Diseases of Peach.pdf

Siddu Lakshmi Prasanna
Course No.: PATH 2.7.1.
Course Title: Diseases of Fruit, Plantation, Medicinal
and Aromatic crops
By
Dr. Siddu Lakshmi Prasanna
Ph. D (Agri.)
Dept. of Plant Pathology

Peach
Sr.
No.
Disease Causal organism
1. Leaf curl Taphrina deformans
2. Rust Puccinia pruni-spinosae var.
discolor
3. Scab Cladosporium carpophilum
Scientific name: Prunus persica

Minor diseases
1. Powdery mildew –Sphaerotheca pannosa var. persicae
2. Brown rot of fruits – Monilinia fructicola, M.fructigena, M. laxa f. sp. mali
3. Frosty mildews – Cercosporella persicae
4. Target leaf spot – Phyllosticta persicae
5. Bacterial leaf spot: Pseudomonas syringae pv. persicae
6. Gummosis: Prunus dwarf virus
7. Mosaic virus
8. Necrotic Leaf spot: virus
9. Peach- X : Phytoplasma like organism
10. Peach yellows : Phytoplasma like organism

SYMPTOMS:
➢ The disease first appears in the early spring as the
leaves begin to unfold.
➢The leaf blade thickens, puckered along midrib &curl.
➢Leaves 2-3 times longer than healthy and develop red
or purple colour.
➢Puckered parts of leaf may turn yellowish and then
greyich white, as velvety spores are produced on the
surface. Siddu Lakshmi Prasanna

➢Finally leaf turn to reddish purple tint.
➢The reddish velvety surface of lamina is soon covered with a whitish
grey bloom of the fungus on the upper surface.
➢Both the leaves & petiole may curl.
➢Affected leaves die & drop immaturely.
➢Twigs become pale green to yellow, swollen, stunted & exude gummy
material and die.
➢Flowers and fruits are also infected & drop prematurely

Etiology:
• Mycelia are intercellular and it does not produce specific ascocarp.
• Asci are produced (Open ascus) individually and measure 25 to 40 into 8 to11 micro
meter.
• Each ascus bears eight ascospores with a diameter of 3 to 7 micro meter.
Epidemiology:
• The disease is prevalent in areas where cool mist spring weather prevails and the dry
hot weather hastens defoliation.
Primary source of inoculum: Fungus over winter as ascospores or as thick walled
conidia on the bud scales or as perennial mycelium.
Secondary source of inoculum: Air borne ascospores/conidia.

Management:
• Removal & burning of infected shoots reduce the spread of the disease.
• A dormant spray with Bordeaux mixture (1%) with an adhesive & a winter
spray with Bordeaux mixture 1% before bud burst controls the disease.
• Spraying of copper oxychloride 0.3% or carbendazim 0.1% or chlorothalonil
0.1% either before bud swell in spraying or after general leaf fall in autumn.
• Resistant varieties Red heaven, favorite, modeline pouyet.

Symptoms:
➢Pale yellow spots appear on both the surfaces of the
leaves. Later the spots become bright yellow,
angular spots from the top and blisters with rusty
spores on the bottom.
➢Leaf cankers turn necrotic, causing leaf drop and
early bloom in winter.
➢Affected leaves remaining on the tree contain
overwintering structures that allow infection in
spring.
Rust
Causal organism: Puccinia pruni-spinosae var. discolor

➢Symptoms on young stems: starts as water
soaked lesions, develop into splits with uredinia
formation.
➢Twig cankers appear as blisters, with splits
measuring upto ¼ inch long usually visible on
the upper side of the twig.
➢After the twig lesions emerge, rusty brown,
powdery masses of spores (urediniospores) are
produced in the cankers.

➢Fruits- On immature, yellow or green fruit, lesions develop as small,
brownish spots about 0.1 inch diameter with green halos.
➢When the fruit matures and develops darker skin colour, these lesion halos
become greenish yellow.
➢The lesions are sunken and extend several millimeters into the fruit.
➢Numerous infections may develop on each fruit and these can lead to
secondary infections by other fungal species and cause fruit decay.

Primary source of inoculum:
• Survives as perennial mycelium in the underground stems of Anemone coronaria
(alternate host) on which the fungus produces its aecial stage.
• Can also survive as Uredosori on twigs.
Secondary source of inoculum: wind borne Uredospores
Etiology:
• The fungus persists as perennial mycelium, in the under ground stems.
• The basidia produced on this plant during spring infect peach leaves.

Management:
• Destruction of alternate host
• Cut & burn the affected leaves or plant part.
• Spray with zineb 0.2% or dusting with wettable sulphur.
• Spraying of ergosterol biosynthesis inhibitors like
propiconazole or myclobutanil etc.

SYMPTOMS:
➢The disease occurs on fruit, twigs &
leaves.
➢Leaves- infections appear as
inconspicuous chlorotic yellow spots on
the lower surface. When the necrotic
tissue falls out, shot holes appear on
leaves.
SCAB /freckle /black spot
Causal organism: Cladosporium carpophilum

➢On the twigs, light brown oval lesions are formed which
enlarge & turn dark brown.
➢Dark brown, long& narrow lesions are noticed on the
midrib.
➢Circular & dark –olivaceous lesions appear on fruits.
➢In severe infection the individual spots merge & form a
uniform, dark olivaceous, velvety blotch.
➢A thicky or corky layer of cells is produced below
surface the scabbed region.
➢The fruit becomes abnormal in shape & cracks.

Disease cycle

Etiology: Dormant mycelia, septate mycelia
Primary source of inoculum:
• Fungus overwinters in lesions on twigs. Conidia, mycelium and chlamydospores for
its dispersal and survival structures.
• Dormant mycelia in fallen leaves.
Secondary source of inoculum: spilocea type of conidia (air borne) or water splashes.
Infection takes place in between the cuticle & epidermis.
Epidemiology:
• 9 hour of leaf wetness period, 17-18°C temperature, susceptible host.
• In fallen leaves if 200-300 pseudothecia present & leaf wetness is 9 hour, single
pseudothecia produces 800-900 ascospores.

Management:
• Cut & burn affected plant part.
• Low- lying fields should be avoided for cultivation.
• Tree should be properly pruned to permit free air circulation.
• Timely application of the standard fungicide sprays controls the scab.
• Spraying of 5% urea solution to the fallen leaves.
• Chemical spray with scheduling times like :
a) silver tip to green tip- mancozeb 4g/liter, b) Pink bud stage-carbendazin @ 1g/ liter.
c) Petal form stage- Bittertenol, d) Fruit stage-(pea nut stage) – capton 3g/ liter
e) 40 days before harvest –hexaconozole 1.5g /liter.
• Biological agent’s like- Althelia species, Chaetonium globosum.

Diseases of Peach.pdf

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Diseases of Peach.pdf