Peronospora farinosa f.sp. betae (sugarbeet downy mildew)
Identity
- Preferred Scientific Name
- Peronospora farinosa f.sp. betae Byford (1967)
- Preferred Common Name
- sugarbeet downy mildew
- Other Scientific Names
- Peronospora betae Kuehn
- Peronospora schachtii Fuckel (1865)
- International Common Names
- Englishdowny mildew: beet
- Spanishmildiu
- Frenchmildiou de la betterave
- Local Common Names
- GermanyFalscher Mehltau: Betaruebe
Pictures
Symptoms on leaves
M. Fawaz Azmeh/University of Damascus
Symptoms
Semi-systemic infection on inner leaves.
M. Fawaz Azmeh/University of Damascus
Symptoms
Sporulation on young leaves.
M. Fawaz Azmeh/University of Damascus
Symptoms
Symptoms of Peronospora farinosa f.sp. betae.
M. Fawaz Azmeh/University of Damascus
Symptoms
Sporulation on young leaves.
M. Fawaz Azmeh/University of Damascus
Systemically infected plant
The leaves are distorted, paler green than normal and covered with a fine grey 'down' of sporangiophores and sporangia.
David S. Ingram
Peronospora farinosa f.sp. betae
Cesar Calderon, USDA APHIS, bugwood.org
Refer to Bugwood: http://www.bugwood.org/ImageUsage.html
Peronospora farinosa f.sp. betae
Cesar Calderon, USDA APHIS, bugwood.org
Refer to Bugwood: http://www.bugwood.org/ImageUsage.html
Peronospora farinosa f.sp. betae
Cesar Calderon, USDA APHIS, bugwood.org
Refer to Bugwood: http://www.bugwood.org/ImageUsage.html
Peronospora farinosa f.sp. betae
Cesar Calderon, USDA APHIS, bugwood.org
Refer to Bugwood: http://www.bugwood.org/ImageUsage.html
Distribution
Host Plants and Other Plants Affected
| Host | Host status | References |
|---|---|---|
| Beta | Unknown | |
| Beta vulgaris (beetroot) | Unknown | |
| Beta vulgaris var. saccharifera (sugarbeet) | Unknown |
Symptoms
External symptoms of the disease caused by P. farinosa f.sp. betae are of a typical downy mildew. Internal symptoms of the disease included vertical constrictions at the neck of the root and browning of the secondary xylem at the root neck due to deposition of phenolic compounds.
List of Symptoms/Signs
| Symptom or sign | Life stages | Sign or diagnosis |
|---|---|---|
| Plants/Leaves/abnormal colours | ||
| Plants/Leaves/necrotic areas | ||
| Plants/Leaves/yellowed or dead | ||
| Plants/Whole plant/discoloration |
Prevention and Control
Introduction
Control of the disease by fungicidal sprays has not proved very successful although recently metalaxyl applied as a seed dressing has given protection for about 28 days. The principal control measure advocated is good crop hygiene; separation of seed and root crops, destruction of groundkeepers and prompt clearance of old cleaner-loader sites. Varieties differ in their susceptibility but the limited economic importance of the disease has not favoured attempts to produce resistant varieties. Russell (1969) summarizes breeding work carried out in the UK at the Plant Breeding Institute, Cambridge.
Chemical Control
Korhon (1996) reported that results obtained in a trial with an intermediately resistant and resistant cultivar indicated that cyproconazole + carbendazim was the most effective treatment against the disease.Anon. (1988) presented guidelines for experimental conditions, application of treatments, mode of assessment, recording and measurements and presentation of results for fungicide trials for the control of P. farinosa f.sp. betae on beet.Solovei (1981) reported that spraying with zineb reduced infection in nursery plots; spraying of field crops with cuprosan or fundazol gave good results.
Cultural Control
Fagasova and Bojnansky (1992) suggested that the predominant wind direction should be assessed before choosing the fields for sowing sugarbeet seed crops and that crops should be planted as far apart as possible.Peretyat'ko et al. (1990) reported that cultivars Druzhba MS34 and E87-87 were resistant to P. farinosa f.sp. betae infection.Lewellen and Skoyen (1988) reported that cultivar C789/2 showed moderate resistance to downy mildew (and also to bolting and curly top) although it showed only average root and sugar yield.
Impact
Fagasova and Bojnansky (1993) reported that in mild winters, the highest incidence recorded in field stands was 45% of plants destroyed.Ahrens (1988) reported that, in 1987, a 1.2% infection rate at the end of June, increasing to 8.6% at the end of July and 16.4% at the end of October, caused yield reductions of 2.2-5.5%. Individual diseased beets lost 25-32% in weight, had 1.5-2.3% less sugar content and a reduction in juice purity of 4.1-7.6%.Koch (1986) found that there were problems associated with estimating losses caused by downy mildew. These include the effects of environmental and cultural factors. A review is presented of disease characteristics, control methods and loss estimates (including equations, where available) from the literature.
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Copyright © CABI. CABI is a registered EU trademark. This article is published under a Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
History
Published online: 22 August 2022
Language
English
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