stage is reached 

in late August to early September, the plant becomes 

signifi cantly dehydrated and encapsulation of the 

larvae within a “soil cocoon” begins. This “larval 

cocoon” overwinters among the remaining roots in the 

soil. Overwintering larvae have been recovered from a 

depth of 15 inches (38 cm) in North Dakota. 

Damage: The sunfl ower root weevil adult, like the 

other two stem weevils, causes negligible mechanical 

injury to the foliage of the sunfl ower plant. The destruction 

of root tissue by the larvae of the sunfl ower 

root weevil causes the plants to wilt and lodge if the 

infestation is severe. The damage to fi elds attacked by 

the weevil tends to be localized. 


developed because damage caused by this pest has 

been minor. 



for the control of the sunfl ower root weevil. 

■ Figure 50. Larva - Sunfl ower root weevil Baris 

strenua. (Extension Entomology) 

Insects 

43

44 

■ Thistle Caterpillar (Painted Lady) 

Species: Vanessa cardui (Linnaeus) 

Description: The body of the adult is about 1 inch 

(25 mm) long with a wingspread of about 2 inches 

(50 mm) (Figure 51). The upper wing surfaces are 

brown with red and orange mottling and white and 

black spots. The undersides of the wings are marble 

gray, buff and white. Each hind wing possesses a row 

of four distinct and obscure eyespots. Eggs are small, 

spherical and white. The larvae are brown to black and 

spiny, with a pale yellow stripe on each side (Figure 

52). When mature, the larvae are 1.25 to 1.5 inches 

(32 to 38 mm) long. The chrysalis, or pupa, is molten 

gold and about 1 inch (25 mm) long. 

■ Figure 51. Adult - Painted lady butterfl y Vanessa 

cardui. (Extension Entomology) 

■ Figure 52. Larva - Painted lady butterfl y Vanessa 

cardui. (Extension Entomology) 

Life Cycle: The painted lady butterfl y is indigenous 

to the southern U.S. and migrates annually to the 

northern U.S. and Canada. The painted lady breeds in 

the north-central states and Canada, migrates south for 

the winter and returns to the northern areas in early 

June. Eggs are laid on Canada thistle, wild and cultivated 

sunfl ower, and many other host plants. Hatching 

occurs in about one week. Larvae feed on sunfl ower 

until they reach maturity in late June or early July. 

Chrysalids are formed and hang from the leaves of the 

plant. Butterfl ies will emerge in about 10 days from 

the chrysalid and a second generation begins. 

Damage: The caterpillars (larvae) feed on the leaves 

and, when numerous, may defoliate infested plants. 

The larvae produce a loose silk webbing that covers 

them during their feeding activity. Black fecal pellets 

produced by the larvae often are found in proximity to 

the webbing. 

The effect of defoliation by the larvae on the yield of 

sunfl ower is similar to that described for defoliation by 

sunfl ower beetle larvae. 


75 to 100 feet (23 to 31 m) from the fi eld margins 

when collecting data to determine whether an entire 

fi eld should be treated. Infestations frequently will be 

concentrated in areas of a fi eld where Canada thistle 

plants are abundant. Plants should be examined carefully 

for the presence of eggs and/or larvae. 

The fi eld should be monitored by using the X pattern, 

counting 20 plants per sampling site for a total of 100 

plants to determine percent defoliation (Figure 35). 

Economic Threshold: The threshold is 25 percent defoliation, 

provided that most of the larvae are still less 

than 1.25 inch (32 mm) long. If the majority of the 

larvae are 1.25 to 1.5 inches (32 to 38 mm) long, most 

of the feeding damage already will have occurred and 

treatment is not advised. 

Management: Insecticide use generally has not been 

warranted for control of larvae of the painted lady. 

However, instances of high localized infestations have 

occurred within certain fi elds where spot treating may 

be necessary. Disease outbreaks, indicated by dying 

larvae present on leaves, often occur when large populations 

are present.

■ Sunfl ower Midge 

Species: Contarinia schulzi Gagne' 

Description: The tan body of the adult sunfl ower 

midge is about 0.07 inch (1.69 mm) long, with a 

wingspan of about 0.19 inch (4 mm) (Figure 53). The 

wings are transparent with no markings except the 

veins. The larvae attain a length of nearly 0.09 inch 

(2.42 mm) at maturity and they are cream to yellowish 

orange when fully grown (Figure 54). They are 

tapered at the front and rear, with no legs or apparent 

head capsule. 

Life Cycle: The sunfl ower midge overwinters in the 

soil as a cocooned larva and pupates during June and 

July in North Dakota and Minnesota. Typically, the 

initial peak of fi rst-generation adult emergence occurs 

in early to mid-July. A second peak occurs about seven 

to 10 days later. They prefer to lay eggs on sunfl ower 

buds with a diameter greater than 1 inch (25 mm). 

Larvae initially feed on margins of the head between 

the bracts surrounding the heads. Larvae migrate to 

the base of the developing seeds and to the center 

of the head as it develops. Presence of the larvae 

frequently is determined by necrotic areas at the base 

of or between the bracts. As midge larvae mature, 

they move to the surface of the head and drop to the 

ground. A partial, second generation occurs in August. 

Second-generation adults oviposit among the seeds. 

Damage: Damage to sunfl ower is a result of fi rstgeneration 

larval feeding in developing heads. When 

populations are low, damage is restricted to the base 

of the bracts of the head and causes slight localized 

necrosis but little if any economic loss. When many 

larvae are present, feeding prevents ray petal formation 

and distorts the growth of the developing sunfl 

ower head. If the abnormal growth is severe, the back 

of the head overgrows the front and little or no seed 

production occurs (Figure 55). If an infestation occurs 

in the early bud stage, the bud may be killed. 

Often midge damage is restricted to fi eld margins 

or small portions of fi elds and economic losses are 

minimal. However, when populations are very heavy, 

damage will extend throughout the fi eld and substantial 

economic losses occur. The extent of damage from 

second generation larvae is unknown. 

Scouting Method: None established. 


Management: Because effective chemical and other 

controls are not available, sunfl ower midge management 

relies on cultural practices done prior to planting. 

If a midge infestation is anticipated, new fi elds 

should be established away from fi elds damaged the 

previous season. To minimize the risk of all plantings 

being at their most susceptible stage at midge emergence, 

several planting dates should be used. If available, 

growers should consider using a tolerant hybrid. 

■ Figure 

53. Adult 

- Sunfl ower 

midge 

Contarinia 

schulzi. 

(Extension 

Entomology) 

■ Figure 54. Larva - Sunfl ower midge Contarinia 

schulzi. (Extension Entomology) 

■ Figure 55. Severe damage to receptacle and seed 

development occurs when midge infection is high. 


Insects 

45

46 

■ Red Sunfl ower Seed Weevil 

Species: Smicronyx fulvus LeConte 

Description: Red sunfl ower seed weevil adults are 0.1 

to 0.12 inch (2.5 to 3.06 mm) long and reddish brown 

(Figure 56). The larvae are small, 0.10 inch (2.54 mm) 

long, cream-colored, legless and C-shaped (Figure 57). 

Life Cycle: Red sunfl ower seed weevil emergence 

occurs in late June and early July. The newly emerged 

adults feed on sunfl ower buds or fl oral tissues. Once 

pollen is available, the adults include it in their diet. 

Females need to feed on sunfl ower pollen for several 

days prior to egg deposition. Eggs are deposited 

within young developing seeds. Normally a single 

egg is placed in each seed, although 8 percent to 12 

percent of the seeds may contain several eggs. 

■ Figure 56. Adult - Red sunfl ower seed weevil 

Smicronyx fulvus. (Extension Entomology) 

■ Figure 57. Larva - Red sunfl ower seed weevil 

Smicronyx fulvus. (Extension Entomology) 

The small, white eggs hatch in approximately one 

week. The larvae consume a portion of the kernel, and 

this feeding causes economic damage. After completion 

of larval development, the majority of the larvae 

drop to the ground. Larval drop occurs from mid- 

August through September. The larvae overwinter in 

the soil at a depth of about 6 inches (15 cm). Larvae 

pupate in late June of the following year and the pupal 

period lasts about one week. A single generation per 

year is produced in North Dakota. 

Damage: While the kernel of some seeds may be 

totally eaten, most seeds are only partially consumed. 

The separation of undamaged from weevil-damaged 

seed is diffi cult. 

Most larvae drop from the head to the soil after completing 

their development, but a small percentage may 

remain in the seed and are present at harvest. Growers 

who encounter a seed weevil infestation may want to 

delay harvest to allow most of the weevil larvae to exit 

the seeds to avoid having larvae in the harvest bin. 

Larvae that are still in the seed at bin fi lling time are 

done feeding and can cause heating and moisture 

problems. Larvae harvested with the seed cannot be 

controlled until they have completed development and 

have emerged from the infested seeds. Once emerged, 

they are susceptible to fumigation. But fumigation 

normally is not recommended. However, the most 

advantageous time to initiate control of seed weevil is 

in the fi eld when the adult weevils are active, but prior 

to egg deposition. 

Economic Thresholds: The economic threshold varies 

with differences in plant population, the cost of insecticide 

application and the market price of sunfl ower. 

The procedure for calculating the economic threshold 

is discussed in the NDSU Extension sunfl ower seed 

weevil publication (E-817). Currently, an infestation 

level of four to seven seed weevil adults per head in 

oil sunfl ower or one seed weevil per head in confectionery 

sunfl ower is the average economic threshold. 

The optimal period for insecticide treatment is when 

at least three out of 10 plants in the fi eld are at early 

bloom (R-5.1 to R-5.4, Figure 4) and the economic 

threshold has been reached. If spray application is 

delayed past when more than four out of 10 plants are 

at stage R-5.4, many eggs already will be laid in the 

developing seeds and those eggs and larvae cannot be 

controlled. If fi elds are sprayed too early, reinfesta-

tion may occur in areas with a high weevil population. 

After spraying, fi elds should be rechecked periodically 

to determine if reinfestation is reaching the economic 

threshold. Continue rechecking until most of the heads 

in the fi eld have reached the R-5.7 stage. At that stage, 

most eggs already will have been laid and most seeds 

will be too mature to be suitable for further red seed 

weevil egg oviposition. 

Scouting Method: Begin by taking samples from 12 

plants, three plants from each of the four fi eld sides. 

Sampling sites should be at least 75 feet (21 m) in 

from fi eld borders, which often have an inordinately 

high number of weevils. The total number of weevils 

counted should be compared to the sequential sampling 

table in the most recent NDSU Extension sunfl 

ower seed weevil publication (E-817). According to 

the table, take one of three possible actions: Stop sampling, 

no action is needed; stop sampling and treat; 

or, take more samples because a decision cannot be 

reached. When populations are low or high, sequential 

sampling allows a quick decision with few samples. 

If populations are near the economic threshold, more 

precision is needed to making an accurate determination 

and more samples are required. 

NOTE: To more precisely check individual sunfl ower 

heads for red sunfl ower seed weevils, the face of the 

heads should be sprayed with a commercial formulation 

of mosquito repellent containing diethyl toluamide 

(DEET). This will cause the weevils to move 

out from between the fl orets where they can be more 

accurately counted. Consult the most recent NDSU 

Extension sunfl ower seed weevil publication (E-817) 

for a table to convert the visual counts to the absolute 

number of weevils (both counted and uncounted). 

Management: Several federally registered insecticides 

are available for control of sunfl ower seed weevils in 

the U.S. Early planting of sunfl ower reduces achene 

damage caused by the red sunfl ower seed weevil without 

causing a measurable reduction in oil content and 

achene weight. 

Surrounding a sunfl ower fi eld with a ring of early 

blooming sunfl ower effectively can trap immigrating 

red sunfl ower seed weevils into a small portion 

of the fi eld, where they can be controlled effi ciently. 

The trap cropping method given in publication E-817 

is as effective and more cost effi cient than standard 

insecticide treatment for control of red sunfl ower seed 

weevils. 

■ Gray Sunfl ower Seed Weevil 

Species: Smicronyx sordidus LeConte 

Description: Adults of the gray sunfl ower seed weevil 

are slightly larger (0.14 inch long) than S. fulvus and 

gray (Figure 58). The larvae are small, 0.12 inch 

long (3.1 mm), cream-colored, legless and C-shaped 

(Figure 59). 

Life Cycle: Gray sunfl ower seed weevil emergence occurs 

in late June and early July and reaches 50 percent 

emergence about 10 days before the red sunfl ower 

seed weevil. The newly emerged adults feed on fl oral 

buds. Oviposition occurs on fl owers in the bud stage 

and before red sunfl ower seed weevil oviposition 

begins. Female gray sunfl ower seed weevils do not lay 

as many eggs as do females of the red sunfl ower seed 

weevil. 

■ Figure 58. Adult - Gray sunfl ower seed weevil 

Smicronyx sordidus. (Extension Entomology) 

■ Figure 59. Larva - Gray sunfl ower seed weevil 

Smicronyx sordidus. (Extension Entomology) 

Insects 

47

48 

The larvae feed in a single achene, and infested 

achenes are enlarged and protrude above surrounding 

uninfested achenes. The majority of the larvae drops 

to the ground from mid-August through September 

and overwinters in the soil. Larvae pupate in late June 

and a single generation per year is produced in North 

Dakota. 

Damage: Seeds infested by the gray seed weevil lack 

a kernel and, due to their light weight, the seeds may 

be lost during the harvesting process. Because of their 

low population levels and low fecundity, the gray sunfl 

ower seed weevil usually does not cause economic 

damage, especially in oil sunfl ower fi elds. In confection 

fi elds, however, populations of the gray sunfl ower 

seed weevil may be suffi ciently high to warrant treatment 

at the late bud stage (R-3 to R-4). 

As with the red sunfl ower seed weevil, larvae normally 

drop from the head to the soil after completing their 

development. Larvae that do not emerge will present 

the grower with the same problem as unemerged red 

sunfl ower seed weevil larvae. 

Scouting Method: Normally, gray sunfl ower seed 

weevil populations are too low to cause economic 

damage. However, if an area has had a history of high 

populations, fi elds, especially confection fi elds, should 

be sampled beginning at bud stage R-2 (Figure 4). 

Sampling should be done as for the red sunfl ower seed 

weevil and continue until plants are blooming. 

Economic Thresholds: None established. 

Management: Several insecticides are federally registered 

for control of sunfl ower seed weevils in the U.S. 

If fi elds are to be treated with insecticides, they should 

be sprayed while the plants are still in early bud stage. 

By late bud stage, most oviposition already will have 

occurred. 

■ Sunfl ower Moth 

Species: Homoeosoma electellum (Hulst) 

Description: The adult is a shiny gray to grayish tan 

moth about 0.38 inch (9 mm) long, with a wingspan 

of about 0.75 inch (19 mm) (Figure 60). The hind 

wings are devoid of markings; however, the forewings 

have a small, dark, discal dot near the center of each 

wing and two or three small, dark dots near the leading 

margin of each wing. When at rest, the wings are 

held tightly to the body, giving the moth a somewhat 

cigar-shaped appearance. The larva has alternate dark 

and light-colored longitudinal stripes on a light brown 

body (Figure 61). The larva is about 0.75 inch (19 

mm) long at maturity. 

■ Figure 60. Adult - Sunfl ower moth Homoeosoma 

electellum. (Extension Entomology) 

■ Figure 61. Larva - Sunfl ower moth Homoeosoma 

electellum. (Extension Entomology)

Life Cycle: Sunfl ower moth migrations from the 

south-central U.S. normally appear in North Dakota 

in early to mid-July. The moths are highly attracted 

to sunfl ower that is beginning to bloom. Individual 

female moths will deposit up to 30 eggs per day on 

the surface of open sunfl ower heads. The eggs hatch 

within 48 to 72 hours and the newly emerged larvae 

feed on pollen and fl orets. The larvae begin tunneling 

into seeds upon reaching the third instar (larval 

growth stage). This tunneling continues throughout 

the remainder of larval development. Larval development 

from hatching to full maturity takes about 15 to 

19 days. 

Damage: The young larvae of the sunfl ower moth feed 

primarily on fl orets and pollen. Older larvae tunnel 

through immature seeds and other parts of the head. A 

single larva may feed on three to 12 seeds and forms 

tunnels in both the seeds and head tissue. Larvae spin 

silken threads, which bind with dying fl orets and frass 

to give the head a trashy appearance. Severe larval infestations 

can cause 30 percent to 60 percent loss, and 

in some cases, the entire head can be destroyed. Sunfl 

ower infested with sunfl ower moth has an increased 

incidence or risk of Rhizopus head rot. 


75 to 100 feet (23 to 31 m) from fi eld margins. The X 

pattern should be used in monitoring a fi eld, counting 

moths on 20 heads per sampling site for a total of 100 

heads. Scouting is most accurate in the early morning 

or late evening, when moths are active. Sex pheromone 

lures are available commercially for monitoring 

with traps to indicate their arrival and local populations. 

Insecticide applications should be considered 

when pheromone trap catches average four moths per 

trap per day from the R-3 through R-5 growth stages. 

Economic Threshold: The economic threshold for 

sunfl ower moth is one to two adults per fi ve plants at 

the onset of bloom or within seven days of the adult 

moth’s fi rst appearance. If using pheromone traps, 

consider the threshold mentioned in the Scouting 

Method section. 

Management: A number of federally labeled insecticides 

are registered for control of the sunfl ower moth. 

■ Banded Sunfl ower Moth 

Species: Cochylis hospes Walsingham 

Description: The adult has a dark band across the buff 

or yellowish-tan forewings (Figure 62 ). The wingspan 

is about 0.5 inch (13 mm). Early instar larvae are 

off-white; late instar larvae are pinkish to red with a 

brown head capsule (Figure 63). Larvae will be about 

0.44 inch (11 mm) at maturity. 

Life Cycle: The life cycle of the banded sunfl ower 

moth is similar to that of the sunfl ower moth, except 

that the adults emerge from local overwintering sites 

rather than migrating into North Dakota. Banded 

■ Figure 62. Adult and eggs - Banded sunfl ower moth 

Cochylis hospes. (Extension Entomology) 

■ Figure 63. Larva - Banded sunfl ower moth Cochylis 

hospes. (Extension Entomology) 

Insects 

49

50 

sunfl ower moths begin to emerge from the soil about 

mid-July and are present in the fi eld until mid-August. 

Adults tend to congregate in fi eld margins on weeds or 

adjacent crops during the day and then move into the 

crop in the evening. Within a week after emergence, 

they begin to lay eggs on the outside of the bracts of 

the sunfl ower head. Eggs may be found through early 

August and hatch in fi ve to eight days. Larvae develop 

through fi ve instars and are present in sunfl ower heads 

from mid-July to mid-September. After feeding to 

maturity, larvae drop to the ground and spin cocoons 

in the soil to overwinter. Pupation takes place in late 

June or early July the following year. The pupal period 

lasts about 12 days. 

Damage: The newly hatched larvae move from the 

bracts to the fl orets of the sunfl ower head, where they 

enter open fl orets to feed. When the eggs hatch, young 

larvae feed on bract tissue before moving into the 

head. A sunfl ower head is susceptible to infestation 

only during the fl owering period. The larvae feed in 

the fl orets until the third instar. During later stages 

of larval development, the insect tunnels through the 

base of the fl oret into the seed. The larvae may consume 

part or all of the contents of the developing seed. 

The larvae usually enter near the top of the seed and 

leave by way of the same opening after the contents 

are eaten. Each larva may destroy several (fi ve to 

seven) seeds. Small areas of silken webbing on mature 

sunfl ower heads indicate the presence of banded sunfl 

ower moth larvae within the head. 

Adult Scouting Method and Economic Threshold: 

Sampling sites should be at least 75 to 100 feet from 

the fi eld margins. In monitoring a fi eld, use the X 

pattern (Figure 17), counting moths on 20 plants per 

sampling site to obtain the total number of moths per 

100 plants. Sampling should be conducted in the late 

bud stage (R3), usually during mid-July. If treatment 

is warranted, it should be applied at the R5.1 sunfl ower 

plant growth stage (when 10% of head area has disk 

fl owers that are fl owering or completed fl owering.) 

During the day (late morning to early afternoon) the 

moths remain quiet, resting on upper or lower surfaces 

of the leaves of sunfl ower plants. When disturbed, 

they fl utter from plant to plant. When sampling for 

moths during the day, the decision to treat or not is 

based on comparing the mean number of adult moths 

in the fi eld to the EIL for moths. The EIL number is 

the number of moths per head that will, if not man- 

aged, result in seed damage with a value equal to the 

cost of treatment. Use the following formula based on 

treatment costs, plant population and market price to 

determine the adult EIL for day sampling. 

EIL 

(moths per 100 plants) = 

[[ 

(Treatment Cost ($)/Market Price) x 582.9 – 0.7 

Plant Population 

The constants in the formula simplify the calculation 

and include the amount of loss attributable to each 

banded sunfl ower moth larva produced per plant. 

A sample calculation of the EIL based on moth sampling 

for the following conditions is given below. 

Insecticide treatment cost = $8/acre 

Market price = $0.09/lb. 

Plant population = 20,000/acre 

[[[ [ 

EIL = ($8/$0.09) x 582.9 – 0.7 

20,000 

= 19 moths per 100 plants 

For this set of variables, an infestation of about 1.9 

moths per 100 plants will result in suffi cient larvae 

to destroy seeds in the sunfl ower head equal to the $8 

treatment cost per acre in a fi eld of 20,000 plants per 

acre with a market value of 9 cents per pound. If the 

adult population has reached or exceeded this level, 

then the growner should consider the use of a chemical 

insecticide to prevent larval seed damage. 

Egg Scouting Method and Economic Threshold: 

Banded sunfl ower moth eggs can be counted accurately 

using a low power magnifi er. A head-mounted 3.5X 

magnifi er is recommended. Egg counts should be 

made when most of the sunfl ower plants are at stage 

R-3. However, buds should be selected randomly to 

avoid bias. Sampling for banded sunfl ower moth egg 

populations in commercial fi elds should be conducted 

as follows: 

1. Divide each side of the fi eld to be surveyed into 

1,312-foot (400 m) sections. 

2. Sample the center of each 1,312-foot (400 m) 

section at 20 feet (6 m) into the fi eld from the 

fi eld margin. 

3. Randomly select fi ve buds at each sample site. 

4. Randomly select six bracts from the outer whorl 

on each bud and count the banded moth eggs. 

Average the egg counts from the fi ve buds. 

Compare the average egg count to the EIL.

Economic Injury Level (EIL) is the number of eggs 

per six bracts. 

TC 

EIL = 

V x PP x 0.00078 

V = Market value per lb 

PP = Plant population per acre 

TC = Treatment cost 

Example: TC = $8, V = $0.10, and PP = 16,000 

The EIL is 6.4 eggs per six bracts. 

Economic Distance (ED) is the distance into a fi eld 

from a sample site on the fi eld edge where an economically 

damaging population is expected to extend. 

ED gives you the capability to diagram the extent of 

the EIL within a fi eld. Economic Distance: 

ED = e 

[[ 

EIL – 1.29 

(E) 

– .194 

E = Average six bract egg count at 20 feet (6 m) 

*EIL based on eggs per six bracts 

Economic Distance Example: 

Field Size: 800 m by 800 m with average egg 

counts of 15 per six bracts per sample site. 

The EIL is 6.4 eggs per six bracts. 

The ED is 280 feet. 

In this case, only 37 percent of the fi eld would 

need treatment, resulting in a savings of 63 percent. 

Management: Deep fall plowing of sunfl ower stubble 

in Manitoba has reduced moth emergence the following 

season by about 80 percent; however, this is not 

practical for areas practicing conservation tillage. Research 

in North Dakota has demonstrated that delaying 

planting of sunfl ower until late May or early June 

helps reduce infestation levels of the banded sunfl ower 

moth. Parasitic wasps attack both the eggs and larvae 

of the moth. Predators also consume eggs and larvae. 

Since banded sunfl ower moths have a tendency to 

congregate around fi eld margins, perimeter spraying 

has been used with some success. This will minimize 

insecticide treatment costs and impact on pollinators. 

■ Lygus bugs 

Species: Tarnished plant bug, Lygus lineolaris (Palisot 

de Beauvois) and other Lygus species 

Description: The most common species occurring in 

sunfl ower fi elds is the tarnished plant bug. It attacks at 

least 385 different plant species and occurs in 39 U.S. 

states and fi ve Canadian provinces. Adults (Figure 64) 

are small, cryptically colored insects with a distinctive 

yellow triangle or “V” on the wings and 0.2 inch (4 to 

5 mm) in length. They vary in color from pale green to 

dark brown. The immature stages, or nymphs (Figure 

65), are similar in appearance to the adults, but lack 

wings and are usually green in color. They often are 

confused with aphids, but lygus move much more 

rapidly. 

■ Figure 64. Adult - Lygus bug (Tarnished plant bug) 

Lygus lineolaris. (Scott Bauer, http://www.ars.usda.gov/ 

is/graphics/photos/insectsimages.new.htm) 

■ Figure 65. Nymphs - Lygus bug Lygus lineolaris. 

(Scott Bauer, http://www.ars.usda.gov/is/graphics/photos/ 

insectsimages.new.htm) 

Insects 

51

52 

Life Cycle: Adults overwinter in plant debris along 

fi eld margins and shelterbelts. Populations probably 

move to sunfl ower from alfalfa, canola or other 

crops when those plants either have senesced or been 

harvested. Sticky trap catches in North Dakota showed 

that lygus bugs were present throughout the reproductive 

growth stages of sunfl ower. These insects produce 

at least two generations per year in the northern 

Plains. The biology of other Lygus species is similar. 

Damage: Oilseed sunfl ower are not believed to be 

at risk to damage from Lygus feeding at this time. 

The presence of scarring on confection or nonoilseed 

sunfl ower seeds, known as kernel brown spot (Figure 

66), is caused by lygus bugs feeding on the developing 

seed. The quality issue is signifi cant because processors 

discount the fi nished product with only 0.5 percent 

damage. The incidence of damage in 2006 ranged 

between 1 percent and 5 percent in some production 

areas of the northern Plains. Lygus feed preferentially 

on either the developing reproductive organs or on the 

apical meristematic and leaf primordial tissue, causing 

a necrosis around the feeding site due to the injection 

■ Figure 66. Kernel brown spot caused by Lygus bug. 

(Larry Charlet) 

of enzymes. This tissue destruction causes the brown 

spot on the sunfl ower kernel, resulting in a bitter taste 

to the seeds. Greenhouse and fi eld studies showed that 

33 to 38 seeds were damaged per adult lygus bug, and 

that all reproductive growth stages (R-4 to R-5) were 

vulnerable to attack. Damage was reduced if heads 

were infested after fl owering was completed (R-6 to 

R-7). 


developed for lygus bug in sunfl ower. 

Economic Threshold: Approximately 36 seeds are 

damaged by each adult. Therefore, 0.5 percent damage 

on heads with 800 seeds would occur with feeding on 

only four seeds per head. Thus, populations of adult 

lygus at levels of one per nine heads could result in 

economic loss to the producer through the reduction 

of seed quality. 

Management: Lygus can be treated at the same time 

confection sunfl ower is treated for other insects, such 

as the seed weevil and banded sunfl ower moth. Two 

treatments are recommended to suffi ciently protect 

confection sunfl ower heads from insect feeding: one 

application at the onset of pollen shed, or approximately 

10 percent bloom, followed by a second treatment 

seven days later. This program should control 

insects adequately on confection sunfl ower throughout 

fl owering, minimizing the potential feeding damage.

■ Sunfl ower Headclipping Weevil 

Species: Haplorhynchites aeneus (Boheman) 

Description: The sunfl ower headclipping weevil adult 

is shiny black (Figure 67). The weevil is about 0.31 

inch (8 mm) long from the tip of the snout to the rear 

of the abdomen. The area behind the head and thorax 

is large and “squared” in relation to the narrow and 

prolonged head and snout. 

Headclipping weevil larvae are cream-colored, somewhat 

C-shaped and grublike and 0.16 to 0.24 inch (4 

to 6 mm) long (Figure 68). 

Life Cycle: Adults emerge in mid-July and are active 

for a two- to three-week period. The females feed on 

pollen and nectar of fl owering heads. In preparation 

for egg laying, the female makes one nearly complete 

row of feeding punctures around the circumference of 

the stalk just below the head and then lays an egg in 

the head. The girdled head subsequently falls to the 

ground, where larval development and overwintering 

occur. 

Damage: Head clipping by H. aeneus is the most 

apparent type of damage caused by this weevil and 

frequently occurs along fi eld margins. The percent 

of “clipped heads” in a fi eld is normally very low (1 

percent to 3 percent). However, losses up to 25 percent 

have been reported in individual fi elds (Figure 69). 

Scouting Method: The weevils’ presence is determined 

using the X scouting pattern. If the adults are 

encountered only periodically throughout the sampling 

sites, controls should not be necessary. 



for control of the sunfl ower headclipping weevil. 

■ Figure 67. Adult - Sunfl ower headclipping weevil 

Haplorhynchites aeneus. (Extension Entomology) 

■ Figure 68. Larva- Sunfl ower headclipping weevil 

Haplorhynchites aeneus. (Extension Entomology) 

■ Figure 69. Sunfl ower headclipping weevil damage. 


Insects 

53

54 

Diseases of Sunfl ower 

(Carl Bradley, Sam Markell and Tom Gulya) 

Sunfl ower (Helianthus annuus) is unique in that it 

is one of the few crop plants that are native to North 

America. The genus Helianthus comprises more than 

60 annual and perennial species, with one to several 

species found in every state. Since wild sunfl ower 

is a native plant, a native population of diseases and 

insects that can attack cultivated sunfl ower also is 

present in most areas of the U.S. Sunfl ower is also 

unusual in that it is both a fi eld crop, with two distinct 

subtypes (oil and confection), and is grown as a 

garden fl ower and for the cut-fl ower industry. At least 

30 diseases, caused by various fungi, bacteria and 

viruses, have been identifi ed on wild or cultivated 

sunfl ower, but fortunately, only a few are of economic 

signifi cance as far as causing yield losses. When considering 

sunfl owers as an ornamental plant, even small 

spots on the foliage are enough to reduce marketability, 

and thus proper disease identifi cation is necessary 

to decide upon appropriate disease management. See 

Appendix 1 for a listing of all known sunfl ower diseases 

that occur in the world. 

The most important diseases in the northern Great 

Plains are Sclerotinia wilt, Sclerotinia head rot and 

downy mildew. Rust, especially on confection sunfl 

owers, and Phomopsis stem canker are important in 

some years, but are of less overall concern. Phoma 

black stem is almost universally prevalent, but is not 

thought to cause yield losses. Leaf diseases caused by 

Alternaria, Septoria and powdery mildew, head rots 

caused by Botrytis and Erwinia, and Verticillium leaf 

mottle are diseases that either are observed infrequently 

in the northern Great Plains or have not occurred 

with suffi cient intensity to be considered serious. 

The most important sunfl ower disease in both the 

central Great Plains (Kansas, Nebraska, Colorado, 

Texas) and California is Rhizopus head rot. Sclerotinia 

head rot and wilt, downy mildew and Phoma black 

stem are of sporadic importance. In the central Great 

Plains, rust can be severe on sunfl ower grown under 

center pivot irrigation, and Phomopsis stem canker has 

been of concern in years of plentiful rainfall. Under 

drought conditions, charcoal rot is also of concern in 

the central Great Plains. In California, rust, followed 

by various stalk rots, are the most prevalent diseases 

after Rhizopus head rot. For complete details on the 

incidence and severity of sunfl ower diseases, visit the 

National Sunfl ower Association Web site (www.sunfl 

owernsa.com), where the proceedings of the annual 

“Sunfl ower Research Workshop” are posted. 

The production of ornamental sunfl owers in the U.S. 

is scattered across at least 41 states, and includes both 

fi eld and greenhouse production. Greenhouse-grown 

sunfl ower is prone to Pythium and Phytophthora root 

rot and Botrytis blight, as well as the range of sunfl 

ower-specifi c pathogens. Field-grown ornamental 

sunfl ower, especially in the Midwest, is prone to the 

same pathogens that attack oilseed sunfl ower. Sclerotinia 

wilt, rust, powdery mildew, Rhizopus head rot, 

southern blight and root knot nematodes are cited as 

the major diseases. Since cosmetic appearance is so 

important on ornamental crops, even diseases considered 

as minor on an oilseed sunfl ower crop are of 

consequence to ornamental sunfl ower. Thus, obscure 

diseases, such as leaf smut, cocklebur rust and petal 

blight, have been cited as causing losses to ornamental 

sunfl ower in the U.S. and abroad. 

Effective control measures for most sunfl ower diseases 

are: 

• Planting resistant hybrids 

• A minimum rotation of four years between successive 

sunfl ower crops 

• Seed treatment for control of downy mildew and 

damping-off 

• Tillage to bury crop residue that may harbor 

pathogens 

• Foliar fungicides for rust and other foliar diseases

Many sunfl ower diseases are controlled by single 

dominant genes for resistance (e.g., downy mildew, 

Verticillium leaf mottle). Most sunfl ower hybrids in 

the U.S. have resistance to Verticillium leaf mottle, 

several races of downy mildew and several races 

of rust. Unfortunately, the rust and downy mildew 

pathogens continue to evolve and new races are found 

periodically. This requires commercial seed companies 

to add new genes to their hybrids so their hybrids can 

remain resistant to the ever-changing pathogens. Some 

other disease organisms, such as Sclerotinia, require 

multiple genes for resistance, which makes development 

of resistant hybrids much more diffi cult. Great 

strides have been made in making sunfl ower hybrids 

more tolerant of both Sclerotinia wilt (root rot) and 

Sclerotinia head rot. No current hybrids can be considered 

immune to either type of Sclerotinia infection, 

but then again, breeders have so far been unable to 

develop immune varieties for other Sclerotinia-susceptible 

crops. Disease reaction varies widely among 

hybrids, and growers are encouraged to consult seed 

companies and Extension or public research personnel 

for recommended disease-resistant varieties. Producers 

also should remember that disease response is 

highly infl uenced by environment. Disease evaluations 

made in only one location may not accurately predict a 

hybrid’s performance in all areas. 

Crop rotation helps reduce populations of many important 

sunfl ower pathogens in the soil. Most sunfl ower 

diseases are caused by pathogens specifi c to sunfl 

ower. Sclerotinia, however, attacks many crops, and 

susceptible crops (such as mustard, canola, crambe, 

soybean and dry edible bean) should be interspersed 

in rotation with corn and cereals, which are nonhosts 

of Sclerotinia. Rotation time away from sunfl ower is 

infl uenced by the occurrence and severity of diseases 

noted in the current year. Regular monitoring of fi elds 

and maintaining accurate records are also important 

in determining rotation practices. Rotation will have 

a minimal effect on foliar diseases since the pathogen 

spores may be carried by wind from distant fi elds. 

Currently, only two fungicides are employed for foliar 

disease control, with several others in the registration 

process. Consult state Extension publications for more 

details. 

The arrangement of the sunfl ower diseases in the 

following section is based on time of appearance 

during the growing season and the plant part affected. 

Early season diseases (e.g., downy mildew and apical 

chlorosis) are covered fi rst, followed by foliar diseases 

(including virus diseases), stalk and root infecting 

diseases (including nematodes) and fi nally, head rots 

and other diseases of mature plants. 

For additional information and photos of sunfl ower 

diseases, visit the National Sunfl ower Association 

Web site (www.sunfl owernsa.com) and the Web 

site of the USDA Sunfl ower Research Unit in 

Fargo, N.D. (www.ars.usda.gov/main/site_main. 

htm?modecode=54420520), as well as the heavily referenced 

chapter on sunfl ower diseases in “Sunfl ower 

Technology and Production” edited by A.A. Schneiter 

and published by the Agronomy Society of America 

as Monograph No. 35. For current information on 

the disease resistance of commercial hybrids, please 

consult NDSU publication A652, “Hybrid Sunfl ower 

Performance Testing,” available in hard copy or on 

the Web at www.ext.nodak.edu/extpubs/plantsci/rowcrops/a652.pdf. 

Diseases 

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56 

I. Early Season Diseases 

■ Downy Mildew 

Description: Downy mildew has been observed on 

cultivated and wild sunfl ower throughout the U.S. 

and was quite common before the advent of resistant 

hybrids and the use of fungicides as seed treatments. It 

is most serious in areas with fl at topography or heavy, 

clay soils that foster waterlogged conditions conducive 

for disease development. 

Typical systemic symptoms in seedlings include 

dwarfi ng and yellowing (chlorosis) of the leaves 

(Figure 70) and the appearance of white, cottony 

masses (fungal mycelium and spores) on the lower and 

sometimes upper leaf surface during periods of high 

humidity or dew (Figure 71). Most infected seedlings 

are killed, but those that survive will produce stunted 

■ Figure 70. Dwarfi ng and discoloration of sunfl ower 

resulting from infection by downy mildew. 

(D.E. Zimmer) 

■ Figure 71. Lower surface leaves on downy mildew 

infected plants frequently exhibit a white cottony 

growth of fungus. (D.E. Zimmer) 

plants with erect, horizontal heads with little, if any, 

seed (Figure 72). When seedlings are infected several 

weeks after emergence, or a fungicide seed treatment 

inhibits rather than prevents infection, the plants usually 

start showing symptoms at the four-, six- or eightleaf 

stage. This situation is referred to as “delayed 

systemic infection.” These plants are characterized by 

some degree of stunting, with typical downy mildew 

leaf symptoms starting at some level in the plant (with 

lower leaves appearing normal). If susceptible plants 

are exposed to the mildew pathogen after the seedling 

stage, they also may develop a thickened, clublike 

root and become stunted, but may not show foliar 

symptoms. All infected plants serve to perpetuate the 

pathogen in the soil and are more prone to drought 

stress and lodging. 

Sunfl ower plants also display localized foliar lesions 

due to airborne downy mildew spores. The infected 

spots are generally small, angular lesions (delimited 

by veinlets) with white sporulation on the underside of 

the lesion. These local lesions may coalesce into larger 

lesions, but they rarely result in a systemic infection, 

and thus have minimal impact upon yield. 

Dwarfi ng and distortion of leaves also are symptoms 

typical of herbicide drift damage, especially from 

2,4-D and related phenoxy compounds, and may be 

confused with downy mildew symptoms (Figure 73). 

Herbicide damage, however, never will exhibit the 

white appearance (fungal mycelium and spores) on 

the underside of the leaves nor the chlorosis typical of 

downy mildew. 

■ Figure 72. Plants infected with downy mildew 

seldom produce heads; when they do, the heads 

do not nod but remain erect and produce little or no 

seed. (T. Gulya)

Disease Cycle: Downy mildew is caused by the obligate 

fungus Plasmopara halstedii, which is soil-borne, 

wind-borne and seed-borne. Sunfl ower plants are susceptible 

to systemic infection before the seedling roots 

exceed 2 inches in length. This short period may range 

up to a maximum of two to three weeks, depending on 

soil temperature and moisture. Cool, water-saturated 

soil during this period greatly favors infection. The 

fungus may persist in the soil for fi ve to 10 years as 

long-lived oospores. While this downy mildew fungus 

does not infect any crops other than sunfl ower and 

Jerusalem artichoke, weeds in the Compositae family, 

such as marsh elder, are susceptible, and thus may 

serve as reservoirs for the fungus. 

Sunfl ower planted on land with no previous sunfl ower 

history occasionally has shown downy mildew infection. 

There are three principle ways downy mildew 

may occur in fi elds with no previous history of sunfl 

ower. Windblown and soil-borne spores account for 

the majority of such infections. Spores of the fungus 

occurring on volunteer sunfl ower or wild annual 

sunfl ower, even a few miles distant, may be blown to 

newly planted fi elds and result in substantial infection 

under favorable conditions of cool, water-logged soils. 

Spores also may adhere to soil particles and move to 

neighboring fi elds during dust storms. Water running 

through an infested fi eld also may carry mildew 

spores into a previously disease-free fi eld. 

Modern seed production practices, coupled with stringent 

inspection of certifi ed seed, virtually eliminate 

the possibility of introducing downy mildew into a 

“clean” fi eld via infected seed. Seed from infected 

■ Figure 73. Damage to sunfl ower from 2,4-D or 

growth regulator type herbicides may be mistaken 

for downy mildew symptom. (D.E. Zimmer) 

plants is generally either nonviable or so light in 

weight that it is separated during seed processing. 

A slight possibility remains that viable seed may be 

produced on infected plants. These seeds may produce 

healthy plants, systemically infected seedlings 

or plants with latent infection in which the fungus is 

localized in the roots and does not produce symptoms 

on the leaves. These latent infections, however, will 

help perpetuate the disease in the fi eld. 

Damage: Severely infected plants may die before or 

shortly after emergence or in the seedling stage. The 

few plants reaching maturity seldom produce viable 

seed. Heads on these plants typically face straight up, 

rendering them extremely vulnerable to bird feeding. 

Yield losses from downy mildew can be substantial, 

depending on the percentage of infected plants and 

their distribution within the fi eld. If infected plants 

are scattered randomly throughout a fi eld, yield losses 

probably will not be observed unless infection exceeds 

15 percent. Sunfl ower have excellent compensating 

ability when healthy plants are adjacent to infected 

plants. When the disease is in a localized area, such 

as a low spot in a fi eld, and all plants are infected, the 

resultant yield loss is much greater. 

Management: The continued discovery of new downy 

mildew races and the occurrence of mildew strains 

resistant to Apron XL (mefenoxam) and Allegiance 

(metalaxyl) seed treatment have altered management 

strategies. When these seed treatments were effective, 

seed companies had no need to develop resistant 

varieties. Now most seed companies are developing 

hybrids that use multirace immunity, which should be 

effective despite the development of new races. Not 

all hybrids in a company’s lineup will have downy 

mildew resistance, however. At least two dozen races 

of the fungus have been identifi ed in the U.S., but annually, 

usually two to three races make up the majority 

of races. Fortunately, lines released by the USDA are 

available that confer resistance to all known races. 

With the appearance of downy mildew strains that 

are insensitive to metalaxyl and mefenoxam fungicide 

seed treatments (Apron XL, Allegiance), efforts 

are under way to fi nd replacement seed treatments. 

The fungicide azoxystrobin (Dynasty) recently has 

been labeled for use on sunfl ower as a seed treatment 

Diseases 

57

58 

for downy mildew suppression. As other effective 

chemicals are registered for use as sunfl ower seed 

treatments, the most effective management strategy 

would be to use two fungicides at the same time. A 

two-fungicide treatment will improve disease control 

and probably be less costly, in addition to delaying the 

development of fungicide resistance in downy mildew. 

Seed-applied fungicides will protect against root infection 

by all races, and thus will augment protection 

offered by resistant hybrids. 

Seed applications, however, will not protect against 

foliar infection. Since the fungicides are water-soluble, 

they can be washed off shallow-planted seed with 

excessive rainfall, resulting in poor disease control. 

Selection of downy mildew-resistant hybrids is the 

most effective way of controlling downy mildew. 

Seed companies are actively incorporating genes that 

control all known races, and these hybrids will be 

immune, at least until a new race emerges. Additional 

management practices that minimize downy mildew 

problems include extended crop rotations, eradication 

of volunteer sunfl ower, avoiding poorly drained fi elds 

or those with excessive low areas and delaying planting 

until warm soil temperatures foster rapid seedling 

growth. 

■ Apical Chlorosis 

Description: Apical chlorosis is the one of two bacterial 

diseases of sunfl ower that is noticed with any 

regularity in the U.S. The causal organism is Pseudomonas 

syringae pv. tagetis. Apical chlorosis is striking 

and seldom goes unnoticed. The major symptom of 

the disease is the extreme bleaching or chlorosis of 

the upper leaves (Figure 74). Apical chlorosis may be 

distinguished from iron chlorosis or nitrogen defi - 

ciency by the complete lack of green pigment and the 

uniformity of the chlorosis. With mineral defi ciencies, 

the veins characteristically remain green. In addition, 

the white leaves affected by apical chlorosis never 

will “regreen,” while those due to mineral defi ciencies 

will. 

Disease Cycle: Apical chlorosis occurs only during 

the vegetative growth stage when leaves are actively 

expanding. It is most severe in young seedlings during 

cold weather and in water-logged soils. 

Damage: Plants affected by apical chlorosis usually 

will produce new green leaves in several weeks 

with little discernible effect other than striking white 

leaves in the middle of the plant. Thus, yield reductions 

due to apical chlorosis are minimal. However, 

if long periods of cold spring temperatures coincide 

with water-logged soils, seedlings affected by apical 

chlorosis may die. Yield losses still will be minimal as 

healthy neighboring plants should compensate for the 

dead seedlings. 

Management: No hybrids are completely immune to 

apical chlorosis. The only control recommendation 

at present is to follow a four-year rotation to avoid 

increasing the population of the bacteria in the soil. 

Roguing (identifying and removing) infected plants 

in seed production fi elds will eliminate the disease 

and minimize the possibility of infected seed. This 

same bacterium will produce apical chlorosis on other 

Compositae weeds, such as thistles, ragweed, other 

Helianthus species (including cultivated Jerusalem 

artichoke), marigold and zinnia. Thus, controlling volunteer 

sunfl owers and Compositae weeds, as potential 

disease reservoirs, will help minimize soil populations 

of this bacterium. 

■ Figure 74. Apical chlorosis is characterized by an 

extreme bleaching or chlorosis of the upper leaves. 

(William K. Pfeifer)

II. Foliar Diseases 

■ Rust 

On most crops, rust refers to a single fungal species. 

On sunfl ower, the main fungus causing rust is Puccinia 

helianthi, which is worldwide in distribution and 

causes economic losses. In North America, four other 

Puccinia species are found on wild and cultivated sunfl 

ower: P. canaliculata (nutsedge rust), P. enceliae, P. 

massalis and P. xanthii (cocklebur rust), plus one rust 

from another genus, Coleosporium helianthi. The following 

discussion will deal mainly with P. helianthi, 

with minimal descriptions of the other rust fungi. 

Description: Rust occurs in all sunfl ower production 

areas of the U.S. and Canada and also is widespread 

on wild sunfl ower. Most oilseed hybrids have 

had good resistance to the prevailing rust races, but 

changes in the rust population in the last decade 

have resulted in greater rust severity and occasionally 

in substantial losses in seed yield or seed quality. 

Confection hybrids are generally more susceptible 

to rust (and other diseases) than oilseed hybrids. At 

least 25 different rust races have been identifi ed in 

the U.S., which makes breeding for rust resistance a 

challenge. Rust, incited by the fungus Puccinia helianthi, 

is characterized by cinnamon-colored spots or 

uredial pustules, which primarily occur on the leaves 

(Figure 75) but also on the stems, petioles, bracts and 

the back of the head under severe infestations. The 

initial appearance of rust is determined by adequate 

rainfall and warm temperatures, so the disease usually 

occurs in late summer in the northern Great Plains. 

The uredial pustules turn black with the advent of cool 

temperatures as the brown urediospores are replaced 

by black overwintering teliospores. 

Disease Cycle: This rust completes its entire life cycle 

on sunfl ower and does not require an alternate host, as 

do some cereal rusts. Puccinia helianthi overwinters 

on plant debris as teliospores (thick walled, resting 

spores). These spores germinate in the spring to 

produce basidiospores that infect volunteer seedlings 

or wild sunfl owers. This initial infection results in the 

formation of pycnia (generally on the underside of 

leaves), which, in turn, leads to aecial pustules, generally 

on the upper surfaces of leaves or cotyledons. The 

aecia are small (1/8 inch), orange cup-shaped pustules 

that may occur singly or in small clusters (Figure 76). 

The aeciospores are spread by wind to other sunfl ower 

plants, where they initiate the cinnamon-brown uredial 

pustules. The uredial stage is the repeating portion of 

the rust life cycle. Rust multiplies rapidly under favorable 

conditions of warm temperatures and either rain 

or dew. Thus, even in dry years, if night temperatures 

are low enough to promote dew formation on leaves, 

this minimal amount of leaf wetness will be suffi cient 

to initiate rust infection. Excessive rates of nitrogen 

fertilization and abnormally high seeding rates result 

in excessive foliage, which increases humidity within 

the canopy and favors rust development. 

Damage: Rust not only reduces yield, but also reduces 

oil, seed size, test weight and kernel-to-hull ratios. 

Late-planted fi elds of susceptible hybrids are generally 

more severely damaged by rust than earlier-planted 

fi elds. Irrigated fi elds also are apt to have more severe 

infection as the constantly wet leaves provide an ideal 

environment for the rust fungus to multiply. 

■ Figure 75. Rust occurs most commonly on leaves 

and after fl owering. The cinnamon-red pustules 

produce summer spores; the black pustules occur late 

fall and produce overwintering spores. (D.E. Zimmer) 

■ Figure 76. Aecial cups of Puccinia helianthi. 

(T. Gulya) 

Diseases 

59

60 

Management: The most effective way to avoid loss 

from rust is by planting rust-resistant hybrids. With 

sunfl owers grown under center pivot irrigation, night 

irrigation fosters more rust infection since the spores 

germinate best in the dark. Headline (pyraclostrobin) 

and Quadris (azoxystrobin) are registered for control 

of rust on sunfl ower, and additional fungicides may 

become registered. Refer to the most current edition 

of the “North Dakota Field Crop Fungicide Guide” 

(PP-622) available from the NDSU Extension Service 

to view fungicide products registered on sunfl ower. 

The injury threshold (i.e., disease severity above 

which fungicide spraying is warranted to minimize 

yield loss) developed for using tebuconazole is when 

the rust severity on the upper four leaves is 3 percent 

or greater. High rust severity on lower leaves has 

less impact upon seed yields, as the upper leaves are 

the ones supplying most of the photosynthate for the 

developing seeds. 

Sunfl ower rust, like cereal rusts, occurs as many different 

“physiological races,” which constantly change. 

Thus, hybrids selected for rust resistance eventually 

become susceptible as rust races change. Seed companies 

continually are testing their hybrids in different 

locations to determine rust resistance against the 

various races from region to region. Rust evaluations 

made under conditions of natural infection or with 

artifi cial inoculation of specifi c races also are done 

by university research centers, and this information 

frequently is found in the NDSU publication “Hybrid 

Sunfl ower Performance Testing” (A652). A few other 

management practices, besides rust-resistant hybrids, 

that can minimize rust are available. Destruction of 

volunteer plants and wild annual sunfl ower occurring 

in the vicinity of commercial fi elds as early in the 

spring as possible will reduce sources of inoculum. 

High rates of nitrogen fertilizer and high plant populations 

both foster dense canopy development that in 

turn create ideal conditions for rust infection, and thus 

should be avoided if rust is of concern. 

Other Rusts: As mentioned previously, four other 

Puccinia species and one Coleosporium species of 

rust can infect sunfl ower in parts of the U.S. None 

of them have yet to be reported to be of economic 

signifi cance on cultivated sunfl ower, but they might 

be considered potential nuisance foliar pathogens 

on ornamental sunfl owers. As sunfl ower production 

expands into new areas, especially in the south-central 

and southwestern U.S., the possibility of other Puccinia 

species attacking cultivated sunfl ower increases. 

Puccinia xanthii, commonly known as cocklebur 

rust, is easy to distinguish from P. helianthi based on 

pustule size. This rust is microcyclic, with only telia 

and basidiospores, and does not exhibit the fi ve spore 

stages of a full-cycle (macrocyclic) rust such as P. 

helianthi. On sunfl ower, the telial pustules are few in 

number, range from 1/4 to 3/8 inch in diameter, are 

distinctly puckered (convex) and bear a layer of dark 

brown spores only on the underside of leaves. As the 

teliospores germinate in place, the spore layer changes 

from brown to gray. As little as two to three hours of 

dew at temperatures of 68 to 77 F is suffi cient for P. 

xanthii infection. Sunfl ower is minimally susceptible 

to this rust. The main host for this rust is cocklebur 

(Xanthium species), with some authors also listing 

ragweed (Ambrosia). This rust has been seen only 

once on sunfl ower, and only in North Dakota. 

Puccinia enceliae and P. massalis are two rusts 

that are recorded on wild Helianthus species in the 

southwestern U.S. and have been shown to infect 

cultivated sunfl ower in greenhouse tests. No reports 

of them being identifi ed on or causing yield losses to 

cultivated sunfl ower are known. Puccinia massalis is 

reported only on Texas blueweed (Helianthus ciliaris) 

in the Rio Grande Valley of Texas and New Mexico. 

Uredial pustules are indistinguishable from those of P. 

helianthi. Positive identifi cation of P. massalis requires 

microscopic examination of teliospores for the placement 

of germ pores. Puccinia enceliae occurs on wild 

Helianthus and dessert shrubs in the genera Viguiera 

(goldeneye and resin bush), Encelia (brittlebush) and 

Tithonia (Mexican sunfl ower) in the desert regions of 

western U.S. and northern Mexico. Uredial and telial 

pustules of P. enceliae on sunfl ower are similar in 

appearance to those of P. helianthi. Positive identifi cation 

of P. enceliae requires microscopic examination 

of teliospores. Neither of these two Puccinia species 

has been observed on sunfl ower in the northern Great 

Plains. 

Puccinia canaliculata is a full-cycle, heteroecious rust 

that has its aecial stage on sunfl ower and cocklebur 

(Xanthium strumarium), and its uredial and telial stage

on sedges of the genus Cyperus. This rust had been 

considered as a possible mycoherbicide for control of 

the noxious weed yellow nutsedge. On sunfl ower, the 

aecial pustules look very similar to the telial pustules 

of P. xanthii in shape, with the main difference that the 

P. canaliculata aecia on the underside of the leaf are 

orange, as compared with the dark brown of the telia 

of P. xanthii. This rust has been observed in Kansas in 

a sunfl ower fi eld infested with nutsedge. Since the rust 

requires both hosts to complete its life cycle, elimination 

of the nutsedge effectively will limit this rust 

infection of sunfl ower. 

Coleosporium species are commonly referred to as 

pine needle rusts and are heteroecious rusts (requiring 

two different hosts to complete their life cycle). 

Coleosporium helianthi has its uredial and telial stages 

on sunfl ower, and the remainder of its life cycle on 

two- and three-needle pines, such as Jack pine, Virginia 

pine and loblolly pine. The rust is of minimal economic 

importance in pine plantations and never has 

been observed on cultivated sunfl ower. On Jerusalem 

artichoke (and other perennial Helianthus species), C. 

helianthi infections can be quite severe and potentially 

cause yield losses. Preliminary greenhouse tests have 

shown that cultivated sunfl ower is susceptible, with 

little differences between commercial hybrids. The 

most effective way to prevent C. helianthi infection 

on sunfl ower is to avoid planting near shelter belts or 

areas with two-needle pines. 

■ Albugo or “White” Rust 

Description: White rust is one of the rarest sunfl 

ower diseases in North America, but is considered a 

potentially serious disease in countries such as South 

Africa and Argentina. Despite the word “rust” in the 

common name, this disease is caused by a pathogen 

more closely related to downy mildew. White rust has 

been recorded on sunfl ower in North America only 

in western Kansas, eastern Colorado and adjacent 

Nebraska during the late 1990s and seldom is seen 

in this area. In North Dakota, it has been recorded on 

ragweed (Ambrosia spp.), various sage and sagebrush 

(Artemisia spp.) and goatsbeard (Tragopogon). White 

rust has not been recorded on either wild sunfl ower or 

cultivated sunfl ower in the northern Great Plains or in 

Canada on sunfl ower. 

Foliar lesions, consisting of raised, chlorotic pustules 

up to 3/8 inch in diameter, are the most commonly 

seen symptom on sunfl ower in the U.S. (Figure 77). A 

dull, white layer of spores forms in these pustules on 

the underside of the leaf, which could be mistaken for 

local lesions caused by downy mildew. If the Albugo 

pustules are numerous enough, they will merge as they 

enlarge, and entire areas of the leaf will turn necrotic 

as secondary fungi colonize the pustules. 

One striking feature often seen with Albugo is that a 

single horizontal “layer” of leaves in the crop canopy 

usually is affected, with a sharp demarcation of 

healthy leaves above and below the affected leaves. 

This delimited layer of infected leaves suggests that 

environmental conditions and Albugo spores were 

■ Figure 77. Albugo lesions on upper leaf surface (left) and lower leaf surface (right). (T. Gulya) 

Diseases 

61

62 

present for a very short time, thus only one layer of 

leaves shows symptoms. Albugo also can cause lesions 

on stems, petioles, bracts and the back of heads. The 

lesions on stems (Figure 78), petioles and the back of 

the heads are much different from those on leaves, and 

appear to be dark, bruiselike lesions. This appearance 

is due to the presence of black oopsores just beneath 

the epidermis. No white sporangia ever are seen in 

the stem or petiole lesions. Stem lesions often are 

colonized by other fungi and may lead to stalk rot and 

lodging by the secondary fungi. Petiole lesions may 

girdle the petiole and cause the affected leaf to wilt, 

thus causing considerable damage and yield loss. 

Disease Cycle: The causal agent of white rust is the 

obligate fungus Albugo tragopogonis, which recently 

has been reclassifi ed as Pustula tragopogonis. In 

addition to sunfl ower, this fungus infects cocklebur 

(Xanthium), groundsel (Senecio), marsh elder (Iva), 

ragweed (Ambrosia) and several other weedy Composites. 

The fungus appears to have host-specifi c races, 

however, so white rust occurring on one host genus 

may not infect other genera or cause only minimal 

infection. Albugo overwinters as oospores in infected 

plant debris. Rain splashes the oospores onto nearby 

seedlings, where they germinate to form motile zoospores 

that enter through stomates. The pustules that 

develop contain masses of dry, white asexual sporangia. 

The pustules rupture to release sporangia that are 

windblown to other plants to continue leaf infection. 

Sporangia also can initiate infection on stems, petioles 

and bracts. Optimal conditions for Albugo infection 

■ Figure 78. Albugo lesions on stems. (T. Gulya) 

are cool nights (50 to 60 F) with rain or dew, but lesion 

development is favored by warm days (70 to 80 

F). 

Damage: Foliar infection by Albugo seldom causes 

yield loss, although the symptoms are quite noticeable. 

Lesions on stems and petioles, which fortunately 

are seen seldom in the U.S., are much more serious. 

Petiole lesions lead to defoliation, with signifi cant 

yield losses, and stem lesions may become colonized 

by other fungi and result in lodging. Albugo infections 

on the head may result in seed infection, which would 

be of concern in seed production fi elds. 

Management: Field trials have shown that sunfl ower 

plants can tolerate a high proportion of foliage infection 

by Albugo before yield losses are observed. Stem 

and petiole lesions caused by Albugo are more serious, 

as stem lesions can result in lodging and petiole 

lesions will result in defoliation. In countries where 

Albugo is serious, commercial seed companies have 

made the effort to develop resistant hybrids. In the 

U.S., no information is available regarding the reaction 

of hybrids to white rust. Evaluations of USDA breeding 

material have shown that resistance probably is 

controlled by several genes, each governing infection 

of leaves, stem, petioles and heads. Since Albugo is an 

Oomycete, like downy mildew, the same fungicides 

that control downy mildew have been effective against 

white rust. Thus, seed treatment with metalaxyl or 

mefenoxam will offer protection against both systemic 

infection and foliar infection for a limited time. Rotation 

is of limited use with Albugo, as the spores can be 

windblown from adjacent fi elds.

■ Alternaria Leaf and Stem Spot 

Description: Alternaria leaf spot is a ubiquitous 

disease on senescing leaves and generally of little 

concern, but under warm, humid conditions it can be a 

serious defoliating disease. The Midwest has two main 

species of Alternaria: A. helianthi and A. zinniae, of 

which A. helianthi is the more prevalent and more 

serious. In addition, several other Alternaria species 

have been reported on sunfl ower, including A. alternata, 

A. helianthicola, A. helianthinfi ciens and A. protenta. 

Alternaria helianthi and A. zinniae both produce 

dark brown spots on leaves. These spots are irregular 

in size and shape with a very dark border and a gray 

center (Figure 79). The spots on young plants may 

have a yellow halo. Leaf lesions may coalesce, causing 

leaves to wither. Stem lesions begin as dark fl ecks 

that enlarge to form long, narrow lesions (Figure 

80). These stem lesions often coalesce to form large 

blackened areas, resulting in stem breakage. Stem 

lesions are distributed randomly on the stem and are 

not associated with the point of attachment of the leaf 

petiole. Brown, sunken lesions also may form on the 

back of the head, especially following any mechanical 

damage such as that caused by hail or birds. The 

leaf and stem lesions caused by the various Alternaria 

species are similar and thus not diagnostic. Therefore, 

microscopic examination is required to distinguish 

which Alternaria species is present. 

Disease Cycle: All Alternaria fungi overwinter on 

diseased stalks. They can be seed-borne at low levels, 

■ Figure 79. Leaf lesions caused by Alternaria 

hellanthi. (B.D. Nelson) 

although seed is a relatively unimportant source of 

the inoculum under most conditions. Seedling blights 

caused by Alternaria may develop when sunfl ower 

plants emerge in rainy weather on Alternaria-infested 

soil. However, plants at the fl owering to maturing 

stage are more susceptible than plants in the vegetative 

or budding stage. Saffl ower and cocklebur also can be 

alternate hosts of A. helianthi. 

Disease development in A. helianthi is favored by 

77 to 82 F temperatures and at least 12 hours of wet 

foliage. Extended wet periods of three to four days can 

cause serious losses as the spots enlarge. 

Damage: The primary damage that all Alternaria 

species cause is the leaf blights that lead to defoliation 

which increases the potential for yield loss. In 

the northern Great Plains, the climate is usually not 

conducive for Alternaria epidemics, and Alternaria 

generally affects only the lower, senescing leaves. 

However, in warmer climates with plentiful rainfall, 

the potential for defoliation by Alternaria species 

and subsequent yield loss is much greater. In addition 

to the direct yield loss caused by foliar Alternaria 

infection, this fungus also has been noted to cause 

blemishes on the achenes. While this damage may be 

only superfi cial, if the achenes are on confection sunfl 

owers destined for human consumption, the impact 

of “achene blemish” can be signifi cant. This achene 

■ Figure 80. Stem lesions caused by Alternaria 

hellanthi. (T. Gulya) 

Diseases 

63

64 

blemish, currently noted only on sunfl ower grown 

in Israel, looks very similar to “kernel black spot,” 

which is caused by feeding by the tarnished plant bug 

(Lygus), with no involvement from Alternaria. 

Management: Alternaria leaf blights are considered a 

major disease in subtropical sunfl ower growing areas, 

where yield losses may range from 15 percent to 90 

percent, but are much less serious in temperate areas 

of the U.S. However, severe epidemics have been 

observed on sunfl ower in the eastern and southeastern 

portions of the U.S. Management practices to minimize 

Alternaria problems include crop rotation and 

burying of infested crop refuse to hasten decomposition. 

Consult university Extension publications, such 

as NDSU’s PP-622, “Field Crop Fungicide Guide,” for 

current recommendations of foliar fungicides registered 

for use on sunfl ower for Alternaria control. Seed 

treatments with metalaxyl or mefenoxam offer no 

control of Alternaria seedling blights. 

■ Septoria Leaf Spot 

Description: Septoria leaf spot develops fi rst on the 

lower leaves and spreads to the upper leaves. The spots 

begin as water-soaked areas (greasy green in appearance). 

The spots become angular, with tan centers 

and brown margins (Figure 81). A narrow yellow halo 

often surrounds young spots. Mature leaf spots may 

contain tiny black specks, the fungal fruiting bodies 

(pycnidia), which are visible with a 5X to 10X hand 

lens. The presence of pycnidia is the best means of 

distinguishing leaf spots caused by Septoria from 

those caused by Alternaria. 

Disease Cycle: Septoria leaf spot can be caused by 

two Septoria species, S. helianthi. and S. helianthina, 

of which the former is the major species in the U.S. 

Septoria can be seed-borne and also can survive on 

infected sunfl ower crop refuse. Septoria leaf spot 

may appear anytime during the growing season and is 

favored by moderately high temperatures and abundant 

rainfall. As such, the disease potentially is more 

severe in southern growing areas, compared with the 

northern Great Plains. 

Damage: In the temperate climate of the Midwest, 

Septoria leaf spot usually causes little damage. Severe 

Septoria infection may cause some defoliation, but if 

this affects only the lower leaves on mature plants, the 

impact upon yield will be minimal. 

Management: Crop rotation, incorporation of sunfl 

ower residue and clean seed are the best means of 

managing Septoria leaf spots. Although resistance to 

Septoria has been identifi ed in breeding material, the 

infrequent occurrence of Septoria has not warranted 

the development of resistant hybrids. 

■ Figure 81.Septoria leaf spot. Note small black 

pycnidia in lesions. (T. Gulya)

■ Powdery Mildew 

Description: Powdery mildew, caused by the fungus 

Erysiphe cichoracearum, can be found in most fi elds 

after full bloom. The symptoms are distinctive and 

easy to recognize: a dull white to gray coating of the 

leaves, starting as individual circular spots and eventually 

merging to cover the entire leaf (Figure 82). This 

coating is the scant mycelial growth of the fungus 

on the leaf surface. Severely infected areas senesce 

prematurely and dry up. Normally the lower leaves are 

more heavily infected than the upper leaves. In other 

countries, two other powdery mildew fungi have been 

documented on sunfl ower: Sphaerothecia fuliginea 

and Leveillula taurica. These both exist in the U.S., 

but to date have not been documented on sunfl ower. 

Disease Cycle: Powdery mildew seldom is seen until 

late in the growing season, as senescing leaves are 

most susceptible to infection. While leaves are the 

most common plant part affected, powdery mildew 

also will form on bracts and the backs of heads. The 

powdery coating seen is a combination of scant mycelia 

and spores of the asexual stage, which is referred to 

as Oidium. As the season progresses, the fungus forms 

small (pinhead-sized) black cleistothecia, the sexual 

fruiting bodies. 

Damage: Powdery mildew generally occurs late 

enough in the season that control measures are not 

needed. Sunfl ower cultivars differ widely in reaction 

to powdery mildew. On ornamental sunfl ower, especially 

those grown in the greenhouse, powdery mildew 

is common. Although the main impact of the disease 

is cosmetic, this alone can cause economic losses. 

Management: Powdery mildew is seldom a problem 

on cultivated sunfl ower in the Midwest, but may be 

of concern in more humid areas and on the southern 

Plains states. On ornamental sunfl owers, powdery 

mildew can be minimized by adequate air movement, 

allowing the leaves to dry, and by the use of registered 

fungicide sprays specifi c for powdery mildew. 

■ Figure 82. Powdery mildew with fungus producing 

white, powdery spores on leaf surface. (Reu V. Hanson) 

■ Diseases Caused by Viruses and 

Phytoplasmas 

Description: Several viruses have been reported 

on sunfl ower from other countries and the warmer 

regions of the U.S. (Florida), but no reports of viruses 

occurring on sunfl ower in the northern Great Plains 

have been confi rmed. Wild sunfl ower is a host of 

Tobacco ring spot virus in the Rio Grande Valley, and 

Cucumber mosaic virus has been reported on sunfl ower 

in Maryland. Viruses reported on sunfl ower outside 

the U.S. include Tobacco streak virus, Tomato big bud 

virus, Sunfl ower rugose mosaic virus, and Tomato 

spotted wilt virus. Confi rmation/identifi cation of a 

virus as the causal agent is based on observation of the 

viral particles using an electron microscope, detailed 

chemical analysis of the viral components or serological 

identifi cation. 

The only well-documented virus found on sunfl ower 

in the U.S. is Sunfl ower mosaic virus (SuMV), currently 

found only in southern Texas on both cultivated 

sunfl ower and wild Helianthus species. Symptoms of 

SuMV are a mottled pattern of light green and normal 

green areas on the leaf, referred to as mosaic (Figure 

83). Affected plants may die in the seedling stage or 

live to maturity, with all leaves affected. 

Aster yellows is a disease at fi rst believed to be caused 

by a virus but which has since been identifi ed as a 

phytoplasma. Phytoplasmas are living cells, in contrast 

to viruses, and are intermediate in size between 

viruses and bacteria. Symptoms on sunfl ower include 

yellowing of leaves and/or the head, which often occurs 

in sectors. A characteristic symptom is a wedgeshaped 

portion of the head that remains green and 

bears small leaves rather than fl oral parts (Figure 84), 

a condition termed “phyllody.” 

Diseases 

65

66 

■ Figure 83. Sunfl ower mosaic virus. (T. Gulya) 

Disease Cycle: SuMV is spread primarily by aphids 

but is also seed-borne to a small extent. Seedlings less 

than a month old are the most susceptible, and mosaic 

symptoms appear within a week after aphid transmission. 

Affected leaves will retain the mosaic pattern for 

the life of the plant, but no stunting due to the virus is 

discernible. 

The aster yellows phytoplasma is transmitted only by 

the aster leaf hopper (Macrosteles quadrilineatus) and 

occurs on a wide variety of plants. Symptoms generally 

appear at fl owering, and affected heads will show 

the symptoms for the remainder of the summer. 

Damage: SuMV, which currently is found only in 

Texas, can substantially reduce yield in individual 

plants. No fi elds have been observed with high incidence. 

This disease is also of quarantine signifi cance, 

and many countries will not accept seed from fi elds 

with any level of SuMV. Aster yellows, which occurs 

throughout the Midwest, is sporadic in occurrence 

and is generally more of a novelty than of economic 

consequence. 

■ Figure 84. Aster yellows. Note wedged 

shaped portion of head which remains 

green. (Donald Henne) 

Management: As both SuMV and aster yellows are 

spread by insects, the easiest means of minimizing 

both diseases is to control their insect vectors. Varietal 

differences to aster yellows have been noted. In contrast, 

no resistance to SuMV is available in commercial 

hybrids, although resistance has been found in 

wild Helianthus species from Texas. 

■ Other Miscellaneous 

Foliar Diseases 

The diseases mentioned above are the most likely leaf 

diseases to be encountered in the main sunfl ower-producing 

areas of the Midwest. As sunfl ower production 

expands into other areas, a possibility exists of other 

fungi causing leaf spots. Some of the fungi recorded 

to cause leaf spots on wild sunfl ower in other areas of 

the U.S. include Ascochyta compositarum, Cercospora 

helianthi, C. pachypus, Colletotrichum helianthi, Entyloma 

compositarum (leaf smut), Epicoccum neglectum, 

Itersonilla perplexans, Myrothecium roridum, 

Phialophora asteris (Phialophora yellows), Phyllosticta 

wisconsinensis and Sordaria fi micola. Check out 

the “Sunfl ower Diseases” chapter by Gulya et al. in 

“Sunfl ower Technology and Production,” published by 

the Agronomy Society of America, for more details on 

these minor foliar pathogens.

III. Stalk- and Root-infecting 

Diseases 

■ Sclerotinia Wilt 

Description: Sclerotina wilt usually is observed fi rst 

as plants start to fl ower. The fi rst symptoms include a 

sudden wilting (Figure 85) with no other leaf symptoms, 

and a characteristic stalk lesion at the soil line. 

The length of time from the fi rst sign of wilt to plant 

death may be as little as four to seven days. The stalk 

lesions that form at the soil line are tan to light-brown 

and eventually may girdle the stem (Figure 86). Under 

very wet soil conditions stalks and roots may be 

covered with white mycelia and hard black structures 

called sclerotia (Figure 87). Sclerotia are irregularshaped 

structures which range in size and shape from 

spherical and 1/8 inch in diameter to cylindrical or 

Y-shaped and up to 1 inch in length. Sometime a series 

of dark “growth” rings produced by the daily extension 

of the fungus can be observed. 

Disease Cycle: Sclerotinia sclerotiorum overwinters as 

sclerotia in the soil or in plant debris. When sunfl ower 

roots grow near sclerotia, the sclerotia are stimulated 

to germinate, and the resulting mycelium infects the 

lateral roots. The fungus grows along the root system 

to the tap root and up into the stem, and the plant wilts 

and dies. Contact between roots of adjacent plants 

within rows allows the fungus to spread from plant to 

plant. The fungus does not move between conventionally 

spaced rows. Sunfl ower is the only crop that S. 

sclerotiorum consistently infects through the roots. 

Other susceptible crops are infected mainly by spores 

on above-ground parts of the plant. 

Sclerotia are formed in the decayed stem pith and on 

the roots as the plant dies. These sclerotia then are 

returned to the soil during tillage operations and serve 

as sources of inoculum for the next susceptible crop. 

Sclerotia can survive in the soil for fi ve or more years, 

with a portion of them dying each year if they fail to 

infect a host. The higher the inoculum density (i.e., the 

number of sclerotia in the soil), the longer the period a 

■ Figure 

85. Sudden 

wilting is a 

characteristic 

symptom of 

Sclerotinia 

wilt. 

(B.D. Nelson) 

■ Figure 86. Basal canker formed from Sclerotinia 

wilt infection. (B.D. Nelson) 

■ Figure 87. 

Dense white 

mold may form 

on the surface 

of the basal 

canker. Hard 

black bodies 

called sclerotia 

also form on the 

outside and the 

inside of stems. 

(D.E. Zimmer) 

Diseases 

67

68 

fi eld will remain infested. Soil moisture and temperature 

during the growing season are not critical factors 

affecting wilt incidence. Plant population, in the range 

from 15,000 to 30,000 plants per acre on 30- or 36inch 

rows, is not a factor affecting disease incidence, 

although solid seeding should be avoided. Lodging of 

wilted plants, however, increases at high plant populations 

due to smaller stem diameter. 

Damage: Historically, wilt is the most prevalent of 

the Sclerotinia diseases, with the disease found in one 

out of two fi elds in the Dakotas, and about 3 percent 

of the crop affected. Wilt occurs whenever sunfl ower 

is planted on Sclerotinia-infested soil and can cause 

severe yield loss. Infected plants die rapidly, and if 

this occurs before the seed is fully mature, the result is 

a loss of seed yield accompanied by lower test weight 

and lower oil content. Since plant death occurs late in 

the season, healthy adjacent plants have little opportunity 

to compensate for the loss of the Sclerotinia-infected 

plant. On the average, infected plants yield less 

than 50 percent of healthy plants. Equally important, 

however, is that Sclerotinia wilt leads to increased 

numbers of sclerotia in the soil, thus contaminating 

the fi eld for all susceptible crops that would be in the 

rotation. 

Management: Sclerotinia wilt is a diffi cult disease 

to manage for several reasons. First, the fungus has a 

very broad host range and basically is able to infect all 

broadleaf crops to some extent. Rotation to minimize 

Sclerotinia is most effective with cereal grains and 

corn. Second, since the sclerotia can persist in the soil 

for long periods of time, long rotations away from 

broadleaf crops are necessary to minimize sclerotial 

populations in the soil. This may not be feasible 

because repeated cropping of cereal grains will lead to 

a buildup of cereal diseases, especially Fusarium head 

blight. Sunfl ower breeders have strived to increase the 

level of resistance to Sclerotinia wilt and tremendous 

improvements have been made, but no immune hybrids 

are on the market yet. Based on several years of 

tests with artifi cial inoculations, commercial hybrids 

with extremely good levels of resistance are available. 

Information on hybrid ratings for Sclerotinia stalk 

rot resistance is found in NDSU publication A-652, 

“Hybrid Sunfl ower Performance Testing.” 

Lastly, chemical control is not an option since the 

sclerotia are low in number and scattered throughout 

the soil. The most effective chemicals would be soil 

fumigants used for nematocide control, and even if 

the chemicals were registered on sunfl ower, the cost 

would be prohibitive. Two management strategies hold 

promise to minimize, but not eliminate Sclerotinia. 

One is the use of biocontrol. Various fungi, termed 

mycoparasites because they feed upon other fungi, 

have been shown to attack Sclerotinia. One such 

fungus is Coniothryium minitans, which is found in 

the registered product called “Contans.” If this product 

is applied to the soil (and preferably to the crop before 

disking), the mycoparasite Coniothryium will colonize 

the sclerotia and kill the sclerotia in several months 

rather than years. This will allow shortened rotations 

to be used, but replanting a Sclerotinia-infested fi eld to 

a susceptible crop (e.g., dry bean, canola, sunfl ower) 

the following year still is inadvisable. 

Another management option is tillage, and this is at 

the center of two schools of thought. One opinion is 

that deep tillage (inversion of the soil profi le via moldboard 

plowing) will put the sclerotia deep into the 

soil in an anaerobic environment where they are more 

prone to bacterial degradation and are out of the plant 

root zone. If deep tillage is used, producers should 

practice reduced tillage in the following years to prevent 

bringing the buried sclerotia back to the surface. 

The second school of thought is to let the sclerotia 

remain on the soil surface, where they are subject both 

to weathering and attack by other fungi. No conclusive 

evidence is available to show that either no-till or deep 

tillage produces signifi cantly less Sclerotinia wilt with 

sunfl ower, although research on soybeans strongly 

favors no-till to reduce sclerotia numbers.

■ Sclerotinia Middle Stalk Rot 

and Head Rot 

Description: Middle stalk rot is the disease least often 

caused by Sclerotinia, and is fi rst observed in the middle 

to upper portion of the stalk at or before fl owering. 

Midstalk rot begins with infection of the leaf, and the 

fungus progresses internally through the petiole until 

it reaches the stem (Figure 88). Symptoms of Sclerotinia 

leaf infection are not unique enough to identify 

the fungus, but once the stem lesion forms, the 

symptoms are identical with the lesion formed by root 

infection. The characteristic pith decay and formation 

of sclerotia both within the stem and sometimes on the 

exterior are highly diagnostic. The stalk usually lodges 

at the lesion site and the leaves above the canker die. 

With time, the fungus completely disintegrates the 

stalk, and the affected area will have a shredded appearance, 

as only the vascular elements of the stem 

remain. 

The fi rst symptoms of head rot usually are the appearance 

of water-soaked spots or bleached areas 

on the back of the heads. The fungus can decay the 

entire head, with the seed layer falling away completely, 

leaving only a bleached, shredded skeleton 

interspersed with large sclerotia (Figure 89). These 

bleached, skeletonized heads, which resemble straw 

brooms, are very obvious in the fi eld, even from a 

distance. During harvest, infected heads often shatter 

and any remaining seeds are lost. The large sclerotia 

in the heads may be 0.5 inch (12 mm) or greater in 

diameter and many are harvested along with the seed 

(Figure 90). 

Disease Cycle: If soil is very wet for seven to 14 days, 

sclerotia in the upper several inches of soil can germinate 

to form small mushrooms called apothecia. These 

apothecia produce ascospores for a week or more. The 

ascospores can originate within the sunfl ower fi eld or 

can be blown in from adjacent fi elds. Thus, sunfl ower 

fi elds with no history of Sclerotinia can became affected 

by head and middle stalk rot. Apothecia are 

not usually observed until after the crop canopy has 

completely covered the rows. Apothecia are more 

likely to form in crops with dense canopies, such as 

small grains, and the resultant spores can be blown a 

distance to nearby sunfl ower fi elds (Figure 91). Ascospores 

require both free water (dew or rain) and a food 

base such as dead or senescing plant tissue to germinate 

and infect. The fungus cannot penetrate unbroken 

■ Figure 88. 

Middle stalk 

rot occurs 

via ascospore 

infection. 

(B.D. Nelson) 

■ Figure 89. Head rot showing skeleton head fi lled 

with sclerotia. (B.D. Nelson) 

■ Figure 90. Sunfl ower seed contaminated with 

sclerotia. 

Diseases 

69

70 

■ Figure 91. Apothecia in fi eld of soybean plants. 

(B.D. Nelson) 

tissue. Midstalk infection may result from either leaf 

infection or infection at the leaf axil. Head infection 

actually starts as ascospores colonize the dead fl orets 

and pollen on the face of the head. Thus, when lesions 

are seen on the back of the head, several weeks have 

elapsed since infection took place. 

Damage: Middle stalk rot is the least often seen phase 

of Sclerotinia diseases. Head rot incidence fl uctuates 

dramatically, dependent entirely upon weather conditions. 

In dry years, head rot is entirely absent, while in 

years and locations where rainfall is frequent during 

and after fl owering, head rot may be present in nearly 

all fi elds to some degree. Currently the incidence of 

head rot and wilt in the Dakotas is about equal, with 

approximately 3 percent of the crop affected by each 

disease. Yield loss from head rot on an individual 

plant may range from minimal to total loss since the 

affected head may disintegrate and drop all of the seed 

on the ground prior to harvest. Intact but diseased 

heads will have light and fewer seeds, with lower oil 

concentration, and also will shatter during harvest. 

The sclerotia that form in the diseased stalks and 

heads are returned to the soil at harvest, thus contaminating 

the fi eld for subsequent broadleaf crops. 

Management: The same comments made about Sclerotinia 

wilt also apply to head rot management, with 

some exceptions. Since ascospores that cause head 

rot can be blown into a fi eld, rotation will have less 

consistent impact upon head rot, even though it may 

reduce the levels of sclerotia in the fi eld. Anything 

that can minimize the crop canopy will help modify 

the environment necessary for ascospore infection. 

Thus, lower plant populations will facilitate more air 

movement and hasten leaf drying. Moderate levels 

of nitrogen fertilization also will minimize excessive 

foliage, but this needs to be counterbalanced with 

adequate fertilization to optimize yields. 

One of the most important tools for managing all 

Sclerotinia diseases is monitoring the incidence of 

Sclerotinia diseases on any preceding crop. If Sclerotinia 

is observed on a crop, the grower then knows 

that planting any susceptible crop in that fi eld the 

next year is imprudent. The number of years necessary 

to rotate away from susceptible broadleaf crops 

(while the population of sclerotia declines) depends 

upon the initial Sclerotinia incidence. As a general 

rule of thumb, most researchers suggest that four 

years away from broadleaf crops should reduce the 

sclerotial population to below a threshold level. Since 

sunfl ower is the only crop prone to root infection, and 

root infection can happen even in dry years, sunfl ower 

obviously would be the worst crop choice to plant in 

a known infested fi eld, with dry bean and canola following 

closely behind. As stated earlier, the best crops 

to break the Sclerotinia cycle are monocots (small 

grains, corn, sorghum). 

Sunfl ower hybrids do exhibit different degrees of susceptibility 

to head rot, but no totally resistant hybrids 

are available. An extensive testing program is under 

way to evaluate commercial hybrids for head rot resistance. 

Several university research centers have established 

mist-irrigated plots, which when coupled with 

artifi cial inoculations with ascospores, have produced 

high levels of infection to accurately assess hybrid 

disease response. After the most resistant hybrids have 

been tested in multiple locations, this information will 

be published in the NDSU publication “Hybrid Sunfl 

ower Performance Testing” (A652), also available 

online at www.ag.ndsu.edu/pubs/plantsci/rowcrops/ 

a652.pdf. No chemical is registered for control of head 

rot in the U.S. Even if a chemical were registered, it 

would have to be applied as a preventative because 

when symptoms become visible, the infection already 

took place two to three weeks earlier and the fungus 

has become well-established in the head. 

For more information on sclerotinia, consult NDSU 

Extension Service publication “Sclerotinia Disease 

of Sunfl ower” (PP-840), also viewable on the Internet 

at www.ag.ndsu.edu/pubs/plantsci/rowcrops/pp840w. 

htm.

■ Stem Rots Caused by Sclerotinia 

Minor and Sclerotium Rolfsii 

Description: Stem rots caused by Sclerotinia minor 

or Sclerotium rolfsii are very similar in appearance 

and will be covered together. Sclerotinia minor on 

sunfl ower is seen in California and the southern Great 

Plains, but has not been reported in the northern 

Great Plains. Stem rot caused by Sclerotium rolfsii, 

also called Southern blight, primarily is observed on 

sunfl ower in warm climates such as California, Florida 

and irrigated fi elds in the southern Great Plains. Sclerotium 

rolfsii has not been observed on sunfl ower in 

the northern Great Plains, but has been noted in nursery 

stock in Minnesota, suggesting it could become 

established in the northern latitudes. Both fungi have 

a very broad host range encompassing many broadleaf 

crops. 

The symptoms of both Sclerotinia minor and Sclerotium 

rolfsii are outwardly very similar to the root 

infection and wilt caused by Sclerotinia sclerotiorum. 

Affected plants have a water-soaked lesion on the stem 

at the soil line that turns light brown. Under humid 

conditions, white mycelium also may be found on the 

lesion. In some instances, the lesion also may have a 

series of dark rings due to the diurnal growth pattern 

of the fungus. Plants infected with either fungus wilt 

and die suddenly, without any distinctive foliar symptoms, 

within a week of the onset of wilting. The major 

fi eld sign to distinguish S. sclerotiorum from S. minor 

is the size and shape of the sclerotia. In S. minor, the 

sclerotia are always round and generally less than 1/12 

inch (2mm) in diameter (Figure 92), and thus much 

smaller than sclerotia of S. sclerotiorum. Sclerotia of 

Sclerotium rolfsii are also round and the same size (< 

1/12 inch) as those of S. minor, but Sclerotium rolfsii 

sclerotia are tan to light brown. Sclerotia of these 

two fungi can be found within pith tissue and on the 

surface of the tap root. 

Disease Cycle: Both fungi overwinter in infected plant 

debris or can persist for several years as free sclerotia 

in the soil. The sclerotia germinate in response to root 

exudates to form mycelia that infect roots of adjacent 

sunfl ower plants. As the fungus moves up the root system 

and reaches the tap root and the stem, it produces 

toxins and oxalic acid that cause the plant to wilt. 

Both fungi are capable of infecting adjacent sunfl ower 

plants by root-to-root spread. Neither fungus produces 

any spores to initiate leaf or head infection, in contrast 

to S. sclerotiorum. 

Damage: Both Sclerotinia minor and Sclerotium rolfsii 

are as potentially damaging as S. sclerotiorum, with 

the caveat that the fi rst two species only cause a root 

rot and subsequent wilt. Plants infected near anthesis 

will suffer substantial seed losses, and if the affected 

plants lodge, further yield losses occur. Additionally, 

the sclerotia produced by these two fungi will contaminate 

the fi eld and make subsequent crops of other 

host plants prone to infection. 

Management: Crop rotation, elimination of infected 

residue and weed control will help reduce disease 

caused by either fungus. Since both fungi are highly 

aerobic, deep plowing (>12 inches), especially if 

complete inversion of the soil profi le is possible, will 

remove most of the sclerotia from the root zone and 

place the sclerotia where they are most vulnerable to 

attack by soil bacteria. Differences in hybrid susceptibility 

have not been investigated in the U.S. because 

neither disease is present in the major sunfl ower 

production areas. 

■ Figure 92. Sclerotia of Sclerotinia 

sclerotiorum (left) and S. minor (right) 

from sunfl ower stalks. Ruler at top in 

centimeters. (T. Gulya) 

Diseases 

71

72 

■ Charcoal Rot 

Description: Charcoal rot is caused by Macrophomina 

phaseolina, a fungus that attacks about 400 

plant species, including sunfl ower, dry bean, soybean, 

corn and sorghum. Charcoal rot is found throughout 

the Great Plains, but the disease is most common and 

severe in southern areas such as Texas, Kansas and 

Nebraska. Charcoal rot has been found on sunfl ower 

in western North Dakota and north-central South 

Dakota recently, and also on corn and soybean in both 

states. Charcoal rot generally appears after fl owering 

but seedling blights have been reported. Symptoms on 

stalks appear as silver-gray lesions near the soil line 

(Figure 93), which eventually decay the stem and tap 

root, leaving a shredded appearance. Stems are hollow 

and rotted, and lodge easily. Plants show poor seed fi ll 

and undersized heads. Seed yield, test weight and oil 

concentration are reduced. Numerous tiny black fungus 

bodies, called microsclerotia, form on the outside 

of the stalk and in the pith. To the unaided eye, the microsclerotia 

look like pepper grains; with a 5X to 10X 

lens they are clearly distinguishable as black, spherical 

sclerotia. Another unique characteristic of charcoal rot 

is the compressing of pith tissue into horizontal layers, 

like a stack of separated coins (Figure 94). This is a 

diagnostic characteristic of the disease. 

Disease Cycle: The primary source of inoculum is 

sclerotia in the soil, but Macrophomina also can be 

seed-borne. Upon stimulation by nearby root exudates, 

the sclerotia germinate to form mycelium that 

colonizes the roots. Macrophomina may colonize 

roots early in the season, but disease symptoms do 

not manifest themselves until anthesis. Once the root 

system is colonized, the fungus enters the stem and 

colonizes the vascular system, resulting in wilt and 

partial degradation of the pith. Disease development 

is favored by soil temperatures above 85 F. Moisture 

stress during the post-fl owering period greatly favors 

disease development. 

Damage: Post-fl owering stresses due to high plant 

population or drought coupled with heavy applications 

of nitrogen fertilizer, hail or insect damage promote 

disease development and accentuate the impact of 

charcoal rot. Yield losses can be signifi cant if disease 

incidence is high, as infected plants die before seed set 

is complete. 

Management: Crop rotation, balanced fertilizer programs 

and practices to reduce moisture stress all help 

minimize the impact of charcoal rot. Certain hybrids 

offer some resistance, possibly through drought tolerance. 

Since the fungus also attacks corn, sorghum and 

soybeans, not growing sunfl ower and these crops in 

successive years on the same ground would be advisable 

if charcoal rot has been observed. 

■ Figure 93. Silver grey discoloration of lower stem 

caused by charcoal rot compared with healthy green 

stalk (left). (T. Gulya) 

■ Figure 94. Charcoal rot affected stalk split apart to 

reveal characteristic compression of pith into layers. 

(T. Gulya)

Texas Root Rot 

Description: Texas root rot, or cotton root rot, is a 

soil-borne fungal disease found only in Texas, New 

Mexico, Arizona, southeastern California and northern 

Mexico. The causal agent, Phymatotrichopsis 

omnivora (synonym: Phymatotrichum omnivorum) has 

a very broad host range of more than 1,800 species of 

broadleaf herbaceous crops and weeds. On sunfl ower, 

as with most crops, the initial symptom is wilting followed 

quickly by death of affected plants. The disease 

in Texas develops in late spring and usually occurs in 

circular spots in the fi eld, which enlarge after rain or 

irrigation. No diagnostic symptoms appear on leaves 

or stems, but white mycelial strands on roots, visible 

with a 5X to 10X hand lens, are characteristic of this 

fungus. Following rain or irrigation, the fungus may 

produce white mycelial mats up to 12 inches in diameter 

and up to ¾ inch thick on the soil surface. 

Disease Cycle: The Texas root rot fungus survives for 

many years in the soil as sclerotia. These germinate to 

produce mycelial strands that can grow some distance 

in the soil until root contact is made. This ability also 

allows the fungus to spread from plant to plant in a 

row via overlapping root systems. The disease is most 

severe in moist, warm (80 F or higher at a 1-foot 

depth) soils that are high pH and high clay content. 

Sclerotia, at fi rst white and turning tan to dark brown, 

are round and generally greater than 1/12 inch in diameter. 

Sclerotia may form in the soil away from plant 

roots. On roots, the sclerotia may form at irregular 

intervals, giving the appearance of a string of beads. 

Damage: Like other root-infecting, stalk-rotting fungi, 

Phymatotrichum can cause considerable yield losses 

if plants are infected near bloom. Even if seed yield is 

not reduced, the fungal infection will lower oil content 

and result in lower test weight. In fi eld trials in western 

Texas, disease incidences up to 60 percent were 

observed, which cut yields by at least half. 

Management: The fungus persists in the soil for many 

years as sclerotia, which are the propagules that infect 

subsequent crops. Resistance has not been observed 

in sunfl ower. The best disease management is rotation 

with nonhosts, such as corn, sorghum, small grains or 

grass. Planting after cotton or alfalfa, especially where 

Texas root rot was observed, would be the worst-case 

scenario. 

■ Phoma Black Stem 

Description: Phoma black stem, caused by the soilborne 

fungus Phoma macdonaldii, is characterized 

by large, jet black lesions on the stem, sometimes 

reaching 2 inches in length. In addition, the fungus 

produces lesions on the leaves, on the back of the head 

and at the base of the stalk. The typical stem lesions 

originate with leaf infections that progress down the 

petiole to the stalk. Under favorable conditions, the 

leaf wilts, the petiole turns uniformly black and the 

stem lesions expand to form a large, shiny, black patch 

with defi nite borders (Figure 95). Small circular fruiting 

bodies of the fungus are produced on the surface 

of the stem, but these are inconspicuous to the naked 

eye and require a hand lens to observe. 

Disease Cycle: Phoma infection occurs throughout the 

growing season, although it usually is not noticed until 

the stem lesions become obvious later in the summer. 

The fungus overwinters in infected debris and conidia 

are spread by splashing rain. Insects such as Apion 

and Cylindrocopturus stem weevils also can carry 

Phoma spores both internally and externally. Adult 

weevils feeding on the leaves cause leaf lesions, while 

contaminated larvae spread the fungus as they tunnel 

throughout the stem. Disease transmission through 

infected seed is of minor importance. 

■ Figure 95. Large black lesions associated with 

the point of attachment of the leaf to the stem is a 

characteristic symptom of Phoma black stem. 

(D.E. Zimmer) 

Diseases 

73

74 

Damage: Phoma black stem is the most widespread 

stalk disease noted on sunfl ower in the northern Great 

Plains, but yield losses attributable solely to Phoma 

generally are considered minimal. Infected plants may 

produce smaller heads with reduced seed yield and oil. 

Phoma stem lesions are generally superfi cial and do 

not result in pith damage or lodging. However, if stem 

weevil larva tunneling spreads Phoma spores in the 

pith, extensive pith degeneration can occur. 

Management: No control measures are totally effective. 

A four-year rotation to other crops will minimize 

the concentration of Phoma within the soil. Control 

of stem weevils can help reduce transmission of the 

fungus. However, such control is not recommended 

solely for management of Phoma. No hybrids have 

been identifi ed as being immune to the disease, but 

some hybrids are more tolerant than others. 

■ Phomopsis Stem Canker 

Description: Phomopsis stem canker, caused by Phomopsis 

helianthi (sexual stage = Diaporthe helianthi) 

is a serious disease that fi rst was observed in Europe 

in the late 1970s and in the U.S. in 1984. The distinguishing 

feature of the disease is the large tan to light 

brown lesion or canker that typically surrounds the 

leaf petiole (Figure 96). Compared with Phoma black 

stem, the Phomopsis lesion is much larger, reaching 6 

inches in some cases, is brown rather than black and 

typically has a sunken border. Phomopsis also causes 

more extensive pith degradation than Phoma, so the 

■ Figure 96. Phomopsis is characterized by the 

large light brown lesion or canker which typically 

surrounds the leaf petiole. (T. Gulya) 

stalk may be crushed with moderate thumb pressure. 

Phomopsis-infected plants also are more prone to 

lodging than Phoma-infected plants. 

Disease cycle: The fungus overwinters predominantly 

as perithecia of Diaporthe in infected plant debris. 

The ascospores released from the perithecia are 

rain splashed or windblown onto leaves. The infection 

starts on the margins of lower leaves. A brown 

necrotic area develops and may be bordered by a 

chlorotic margin. The infection spreads down through 

the veins to the petiole and fi nally to the stem. These 

symptoms look similar to those of Verticillium leaf 

mottle, but with Verticillium, the necrotic areas are 

between the veins. Stem lesions usually do not appear 

until fl owering. Girdling stem lesions result in wilting 

and make the plant more prone to lodging. The disease 

may be diffi cult to identify when both Phoma and 

Phomopsis are present, in which case the stem lesion 

may be intermediate in color between the black lesion 

associated with Phoma and the brown typically associated 

with Phomopsis. In these cases, microscopic 

identifi cation of the fungus is necessary. 

Damage: Phomopsis stem canker has been found in 

both the central and northern areas of the Great Plains. 

Since the fungus is specifi c to sunfl ower, it likely 

would not be found in areas without a history of sunfl 

ower production. The disease is most severe under 

conditions of prolonged high temperatures and high 

rainfall. Yield losses result from smaller heads and 

lighter seed, and from lodging due to weakened stems, 

which can be quite extensive. 

Management: Since the fungus overwinters in infected 

sunfl ower debris on the soil surface, thorough 

disking in the fall to bury plant residue and crop 

rotation can reduce disease incidence and severity. 

Leaving crop residue on the soil surface would foster 

the best development of Phomopsis. Most U.S. sunfl 

ower companies are trying to incorporate some levels 

of Phomopsis resistance into their hybrids, using 

parental lines developed in Europe, where the disease 

is particularly severe. No U.S. commercial hybrids are 

immune to Phomopsis stem canker, nor are any fungicides 

registered in the U.S. for control of Phomopsis. 

Please consult NDSU publication A-652 for information 

on ratings of commercial hybrids to Phomopsis.

■ Verticillium Leaf Mottle 

Description: Verticillium wilt, or more accurately, 

leaf mottle, is caused by the soil-borne fungus Verticillium 

dahliae. The fungus has a wide host range 

and causes wilt of several other cultivated plants and 

weeds. Potato is the other important crop host of 

Verticillium in the northern Great Plains. Verticillium 

leaf mottle typically causes necrosis between the main 

leaf veins with yellow margins. The contrast between 

the necrotic tissue surrounded by chlorosis and the 

healthy green leaf tissue is striking and quite diagnostic. 

Symptoms begin on the lower leaves and progress 

slowly upward (Figure 97) and may encompass all 

leaves. Affected leaves rapidly become completely dry, 

but do not wilt to the same degree as with Sclerotinia 

wilt. Thus, the term leaf mottle may be more appropriate 

than Verticillium wilt. Symptoms usually are not 

observed until fl owering, but under severe conditions, 

they may occur as early as the six-leaf stage. The 

vascular system of infected plants may be discolored 

brown, visible as a brown ring in a cross-section of the 

stem. The pith of severely diseased plants is blackened 

with a layer of tiny black fruiting bodies (microsclerotia). 

These microsclerotia are much smaller than 

microsclerotia of charcoal rot and are not visible with 

a hand lens. Under a microscope, Verticillium microsclerotia 

are irregular to club-shaped (< 0.1 mm long), 

while charcoal rot microsclerotia are more uniformly 

spherical and larger (0.1 to 1.0 mm in diameter). Another 

fungus, Phialophora asteris, causes quite similar 

symptoms on sunfl ower. This fungus does not form 

microsclerotia, which is one way to distinguish it from 

Verticillium. 

Life Cycle: Verticillium overwinters as mycelium or 

microsclerotia in infected plant debris. The microsclerotia 

germinate in response to root contact and colonize 

the root system. As the fungus reaches the tap 

root and lower stem, toxins produced by the fungus 

are translocated to the leaves to produce the chlorotic 

and necrotic areas between the veins. Verticillium 

remains within the stem tissue and cannot be isolated 

from symptomatic leaves. The fungus is isolated most 

easily from stems and petioles of infected plants. No 

involvement of conidia occurs in disease development, 

although the fungus does produce conidia in culture. 

Damage: Sunfl owers infected with Verticillium usually 

die before seeds are completely mature, and thus yield 

losses result from smaller head size, lighter test weigh 

and reduced oil concentration. The stems of Verticillium-infected 

plants are weakened as the pith shrinks, 

and are more prone to lodging. 

Management: Resistance to Verticillium dahliae is 

controlled by a single dominant gene (V-1), and most 

U.S. oilseed hybrids contain this resistance. However, 

a new strain of Verticillium that is able to overcome 

the V-1 gene recently was identifi ed both in the U.S. 

and Canada. Thus, hybrids that previously were considered 

resistant have shown symptoms of Verticillium 

wilt due to infection by this new strain. Confection 

hybrids as a group are more susceptible to Verticillium 

than are oilseed hybrids. Verticillium leaf mottle is a 

serious disease on lighter soils with a history of sunfl 

ower cropping, and is seen less frequently on heavy, 

clay soils. This disease will cause some yield loss each 

time a susceptible crop is planted, as the fungus can 

persists for fi ve to 10 years as microsclerotia. 

■ Figure 97. Plants infected with Verticillium 

wilt show interveinal necrosis with yellow 

margins. (T. Gulya) 

Diseases 

75

76 

■ Bacterial Stalk Rot 

Description: Bacterial stalk rot occurs sporadically in 

the Great Plains and generally is not considered a major 

sunfl ower disease. The pathogen is Erwinia carotovora, 

a bacterium that causes soft rot on potato and 

other vegetables. Typical disease symptoms are stem 

discoloration (dark brown to black), often centered 

on a petiole axil, and a wet, slimy, soft rot of internal 

stem tissue. A pungent odor, reminiscent of rotting 

potatoes, is also characteristic. Due to pressure from 

the gas produced by the bacteria, the stem may be split 

open. Symptoms may extend down the stem into the 

roots. The bacterium also can infect the head, causing 

a wet, slimy rot of the receptacle. Infected stems are 

prone to lodging, and infected heads quickly fall apart. 

After the plant dies, the affected stalk or head dries up 

and may leave little indication of prior mushy rot. 

Disease Cycle: The main source of the bacteria is 

infested plant residue on the soil surface. The bacteria 

enter the plant through wounds caused by insects, hail 

and windblown sand; they cannot penetrate unbroken 

epidermis like fungal pathogens. Extended wet 

and warm periods favor disease development. Most 

diseased plants are observed later in the season. Young 

plants are more resistant to stalk decay than plants 

nearing senescence. Varietal differences in susceptibility 

to bacterial stalk rot are reported. 

Damage: Bacterial stalk rot is seen infrequently. Plants 

affected by this disease will be killed and produce 

little or no seed, but disease incidence within a fi eld is 

generally low. 

Management: While differences in resistance have 

been observed, little information is available on the 

resistance of current hybrids. Control of stem feeding 

insects will minimize the potential of insect transmission. 

■ Nematode Diseases 

Description: Nematodes are microscopic, nonsegmented 

roundworms that can cause serious damage to 

the roots of many crops. While many different types of 

nematodes have been found in sunfl ower fi elds, their 

economic impact on the plant is undocumented or 

highly variable. 

Genera of nematodes that have been reported on sunfl 

ower in the northern Great Plains include Heliocotylenchus, 

Tylenchrohynchus, Paratylenchus, Hoplolaimus 

and Xiphinema; the fi rst two genera are the most 

widely distributed in North Dakota, while Paratylenchus 

is the dominant nematode in South Dakota. 

All these nematodes are ectoparasites, meaning that 

they feed either on the root surface or burrow partially 

into the roots. Root-knot nematodes (Meloidogyne 

spp.), damaging pests of many crops, have been 

reported on sunfl ower in Florida and in warm areas of 

other countries but have not been recorded on sunfl 

ower in the upper Great Plains states. Sunfl ower is 

not a host for the soybean cyst nematode (Heterodera 

glycines), making sunfl ower suitable for rotation with 

soybean where the cyst nematode is a problem. 

Disease Cycle: Nematodes overwinter in the soil as 

eggs and colonize plant root systems throughout the 

growing season. Symptoms caused by nematodes are 

not distinctive and mimic those due to drought and 

nutrient defi ciencies. In severe infestations, the foliage 

wilts and turns yellow, and stunting may occur. The 

pattern of affected plants in the fi eld may have little or 

no relationship with topography. Examination of roots 

is necessary to prove nematode damage. Identifi cation 

of nematodes to genus requires their extraction from 

soil and roots, followed by microscopic examination. 

Damage: High populations of nematodes have caused 

yield reductions in greenhouse studies. 

Management: Applications of nematocides in fi eld 

trials have produced variable yield responses. No 

nematocides are registered for use on sunfl ower, and 

the potential cost return makes their use questionable. 

Tolerance to nematode damage appears related to the 

extensive root system of sunfl ower.

IV. Head Rots and Diseases 

of Mature Plants 

■ Head Rots, Other Than Sclerotinia 

Description: Several head rots (other than Sclerotinia) 

occur on sunfl ower in the U.S., and these are caused 

by several fungi, including Rhizopus, Botrytis and the 

bacterium Erwinia, covered previously. 

Rhizopus head rot, caused by Rhizopus arrhizus and 

R. stolonifera, was considered a sporadic disease in 

the Great Plains, but recent surveys have shown it to 

be the most widespread disease in the central Great 

Plains (Figure 98). Initial symptoms are brown, watery 

spots on the receptacle. Rhizopus species rot the soft 

tissues of the head, turning it brown and mushy. A 

threadlike, whitish fungal mycelium develops on and 

within the receptacle. Tiny black pinhead-sized fruiting 

structures (sporangia) form within the head tissue, 

giving the appearance of pepper grains. 

Botrytis head rot is caused by the widespread fungus 

Botrytis cinerea, and is distinguished from Rhizopus 

by the gray “fuzz” on the heads (caused by mycelium 

and spores). Heads affected by Botrytis eventually will 

disintegrate and may contain small sclerotia, similar in 

size to those caused by Sclerotinia. 

Bacterial head rot caused by Erwinia carotovora is 

rare in the Great Plains. This disease is characterized 

by a slimy, wet, brownish rot of the head with no fungus 

growth or spores in the tissues. Often such heads 

have a putrid odor. 

Disease Cycle: Rhizopus enters the head through 

wounds caused by hail, birds and insects and has been 

associated with head moth and midge damage. The 

susceptibility of heads increases from the bud stage up 

to the full bloom and ripening stages. Disease development 

is most rapid in warm, humid weather. Once 

the head is fully colonized and all tissue killed, the 

head dries up and becomes hard and “mummifi ed.” 

Botrytis infects sunfl ower heads during cool, wet 

weather and requires organic debris, such as fl ower 

parts or senescing tissue, to initiate growth. Late attacks 

start from the senescent petals and head bracts 

and may be serious during a wet fall and late harvesting. 

Head rot symptoms start as brown spots on the 

back of the head, which is identical to the initial symptoms 

of all head-rotting fungi. These spots become 

covered with gray powdery Botrytis conidia, giving 

the head a “fuzzy” appearance. These spores generally 

form on the surface tissues and not inside the tissues, 

as with Rhizopus. In wet weather, the infection spreads 

throughout the tissues, and the head becomes a rotten, 

spongy mass. 

Bacterial head rot, as with bacterial stalk rot, is caused 

when windblown or rain-splashed bacteria fall on 

wounds in the head caused by hail, insects or birds. 

No fruiting structures are associated with bacterial 

diseases, but the putrid odor associated with bacterial 

rotting is distinctive enough for identifi cation. 

Damage: Disease incidence for all three described 

head rots is generally low throughout the northern 

Great Plains, while Rhizopus head rot is common in 

the High Plains. Individual heads affected by any of 

the head rots will have lighter test weight seed, lower 

oil content and reduced seed yield. In severe cases, 

the affected heads may be entirely lost. Seeds from 

heads infected by any of these fungi or bacteria will 

have higher free fatty acid content, resulting in a bitter 

taste. Thus, head rots of confection sunfl ower may 

cause losses due to lowered quality factors, even in 

cases where actual seed yield losses are minimal. 

Management: Insect control may help minimize 

Rhizopus head rot, but will not offer as much disease 

reduction as fungicide sprays. In the U.S., no fungicides 

are registered for control of any head rot, except 

Sclerotinia. No practices are recommended to control 

bacterial head rot, other than to minimize head-feeding 

insects that might transmit the bacterium. 

■ Figure 98. Rhizopus head rot is characterized by 

a dark brown, peppery appearance of tissues in the 

receptacle. (T. Gulya) 

Diseases 

77

78 

Weeds 

(Richard Zollinger) 

Weeds compete with sunfl ower, causing poor growth 

and yield losses. Yield loss from weed competition 

depends on weed species, time of infestation, 

weed density and climatic conditions. All weeds are 

competitors. However, in the northern region of the 

U.S., wild mustard, wild oats and kochia, which grow 

rapidly early in the season, appear more competitive 

than foxtail on a per-plant basis. 

A comprehensive weed management program consisting 

of cultural and/or chemical controls is needed to 

maximize yields. Sunfl ower is a good competitor with 

weeds. However, this competitive advantage occurs 

only after plants are well-established. The fi rst four 

weeks after emergence are most critical in determining 

weed competition damage, so early weed control 

is essential. Weeds competing longer than four weeks 

cause important yield loss even if they are removed. 

All chemical recommendations for weed control have 

a U.S. federal label unless otherwise specifi ed. All 

recommended herbicides have federal registration at 

the time of printing, and rates listed are label rates at 

time of printing. Consult the current issue of NDSU 

Extension publication W-253, “North Dakota Weed 

Control Guide,” or appropriate Extension publications 

from other states for current labeled products, rates 

and method of application. 

WILD MUSTARD (Sinapis arvensis) is a major weed 

that infests sunfl ower. Wild mustard is not controlled 

by most of the herbicides commonly used in sunfl ower. 

Wild mustard emerges early and appears to be most 

competitive with sunfl ower when the early season is 

cool. The cool condition favors wild mustard, but not 

sunfl ower growth. Late seeding with seedbed tillage 

to control early emerged wild mustard can reduce 

infestations. However, wild mustard may continue to 

emerge with timely rains and remain a problem even 

with late seeding. Assert (imazamethabenz) is the only 

herbicide registered for use in conventional sunfl ower 

to control wild mustard. Wild mustard can be controlled 

easily in Clearfi eld sunfl ower with Beyond 

(imazamox) and in Express-resistant sunfl ower with 

Express (tribenuron).Wild mustard is controlled effectively 

by herbicides used in other crops in the rotation. 

Wild mustard seed can remain viable in the soil for 

many years, so plants allowed to produce seed can 

cause an infestation for many subsequent years. 

WILD OAT (Avena fatua) is another cool-season weed 

that is abundant in North Dakota and causes important 

yield losses, especially in early seeded sunfl ower. Wild 

oat germinates early in the spring, and germination 

and emergence generally stop when soil becomes 

warm. Delayed seeding reduces wild oat infestations. 

Wild oat can infest late-seeded sunfl ower when cool 

and moist conditions occur at or after seeding. Wild 

oat is controlled to various degrees by several registered 

herbicides (Table 12). 

GREEN FOXTAIL (Setaria viridis) and YELLOW 

FOXTAIL (Setaria lutescens) are the most abundant 

grassy weeds in North Dakota. Both green and yellow 

foxtail occur throughout the state. Green foxtail has 

been more abundant, but yellow foxtail is the dominant 

species in many areas because herbicides giving 

less control of yellow foxtail have been used in crops. 

The two species have similar appearance, but yellow 

foxtail has a fl at stem with long hairs at the base of 

the leaves, a more brushlike spike and a larger seed. 

Green foxtail has a round stem with no hair on the 

leaves. Foxtail is a warm-season plant, and germination 

and emergence do not occur until the soil reaches 

60 degrees Fahrenheit. Many sunfl ower herbicides 

give excellent control of foxtail species (Table 12). 

KOCHIA (Kochia scoparia) is considered the worst 

weed problem of sunfl ower in North Dakota. Kochia 

is a highly competitive weed that emerges during cool 

periods early in the spring or later with warm temperatures 

and adequate moisture. Most kochia has become 

resistant to ALS (acetolactate synthase) herbicides and 

no registered herbicides in sunfl ower give adequate 

control. Beyond herbicide in Clearfi eld sunfl ower is 

an ALS herbicide and will not control ALS-resistant 

kochia. Soil-applied Spartan (sulfentrazone) controls 

ALS-resistant and susceptible kochia when activated 

by suffi cient moisture after application. Kochia seeds 

do not have a long residual life in the soil. Good 

control of kochia in the crop prior to sunfl ower emergence 

or control before seeding will reduce the kochia 

infestation.

RUSSIAN THISTLE (Salsola iberia) is most common 

in the drier western areas of North Dakota. Russian 

thistle germinates throughout the season. Germination 

is rapid, so light rains anytime will promote a new 

fl ush of Russian thistle growth. Competition data on 

losses from Russian thistle in sunfl ower are not available. 

The plants are normally small and competition 

usually is not expected. However, Russian thistle is 

drought tolerant and losses may be severe, even from 

a small number of plants under conditions of limited 

moisture. 

Table 12. Relative effectiveness of herbicides for various weeds. 

Herbicide 

Green/yellow foxtail 

Wild oat 

Wild buckwheat 

Comn. cockle bur 

Preplant herbicides 

Glyphosate E E F-G E F-E P-E G-E E F-G E G-E G-E G-E 

Paraquat G G F F-G G-E E G E G-E E E - P 

Soil-applied herbicides 

Eptam (EPTC) E G-E F P F F N P F G P N N 

Prowl 

(pendimethalin) G-E P P N F G N N N G F-G N N 

Sonalan 

(ethalfl uralin) E P-F P-F N F E N N P G-E G-E N N 

Dual Magnum 

(s-metolachlor) G-E P P N P P-F N P P F-G P N N 

Spartan 

(sulfentrazone) P N P-F N E E P-G P-F E E G-E G-E N 

Trifl uralin E P P N F G N N N F-G F-G N N 

POST-applied herbicides 

Assert 

(imazamethabenz) P G-E F-G P N P N E N P P-F N N 

Beyond* (imazamox) E E P G-E E1 F G-E E E E G-E P N 

Poast (sethoxydim) E G-E1 N N N N N N N N N N N 

Select (clethodim) E E N N N N N N N N N N N 

* = Clearfi eld sunfl ower. 

1 = Herbicides will not control resistant biotypes. 

E = Excellent, G = Good, F = Fair, P = Poor and N = None. 

The ratings in the table indicate relative effectiveness, with effectiveness of each herbicide varying with environment and 

method of application. 

Kochia 

OTHER WEEDS important in sunfl ower are wild 

buckwheat (Polygonum convolvulus), redroot pigweed 

(Amaranthus retrofl exus), common lambsquarters 

(Chenopodium album), fi eld bindweed (Convolvulus 

arvensis), Canada thistle (Cirsium arvense), cocklebur 

(Xanthium strumarium), marshelder (Iva xanthifolia), 

biennial wormwood (Artemisia biennis), nightshades 

(Solanum spp.) and wild sunfl ower. Some of these 

weeds are controlled partially by soil-applied trifl ualin 

or Sonalan (ethalfl uralin), but these products cannot 

be used in no-till sunfl ower production because of 

Comn. lambsquarters 

Marshelder 

Wild mustard 

Nightshade spp. 

R. root pigweed 

Russian thistle 

Bien. wormwood 

Canada thistle 

Weeds 

79

80 

their soil incorporation requirement. Pre-emergence 

Spartan controls most small-seeded broadleaf weeds 

and suppresses wild buckwheat, marshelder and 

foxtail. However, no herbicides are available for selective 

control of wild buckwheat, Canada thistle, fi eld 

bindweed, cocklebur, marshelder or wild sunfl ower. 

Beyond in Clearfi eld sunfl ower controls most annual 

grass and broadleaf weeds except ALS-resistant 

weeds, including kochia, but has no activity on perennial 

broadleaf weeds. Weeds for which no herbicides 

are available need to be controlled in previous crops in 

rotation, or through tillage or the use of herbicides in 

or between other crops in the rotation. 

The sunfl ower yield loss from individual weeds varies 

with the weed species, environment and time of weed 

emergence relative to the crop. Sunfl ower yield losses 

from several weeds at various infestations are presented 

in Figure 99. The values are averages from several 

years and losses from an individual weed would vary 

with conditions. A weed that emerges before the sunfl 

ower would be more competitive than one emerging 

after sunfl ower establishment, and an environment that 

favored the growth of the weed would cause a greater 

loss than if the environment favored the sunfl ower. 

■ Weed Management 

(Richard Zollinger) 

Cultural 

Cultural weed control requires an integrated system of 

tillage operations. Weeds must be controlled in other 

crops in the rotation to reduce the potential infestation 

level in sunfl ower. Preplant, pre-emergence and 

postemergence tillage practices all must be followed 

for effective weed control using only tillage. Poor 

timing or missing any tillage operation can reduce 

the effectiveness of the cultural weed control program 

drastically. 

Preplant tillage can control one or more weed fl ushes. 

Sunfl ower should be planted immediately after the last 

tillage operation so the crop can germinate rapidly and 

compete more favorably. Weeds frequently emerge before 

sunfl ower, especially during cool weather. These 

weeds can be controlled by pre-emergence harrowing. 

Postemergence mechanical weed control consists 

of harrowing and cultivating. Small weeds can be 

controlled by harrowing after the sunfl ower is in the 

four- to six-leaf stage (V-4 to V-6) and can resist burial 

and breaking (Figure 100). Postemergence harrowing 

should be done across rows and preferably on a warm, 

clear day to assure suffi cient weed kill with the least 

damage to the sunfl ower. Sunfl ower seedlings, which 

are strongly rooted, can be harrowed three to fi ve 

times during the four- to six-leaf stage (V-4 toV-6). 

The harrow should be kept free of trash. Spring tooth 

harrows are recommended; solid spike-tooth harrows 

should not be used, as excessive damage may result. 

■ Figure 99. Percent reduction in sunfl ower seed yield from several weeds. (J.D. Nalewaja)

■ Figure 100. This fi eld was harrowed before 

sunfl ower emergence and was being harrowed at 

about the four leaf stage to control seedling weeds. 

(GTA-Farmers Union) 

The direction of travel during harrowing is determined 

by considering the stand, weed growth and herbicide 

treatment. Harrowing diagonally to the rows will give 

better in-the-row weed control than with the row harrowing. 

However, sunfl ower damage will occur from 

the tractor wheels with diagonal harrowing. Harrowing 

may be necessary if a soil-applied herbicide was 

not activated by rainfall, if a fi eld previously treated 

with a herbicide has weeds resistant to the herbicide 

or if adverse climatic conditions reduce herbicide effectiveness. 

If the herbicide is band-applied, harrowing 

should be parallel to the rows to prevent dilution 

with untreated soil. A rotary hoe also is effective for 

postemergence weed control, but weeds must be just 

emerging for good control. Setting the harrow or 

“weighting” the rotary hoe to do the most damage 

to weeds and the least damage to sunfl ower can be 

accomplished on a “try-and-adjust” system. Postemergence 

harrowing will kill some sunfl ower (5 percent 

to 8 percent loss can be expected), so if this system 

of weed control is planned, the sunfl ower should be 

seeded at higher rates than normal. 

After postemergence harrowing, weed control for 

the remainder of the season depends on the row-crop 

cultivator. During the fi rst cultivation, producers must 

take care not to cover the sunfl ower. One to three or 

more cultivations may be necessary, depending on 

the weed situation in the fi eld. Lateral sunfl ower roots 

are shallow and can be damaged easily by cultivating 

too deeply and too closely to the plants. Cultivation 

should be no closer to the row center than the leaf 

spread of the plants. During later cultivations, soil may 

be thrown into the row to bury weed seedlings and 

provide the sunfl ower extra support. 

Registration of Spartan and Clearfi eld sunfl ower will 

allow and encourage no-till sunfl ower production. Notill 

farming increases dependence on chemicals and 

increases selection pressure for resistant weeds. 

Chemical 

The most effective weed management is accomplished 

by an integrated system that uses both cultural and 

chemical control. Preplant cultural practices to reduce 

weed seed populations, pre-emergence tillage and 

postemergence cultivation may be needed to supplement 

the herbicides under adverse climatic conditions 

and to control late-emerging weeds or weeds that are 

not controlled by herbicides. Herbicides vary in their 

effectiveness against various weeds (Table 12). 

Preplant and Pre-emergence 

GLYPHOSATE at 1 to 2 pt/A of 3 lb/gal concentrate 

(0.38 to 0.75 lb ai/A) is registered for the control 

of emerged weed seedlings before, during or after 

planting but before the crop emerges. Glyphosate is 

a nonselective, systemic, nonresidual herbicide, so 

treatment must be made before sunfl ower emergence 

and after weeds emerge. Several formulations are 

available, so follow label directions for rates, weed 

sizes, application volume and addition of nonionic 

surfactant. 

PARAQUAT at 2.5 to 4 pt/A (0.63 to 1 lb ai/A) is 

registered for the control of emerged weed seedlings 

before, during or after planting but before the crop 

emerges. Paraquat is a nonselective contact herbicide, 

so treatment must be before sunfl ower emergence. 

However, application must be after weed emergence, 

as paraquat has no soil residual to control late-emerging 

weeds. A nonionic surfactant at 0.25 percent v/v 

should be added to the spray solution to increase spray 

droplet contact with the leaf surface and retention by 

the leaf. Spray should be applied at 20 gallons per 

acre by ground equipment or 5 gallons per acre by air. 

Paraquat is a restricted-use herbicide. 

Weeds 

81

82 

EPTAM (EPTC) at 2.5 to 3.5 pt/A (2 to 3 lb ai/A) 

applied before planting or at 4.5 to 5.25 pt/A or 20 to 

22.55 lb 10G per acre applied after Oct. 15 controls 

some annual grass and broadleaf weed species. Eptam 

is degraded within three weeks after application. The 

3 pound- per-acre rate spring applied occasionally 

has caused sunfl ower injury on coarse-textured, low 

organic matter soils. The risk of sunfl ower injury can 

be reduced by using lower rates on these soils. Immediate 

and thorough incorporation is essential, as the 

herbicide is volatile. A 15-minute delay in incorporation 

during warm weather with moist soil may result 

in signifi cant vapor loss and poor weed control. Proper 

incorporation can be accomplished by tandem disking 

twice in cross directions (4 to 6 inches deep) or by 

any other method that thoroughly mixes the chemical 

within the top 3 inches of soil. Eptam generally 

gives good short-term weed control but is weak on 

wild mustard, Russian thistle, common cocklebur, 

smartweed and all perennial broadleaf weeds. Wild oat 

control is good. 

PROWL or PROWL H20 (pendimethalin) at 2.4 to 

3.6 pt/A EC, 2.1 to 3 pt/A ACS preplant incorporated 

or pre-emergence in no-till sunfl ower is registered for 

control of most grass and certain broadleaf weeds in 

sunfl ower. Prowl can be applied in the fall at 2.4 to 

4.25 pt/A and incorporated when soil temperature is 

less than 45 degrees. Prowl is registered only as an incorporated 

treatment for conventionally tilled sunfl ower 

because of greater consistency of weed control and 

greater crop safety. Prowl plus Spartan controls many 

grass and broadleaf weeds in no-till sunfl ower. No-till 

sunfl ower is treated with higher rates of Prowl than 

conventionally tilled sunfl ower. The higher rates help 

overcome the reduced control from pre-emergence vs. 

PPI treatment and from Prowl being absorbed on the 

crop residue. Prowl is registered at 2.4 pt/A in no-till 

sunfl ower for coarse-textured soils with less than 3 

percent organic matter and 3.6 pt/A for all other soils, 

including coarse-textured soils with greater than 3 

percent organic matter. 

Prowl may be applied up to 30 days before seeding 

no-till sunfl ower. Spray volume greater than 20 gallons 

per acre should be used to aid penetration to the 

soil in fi elds with high amounts of crop residue. Prowl 

does not control emerged weeds, so either glyphosate 

or paraquat would be needed to control emerged 

weeds in no-till sunfl ower prior to planting. Prowl has 

state registration for no-till sunfl ower in North Dakota, 

South Dakota and Minnesota. 

SONALAN (ethalfl uralin) at 1.5 to 3 pt/A (0.55 to 

1.15 lb ai/A) preplant incorporated in the spring is 

registered for the control of annual grass and some 

small-seeded broadleaf weeds in sunfl ower. The 

granular formulation (Sonalan 10G) can be applied 

in the spring or fall between Oct. 10 and Dec. 31 at 

5.5 to 11.5 lb 10G/A. Sonalan does not control wild 

mustard. The fi rst incorporation into the soil may be 

delayed no longer than two days after application. 

The second incorporation should be delayed three 

to fi ve days after the fi rst. Sonalan has a shorter soil 

residual than trifl uralin and is slightly more effective 

in controlling wild oats, Russian thistle and a few 

other broadleaf weeds. Sonalan is registered for tank 

mixtures with Eptam. 

Recent labeling allows use of Sonalan in reducedtillage 

systems for suppression of foxtail species. 

Sonalan 10G may be applied at 7.5 to 12.5 pounds per 

acre in the fall to small-grain stubble and incorporated 

once in the fall and once in the spring with a V-blade 

prior to planting sunfl ower. Sonalan 10G may be 

applied in the spring and incorporated twice using a Vblade. 

For spring applications, a delay of at least three 

weeks between incorporations should be observed 

unless a minimum of 0.5 inch of precipitation occurs 

after the fi rst incorporation. The delay then may be 

shortened to 10 days. The incorporations should be 

made at approximately 5 mph using a V-blade implement 

with 12- to 32-inch-wide sweeps. Both incorporations 

should be no deeper than 2 to 2.5 inches. 

DUAL MAGNUM (s-metolachlor) at 1 to 2 pt/A (0.95 

to 1.9) preplant incorporated or preplant will control 

green foxtail and several other weeds, such as pigweed 

and lambsquarters. It will not control wild mustard or 

wild oats. Incorporation improves weed control and 

consistency of control. It requires soil moisture for 

activation and better weed management. Use higher 

rates for clay soils high in organic matter. 

SPARTAN (sulfentrazone) at 3 to 8 fl oz F (1.5 to 4 

oz ai/A) applied pre-emergence controls most annual 

small-seeded broadleaf weeds, such as kochia, pigweed 

species, lambsquarters, nightshade, smartweed, 

Russian thistle and biennial wormwood, and may 

suppress buckwheat, mustard, ragweed and Russian 

thistle. Spartan may provide some grass but no peren-

nial weed control. Adjust rate based on organic matter 

and use higher rates if applied up to 30 days prior to 

planting. Sunfl ower has good tolerance to Spartan 

on medium to fi ne-textured soils with organic matter 

above 3 percent. Crop injury may occur on soils 

with low organic matter and soil pH greater than 8.0, 

especially on calcareous outcropping. Do not use on 

coarse-textured soils with less than 1 percent organic 

matter. Closely furrow at planting to avoid injury. Poor 

growing conditions at and following sunfl ower emergence, 

cold temperatures, soil compaction or a rate too 

high based on soil type and organic matter may result 

in sunfl ower injury. Consistent weed control greatly 

depends on at least 0.75 inch rainfall shortly after application 

and before weeds emerge. Spartan is a PPO 

inhibitor mode-of-action herbicide in which no weed 

resistance has been documented. 

TRIFLURALIN at 1 to 2 pt/A or 5 to 10 lb 10G/A 

(0.5 to 1 lb ai/A) is a preplant incorporated herbicide 

for grass and certain broadleaf weed control in 

sunfl ower. Incorporation should be by tandem disk or 

fi eld cultivator twice in cross directions (4 to 6 inches 

deep) at about 6 mph. Thorough incorporation is essential 

for optimum, consistent weed control. Trifl uralin 

is less volatile than EPTC (Eptam). Immediate 

soil incorporation is preferred, but with cold, dry soil 

and low wind, incorporation may be delayed up to 24 

hours. The lower rate should be used on soils of coarse 

texture and low organic matter. Trifl uralin gives seasonlong 

control of some annual grass and broadleaf 

weeds. Wild mustard is not controlled, and wild oat 

control is poor. 

Postemergence 

ASSERT (imazamethabenz) at 0.6 to 0.8 pt/A (0.19 

to 0.25 lb ai/A) controls wild mustard in sunfl ower. 

Assert should be applied before sunfl ower exceeds 15 

inches in height. Wild mustard should be in the rosette 

stage but prior to bloom. Sunfl ower injury may occur 

from Assert if applied during high temperatures and 

humidity. 

POAST (sethoxydim) at 0.5 to 1.5 pt/A (0.1 to 0.3 lb 

ai/A) applied postemergence in sunfl ower controls annual 

grasses and suppresses quackgrass. Oil adjuvant 

should be included at 1 qt/A. Poast at 0.5 pt/A controls 

wild proso millet; at 1 pt/A controls volunteer corn, 

green and yellow foxtail, and barnyardgrass; and at 

1.5 pt/A controls wild oats and volunteer cereals. 

Quackgrass that is 6 to 8 inches tall can be suppressed 

with Poast at 1.5 pt/A. Quackgrass regrowth should 

be treated at 1 pt/A. Cultivation between 14 to 21 days 

after application will improve quackgrass control. The 

addition of 2 to 4 quarts per acre of liquid nitrogen 

solution or 2.5 pounds per acre of ammonium sulfate 

in addition to the oil adjuvant may increase control of 

volunteer corn, cereal grains and quackgrass. Sunfl 

ower should not be harvested before 70 days after 

application. 

CLETHODIM (several trade names) at 6 to 8 fl oz 

or SELECT MAX (clethodim) at 9 to 32 fl oz/A (1 

to 3.9 oz ai/A) applied postemergence in sunfl ower 

controls annual grasses, volunteer cereals and perennial 

grasses, including quackgrass. See label rates to 

control individual type of grasses. Oil adjuvant should 

be included at 1 qt/A. oz/A. Cultivation between 14 

and 21 days after application will improve quackgrass 

control. The addition of 2 to 4 qt/A of liquid nitrogen 

solution or 2.5 lb/A of ammonium sulfate in addition 

to the oil adjuvant may increase grass control. Sunfl 

owers should not be harvested before 70 days after 

application. 

■ Herbicide-resistant Sunfl ower 

Clearfi eld sunfl ower 

BEYOND (imazamox) at 4 fl oz/A (0.5 oz ai/A) applied 

postemergence to Clearfi eld sunfl ower varieties 

from the two- to eight-leaf stage controls most annual 

grass and broadleaf weeds. Apply with NIS at 0.25 

percent v/v alone or with UAN liquid fertilizer at 1 to 

2 qt/A. Beyond will not control wild buckwheat, biennial 

wormwood, large common lambsquarters, Canada 

thistle or ALS-resistant weeds, including kochia. 

Clearfi eld sunfl ower can be planted on land previously 

treated with Assert or Pursuit to reduce or eliminate 

injury from long residual sulfonylurea herbicides. 

Clearfi eld sunfl ower may facilitate no-till sunfl ower 

production. 

EXPRESS (tribenuron) at 0.25 to 0.5 oz/A (0.188 

to 0.38 oz ai/A) applied postemergence to Express 

Sun sunfl ower varieties will control annual broadleaf 

weeds, including wild mustard. It will not control 

ALS-resistant weeds, including kochia or grass weeds. 

Control or suppression of Canada thistle can be expected 

at the higher rate. Apply early postemergence 

to Express-resistant sunfl ower in the one-leaf stage 

Weeds 

83

84 

but prior to bud formation. Broadleaf weeds should 

be 3 inches or less in height. Apply with MSO-type 

oil adjuvants at 1 percent v/v. NIS or petroleum oil 

adjuvants are not prohibited. 

Sequential applications are allowed but observe a 14day 

interval between applications and do not exceed 

1 oz/A during any growing season. Allow a 70-day 

preharvest interval. Express Sun application may help 

facilitate no-till sunfl ower production. 

■ Preharvest Application 

GRAMOXONE INTEON (paraquat) at 1.5 to 2 pt/A 

(0.375 to 0.5 lb ai/A) can be used as a harvest aid in 

oilseed sunfl ower. Application should be made when 

the backside of the sunfl ower heads is yellow, bracts 

are turning brown and seed moisture is less than 35 

percent. Paraquat can be used on both confectionary 

and oilseed hybrid cultivars. Apply with a nonionic 

surfactant at 1 to 2 pints per 100 gallon of water. A 

seven-day interval must elapse between application 

and harvest. Paraquat is a restricted-use herbicide. 

DREXEL DEFOL (sodium chlorate) at 1 to 2 gal/A (6 

to 12 lb ai/A) can be used as a desiccant with both oilseed 

and confectionary sunfl ower. Application should 

be made when the backside of the sunfl ower heads is 

yellow, bracts are turning brown and seed moisture is 

less than 35 percent. Apply at 20 to 30 gallons per acre 

by ground and 5 to 10 gallons per acre by air. 

Roundup Preharvest Application in Sunfl ower 

Monsanto has issued a Supplemental label allowing 

certain applications of glyphosate (Roundup) for control 

of annual and perennial weeds in sunfl ower. Apply 

no more than a total of 22 fl oz of the 4.5 lb. acid 

equivalent/gal formulation at preharvest. See label for 

rates suggested. 

For preharvest use in sunfl ower, apply for weed 

control, NOT crop desiccation when sunfl ower plants 

are physiologically mature. Apply when the backsides 

of sunfl ower heads are yellow and bracts are turning 

brown and seed moisture is less than 35%. Generally 

the dry chaffy material from the disk fl owers on the 

head can be easily rubbed off by hand and expose the 

seeds at this stage of maturity. Allow a minimum of 7 

day preharvest interval (PHI) for sunfl ower following 

application. 

For post-harvest weed control, the products may be 

applied after harvest of sunfl ower. Higher rates may be 

required for control of large weeds, which were growing 

in the crops at the time of harvest. Tank mixtures 

with 2,4-D or dicamba may be used after harvest. 

Always follow the pesticide label when applying any 

product to sunfl ower. 

■ Control of Volunteer Sunfl ower 

in Crops 

Crops following sunfl ower often are infested with 

volunteer sunfl ower plants. In small grains, 2,4-D 

and MCPA at rates of at least 1 pt/A are needed for 

consistent control. Bromoxynil plus MCPA at 0.5 pt/A 

+ 0.5 pt/A has given excellent, consistent volunteer 

sunfl ower control. Dicamba plus MCPA at 4 fl oz/A + 

0.5 pt/A has given good control. Several sulfonylurea 

herbicides plus 2,4-D or MCPA, and Curtail or Curtail 

M also control sunfl ower. Sunfl ower can emerge from 

deep in the soil, and these late-emerging plants may 

escape an early herbicide application. However, delaying 

treatment until all sunfl ower emerge may result in 

poor control and some yield loss from competition. 

Some judgment is needed to determine the proper 

time for application, and two applications may be 

needed in some situations. 

In corn, preplant Hornet (fl umetsulam plus clopyralid), 

postemergence bromoxynil, Basagran (bentazon), 

dicamba, Distinct (dicamba + difl ufenzopyr), 

Hornet, Callisto (mesotrione), Permit (halosulfuron), 

NorthStar (dicamba + primisulfuron) and Option 

(foramsulfuron) control volunteer sunfl ower. Volunteer 

sunfl ower also can be controlled with glyphosate in 

Roundup Ready corn. 

In soybean, preplant Pursuit Plus (imazethapyr + 

pendimethalin), Gangster (fl umioxazin + cloransulam), 

postemergence bentazon, Result (bentazon 

+ sethoxydim), FirstRate (cloransulam), Pursuit 

(imazethapyr), Raptor (imazamox) and glyphosate 

in Roundup Ready soybean will control volunteer 

sunfl ower. 

Refer to the herbicide label or the most current 

edition of the “North Dakota Weed Control Guide,” 

NDSU Extension publication W-253, for rates, 

adjuvants and application guidelines.

Birds 

(George M. Linz and Jim Hanzel) 

Sunfl ower, due to the easy accessibility and high 

nutritional value of its seed, is particularly vulnerable 

to damage by birds (Figure 101). Seeds are exposed 

and the large head serves as a perch during feeding. 

Sunfl ower seed is a preferred bird food because the 

seed contains many proteins and fats essential to their 

growth, molt, fat storage and weight maintenance 

processes. Although many species of birds feed in maturing 

sunfl ower fi elds, the greatest losses are caused 

by migrating fl ocks of red-winged blackbirds, yellow-headed 

blackbirds and common grackles (Figure 

102). Signifi cant losses can occur in fi elds near cattail 

marshes. 

■ Figure 101. Sunfl ower may be depredated by birds. 

Birds perch on sunfl ower heads and pluck the seeds. 

(Reu V. Hanson) 

■ Migrating and Feeding 

Habits of Blackbirds 

The adult male blackbird is the fi rst of his species 

to arrive in the spring. He establishes a territory and 

awaits the arrival of the females. As females arrive, 

they disperse to the males’ territories and breeding 

takes place. Each female produces a clutch of three 

or four eggs. Nests are built in dense vegetation, most 

often in cattails, which have an abundant food supply. 

Their diet throughout the nesting season includes 

insects, weed seeds and waste grains. 

Following nesting in July, blackbirds form large fl ocks 

and begin feeding in grain fi elds. Blackbirds start 

feeding on sunfl ower seed soon after the petals begin 

to wilt and cause most of the damage during the following 

three weeks. Peak concentrations of blackbirds 

occur in mid-September in the northern growing area 

(Figure 103). This period coincides with the time that 

sunfl ower nears physiological maturity. Most often, 

the birds roost in the cattail marshes at night and move 

to the fi eld for feeding during the day. 

Blackbirds feed on insects and weed seeds in small 

grain, corn or sunfl ower fi elds before these crops are 

vulnerable to damage. They become used to feeding in 

a certain location and include sunfl ower seeds in their 

■ Figure 102. The red-winged blackbird is the most 

serious bird pest of sunfl ower in the northern Plains. 

(Reu V. Hanson) 

Birds 

85

86 

■ Figure 103. Blackbirds cause the most damage in 

early to mid-September. (Reu V. Hanson, George Linz) 

diets as the crop matures. Efforts made by the producer 

to move birds from a fi eld often are unsuccessful 

because the birds are in the habit of feeding there. 

Management 

Blackbirds are protected under the Migratory Bird 

Treaty Act. However, Section 21.43, Title 50 CFR, 

provides: “A federal permit shall not be required 

to control yellow-headed, red-winged, tri-colored 

red-winged, and Brewer’s blackbirds, cowbirds, all 

grackles, crows and magpies when found committing 

or about to commit depredations upon ornamental or 

shade trees, agricultural crops… .” Cultural practices 

in combination with mechanical and chemical harassment 

practices should be used to control blackbirds. 

Cultural Control 

A combination of cultural practices may be used to reduce 

the risk of bird damage to sunfl ower. If possible, 

sunfl ower should not be planted near cattail marshes 

or woodlots. Unplanted access trails allow easier access 

to fi elds while scaring blackbirds from the center 

of the fi eld. Planting should be done at the same time 

as neighbors because earlier and later ripening fi elds 

take more damage. 

Weed and insect control should begin early. Insects 

and weeds in the crop are often an attractive food 

source for blackbirds before the crop reaches a suscep- 

tible stage. Once blackbirds have developed patterns 

in insect-infested or weedy fi elds, they will begin to 

include the maturing cultivated crops in their diet. 

The plow-down of harvest stubble should be delayed 

until after sunfl ower harvest. Crop stubble serves as 

an alternate feeding area for harassed birds and other 

wildlife. Sunfl ower should be harvested as early as 

possible to avoid prolonged exposure to bird damage. 

Desiccation to advance harvest will reduce exposure 

to birds. 

Cattail Management 

Dense cattail marshes serving as roosting sites for 

blackbirds can be managed with a registered aquatic 

herbicide (e.g., glyphosate) to remove cattails used 

by these birds (Figure 104). Generally, cattails must 

be treated one year before sunfl ower is planted in the 

vicinity of the marsh to allow time for the cattails to 

decompose. However, herbicide applications made 

in mid-July might reduce blackbird use of the marsh 

in the year of application. The herbicide should be 

applied from mid-July to late August to at least 70 

percent of the marsh with an agriculture spray plane 

or helicopter (Figure 105). Use 2 quarts of herbicide 

per acre. Managing these marshes reduces blackbird 

use and improves the habitat for other more desirable 

wildlife, such as waterfowl. North Dakota/South 

Dakota Wildlife Services, telephone (701) 250-4405, 

is a unit within the U.S. Department of Agriculture’s 

Animal and Plant Health Inspection Service. It operates 

a cost-share cattail management program in North 

Dakota and South Dakota. 

Decoy Crops 

Blackbirds can be attracted readily to small plots of 

oilseed sunfl ower or other desirable crops planted near 

traditional wetland and tree roost sites. This strategy 

can be effective for the protection of high-valued 

confectionery and oilseed varieties. The plots must 

produce suffi cient seeds to feed the expected population 

of blackbirds. Each bird can eat about 1 pound 

of sunfl ower seeds. Thus, if a grower expects 30,000 

blackbirds, then a 20-acre plot must produce about 

1,500 lb/acre to feed the birds for a season. These 

plots also provide essential food and cover for other 

migrating and game birds. The North Dakota/South 

Dakota Wildlife Service’s National Wildlife Research 

Center, at telephone (701) 250-4469, is developing 

and refi ning the decoy crop concept. A cost-share 

program is available to sunfl ower growers.

Birds are kept out of sunfl ower fi elds most successfully 

by starting methods to frighten them as soon as the 

birds are seen in the vicinity, regardless of their diet. 

Various ways of moving birds mechanically are listed. 

Use of .22-caliber Rifl e 

This method should be used only where legal and safe. 

One rifl eman can protect 100 acres by fi ring from a 

high position into the midst of settling birds. Several 

more rounds fi red into the lifting fl ock often will send 

them on their way. Rifl emen must use extreme care 

with the use of rifl es since the bullet may carry a mile 

or more. Sometimes good results can be obtained with 

this method if used consistently. 

■ Figure 104. Cattails used by roosting blackbirds 

can be removed by aquatic herbicide (e.g. 

glyphosate). (George Linz) 

■ Figure 105. An aquatic herbicide such as Rodeo 

(glyphosate) should be applied by airplane or 

helicopter. (James Hanzel) 

Automatic Exploders (Figure 106) 

Automatic exploders or bird-scaring cannons automatically 

detonate a gas to produce an extremely loud 

explosion. These devices range from relatively simple 

mechanisms to deluxe models with photoelectric regulators 

and programmable fi ring sequences. The device 

should be operated before birds begin to arrive from 

their roosting area at sunrise and continued as long as 

birds are in the fi eld. It should be shut off at night. The 

exploder should be placed on a stand above the crop. 

It should be adjusted to fi re slowly, about every four to 

fi ve minutes. The exploder should be moved every two 

or three days, as birds will become accustomed to the 

noise if operated in the same location day after day. 

One exploder can protect 10 to 20 acres, especially if 

used with other mechanical devices and shooting. 

Electronic Frightening Devices 

Devices that broadcast distress calls of blackbirds are 

marginally effective and their application is somewhat 

limited because of their high cost and limited broadcast 

range. Furthermore, because they make extensive 

use of batteries, sophisticated electronic equipment 

and loud speakers, they are subject to vandalism and 

theft. 

Pyrotechnic Devices 

These include cracker-shells, fl ares, whistlers (fi red 

or pistol launched) and fi recrackers. Most of these 

products are effective in startling birds and are used 

commonly by many growers. These devices must be 

used with care, however, because of the potential for 

■ Figure 106. Gas exploder, when properly located 

and moved within the fi eld every 2 to 3 days can 

reduce bird damage. (Reu V. Hanson) 

Birds 

87

88 

mishaps. Safety glasses and hearing protectors are 

strongly recommended since these devices occasionally 

detonate prematurely. They also may be a fi re 

hazard during dry periods. 

Shotgun 

This tool is costly and ineffective as a direct control 

device. Killing a few birds has little if any direct effect 

on the rest of the fl ock. However, shotguns can be 

used to reinforce automatic exploders and pyrotechnic 

devices. 

Airplane Hazing 

Harassing feeding blackbirds with airplanes sometimes 

can be a marginally effective method of chasing 

fl ocks from sunfl ower fi elds. This technique is 

especially effective if combined with other mechanical 

methods, such as shotguns and pyrotechnic devices. 

Check with local authorities for permits needed to 

conduct low-level fl ying. 

Repellents 

Avitrol, a chemical frightening agent, and Bird Shield, 

a chemical repellent, are the only chemicals registered 

for management of blackbirds in sunfl ower. Avitrol 

is a cracked-corn bait in which one out of every 100 

particles is treated with the active ingredient 4-aminopyridine. 

The bait is applied by airplane or ground 

vehicle along access lanes placed in fi elds. When a 

blackbird eats one or more treated particles, it fl ies erratically 

and emits distress calls. This abnormal behavior 

sometimes causes the remaining birds in the fl ock 

to leave the fi eld. Bird Shield is a newly registered 

product that is formulated with the active ingredient 

methyl anthranilate. Research results to date indicate 

that the effi cacy of both Avitrol and Bird Shield are 

inconsistent. 

Best results are obtained by using an integrated pest 

management system that includes controlling insects 

and weeds that might attract blackbirds prior to sunfl 

ower ripening and by using a combination of harassment 

devices. Any device used must be operated when 

the birds are in the fi eld. 

Other Pests and Damage 


Several sources of sunfl ower injury exist. Some of 

them are confused with damage from insects or diseases. 

Rabbits 

Rabbits will start foraging soon after seedling emergence, 

especially near the edges of fi elds. They will 

tend to concentrate on one row and apparently eat 

their fi ll, then leave until the next feeding period. Continued 

feeding by rabbits has been observed until the 

plants are 8 to 10 inches tall. Rabbit feeding on such 

large plants may be confused with deer. However, deer 

can be detected by their tracks. 

Deer 

Deer begin foraging on sunfl ower plants when the 

plants reach 8 to 10 inches and continue through 

harvest. They feed in areas near cover, such as wooded 

areas. All leaves of young plants will be consumed 

below the growing point. Heads will be foraged until 

near maturity and seeds until harvest. Often deer will 

knock down the stalk to facilitate foraging. 

Gophers and Mice 

Gopher and mouse damage usually is seen just after 

planting. It generally occurs next to overgrazed pastures, 

grassland recently converted to cropland and 

fi elds next to abandoned areas. The seed will be dug 

up, split open with the kernel consumed and the hull 

left on the soil. Several seeds in a row will be eaten. 

Seedlings are eaten occasionally when they are 2 to 3 

inches tall. If the growing point is consumed, the seedling 

gradually dies. Shooting or rodenticide-treated 

oats will control gophers and mice.

Lightning 

Lightning damage sometimes is mistaken for a 

disease. It is distinguished from disease damage by 

the sudden death of the plants in the affected area 

and the fact that both sunfl ower and weeds (not grass, 

however) are killed (Figure 107). Near the edge of the 

area, plants are wilted but not dead, and the stalks may 

have a brown to blackened pith. The area may be as 

large as 50 to 100 feet in diameter. The affected area 

usually is circular and does not increase in size after 

the fi rst two weeks. Flags may be placed at the edges 

of the affected area to observe if the damage gradually 

progresses beyond the fl ags. If damage does gradually 

extend beyond the fl ags, this could indicate damage 

from a source other than lightning. 

Flooding 

Soils should have good drainage for sunfl ower production, 

but the crop doesn’t differ greatly from most 

other crops. In fl ooded sunfl ower, research found that 

ethylene increased in the stems and roots below the 

water. Later, chlorophyll breakdown and leaf epinasty 

resulted. Sunfl ower plants fl ooded longer than three 

days may not recover. Cool, cloudy days during the 

fl ooding period reduce the damage, whereas hot and 

sunny days may hasten the death of plants. 

Heat Canker 

Warm temperatures and sunny days can result in heat 

canker injury to young sunfl ower seedlings growing 

■ Figure 107. Two spots in sunfl ower fi eld damaged 

by lightening. (Terry Gregoire) 

in black or dark, moist soils. Hot temperatures at the 

soil line cause cell death in the young stem and the 

plants will show bands of yellowing and constricting. 

In severe cases, the constricted area completely girdles 

the stem at the soil line and the plant topples over. The 

sunfl ower seedling will not recover since the growing 

point is above this site. Plant populations can be 

reduced signifi cantly in some cases. 

Frost Damage 

Sunfl ower seedlings in the cotyledonary stage (VE) 

can withstand temperatures down to 26 degrees Fahrenheit 

when just emerging from the soil. Sunfl ower 

in the V-1, V-2 and V-3 stages become less tolerant to 

frost as they grow and develop. The terminal bud can 

be frost damaged in seedlings with two, four and six 

true leaves. This early frost damage and killing of the 

terminal bud can result in excessive branching as the 

sunfl ower grows and develops. 

Sunfl ower is most susceptible at the bud (R-4) and 

pollination stages (R-5.0 to R-5.9) of development. 

Temperatures of 30 F or less can cause damage to the 

anthers and stigmas of the pollinating disk fl owers. 

(See Figure 108 for frost-damaged sunfl ower head). 

Sunfl ower has a composite type fl ower. Several rows 

of showy yellow ray fl owers encircle the head and 

commonly are called the “petals,” although each is an 

individual fl ower. The center portion of the head, and 

by far the greater part, is composed of inconspicuous 

individual fl owers, one for each seed that may develop. 

These disk fl owers mature in circles from the outside 

■ Figure 108. Frost damage in the center third of 

sunfl ower head. (Duane Berglund) 

Other Pests and Damage 

89

90 

of the fl ower head to the center, so that at various 

stages, the disk fl owers ready for pollination appear as 

a yellow circular band in the brownish or dark center 

of the head. These disk fl owers are sensitive to frost. 

The result of the frost damage in the fl owering period 

is circular bands of undeveloped seed that would vary 

with individual fl ower heads from a band around the 

outside edge to an area in the center. Unopened buds 

are less susceptible to frost than the opened fl ower 

heads. Growers can determine the extent of injury by 

cutting the surface of the fl ower head. 

Once pollination is completed and 10 to 14 days after 

petal drying occurs, the sunfl ower plants can withstand 

frost temperatures as low as 25 F and have only 

minor damage. Twenty-fi ve degrees Fahrenheit at the 

bud stage often will damage the stalk below the bud 

and seeds will not develop. If hard frosts do occur, 

many times only the seed in the center of the head (the 

last to pollinate) will be affected. 

When sunfl ower heads start to turn yellow on the 

backside and the bracts are drying and turning brown, 

most risk of frost damage is very minimal. 

In nonoilseed sunfl ower, frost damage can cause quality 

problems by causing a dark brown to blackened 

nutmeat to result during the roasting process. For 

the birdseed market, light-weight sunfl ower seed and 

brown seeds are the result of frost damage and will be 

discounted. 

For oilseed sunfl ower, reduced test weight per bushel 

and lower oil percent may result from a frosted immature 

sunfl ower crop.

Hail Injury 


Hail storms can and will cause different types of 

sunfl ower plant injury. Plant death, damage to the 

terminal bud, physical injury to the stalk and head, 

and defoliation are all types of injury that can infl uence 

yield. Variables such as hailstone size and degree 

of hardness, speed and density, storm duration and 

plant environmental status, such as whether the leaves 

are fl accid or turgid, infl uence the type and degree of 

crop injury. The stage of plant development is also an 

important factor. Figures 109 and 110 illustrate two 

distinct types of hail damage. As shown in Figure 109, 

almost all heads have been destroyed, while plants 

shown in Figure 108 have a high level of defoliation 

with the heads still attached. 

One of the major factors causing differential growth 

and yield response is the stage at which the injury 

occurred. Data were obtained from a sunfl ower dateof-planting 

study at Carrington, N.D. Five sunfl ower 

hybrids sown at six planting dates between May 1 

and June 20 were damaged by a hail storm on Aug. 6. 

Stages of plant development at the time of the storm 

were from R-1 to R-7. Data were taken approximately 

■ Figure 109. Heads destroyed by hail stones. 

(A.A. Schneiter) 

one week after the storm. Average percent defoliation 

from all planting dates was similar at about 26.4 percent. 

An average of 4.7 stalk and head stone bruises 

occurred per nondestroyed plant. The percent of plants 

destroyed and the percent of the remaining plants with 

heads broken off or bent over but attached decreased 

with plant maturity (Table 13). 

Defoliation: Reduced yield as a result of defoliation 

depends on the amount of leaf loss and the stage at 

which it occurs. Stages R-1 through R-6 appear to 

be the most sensitive to defoliation since much of 

the photosynthate produced at this time is directed to 

head development. At early and late stages of plant 

development, high levels of defoliation may not have a 

major impact on seed yield. Approximate yield reductions 

due to varying degrees of random defoliation 

■ Figure 110. Sunfl owers defoliated by hail. 

(A.A. Schneiter) 

Hail Injury 

91

92 

Table 13. Effect of hail injury on sunfl ower at several 

stages of plant development. 

Injury on nondestroyed plants 

Approx. % Heads 

development % broken over % 

Date stage when Plants % Heads but still Attached 

planted injured destroyed broken off attached heads 

May 1 R-7 19.2 7.6 14.3 78.0 

May 9 R-6 24.1 6.3 17.1 76.6 

May 21 R-5 23.9 17.1 17.8 65.2 

May 30 R-3 29.6 16.1 17.0 66.9 

June 10 R-2 55.7 36.4 23.7 39.9 

June 20 R-1 60.7 39.9 22.6 37.6 

at several stages of growth are presented in Table 14. 

These values are based on investigations conducted at 

Fargo and Carrington and are the best estimates available 

on the effect of defoliation for average growing 

conditions. 

Stand Reduction: Plant death as a result of hail injury 

is a common occurrence, especially at early stages of 

development when plants are small. At early stages 

of plant development, before plants begin competing 

with each other, yield losses due to stand reduction 

caused by hail are not different than those that would 

occur due to reduced seeding rates. If the amount of 

stand reduction is signifi cant and/or occurs when the 

plant has begun to develop and compete with neighboring 

plants, the remaining uninjured plants cannot 

compensate enough and yields will be reduced. Losses 

due to stand reduction increase as the plant matures 

since it decreases the time for remaining plants to 

compensate. 

Approximate yield reductions from variable levels 

of random stand reduction at several stages of plant 

development are presented in Table 15. These values 

are based on studies conducted at Carrington and 

Fargo. These values represent direct stand reduction 

where the plants have been destroyed and no longer 

are competing with uninjured plants for light, water or 

nutrients. 

Injured Plants: In addition to stand reduction and 

defoliation, injuries such as terminal bud removal or 

injury and stem breakage or bruising may occur as 

a result of hail. An example of a living but severely 

injured plant is the gooseneck shown in Figure 111. 

Plants that are injured but living sometimes may reduce 

total crop yield more than if they had been completely 

destroyed since they continue to compete with 

uninjured plants for space, light and nutrients but do 

not produce an equal yield. Competition from injured 

plants may reduce the ability of noninjured plants to 

compensate for the hail-damaged plants. 

The response of plants to a hail injury, such as 

terminal bud removal, varies depending on the stage 

■ Figure 111. Goose-neck and stem bruising caused 

by hail injury. (A.A. Schneiter)

at which the injury occurs. When plants are injured 

in this manner at vegetative (V) stages, they usually 

develop branches that produce small seed-bearing 

heads. When injury to the terminal bud occurs during 

the early reproductive (R) stages, a greater percentage 

of the plants may die. When injury occurs near or after 

fl owering, the plants usually remain green and continue 

to live but do not produce seed. A similar type of 

response can be evident when plants have been injured 

by the head-clipping weevil; however, the injury from 

the head-clipping weevil is a straight cut across the 

stalk. 

The effect of bruising by hailstones is diffi cult to 

determine. If the amount of stalk bruising is such that 

the plant does not weaken or break during the remainder 

of its development prior to combine harvest, 

the effects on yield may be minimal. Stalk injury of 

such magnitude or at a specifi c location on the plant 

Table 14. Approximate percent yield reduction from the indicated percent total leaf area 

destroyed at several stages of sunfl ower plant development. 

Stage * 5 

Percent Leaf Area Destroyed 

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 

- - - - - - - - - - - - - - - - - - - - Approximate percent yield loss - - - - - - - - - - - - - - - - - - - - 

V-E to V-3 

(6-26 days) 

0 0 0 1 1 1 2 2 2 3 3 3 4 4 5 7 8 10 12 15 

V-4 to V-5 

(27-29 days) 

0 0 0 1 2 2 2 2 3 4 4 4 5 5 7 9 12 14 17 21 

V-6 to V-8 

(30-34 days) 

0 0 0 1 2 2 2 2 3 4 4 5 6 6 8 10 14 16 19 22 

V-9 to V-11 

(35-39 days) 

0 0 1 2 3 3 4 4 4 5 5 5 5 7 9 11 14 17 21 24 

V-12 to V-(N) 

(40-43 days) 

0 1 2 3 4 4 5 5 5 6 7 7 9 12 15 18 22 26 31 35 

R-1 

(44-51 days) 

0 2 3 4 5 6 6 6 7 7 8 9 13 16 20 24 29 34 40 47 

R-2 

(52-58 days) 

0 2 3 4 6 8 9 10 11 12 13 14 16 18 23 30 37 45 55 65 

R-3 

(59-67 days) 

0 2 5 8 10 15 17 19 21 24 28 32 38 44 51 59 68 78 88 99 

R-4 

(68-75 days) 

0 2 4 5 7 10 12 12 15 18 22 27 34 39 45 53 61 72 85 99 

R-5 

(76-84 days) 

0 1 2 3 5 7 8 10 13 16 20 25 32 37 43 49 55 67 78 90 

R-6 

(85-92 days) 

0 0 1 1 3 3 4 8 11 15 19 24 29 35 41 46 53 63 72 80 

R-7 

(93-102 days) 

0 0 1 1 1 3 5 7 8 10 11 13 14 16 17 18 19 20 21 22 

R-8 

(103-110 days) 

0 0 1 1 1 2 2 3 4 5 6 7 7 8 9 9 10 10 10 11 

R-9 

(111-maturity) 

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

*Number of days after planting for development to a specifi c stage will vary signifi cantly depending on environmental conditions 

and the hybrid. Interpolating percent of loss between stages may be necessary. 

Hail Injury 

93

94 

resulting in nonharvestable heads certainly would have 

an effect on yield. Physical injury by hailstones on 

the back of a sunfl ower head at or near anthesis can 

result in Rhizopus head rot, especially if wet or humid 

conditions are present. Physical injury can occur as a 

result of bird, insect or hailstone damage. Increased 

dead plant tissue resulting from a hail storm, especially 

on the back of a head, may increase the chance 

of white mold infection. 

Table 15. Approximate percent yield reduction from the Indicated percent stand reduction at 

several stages of sunfl ower plant development. 

Stage * 5 

Percent Stand Reduction 

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 

- - - - - - - - - - - - - - - - - - - - Approximate percent yield loss - - - - - - - - - - - - - - - - - - - - 

V-E to V-3 

(6-26 days) 

0 1 2 3 4 8 10 11 12 12 13 14 16 18 24 32 43 58 77 100 

V-4 to V-5 

(27-29 days) 

0 1 2 3 4 8 10 11 12 12 13 14 16 18 24 32 43 58 77 100 

V-6 to V-8 

(30-34 days) 

0 1 2 3 4 8 10 11 12 12 13 14 16 18 24 33 43 58 77 100 

V-9 to V-11 

(35-39 days) 

0 1 2 3 4 8 10 11 12 12 13 14 16 19 25 33 44 59 77 100 

V-12 to V-(N) 

(40-43 days) 

0 1 2 3 4 8 10 12 12 13 14 15 17 21 27 35 46 60 78 100 

R-1 

(44-51 days) 

1 2 5 9 12 14 15 16 17 18 19 21 25 29 35 43 53 66 81 100 

R-2 

(52-58 days) 

2 3 7 9 13 17 19 21 23 24 26 28 31 35 40 47 57 68 83 100 

R-3 

(59-67 days) 

4 7 11 13 15 17 21 24 27 29 31 34 37 41 46 53 61 72 84 100 

R-4 

(68-75 days) 

5 10 14 18 20 22 25 27 29 32 35 38 42 47 53 60 68 77 88 100 

R-5 

(76-84 days) 

5 10 14 19 20 24 28 31 35 39 42 45 49 54 60 66 73 81 90 100 

R-6 

(85-92 days) 

5 10 15 19 22 26 31 35 39 44 48 52 56 62 68 73 79 85 93 100 

*Number of days after planting for development to a specifi c stage will vary signifi cantly depending on environmental conditions 

and hybrid. It may be necessary to interpolate percent of loss between stages.

Herbicide Drift and 

Chemical Residue 

Herbicide Drift 

Herbicide drift is the movement of herbicide from 

target areas to areas where herbicide application 

was not intended. Herbicide drift generally is caused 

by movement of spray droplets or by movement of 

herbicide vapors. Herbicide granules or dried particles 

of herbicide may move short distances in high winds 

but are not considered important sources of herbicide 

drift. 

Sunfl ower is susceptible to many of the postemergence 

herbicides commonly used on crops grown in proximity 

to sunfl ower. Herbicides that may damage sunfl 

ower include most all ALS (acetolactate synthase) 

herbicides (Accent, Ally, Amber, Beacon, Express, 

Affi nity, Pursuit and Raptor), atrazine, dicamba, bentazon, 

Bronate, Buctril, Curtail, glyphosate, MCPA, 

paraquat, Stinger, 2,4-D and Tordon. 

Sunfl ower yield may be severely reduced by 2,4-D or 

dicamba (Figure 112). The amount of loss varied from 

25 percent to 82 percent, depending on the sunfl ower 

growth stage when the herbicide was applied in tests. 

Sunfl ower yield loss averaged from three rates each of 

2,4-D and dicamba to simulate spray drift was greatest 

when the herbicides were applied in the bud stage 

and least when applied during bloom. Sunfl ower in 

the V-2 to V-4 leaf stage was affected less than larger 

prebloom sunfl ower. 

Only a small portion of an applied herbicide drifts 

from the target area. However, some nontarget areas 

can receive rather high doses of herbicide since herbicide 

drift can accumulate in the nontarget areas. Herbicide 

accumulated in downwind areas occasionally 

may exceed the rate applied to the target fi eld. A small 

portion of the herbicide applied with each sprayer pass 

may accumulate in an adjoining fi eld. Also, a taller 

crop, such as sunfl ower, may intercept more spray 

drift than a shorter crop, such as wheat or barley. The 

amount of herbicide that contacts the sunfl ower and 

the environment during and following application 

infl uences the yield loss caused by herbicide drift. For 

example, experiments at North Dakota State University 

showed that 2,4-D at 0.5 ounce per acre applied 

to 12- to 14-leaf sunfl ower caused a 5 percent loss 

in 1973 and 93 percent loss in 1978. Low but equal 

levels of drift may cause very different effects on 

sunfl ower yield, depending on environment. Sunfl ower 

injury from herbicide drift will be greatest with warm 

temperatures and good soil moisture. 

Sunfl ower may exhibit herbicide injury symptoms 

without a yield loss. Experiments at North Dakota 

State University indicated that sunfl ower height 

reduction, as compared with undamaged sunfl ower, 

caused by 2,4-D, MCPA or dicamba was signifi cantly 

correlated with sunfl ower yield loss. Drift of 2,4-D, 

■ Figure 112. Sunfl ower yield loss from herbicides 

applied at various growth stages averaged over 2,4-D 

rates of 0.5, 1 and 2 oz./A and dicamba at 0.1, 0.5 

and 1.0 oz/A. (A. Dexter) 

Herbicide Drift and Chemical Residue 

95

96 

MCPA or dicamba, which causes a sunfl ower height 

reduction, also would be expected to reduce yield. 

However, typical injury symptoms can occur without 

height reduction and this would not be expected to 

reduce yield. 

MCPA, 2,4-D, dicamba and Tordon are growth-regulator 

herbicides and all produce similar symptoms 

on sunfl ower. Sunfl ower exhibits epinasty, which is 

an abnormal bending of stems and/or leaf petioles, 

shortly after contact with a growth-regulator herbicide. 

Figure 113 shows the bending of sunfl ower only 

24 hours after 2,4-D application while Figure 114 

shows the abnormal twisting of leaf petioles several 

days after 2,4-D application. Sunfl ower growth often 

is slowed or stopped by growth-regulator herbicides. 

■ Figure 113. Bending of sunfl ower only 24 hours 

after 2,4-D application. (A. Dexter) 

■ Figure 114. Abnormal twisting of leaf petioles 

several days after 2,4-D application. (A. Dexter) 

Leaves that develop after contact with a growthregulator 

herbicide often are malformed. Leaves may 

have more parallel vein patterns and abnormal leaf 

shapes (Figure 115). A higher degree of injury from 

a growth-regulator herbicide may stop plant growth 

totally. Some plants die without further growth, some 

will remain green and not grow the rest of the season, 

and some plants will begin growing later after the 

herbicide is partially metabolized. Sunfl ower in Figure 

116 did not grow for several days and then produced a 

stalk and fl ower. 

Affected plants also may branch and produce multiple 

heads when growth resumes (Figure 117). Root 

■ Figure 115. Growth regular herbicides may cause 

leaves of sunfl ower to have more parallel vein 

patterns and abnormal leaf shapes. (A. Dexter) 

■ Figure 116. Interrupted growth of sunfl ower due to 

exposure to growth regulator herbicide. (A. Dexter)

growth may be retarded by growth-regulator herbicides 

and abnormal lumps or knots may develop on 

sunfl ower roots (Figure 118). Sunfl ower contacted by 

growth-regulator herbicides during the bud or fl owering 

stage may develop malformed heads or heads with 

sterility (Figure 119). 

■ Figure 117. Multiple branching and heading of 

sunfl ower due to exposure to growth regulator 

herbicides. (A. Dexter) 

■ Figure 118. Abnormal lumps and knots on 

sunfl ower roots developed after exposure to growth 

regulator herbicides. (A. Dexter) 

Sunfl ower plants contacted with a growth-regulator 

herbicide will not develop all of the symptoms shown 

in Figures 112 through 117. Considerable variation 

in symptomology can occur, depending on herbicide 

rate, sunfl ower stage and environment. 

Symptoms similar to those shown in Figures 114 to 

119 also may be produced by soil residues of herbicide. 

MCPA and 2,4-D have very short soil residual, 

but damage to sunfl ower could occur if they were 

applied just before planting or emergence. Tordon 

has a long soil residual and can carry over from the 

previous year and cause sunfl ower injury. Dicamba at 

rates used in small grains would not be expected to 

carry over to the next year. Dicamba used in the fall at 

rates necessary to control certain perennial weeds may 

persist in the soil and damage sunfl ower the next year. 

Accent, Ally, Amber, atrazine, Beacon and Pursuit are 

long residual herbicides that may persist for more than 

one year at levels that can injure sunfl ower. The length 

of persistence can be affected by pH (high pH causes 

longer residue of some herbicides), application rate 

and soil moisture. 

The symptoms from these herbicides are not similar to 

symptoms from growth-regulator herbicides. Sunfl ower 

affected by Accent, Ally, Amber, Beacon or Pursuit 

emerge and become well-established. Chlorosis starts 

on the young leaves often with a distinct yellowing. 

Top growth and roots may be severely stunted. Plants 

may remain small for several weeks or they may die. 

■ Figure 119. Sunfl owers contacted by growth 

regulator herbicides during bud or fl owering stage 

developed malformed heads or heads with sterility. 

(A. Dexter) 


97

98 

Low doses may cause temporary stunting and plants 

later may begin to grow normally. Sunfl ower affected 

with atrazine emerge and look normal for a short time. 

Leaf burn starts on the outer edges of the oldest leaves 

and progresses toward the middle of the leaf. Veinal 

areas are the last to turn brown in an affected leaf. 

The risk of sunfl ower injury from herbicide drift is 

infl uenced by several factors. 

Spray particle size: Spray drift can be reduced by 

increasing droplet size since larger droplets move 

laterally less than small droplets. Droplet size can be 

increased by reduced spray pressure; increased nozzle 

orifi ce size; use of special nozzles, such as “Raindrop,” 

“LFR,” “XR” or “LP;” use of additives that 

increase spray viscosity; rearward nozzle orientation; 

and increased nozzle pressure on aircraft. Research 

has shown that increasing nozzle pressure in a rearward-oriented 

nozzle in a high-speed air stream will 

produce larger droplets and less fi nes. This is due to 

less secondary wind shear, and does not happen with 

ground sprayers. 

Spray pressure with standard fl at-fan nozzles should 

not be less than 25 pounds per square inch (psi) 

because the spray pattern from the nozzles will not 

be uniform at lower pressures. The “XR” and “LP” 

nozzles are designed to give a good spray pattern at 15 

to 50 psi. Operating at a low spray pressure results in 

larger spray droplets. Some postemergence herbicides, 

such as bentazon, require small droplets for optimum 

performance, so techniques that increase droplet size 

may reduce weed control with certain herbicides. Herbicides 

that readily translocate, such as 2,4-D, MCPA, 

dicamba and Tordon, are affected little by droplet size 

within a normal droplet size range, so drift control 

techniques would not be expected to reduce weed control 

with these herbicides. Glyphosate is translocated 

readily, so droplet size has minimum effect on weed 

control. However, glyphosate is inactivated partially 

by increased water volume and spray volume recommendations 

on the label should be followed. 

Herbicide volatility: All herbicides can drift in spray 

droplets, but some herbicides are suffi ciently volatile 

to cause plant injury from drift of vapor or fumes. The 

ester formulations of 2,4-D and MCPA may produce 

damaging vapors, while the amine formulations are 

essentially nonvolatile. Dicamba is a volatile herbicide 

and can drift in droplets or vapor. 

Herbicide vapors may cause crop injury over greater 

distances than spray droplets. However, spray droplets 

can move long distances under certain environmental 

conditions, so crop injury for a long distance does not 

necessarily result from vapor drift. A wind blowing 

away from a susceptible crop during herbicide application 

will prevent damage from droplet drift, but a later 

wind shift toward the susceptible plants could move 

damaging vapors into the susceptible crop. 

Herbicide volatility increases with increasing temperature. 

The so-called high-volatile esters of 2,4-D or 

MCPA may produce damaging vapors at temperatures 

as low as 40 degrees Fahrenheit, while low-volatile 

esters may produce damaging vapors between 70 and 

90 F. The soil surface temperature often is several 

degrees warmer than air temperature, so a low-volatile 

ester could be exposed to temperature high enough to 

cause damaging vapors, even when the air temperature 

was less than 70 F. 

Wind velocity and air stability: Wind, or the 

horizontal movement of air, is widely recognized as 

an important factor affecting spray drift. However, 

vertical movement of air also has a large infl uence on 

damage to nontarget plants from spray drift. An air 

mass with warmer air next to the ground and decreasing 

temperature with increasing elevation will be unstable. 

That is, the warm air will rise and the cool air 

will sink, providing vertical mixing of air. Stable air, 

often called an inversion, occurs when air temperature 

increases or changes little as elevation increases. With 

these temperature relationships, very little vertical 

movement of air occurs since cool air will not rise into 

warmer air above. Spray droplets or vapor are carried 

aloft and dispersed away from susceptible plants with 

unstable air conditions. With stable air (inversion), 

small spray droplets may be suspended just above the 

ground in the air mass, move long distances laterally 

and be deposited on susceptible plants.

Low wind velocity in combination with unstable air 

generally will result in very little damaging spray drift. 

However, low wind velocity with stable air (inversion) 

can result in severe damage over a long distance. Crop 

injury has been observed two miles or more from 

the site of application with 10 mph or slower winds, 

small spay droplets, stable air, highly susceptible crops 

and nonvolatile but highly active herbicides. Longdistance 

drift can occur with particle drift as well as 

vapor drift. 

Stable air usually can be identifi ed by observing dust 

off a gravel road or smoke from a fi re or smoke bomb. 

Smoke or dust moving horizontally and staying close 

to the ground would indicate stable air. Fog also would 

indicate stable air. Herbicide application should be 

avoided during stable air conditions unless spray drift 

is not a concern. 

Distance between nozzle and target (boom 

height): Less distance between the droplet release 

point and the target will reduce spray drift. Less 

distance means less time to travel from nozzle to 

target, so less drift occurs. Small spray droplets have 

little inertial energy, so a short distance from nozzle to 

target increases the chance that the small droplets can 

reach the target. Also, wind velocity often is greater as 

height above the ground increases, so reduced nozzle 

height will reduce the wind velocity affecting the 

spray droplets. 

Shielded sprayers: Shielded sprayers utilize some 

type of shielding to protect spray droplets from wind. 

The effectiveness of the shields varies, depending 

on the design of the shield, wind velocity and wind 

direction relative to the sprayer. Drift from shielded 

sprayers has varied from about 50 percent to more 

than 95 percent less than from similar nonshielded 

sprayers in experiments with various shield designs 

and conditions. 

Herbicide drift can reduce sunfl ower yield severely. 

The risk of herbicide drift can be reduced greatly 

by increasing droplet size, reducing nozzle height, 

using nonvolatile herbicides, avoiding spraying during 

temperature inversions, using shielded sprayers 

and spraying when the wind is blowing away from a 

susceptible crop. 

Chemical Residue in the 

Tank and Sprayer Cleanout 

Crop injury from a contaminated sprayer may occur 

when a herbicide not registered on sunfl ower was used 

previously in the sprayer. The risk of damage is greatest 

when the previous herbicide is highly phytotoxic to 

sunfl ower in small amounts. Rinsing with water is not 

adequate to remove all herbicides. Some herbicides 

have remained tightly adsorbed in sprayers through 

water rinsing and even through several tank loads of 

other herbicides. Then, when a tank load of solution 

including an oil adjuvant or nitrogen solution was put 

in the sprayer, the herbicide was desorbed, moved into 

the spray solution and damaged susceptible crops. 

Highly active herbicides that have been diffi cult to 

wash from sprayers and have caused crop injury include 

ALS herbicides (Accent, Ally, Beacon, Express, 

Pursuit and Raptor), and growth-regulator herbicides 

(2,4-D and dicamba). 

Herbicides that are diffi cult to remove from sprayers 

are thought to be attaching to residues remaining 

from spray solutions that deposit in a sprayer. The 

herbicide must be desorbed from the residue or the 

residue removed in a cleaning process so the herbicide 

can be removed from the sprayer. Sprayer cleanout 

procedures are given on many herbicide labels and the 

procedure on the label should be followed for specifi c 

herbicides. The following procedure is given as an 

illustration of a thorough sprayer cleanup procedure 

that would be effective for most herbicides. 

Step 1. Drain tank and thoroughly rinse interior 

surfaces of tank with clean water. Spray 

rinse water through the spray boom. Suffi 

cient rinse water should be used for fi ve 

minutes or more of spraying through the 

boom. 

Step 2. Fill the sprayer tank with clean water and 

add a cleaning solution (many herbicide 

labels provide recommended cleaning solutions). 

Fill the boom, hoses and nozzles 

and allow the agitator to operate for 15 

minutes. 

Step 3. Allow the sprayer to sit for eight hours 

while full of cleaning solution. The cleaning 

solution should stay in the sprayer for 

eight hours so that the herbicide can be 

fully desorbed from the residues inside the 

sprayer. 

Chemical Residue 

99

100 

Step 4. Spray the cleaning solution out through 

the booms. 

Step 5. Remove nozzles, screens and fi lters and 

clean thoroughly. Rinse the sprayer to 

remove cleaning solution and spray rinsate 

through the booms. 

Common types of cleaning solutions are chlorine 

bleach, ammonia and commercially formulated tank 

cleaners. Chlorine lowers the pH of the solution, 

which speeds the degradation of some herbicides. 

Ammonia increases the pH of the solution, which 

increases the solubility of some herbicides. Commercially 

formulated tank cleaners generally raise pH and 

act as detergents to assist in removal of herbicides. 

Read the herbicide label for recommended tank cleaning 

solutions and procedures. WARNING: Never mix 

chlorine bleach and ammonia, as a dangerous and 

irritating gas will be released. 

Sprayers should be cleaned as soon as possible after 

use to prevent the deposit of dried spray residues. If a 

sprayer will remain empty overnight without cleaning, 

fi ll the tank with water to prevent dried spray deposits 

from forming. A sprayer kept clean is essential to 

prevent damage from herbicide contamination.

Maturity 

Harvesting 

(Vern Hofman) 

Sunfl ower in the northern Great Plains production area 

usually is ready for harvest in late September or October, 

with a growing season of approximately 120 days. 

The growing season may vary in length, depending on 

summer temperatures, relative moisture distribution 

and fertility levels. The sunfl ower plant is physiologically 

mature when the back of the head has turned 

from green to yellow and the bracts are turning brown 

(Stage R-9), about 30 to 45 days after bloom, and seed 

moisture is about 35 percent. 

Desiccants can be applied to the crop after physiological 

maturity to speed the dry-down process. The 

chemical compounds act much like a frost to kill the 

green tissue on the plant and accelerate its drying. 

After applications of a desiccant, dry down of the seed 

is not as rapid as the dry down of the plant. Growers 

often are tempted to apply desiccants too early when 

potential loss factors are present. Application of a desiccant 

before the plant reaches physiological maturity 

will reduce yield and lower oil percentage. Drying is 

facilitated in most years by a killing frost, but if frost 

occurs too early, yield and oil percentages are reduced. 

Seed shattering loss during harvest and loss from birds 

may be reduced by harvesting sunfl ower at moisture 

contents as high as 25 percent. Sunfl ower seed from 

the combine then is dried in a grain dryer to 9.5 percent, 

which is considered a safe storage level. 

Harvesting Attachments 

Combines suitable for threshing small grains can 

be adapted to harvest sunfl ower. A variety of header 

attachments are available, with many operating on a 

head stripper principle. 

The attachments are designed to gather only the sunfl 

ower heads and eliminate as much stalk as possible. 

Major components of this attachment are catch pans, 

a defl ector and a small reel. Long catch pans extend 

ahead of the cutter bar to catch the seed as it shatters. 

The defl ector mounted above the catch pans pushes 

the stalk forward until only the heads remain above 

the cutter bar. As the heads move below the defl ector, 

the stems contact the cutter bar and are cut just below 

the head. A small reel, mounted directly behind the 

defl ector, pushes the heads into the combine feeder. 

Catch pans are available in various widths. These 

range from narrow 9-inch pans spaced on 12-inch 

centers (Figure 120) to 37-inch pans spaced on 40inch 

centers (Figure 121). The narrow 9-inch pans can 

operate on any row spacing, while the wider and more 

effi cient 30- to 40-inch spaced pans are limited to a 

fi xed-row spacing. 

The defl ector consists of a curved piece of sheet metal 

the full width of the combine head. It is attached to the 

reel support arms above the catch pans. The reel for 

the unit is mounted directly behind the defl ector and 

usually consists of three or four arms. The reel is usually 

16 to 20 inches in diameter and mounted 4 to 5 

inches above the catch pans, so when the heads come 

in contact with the reel, they are pushed back into the 

feeder. The shield and reel can handle tall plants while 

taking only a minimum length of stalk with the head, 

allowing harvest when the seed is dry but stalk moisture 

may remain above 50 percent. Cleaner threshing 

also is accomplished when only the head enters the 

machine. 

Harvesting 

101

102 

Optional forward rotating stalk-walker shafts, introduced 

from Argentina and used mainly in the southern 

Plains, can be mounted under the cutter bar to reduce 

plugging of stalk slots between pans. The stalk-walker 

pulls sunfl ower stalks and weeds down so that only the 

sunfl ower head is fed into the combine. Stalk-walkers 

are reported to be especially useful in fi elds with tall 

weeds. 

A rotating drum with metal projections that replaces 

the defl ector bar and reel often is used (Figure 122). 

The projections are triangular-shaped pieces of strap 

iron welded to its surface. As the drum rotates, the 

projections pass through the slots between the catch 

pans to remove any stalks that may cause clogging. 

The smooth drum acts as a defl ector bar to strip stalks 

■ Figure 120. Catch pans in narrow 9 inch pans 

spaced on 12 inch centers. (V. Hofman) 

■ Figure 121. Catch pans in wide 37 inch pans 

spaced on 36 inch centers. (V. Hofman) 

until one of the projections catches a head and pushes 

it into the cutter bar and into the combine header. 

Row-crop units mounted on combine headers have 

been used successfully to harvest sunfl ower seed 

(Figure 123). One unit uses gathering belts, one on 

each side of the row, to draw the stalk into the cutting 

unit and the header. A large quantity of stalk passes 

through the machine with this unit and may increase 

the foreign matter in the seed, but this unit works well 

picking up lodged sunfl ower and getting the heads into 

the machine. 

Another type of header uses a short section of screw 

conveyor to pull the stalks into the cutter bar and the 

combine header. This unit also works well for picking 

up lodged sunfl ower. 

■ Figure 122. Rotating drum with metal projections. 

(V. Hofman) 

■ Figure 123. All crop header used to harvest 

sunfl ower. (V. Hofman)

Combine Adjustments 

Forward Speed: A combine’s forward speed usually 

should average between 3 and 5 miles per hour. 

Optimum forward speed usually will vary depending 

upon moisture content of the sunfl ower seed and 

yield of the crop. Forward speed should be decreased 

as moisture content of the seed decreases to reduce 

the shatter loss as the heads feed into the combine. 

Faster forward speeds are possible if the moisture of 

the seed is between 12 percent and 15 percent. The 

higher speeds should not overload the cylinder and the 

separating area of the combine except in an extremely 

heavy crop. Seed having 12 percent to 15 percent 

moisture will thresh from the head very easily as it 

passes through the cylinder. 

Cylinder Speed: After the sunfl ower heads are 

separated from the plant, they should be threshed at 

a cylinder speed operating as slow as possible. The 

normal cylinder speed should be about 300 revolutions 

per minute (rpm), depending upon the condition 

of the crop and the combine being used. This cylinder 

speed is for a combine with a 22-inch-diameter 

cylinder to give a cylinder bar travel speed of 1,725 

feet per minute. Combines with smaller cylinders 

will require a faster speed and combines with a larger 

cylinder diameter will require a slower speed. Rotary 

combines, as well as conventional machines, should 

have similar cylinder travel speeds. A rotary combine 

with a 30-inch cylinder will need to be operated at 

220 rpm to have a cylinder bar speed of 1,725 feet per 

minute. A combine with a 17-inch cylinder will need 

to operate at 390 rpm to have a cylinder bar speed of 

1,725 feet per minute. 

If a combine cylinder operates at speeds of 400 to 500 

rpm, giving a cylinder bar speed of more than 2,500 

feet per minute, very little seed should be cracked or 

broken if the moisture content of the seed is above 11 

percent. Cylinder bar speeds of more than 3,000 feet 

per minute should not be used because they will cause 

excessive broken seed and increased dockage. Excess 

dockage and broken seed may overload the sieves and 

the return elevator. 

Concave Adjustment: Sunfl ower threshes relatively 

easily. When crop moisture is at 10 percent or less, 

conventional machines should be set wide open to 

give a cylinder-to-concave spacing of about 1 inch 

at the front of the cylinder and about 0.75 inch at 

the rear. A smaller concave clearance should be used 

only if some seed is left in the heads. If the moisture 

percentage of the crop is between 10 percent and 12 

percent, rather than increase the cylinder speed, the 

cylinder-to-concave clearance should be decreased 

to improve threshing. If seed moisture exceeds 15 

percent to 20 percent, a higher cylinder speed and a 

closer concave setting may be necessary, even though 

foreign material in the seed increases. Seed breakage 

and dehulling may be a problem with close concave 

settings. Make initial adjustments as recommended 

in the operator’s manual. Final adjustments should be 

made based on crop conditions. 

Rotary combines should be set to have a rotor-to-concave 

spacing of about 0.75 to 1 inch. Making initial 

settings as recommended in the operator’s manual usually 

is best. Final adjustments should be made based 

on crop conditions. 

Fan Adjustment: Oilseed and nonoilseed sunfl ower 

weigh about 28 to 32 pounds per bushel and 22 to 26 

pounds per bushel, respectively. The seed is relatively 

light compared with other crops, so excessive 

wind may blow seed over the chaffer and sieve. Seed 

forced over the sieve and into the tailings auger will 

be returned to the cylinder and may be dehulled. Only 

enough wind to keep the trash fl oating across the sieve 

should be used. The chaffer and sieve should be adjusted 

to minimize the amount of material that passes 

through the tailings elevator. 

When the combine is adjusted correctly to thresh 

sunfl ower seed, the threshed heads will come through 

only slightly broken and with only unfi lled seed 

remaining in the head. Cylinder concaves and cleaning 

sieves usually can be set to obtain less than 5 percent 

dockage. Improper settings will crush the seed but 

leave the hull intact. Proper setting is critical, especially 

for nonoilseed sunfl ower that is used for the human 

food market. The upper sieve should be open enough 

to allow an average seed to pass through on end, or 

be set at a ½- to 5/8- inch opening. The lower sieve 

should be adjusted to provide a slightly smaller opening, 

or about 3/8 inch wide. The fi nal adjustments will 

depend on the amount of material returning through 

the tailings elevator and an estimation of the amount 

of dockage in the grain tank. Some operators are able 

to adjust and operate their machine to allow only 2 

percent to 3 percent dockage in the seed. 

Harvesting 

103

104 

Field Loss 

The harvested yield of sunfl ower can be increased by 

making necessary adjustments following a determination 

of fi eld loss. Three main sources of loss are: (a) 

loss in the standing crop ahead of the combine, (b) 

header loss as the crop enters the machine and (c) 

threshing and separating loss. The loss found in any 

of these three areas will give the combine operator a 

good estimate of sources of seed loss and the adjustments 

necessary to minimize seed loss. 

Loss occurring in any of these areas may be estimated 

by counting the seed on the soil surface in a squarefoot 

area. Ten seeds per square foot equal approximately 

1 hundredweight (cwt) per acre loss if seed 

loss is uniform throughout the entire fi eld. 

The loss in the standing crop is estimated by counting 

the seed in a 1-square-foot area ahead of the machine 

at several different places in the fi eld. Header loss can 

be calculated by counting seed in a 1-square-foot area 

behind the head under the combine and subtracting the 

standing crop loss. The loss in combine separation can 

be found by counting the seed in a 1-square-foot area 

directly behind the rear of the combine and subtracting 

the shatter loss and the header loss found under the 

machine. The count made directly behind the combine 

will be concentrated, so an adjustment must be made 

to equalize the loss over the entire width of cut. The 

result should be divided by the ratio: 

Width of Header Cut (feet) 

Width of Rear of Combine (feet) 

The answer is the adjusted separator loss for the width 

of cut. This result must be divided by 10 to obtain the 

combine separator loss in cwt per acre. The total loss 

in cwt per acre is determined by adding the seed loss 

in the standing crop, header loss and separator loss 

and dividing this answer by 10. The percentage loss 

can be found by dividing the total cwt per acre by the 

yield in cwt per acre. 

Harvest without some seed loss is almost impossible. 

Usually a permissible loss is about 3 percent. Loss as 

high as 15 percent to 20 percent has occurred with a 

well-adjusted combine if the ground speed is too fast, 

resulting in machine overload.

Drying and Storage 

(Kenneth Hellevang) 

Harvesting sunfl ower at higher moisture contents 

normally results in higher yields and less fi eld loss. 

Early harvest also reduces exposure to late-season wet 

and cold weather. Frequently, mechanical drying is 

required so harvesting can be completed. 

Natural-air, low-temperature and high-temperature 

bin, batch (Figure 124) and continuous-fl ow dryers 

can be used to dry sunfl ower. 

Natural-air and low-temperature bin drying is energy 

effi cient if designed properly and permits rapid harvest 

since bins can be fi lled at the harvest rate. Drying 

will take three to six weeks, depending on the initial 

moisture content, airfl ow rate and outdoor temperature. 

Required airfl ow rates and drying time for drying 

oil sunfl ower at various moisture contents using air at 

47 degrees Fahrenheit and 65 percent relative humid- 

■ Figure 124. A high temperature column dryer used 

for drying sunfl ower. (K. Hellevang) 

ity (average North Dakota conditions for October) are 

shown in Table 16. Drying times will be twice as long 

at 27 degrees due to the reduced moisture-holding 

capacity at colder temperatures. Heating the air more 

than about 5 degrees normally causes overdrying. 

Table 16. Recommended airfl ow rates and drying 

times for natural-air drying oilseed sunfl ower in 

October. (47 F and 65 percent relative humidity). 

Fan Time 

Moisture Airfl ow 

Content (cfm/bu) hours days 

17% 1.00 648 27 

15% 1.00 480 20 

0.75 720 30 

0.50 960 40 

13% 1.00 336 14 

0.75 504 21 

0.50 672 28 

Add enough heat when needed to dry the sunfl ower to 

the safe storage moisture content. Generally, enough 

heat to warm the air about 5 degrees is the maximum 

amount required. As a rule of thumb, about 2 kilowatts 

(kW) of heater will be required per fan motor 

horsepower. The equation for calculating the heat 

requirement in Btu is: Btu/hr = cfm x 1.1 x temperature 

increase. Convert Btu to kW by dividing by 3,413 

Btu/kW. Refer to NDSU Extension Service publication 

EB-35, “Natural Air and Low Temperature Crop 

Drying,” and publication AE-701, “Grain Drying,” for 

more information on drying sunfl ower. 

A perforated fl oor is recommended. Since air does the 

drying, making sure air reaches all the sunfl ower is 

imperative. The uniform airfl ow distribution required 

for drying is more diffi cult to achieve with ducts than 


105

106 

with perforated fl oors. However, drying can be done 

successfully if ducts are spaced no more than onehalf 

the grain depth apart and the distance from the 

duct to bin wall does not exceed one-fourth the grain 

depth. Provide 1 square foot of duct or fl oor perforated 

surface area for each 25 cubic feet per minute (cfm) of 

airfl ow. One square foot of bin exhaust opening should 

be provided for each 1,000 cfm of airfl ow. 

Drying temperatures up to 220 F do not appear to 

have an adverse effect on oil percentage or fatty 

acid composition. High drying temperatures for the 

nonoil varieties may cause the kernels to be steamed, 

wrinkled or even scorched. 

Column batch and bin batch dryers should be operated 

at 180 and 120 F, respectively. Continuous-fl ow and 

recirculating batch dryers may be operated at temperatures 

up to about 200 F. Temperatures in excess of 110 

F should not be used to dry sunfl ower seed for seeding 

purposes. 

Fire hazards exist in dryers used for sunfl ower. Very 

fi ne hairs or fi bers from the seed are rubbed loose 

during handling and commonly are found fl oating in 

the air around the dryer. These hairs or fi bers or other 

plant materials may be ignited when drawn through 

the drying fan and open burner. A fi re hazard is present 

unless these ignited particles burn themselves out 

before contacting the sunfl ower seed. 

The fi re hazard is decreased if the fans of a portable 

dryer are turned into the wind to draw clean air that 

does not contain fi ne hair or fi bers and by pointing 

stationary dryers into the prevailing wind. A moveable 

air intake duct may be placed on the burner intake 

to draw clean air away from the dryer. However, the 

duct must be large enough to not restrict the airfl ow 

because drying speed will be reduced if the airfl ow is 

reduced. 

Clean the dryer, air ducts and area around the dryer 

at least daily. Frequently remove the collection of 

sunfl ower lint on the dryer column and in the plenum 

chamber, as this material becomes extremely dry and 

can be ignited during dryer operation. A major concern 

is that some sunfl ower seeds will hang up in the 

dryer or be stopped by an accumulation of fi nes and 

become overdried. Make sure the dryer is completely 

cleaned out after each batch, and check a continuousfl 

ow dryer regularly (at least hourly) to see that the 

sunfl ower seed is moving. 

High-speed dryers are like a forge when a fi re gets 

going. However, fi res can be controlled if they are 

noticed immediately, which makes constant monitoring 

necessary. Many fi res can be extinguished by just 

shutting off the fan to cut off the oxygen. A little water 

applied directly to the fi re at the early stages may 

extinguish it if shutting off the fan fails to do so. A fi re 

extinguisher for oil-type fi res should be used for oil 

sunfl ower fi res. Many dryers are designed so that sunfl 

ower can be unloaded rapidly in case of a fi re, before 

the dryer is damaged. In some dryers, just the part of 

the dryer affected by the fi re needs to be unloaded. 

Measuring Moisture Content 

Measuring the moisture content of sunfl ower immediately 

after removal from the dryer results in only an 

estimation. As moisture is removed from the sunfl ower 

seed, the hull dries fi rst and the kernels dry last. Moisture 

testers used by local grain elevators and farm 

operators generally result in a reading that is lower 

than the actual moisture percentage when moisture is 

measured while the moisture variation exists. The initial 

moisture content of the sunfl ower and the temperature 

of the drying air infl uence the amount of error. 

A number of operators have reported that sunfl ower 

removed from the dryer at 9 percent to 10 percent 

moisture (according to the moisture tester) would be 

up to 12 percent moisture later. The moisture rebound 

can be estimated by placing a sample from the dryer 

in a covered jar and then rechecking the moisture after 

12 hours. 

Guidelines for drying sunfl ower are: 

• The area around the dryer and the plenum chamber 

should be cleaned thoroughly. 

• The fan must be fed clean air without seed hairs. 

• A continuous fl ow in all sections of recirculating 

batch and continuous-fl ow dryers should be maintained. 

Uneven fl ow will cause overdried spots 

and increase fi re hazard. 

• Drying equipment must not be left unattended 

day or night. 

• The dried sunfl ower should be cooled to air temperature 

before storing.

Storage 

Farm structures that are structurally adequate to store 

other grains are adequate for storing sunfl ower due to 

sunfl ower’s light test weight, Figure 125. 

Seed should be cleaned for storage. Fines tend to concentrate 

in the center of the bin if a distributor is not 

used. Since this material tends to be wetter, this area 

is more prone to storage problems. Also, airfl ow will 

be restricted by the fi nes, limiting cooling by aeration 

in the center of the bin. Large pieces of head, stalk 

and corolla tubes, which frequently adhere to the seed, 

should be removed because they are higher in moisture 

than the seed. 

Oil sunfl ower should not be stored above 10 percent 

moisture during the winter and 8 percent during the 

summer. Nonoilseed sunfl ower should not be stored 

■ Figure 125. Structures adequate to store other 

grains are adequate for sunfl ower. (K. Hellevang) 

■ Figure 126. Aeration is critical for proper storage. (K. Hellevang) 

above 11 percent moisture during the winter and 10 

percent during the summer. Sunfl ower can be stored 

for short periods in the fall at 12 percent with adequate 

airfl ow to keep the seeds cool. Resistance of 

oilseed sunfl ower to fungal infection during storage at 

10 percent moisture is equal to wheat resistance at 15 

percent stored moisture. 

Aeration to control seed temperature is essential. 

Aeration fans normally are sized to provide 0.05 to 0.2 

cfm/bu. (0.15 to 0.6 cfm per cwt) of sunfl ower (Figure 

126). Sunfl ower should be rotated between bins during 

the storage period when aeration is not available. 

Cooling sunfl ower reduces the potential for sunfl ower 

deterioration from insects and mold. Sunfl ower should 

be cooled to 40 degrees or below before or soon after 

it is put in the bin and to about 25 degrees for winter 

storage. Insects become dormant and will not cause 

damage or multiply if seed temperature is below about 

40 F. 

Moisture and heat accumulate in the peak due to 

moisture migration, which results in crusting, spoilage 

and increased possibility of insect infestations (Figure 

127). This can be prevented by cooling the sunfl ower 

using aeration. 

Bins should be checked initially every two weeks 

for moisture condensation on the roof, crusting and 

changes in temperatures within the pile. Any of these 

conditions could indicate the presence of mold or insects. 

If the sunfl ower has started to heat, it should be 

cooled immediately. The sunfl ower should be checked 

at least monthly after the seeds have been cooled to 

about 25 F for winter storage and a history of temperature 

and moisture content has been developed. 


107

108 

■ Figure 127. Moisture migration leads to increased 

moisture in top center of stored sunfl ower. 

(K. Hellevang) 

Seed lots containing a high percentage of hulled seed 

or immature seed, such as seed resulting from an 

early frost, tend to deteriorate in storage, affecting oil 

quality. 

Refer to NDSU Extension Service publication 

AE-791, “Crop Storage Management,” for more 

information on aeration and storage management.

Feeding Value of Sunfl ower 

Products in Beef Cattle Diets 

(Greg Lardy) 

Sunfl ower Meal 

Nutrients in sunfl ower meal can vary depending on 

several factors. The amount and composition of meal 

is affected by oil content of the seed, extent of hull 

removal and effi ciency of oil extraction. The proportion 

of hull removed before processing differs among 

crushing plants. In some cases, a portion of the hulls 

may be added back to the meal after crushing. The 

amount of hull or fi ber in the meal is the major source 

of variation in nutrients (Table 17). 

Pre-press solvent extraction of whole seeds with no 

dehulling produces meal with a crude protein content 

of 25 percent to 28 percent, partial dehulling yields 

34 percent to 38 percent crude protein content and 

completely dehulled sunfl ower meal commonly yielding 

40-plus percent crude protein. Sunfl ower meal 

is marketed and shipped as meal or pellets. Protein 

required by rumen microbes can be provided in the 

form of rumen-degradable protein from sunfl ower 

meal. Heat treatment or toasting of meal from the 

solvent extraction process may increase the propor- 

Table 17. Nutrient content of solvent-extracted 

sunfl ower meal based on amount of hulls 

retained. 

No Hulls Partially 

Removed Dehulled Dehulled 

Dry Matter, % 90.0 90.0 90.0 

Percent, Dry Matter Basis 

Crude Protein 28.0 34.0 41.0 

Fat 1.5 0.8 0.5 

Crude Fiber 24.0 21.0 14.0 

Ash 6.2 5.9 5.9 

Calcium 0.36 0.35 0.34 

Phosphorus 0.97 0.95 1.30 

Potassium 1.07 1.07 1.07 

Magnesium 0.80 0.79 0.79 

Hesley (ed), National Sunfl ower Association, 1994. 

tion of undegradable protein. Sunfl ower meal is more 

ruminally degradable (74 percent of crude protein) 

than either soybean meal (66 percent) or canola meal 

(68 percent; Table 18). 

Sunfl ower meal has a lower energy value than either 

canola or soybean meal (Table 18). Energy varies 

substantially with fi ber level and residual oil content. 

Higher levels of hulls included in the fi nal meal product 

lower the energy content and reduce bulk density. 

The mechanical process of oil extraction leaves more 

residual oil in the meal, often 5 percent to 6 percent 

or more, depending on the effi ciency of the extraction 

process. Elevated oil content in mechanically extracted 

meals provides greater energy density. Pre-press 

solvent extraction reduces residual oil to 1.5 percent 

or less. 

Sunfl ower Meal in Beef Cattle Diets 

Sunfl ower meal can be used as the sole source of 

supplemental protein in beef rations. In trials comparing 

sunfl ower meal with other protein sources, equal 

animal performance commonly is observed based on 

isonitrogenous diets from different sources. 

Cows consuming low-quality forages, such as winter 

range, crop aftermath or other low-quality forages, can 

utilize supplemental degradable protein to increase 

total intake, forage digestibility and performance. 

Protein can be supplemented with a number of feeds, 

coproducts or oilseed meals. Least costly sources are 

critical to profi tability, and sunfl ower meal often is 

very competitively priced per unit protein. Sunfl ower 

meal has been used widely in beef cow supplementation 

programs but few research trials document 

comparative animal performance. 

Feeding Value of Sunfl ower Products in Beef Cattle Diets 

109

110 

Sunfl ower Silage 

Table 18. Protein and energy fractions for sunfl ower meal, soybean meal 

and canola meal. 

Sunfl ower Soybean Canola 

Item Meal Meal 

Dry Matter Basis, % 

Meal 

Crude Protein 26.0 49.9 

Crude Protein, % 

40.9 

Rumen Degradable 74.0 66.0 68.0 

Rumen Undegradable 26.0 34.0 22.0 

Dry Matter Basis, % 

Crude fi ber 12.7 7.0 13.3 

Neutral Detergent Fiber 40.0 14.9 27.2 

Acid Detergent Fiber 30.0 10.0 17.0 

Net Energy, Maintenance, Mcal/lb 0.67 0.93 0.73 

Net Energy, Gain, Mcal/lb 0.40 0.64 0.45 

Total Digestible Nutrients 65 84 69 

Adapted from NRC, 1996. 

Sunfl ower silage can make a suitable feed for beef 

cows; however, high moisture levels can be a challenge 

since sunfl owers typically don’t dry down well. 

Consequently, dry feed must be added to the silage 

pile to reduce the moisture level to a point where seepage 

is not a major problem. 

Table 19 gives the estimated nutrient content of sunfl 

ower silage produced from either low-oil or high-oil 

varieties of sunfl ower. Depending on what other feeds 

are mixed in the silage pile, nutrient contents may 

change. 

Blending corn and sunfl ower silages together can help 

alleviate the moisture problem. Producers also may 

consider waiting seven to 10 days following a killing 

frost to facilitate dry down. Blending dry forage into 

the silage pile also can reduce moisture content. To 

minimize seepage problems, the moisture level should 

be 65 percent or less. 

Whole Sunfl ower Seeds 

When economical, whole sunfl ower seeds can be used 

as a source of energy and protein in beef cattle diets 

(Table 19). Fat levels can be quite high in whole seeds; 

consequently, amounts fed should be restricted based 

on fat content of the seed. Typically, no more than 4 

percent supplemental fat should be added to cow diets 

to reduce the potential for any detrimental effects on 

fi ber digestion. This will result in inclusion levels of 

approximately 10 percent of the diet. 

Sunfl ower Residue 

Sunfl ower residue is useful for aftermath grazing by 

beef cows. Nutritional value of the head is greater 

than the stalk. Supplementation may be required if 

the volume of residue is limited and nutrient quality 

decreases rapidly after head material is consumed. 

Sunfl ower Screenings 

Sunfl ower screenings from both confection and oil 

seed plants are often available at competitive prices. 

Nutrient content varies widely with the amount of 

meats, which are high in fat and protein, and hull, 

which is low in nutrient content and digestibility. 

Screenings are best used in modest growing or maintenance 

diets when animal performance is not critical. 

The presence of sclerotia bodies does not appear to be 

a problem for palatability, nutrient content or animal 

performance. 

Sunfl ower Hulls 

Sunfl ower hulls are low in protein and energy and 

should be used only as a bedding source.

Summary 

That sunfl ower meal is a useful protein source for 

growing and fi nishing cattle is apparent from the 

limited research. Similarly, beef cows can be provided 

supplemental protein effectively with sunfl ower meal. 

Sunfl ower meal may be especially useful in diets 

where degradable protein is required, such as lower- 

Table 19. Nutrient content of sunfl ower products. 

quality forage or high corn fi nishing rations. The increased 

bulk of this relatively high-fi ber meal may affect 

logistics, but ruminants are positioned to be more 

tolerant of high fi ber levels than other species. Other 

sunfl ower products can be used effectively in ruminant 

diets, given appropriate performance expectations. 

NE m , NE g , 

DM, % TDN, % Mcal/lb Mcal/lb CP, % ADF, % Ca, % P, % 

Sunfl ower Hulls* 90.0 40.0 0.41 0.00 5.0 63.0 0.00 0.114 

Sunfl ower Screenings* 87.0 64.0 0.66 0.39 11.1 29.0 0.72 0.42 

Sunfl ower Seed, Confectionary* 94.9 83.0 0.93 0.63 17.9 39.0 0.18 0.56 

Sunfl ower Seeds, Oil Type* 94.9 121.0 1.42 1.03 17.9 39.0 0.18 0.56 

Sunfl ower Silage, Low-oil Variety** 30.0 61.0 0.61 0.69 11.1 42.0 0.8 0.3 

Sunfl ower Silage, High-oil Variety** 30.0 66.0 0.35 0.42 12.5 39.0 1.50 0.3 

*Adapted from Lardy and Anderson, 2003. 

**Adapted from Park et al., 1997. 

Feeding Value of Sunfl ower Products in Beef Cattle Diets 

111

112 

U.S. Grades and Standards 

for Sunfl ower 


Defi nition of Sunfl ower Seed 

Grain that, before the removal of foreign material, 

consists of 50 percent or more of cultivated sunfl ower 

seed (Helianthus annuus L.) and not more than 10 

percent of other grains for which standards have been 

established under the U.S. Grain Standards Act. 

Defi nition of Other Terms 

Cultivated sunfl ower seed - Sunfl ower seed grown 

for oil content. The term seed in this and other 

defi nitions related to sunfl ower seed refers to both the 

kernel and hull, which is a fruit or achene. 

Damaged sunfl ower seed - Seed and pieces of 

sunfl ower seed that are badly ground-damaged, 

badly weather-damaged, diseased, frost-damaged, 

heat-damaged, mold-damaged, sprout-damaged or 

otherwise materially damaged. 

Dehulled seed - Sunfl ower seed that has the hull 

completely removed from the sunfl ower kernel. 

Foreign material - All matter other than whole 

sunfl ower seeds containing kernels that can be 

removed from the original sample by use of an 

approved device and by handpicking a portion of the 

sample according to procedures prescribed in the 

USDA’s Federal Grain Inspection Service instructions. 

Heat-damaged sunfl ower seed - Seed and pieces 

of sunfl ower seed that are materially discolored and 

damaged by heat. 

Hull (husk) - The ovary wall of the sunfl ower seeds. 

Kernel - The interior contents of the sunfl ower seed 

that are surrounded by the hull. 

Basis of Determination 

Each determination of heat-damaged kernels, damaged 

kernels, test weight per bushel and dehulled 

seed is made on the basis of the grain when free from 

foreign material. Other determinations not specifi cally 

provided for in the general provisions are made on the 

basis of the grain as a whole, except the determination 

of odor is made on either the basis of the grain as a 

whole or the grain when free from foreign material. 

Table 20 lists the U.S. grade requirements for sunfl 

ower according to the Federal Grain and Inspection 

Service. These requirements became effective Sept. 1, 

1984. The table lists the minimum limit for test weight 

and the maximum for damaged and dehulled seed. 

U.S. grades for both oilseed and nonoilseed classes of 

sunfl ower are determined with the requirements listed 

below. 

Table 20. Grade and grade requirements 

for sunfl ower. 

Minimum 

Maximum limits of 

damaged sunfl ower seed 

test weight Heat Dehulled 

Grade per bushel damage Total seed 

(pounds) - - - - - (percent) - - - - - 

U.S. No. 1 25.0 0.5 5.0 5.0 

U.S. No. 2 25.0 1.0 10.0 5.0 

U.S. Sample grade – U.S. sample grade shall be sunfl ower 

seed that: 

(1) Does not meet the requirements for the grades U.S. 

Nos. 1 or 2; or 

(2) In a 600-gram sample, contains eight or more stones 

that have aggregate weight in excess of 0.20 percent of 

the sample weight, two or more pieces of glass, three 

or more crotalaria seeds (Crotalaria spp.), two or more 

castor beans (Ricinus Communis), four or more particles 

of an unknown substance(s), or 10 or more rodent 

pellets, bird droppings or an equivalent quantity of 

other animal fi lth; or 

(3) Has a musty, sour or commercially objectionable 

foreign odor; or 

(4) Is heating or otherwise of distinctly low quality. 

Source: Federal Grain and Inspection Service-USDA

Other Information Sources 

Major Organizations and 

Information Sources 

■ Public Research and 

Nonprofi t Associations 

Supporting the efforts of private companies in the 

development of the sunfl ower industry are public-supported 

research institutions and nonprofi t associations. 

The following is a list and brief description of the 

functions and purposes of such groups: 

State Agricultural Experiment Stations 

and Cooperative Extension Service 

The Agricultural Experiment Stations, which conduct 

research, and Cooperative Extension Services, which 

deliver adult education programs in the major sunfl 

ower production areas, are at: 

Colorado State University, Fort Collins, CO 80523 

Kansas State University, Manhattan, KS 66506 


South Dakota State University, Brookings, SD 

57006 

Texas A & M University, College Station, TX 77843 

(branch stations at Lubbock and Bushland) 

University of California, Davis, CA 95616 

University of Minnesota, St. Paul, MN 55108, and 

Crookston, MN 56716 

Extension Publications 

Many Extension publications giving specifi c information 

on sunfl ower production, insect pests, diseases, 

herbicide use, marketing and food use are available. 

These are readily available through your county or 

state Extension offi ces. 

Federal Research 

The Agricultural Research Service (ARS) of the 

USDA, working with state agricultural experiment stations 

and cooperative Extension personnel in the major 

sunfl ower-producing areas, have developed inbred 

lines for hybrids, conducted research and provided 

information on production, utilization and marketing 

aspects. The main USDA-ARS sunfl ower unit is at the 

Northern Crops Science Laboratory on the campus 

of North Dakota State University, Fargo, ND 58105, 

www.fargo.ars.usda.gov. 

Agriculture and Agri-Food Canada 

Unit 100-101 Route 100 

Morden, Manitoba, R6M 1Y5 CANADA 

www.agr.gc.ca/ 

The National Sunfl ower Association 

4023 State St. N. 

Bismarck, ND 58502-0690 

Tel: (888) 718-7033 or (701) 328-5100 

http://sunfl owernsa.com/ 

The National Sunfl ower Association was organized in 

1975 to promote the sunfl ower industry and to solve 

common problems. This association is intended to 

represent the interest of growers, processors and seed 

companies, including country elevators, exporters 

and other merchandisers. It publishes The Sunfl ower 

magazine and sponsors The Sunfl ower Research Forum, 

a meeting devoted to scientifi c reports and topics 

of general interest. 

National Sunfl ower Association of Canada 

Box 1269 

Carman, MB R0G 0J0 

Phone: (204) 745-6776 

info@canadasunfl ower.com 

www.canadasunfl ower.com/ 

U.S. Grades and Standards / Other Information Sources 

113

114 

The International Sunfl ower Association 

12 Avenue George V 

75008 Paris, France 

The objective of the International Sunfl ower Association 

is to improve international cooperation and to 

exchange information in the promotion of research 

of agronomics, processing techniques and nutrition 

associated with the production, marketing, processing 

and use of sunfl ower. This objective is accomplished 

by sponsoring and publishing the proceedings of international 

conferences and by publishing the Sunfl ower 

Newsletter, a quarterly periodical. 

■ Sources of Information 

of General Interest 

Governmental Statistical Reporting Services 

Sunfl ower production and farm price statistics are 

released by the following state and federal offi ces 

of Economics, Statistics and Cooperative Extension 

Service, USDA: 

North Dakota Agricultural Statistics Service 

P.O. Box 3166 

Fargo, ND 58108-3166 

South Dakota Agricultural Statistics Service 

Box 31 Drawer V 

Sioux Falls, SD 57101 

Minnesota Agricultural Statistics Service 

Seventh and Roberts Street 

Metro Square, Suite 270 

St. Paul, MN 55101 

Texas Agricultural Statistics Service 

Box 70 

Austin, TX 78767 

National Agricultural Statistics Service 

U.S. Department of Agriculture 

Washington, D.C. 20250 

Sunfl ower Technology and Production 

ASA Monograph 35. 1997, 834 pages. Albert A. 

Schneiter, editor. This monograph text is the extensive 

revision of the original Agronomy Monograph 19 

Sunfl ower Science and Technology. The monograph 

has many contributing authors addressing and reporting 

all the scientifi c work on sunfl ower that is in the 

literature. It has become the “bible of knowledge and 

information” for all who wish to read and study about 

the sunfl ower plant, its origin, development, production 

and utilization. 

The Sunfl ower 

(by C.B. Heiser Jr. from Univ. of Oklahoma Press, 

Norman, OK 73069, for $10.95) 

This 200-page book, authored by a botanist and written 

in layman’s language, covers historical development, 

the distribution and interrelationships of 

sunfl ower species. It describes sunfl ower as an international 

commercial crop, as ornamentals and as weeds. 

The Sunfl ower 

(4023 State St. N., Bismarck, ND 58501-0690) 

The Sunfl ower magazine is published nine times 

a year by the National Sunfl ower Association of 

America. It is intended for growers, merchandisers, 

processors, hybrid seed companies, researchers and 

other legitimate interests in the sunfl ower industry. 

Sunfl ower Directory 

(4023 State St. N., Bismarck, ND 58501-0690, $10) 

The directory includes more than 150 companies, in 

addition to several trade organizations, government 

agencies and universities, which have a unique function 

in the sunfl ower industry. More than 400 individuals 

having expertise in sunfl ower also are listed. 

High Plains Sunfl ower Production Handbook 

2005, 44 pages. (Kansas State University- Agric. Experiment 

Station and Cooperative Extension Service). 

Joint publication of Kansas State University, Colorado 

State University, University of Nebraska, University 

of Wyoming and USDA-ARS Central Plains Research 

Center, Akron, Colo. Also supported by: Kansas 

Sunfl ower Commission, National Sunfl ower Association 

– High Plains Committee and Colorado Sunfl ower 

Administrative Committee.

Glossary 

Achene — The sunfl ower fruit consisting of hull 

and “seed;” a small, dry, one-seeded fruit that 

does not open at maturity. 

Apothecium (pl. apothecia) — Cup- or saucershaped 

fruiting structure of some fungi. 

Ascospore — Fungal spore borne in a structure 

within the apothecium. 

Annuala — Plant in which the entire life cycle is 

completed in a single growing season. 

Bract — Modifi ed, reduced leaf structure beneath 

ray fl owers on sunfl ower head. 

Canker — Sharply defi ned dead area of tissue on 

stem. 

Corolla — Collective term for petals of the 

sunfl ower. 

Cytoplasmic Male Sterility — Male 

sterility inherited through hereditary units in 

the cytoplasm, rather than through nuclear 

inheritance. 

Defoliate — To remove leaves of a plant. 

Dehull — Removal of outer seed coat (hull) from 

the “seed.” 

Depredation — A plundering or despoiling; 

robbery. 

Desiccant — A dry-down or defoliating chemical. 

Disk Flower — Tubular fl owers that compose the 

central part of the sunfl ower head; produce the 

seeds. 

Fungicide — A chemical or physical agent that 

kills fungi. 

Fungus (pl. fungi) — A group of organisms that 

lack chlorophyll and that obtain food through 

absorption, frequently from plants. 

Herbicide — A chemical or physical agent that 

kills plants. 

High Oleic — Oilseed sunfl ower that contains a 

trait for high oleic fatty acid content in its oil. 

A premium oil used in the snack food industry. 

Host — The organism affected by a parasite or 

disease. 

Hybrid — The offspring of two unlike parents. 

Insecticide — A chemical or physical agent that 

kills insects. 

Instar — Any stage of insect development; larval 

growth stage. 

Involucral Bract — An individual bract within a 

distinct whorl of bracts that subtend the fl owering 

part of a plant. 

Kernel — Term used for true seed in processing, 

preferred to “nutmeat.” The sunfl ower seed is 

neither “nut” nor “meat.” 

Larva (pl. larvae) — The preadult form of an insect. 

Nonoilseed — Preferred term, equivalent to nonoil 

sunfl ower or confectionery sunfl ower. 

NuSun — Term that describes the new mid-oleic 

sunfl ower oil. It is lower in saturated fat (less 

that 10 percent) than linoleic sunfl ower oil and 

has higher oleic levels (55 percent to 75 percent) 

with the remainder being linoleic (15 percent to 

35 percent) 

Oilseed — Preferred term, equivalent to oil 

sunfl ower. 

Open Pollinated — Naturally pollinated by selfi ng 

or crossing between two related strains. 

Perennial — A plant that continues its growth from 

year to year, not dying after once fl owering. 

Glossary 

115

116 

Petiole — The stalk of the leaf. 

pH — Expression of acidity or alkalinity of soil or 

water. 

Physiological Maturity — Stage at which a seed 

has reached its maximum dry weight. 

Pollinator — Insect that carries pollen from plant 

to plant. 

Pupa (pl. pupae) — The stage between larva and 

adult in some insects. 

Ray Flower — Flattened, ray shaped fl owers on 

margins of sunfl ower head. Commonly referred to 

as the petals. These are sterile and do not produce 

achenes. 

Receptacle — Fleshy, thickened part of sunfl ower 

head just above the stem that bears the fl ower 

parts. 

Sclerotium (pl. sclerotia) — The hard, resting 

bodies of certain fungi. 

“Seed” — True seed in sunfl ower is the kernel; 

however, “seed” commonly is used to describe 

the kernel plus hull, which is equivalent to the 

achene. 

Self Compatability — Production of fruits and 

normal seeds following self pollination. 

Sporea — Reproductive structure of fungi. 

Sunfl ower — The preferred term, equivalent to 

sunfl owers. 

Sun Oil — The preferred term, equivalent to 

sunfl ower oil, sunfl ower seed oil. 

Variety — A subdivision of a species; a distinct 

group of organisms. 

Volunteer Plant — Plant arising from seed 

dispersed from a previous crop.

Appendix 1 

Diseases of Sunfl ower 

(Oilseed, Confection and Ornamental) 

(Helianthus annuus L.) 

■ BACTERIAL DISEASES 

Apical chlorosis Pseudomonas syringae pv. tagetis (Hellmers) Young et al. 

Bacterial leaf spots Pseudomonas syringae pv. aptata (Brown and Jamieson)Young et al. 

P. cichorii (Swingle) Stapp 

P. syringae pv. helianthi (Kawamura) Young et al. 

P. syringae pv. mellea (Johnson) Young et al. 

Bacterial wilt Pseudomonas solanacearum (Smith) Smith 

Crown gall Agrobacterium tumefaciens (Smith and Townsend) Conn 

Bacterial stalk rot Erwinia carotovora subsp. carotovora (Jones) Bergey et al. 

E. carotovora subsp. atroseptica (van Hall) Dye 

■ FUNGAL DISEASES 

Alternaria leaf blight, stem spot and head rot 

Alternaria alternata (Fr.:Fr.) Keissl. = A. tenuis Nees 

A. helianthi (Hansf.) Tub. and Nish. = Helminthosporium helianthi Hansf. 

A. helianthicola Rao and Rajagopalan 

A. helianthinfi ciens Simmons et al. 

A. protenta Simmons 

A. zinniae M.B. Ellis 

Charcoal rot Macrophomina phaseolina (Tassi) Goidanich 

= Sclerotium bataticola Taubenhaus 

= Rhizoctonia bataticola (Taubenhaus) E.J. Butler 

Downy mildew Plasmopara halstedii (Farl.) Berl. and De Toni in Sacc. 

Fusarium stalk rot Fusarium equiseti (Corda) Sacc. = (teleomorph: Gibberella intricans Wollenweb.) 

F. solani (H. Mart.) Sacc. 

= (teleomorph: Nectria haematococca Berk. and Broome) 

Microdochium tabacinum (Van Beyma) Arx 

= Fusarium tabacinum (Van Beyma) Gams 

= (teleomorph: Monographella cucumerina (Lindfors) Arx) 

Fusarium wilt Fusarium moniliforme J. Sheld. 

= (teleomorph: Gibberella fujikuroi (Sawada) Ito in Ito and K. Kimura) 

F. oxysporum Schlechtend.:Fr. 

Gray mold Botrytis cinerea Pers.:Fr. 

= (teleomorph: Botryotinia fuckeliania (de Bary) Whetzel) 

Appendix 1 

117

118 

Leaf smut Entyloma compsitarum Farl. 

= (anamorph: Cercosperella columbrina Ell. and Ever. 

Myrothecium leaf spot Myrothecium roridum Tode:Fr. 

M. verrucaria (Albertini and Schwein.) Ditmar:Fr. 

Petal blight Itersonilia perplexans Derx. 

Phialophora yellows Phialophora asteris (Dowson) Burge and Isaac 

Phoma black stem Phoma macdonaldii Boerema 

= (teleomorph: Leptosphaeria lindquistii Frezzi) 

= P. oleracea Sacc. var. helianthi-tuberosi Sacc. 

Phomopsis stem canker Phomopsis helianthi M. Muntanola-Cvetkovic et al. 

= (teleomorph: Diaporthe helianthi M. Munt.Cvet. et al.) 

Phytophthora stem rot Phytophthora spp. P. drechsleri Tucker 

Powdery mildew Erysiphe cichoracearum DC. = (anamorph: Oidium asteris-punicei Peck) 

E. cichoracearum DC. var. latispora U. Braun 

(anamorph: Oidium latisporum U. Braun) 

Leveillula compositarum Golovin f. helianthi 

L. taurica (Lév.) G. Arnaud 

(anamorph: Oidiopsis sicula Scalia) 

Sphaerotheca fuliginea (Schlechtend.:Fr.) Pollacci 

Pythium seedling blight Pythium spp. 

P. aphanidermatum (Edson) Fitzp. 

P. debaryanum Auct. non R. Hesse 

P. irregulare Buissman 

Rhizoctonia seedling blight 

Rhizoctonia solani Kühn 

(teleomorph: Thanatephorus cucumeris (A.B. Frank) Donk) 

Rhizopus head rot Rhizopus arrhizus A. Fischer = R. nodosus Namyslowski 

R. microsporus Tiegh. 

R. stolonifer (Ehrenb.:Fr.) Vuill = R. nigricans Ehrenb. 

Rusts 

(common sunfl ower rust) Puccinia helianthi Schwein. 

(cocklebur rust) P. xanthii Schwein. 

(nutsedge rust) P. canaliculata (Schw.) Lagerh. 

(unnamed rusts) P. massalis Arthur, P. enceliae Diet. and Holw. 

Pine needle rust Coleosporium helianthi (Schwein.) Arth. 

Sclerotinia basal stalk rot and wilt, mid-stalk rot, head rot 

Sclerotinia sclerotiorum (Lib.) de Bary 

Sclerotinia basal stalk rot and wilt 

Sclerotinia minor Jagger 

Southern blight Sclerotium rolfsii Sacc. 

(teleomorph: Athelia rolfsii (Curzi) Tu and Kimbrough) 

Septoria leaf spot Septoria helianthi Ellis and Kellerm. 

S. helianthina (Petrov and Arsenijevic) 

Texas or cotton root rot Phymatotrichopsis omnivora (Duggar) Hennebert 

= Phymatotrichum omnivorum Duggar 

Verticillium leaf mottle Verticillium dahliae Kleb. 

White rust Albugo tragopogonis (Pers.) S.F. Gray 

= Pustula tragopogonis (Pers.) Thines

Misc. foliar pathogens Ascochyta compositarum J.J. Davis 

Cercospora helianthi Ell. and Ever. 

C. pachypus Ell and Kellerman 

Colletotrichum helianthi J.J. Davis 

Epicoccum neglectum Desm. 

Phyllossticta wisconsinensis H.C Green 

Sordaria fi micola (Rob. ex Desm.) Ces. and Not. 

■ NEMATODES, PARASITIC 

Dagger, American Xiphinema americanum Cobb 

Pin Paratylenchus projectus Jenkins 

Lesion Pratylenchus spp. 

P. hexincisus Taylor and Jenkins 

Reniform Rotylenchulus spp. 

Rotylenchulus reniformis Linford and Oliviera 

Root knot Meloidogyne arenaria (Neal) Chitwood 

M. incognita (Kofoid and White) Chitwood 

M. javanica (Treub) Chitwood 

Spiral Helicotylenchus sp. 

Stunt Tylenchorhynchus nudus Allen 

Quinisulcius acutus (Allen) Siddiqi 

■ VIRUS and PHYTOPLASMA DISEASES. 

Aster yellows 

Sunfl ower mosaic potyvirus (SuMV) 

Sunfl ower chlorotic mottle virus (SuCMoV) 

Cucumber mosaic virus (CMV) 

Tobacco mosaic virus (TMV) 

Tobacco ringspot nepovirus (TRSV) 

Tobacco streak lilarvirus (TSV) 

Tomato spotted wilt tospovirus (TSWV) 

Appendix 1 

119

120

121

Featuring 

Hybrid Seed 


Storage 

Harvesting 

Insects 

Bird Damage 

Diseases 

Grading 


Hail Injury 

Weed Control 

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For more information on this and other topics, see: www.ag.ndsu.edu 

County commissions, North Dakota State University and U.S. Department of Agriculture cooperating. Duane Hauck, director, Fargo, N.D. Distributed in furtherance of 

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