Hyaloperonospora parasitica (downy mildew)
Identity
- Preferred Scientific Name
- Hyaloperonospora parasitica (Pers.) Constant.
- Preferred Common Name
- downy mildew
- Other Scientific Names
- Botrytis parasitica Pers. ex Pers.
- Peronospora brassicae Gäum.
- Peronospora cheiranthi Gäum.
- Peronospora parasitica (Pers.) de Bary
- International Common Names
- Englishdowny mildew of crucifers
- Spanishmildiu de las cruciferas
- Frenchmildiou des cruciferes
- Portuguesemildiú-da-couve
- Local Common Names
- GermanyFalscher Mehltau: Kreuzbluetler
- EPPO code
- PEROPA (Peronospora parasitica)
Pictures
Distribution
Host Plants and Other Plants Affected
List of Symptoms/Signs
Symptom or sign | Life stages | Sign or diagnosis |
---|---|---|
Plants/Inflorescence/lesions on glumes | ||
Plants/Leaves/fungal growth | ||
Plants/Leaves/necrotic areas |
Prevention and Control
Chemical Control
Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:
•
EU pesticides database (http://ec.europa.eu/food/plant/pesticides/eu-pesticides-database/)
•
PAN pesticide database (www.pesticideinfo.org)
•
Your national pesticide guide
Impact
In California, USA, downy mildew of arugula (Eruca sativa) caused by H. parasitica was so severe that at times it reduced the crop quality to the extent that it could not be harvested (Koike, 1998). Also in California, maneb sprays were used to stop an outbreak of H. parasitica on broccoli, but not before an estimated crop loss of $100,000 had occurred (Kontaxis, 1977).
In Germany, in the autumn of 1996, downy mildew of winter oilseed was so severe that at some locations large areas were totally destroyed at the cotyledon stage (Paul et al., 1998).
In India, Mahajan and Gill (1993) indicated the direct effect on gross weight of cauliflower curd by downy mildew disease severity. Disease rating was negatively correlated with all the components of yield. In the Kashmir Valley, market surveys of kale revealed foliage disease indexes of 20-73 in 1981, and 15-57 in 1982. Indirect monetary losses to consumers were assessed at 8-55 and 5-50%, respectively (Puttoo and Choudhary, 1984). In Shanghai, China, a combination of seed treatment, direct sowing, application of fertilisers and fungicide treatments decreased the incidence of H. parasitica on Chinese cabbages and increased yield by 10-18% (Shao et al., 1991). Application of metalaxyl to Chinese cabbage has also been reported to give good control of H. parasitica, subsequently resulting in a 65% increase in yield (Yang et al., 1983).
In radish, disease index was shown to be positively related with crop density. At dense planting (30 x 30 cm), disease severity was 45% on leaves, 35% on stems, 20% on twigs and 22% on pods and resulted in a 50% decrease in yield compared with healthy control (Lakra, 1999). Vasil'eva (1976) reported that under favourable conditions, H. parasitica could infect up to 50-60% of cabbage seeds, subsequently reducing yield by 16-20%.
In Germany, in the autumn of 1996, downy mildew of winter oilseed was so severe that at some locations large areas were totally destroyed at the cotyledon stage (Paul et al., 1998).
In India, Mahajan and Gill (1993) indicated the direct effect on gross weight of cauliflower curd by downy mildew disease severity. Disease rating was negatively correlated with all the components of yield. In the Kashmir Valley, market surveys of kale revealed foliage disease indexes of 20-73 in 1981, and 15-57 in 1982. Indirect monetary losses to consumers were assessed at 8-55 and 5-50%, respectively (Puttoo and Choudhary, 1984). In Shanghai, China, a combination of seed treatment, direct sowing, application of fertilisers and fungicide treatments decreased the incidence of H. parasitica on Chinese cabbages and increased yield by 10-18% (Shao et al., 1991). Application of metalaxyl to Chinese cabbage has also been reported to give good control of H. parasitica, subsequently resulting in a 65% increase in yield (Yang et al., 1983).
In radish, disease index was shown to be positively related with crop density. At dense planting (30 x 30 cm), disease severity was 45% on leaves, 35% on stems, 20% on twigs and 22% on pods and resulted in a 50% decrease in yield compared with healthy control (Lakra, 1999). Vasil'eva (1976) reported that under favourable conditions, H. parasitica could infect up to 50-60% of cabbage seeds, subsequently reducing yield by 16-20%.
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History
Published online: 19 September 2022
Language
English
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