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Plantwise Technical Factsheet

downy mildew (Hyaloperonospora parasitica)

Host plants / species affected
Alliaria petiolata (garlic mustard)
Alyssum (alison)
Armoracia rusticana (horseradish)
Brassica
Brassica juncea var. juncea (Indian mustard)
Brassica nigra (black mustard)
Brassica oleracea (cabbages, cauliflowers)
Brassica oleracea var. alboglabra (Chinese kale)
Brassica oleracea var. botrytis (cauliflower)
Brassica oleracea var. capitata (cabbage)
Brassica oleracea var. gemmifera (Brussels sprouts)
Brassica oleracea var. gongylodes (kohlrabi)
Brassica oleracea var. italica (broccoli)
Brassica oleracea var. viridis (collards)
Brassica rapa subsp. chinensis (Chinese cabbage)
Brassica rapa subsp. oleifera (turnip rape)
Brassica rapa subsp. pekinensis
Brassicaceae (cruciferous crops)
Capsella bursa-pastoris (shepherd's purse)
Cheiranthus
Cucurbitaceae (cucurbits)
Eruca vesicaria (purple-vein rocket)
Erysimum cheiranthoides (Treacle mustard)
Erysimum cheiri (wallflower)
Euphorbia (spurges)
Iberis (candytuft)
Lepidium campestre (Field cress)
Lepidium sativum (garden cress)
Lobularia maritima (sweet alyssum)
Matthiola
Matthiola incana (stock)
Nasturtium officinale (watercress)
Raphanus raphanistrum (wild radish)
Raphanus sativus (radish)
Rorippa islandica (yellow marshcress)
Rumex (Dock)
Sinapis alba (white mustard)
Sinapis arvensis (wild mustard)
Sisymbrium irio
Sisymbrium officinale (Hedge mustard)
Thlaspi arvense (field pennycress)
List of symptoms/signs
Inflorescence  -  lesions on glumes
Leaves  -  fungal growth
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:


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%.

Related treatment support
Plantwise Factsheets for Farmers
Zhang, Y.; CABI, 2014, Chinese language
Gu, P.; CABI, 2012, Chinese language
Pakistan, Directorate General Agriculture (Ext. & A. R.); CABI, 2014, English language
Vietnam, Son La Plant Protection Sub-Department; CABI, Vietnamese language
Pakistan, Directorate General Agriculture (Ext. & A. R.); CABI, 2014, Urdu language
 
Pest Management Decision Guides
Iqbal, M.; Khan, Y. S.; CABI, 2013, English language
Ndungu, J.; Njoroge, C.; Otipa, M.; CABI, 2015, English language
Iqbal, M.; Khan, Y. S.; CABI, 2013, Urdu language
Asghar, M.; CABI, 2014, English language
 
External factsheets
AVRDC International Cooperators' Fact Sheets, Asian Vegetable Research and Development Center (AVRDC), 2001, English language
Pestnet Factsheets, Pestnet, English language
CIMMYT Plant Pest and Disease Factsheets, Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) (International Maize and Wheat Improvement Center), English language
RHS Gardening Advice Factsheets, Royal Horticultural Society, 2012, English language
East West Seed Crop Disease Factsheets, East West Seed, 2013, English language
Video factsheets
Agropedia ICRISAT PPT-Videos, IIT, Kanpur, 2014, English language
Agropedia ICRISAT PPT-Videos, IIT, Kanpur, 2014, English language
Agropedia ICRISAT PPT-Videos, IIT, Kanpur, 2014, English language
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