Diseases

Downy mildew

Peronosporaceae

Downy mildew is a dangerous plant disease caused by oomycetes under high humidity conditions. It manifests as a characteristic growth on the underside of leaves and spotting, which leads to rapid death of vegetative mass and yield reduction.

Mentioned in descriptions 16 384 varieties reference book.

Downy mildew is a group of diseases caused by specialized oomycetes. The disease manifests as the appearance of yellowish or brown angular spots on the upper side of the leaves, delimited by veins. On the underside of the leaf, under humid conditions, a characteristic grey-violet, white, or bluish fuzzy growth forms. Pathogen development leads to yellowing and drying of leaves, stunting of plants, and deformation of fruits, which, in the case of high pathogen aggressiveness, can lead to crop death in a short period.

Disease development depends directly on meteorological conditions and agronomic practices. The pathogen prefers a cool, humid environment, with critical risk factors being heavy dew, fog, prolonged rain, high air humidity, and crop density. Optimal conditions for infection include nighttime temperatures in the range of +13…+20°C and the presence of droplet moisture on the leaf surface for more than 6 hours.

Assessment of variety resistance during variety testing is based on phytopathological recording of the degree of leaf damage, specialized screening of collection samples, and molecular analysis methods using DNA markers to find genetic donors of resistance. In production, a distinction is made between genetically resistant varieties possessing specific Dm-genes and tolerant forms capable of maintaining yield under infection due to active vegetative mass formation. Since new pathogen races can overcome genetic resistance, varieties require regular monitoring and renewal.

Sources10

Breakdown by crop

Downy mildew of lettuce 2 007 Downy mildew of sunflower 905 Downy Mildew of Cucumber 394 Downy mildew of spinach 387 Downy Mildew of Pea 159 Downy Mildew (Peronospora) — Soybean 65 Downy Mildew of Hops 60 Downy mildew — Onion 59 Downy Mildew of Grapevine 58 Downy Mildew of Melon 48 Downy mildew — bulb onion 48 Downy mildew of radish 47 Downy mildew of basil 46 Downy mildew — broccoli 43 Downy Mildew of Grapevine 33 Downy mildew — New Guinea impatiens 32 Downy mildew of rapeseed 24 Downy mildew of zucchini 20 Downy mildew of wall rocket 19 Downy mildew — cauliflower 18 Downy mildew — lettuce 18 Downy mildew — head lettuce 18 Downy Mildew — Impatiens walleriana 18 Downy mildew — cabbage 17

Found in these crops

Lettuce 2 054 Grapevine 1 066 Sunflower 920 Common grape vine 514 Cucumber 414 Spinach 405 Pea 168 Common hop 77 Soybean 71 Onion 61 Onion 51 Melon 51

Varieties that feature this in their description

Selection based on the description text, not official resistance ratings: such data is not available in registers. Mention indicates that the trait is discussed in the variety's sources; see the variety's profile for details on what is specifically stated.

RS 06683549

Active

Spinacia oleracea L. · Spinach

Bayer Holland B.V.

5 records

Ruselago

Active

Pisum sativum L. · Pea

Syngenta Crop Protection AG

7 records

Roxy

Active

Lactuca sativa L. · Lettuce

ENZA ZADEN

4 records

Rosalo

Active

Lactuca sativa L. · Lettuce

Enza Zaden Beheer B.V.

7 records

Romance

Active

Pisum sativum L. · Pea

Seminis Vegetable Seeds

6 records

Romai

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan, NL

8 records

Robinio

Active

Lactuca sativa L. · Lettuce

Syngenta Seeds

6 records

Rivalda

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan, NL

6 records

Rhodenas

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

7 records

Rodos

Active

Cucumis sativus L. · Cucumber

PNOS

6 records

Rockita

Active

Lactuca sativa L. · Lettuce

Syngenta Crop Protection AG

6 records

Reliance

Active

Pisum sativum L. · Pea

Seminis Vegetable Seeds

7 records

Renegade

Active

Spinacia oleracea L. · Spinach

BEJO ZADEN

6 records

Red Tabby

Active

Spinacia oleracea L. · Spinach

RIJK ZWAAN ZAADTEELT EN ZAADHANDEL B.V.

4 records

Redflash

Active

Lactuca sativa L. · Lettuce

NAPOLEONSWEG 152

5 records

Redbat

Active

Lactuca sativa L. · Lettuce

ENZA ZADEN

4 records

Redlo

Active

Lactuca sativa L. · Lettuce

ENZA ZADEN

4 records

Rayma

Active

Brassica oleracea L. (White Cabbage Group) · White cabbage

RIJK ZWAAN WELVER GmbH, DE

4 records

Requena

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

6 records

Racoon

Active

Spinacia oleracea L. · Spinach

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

5 records

Red Ace

Active

Beta vulgaris Garden Beet Group · Garden beet

BEJO ZADEN

4 records

Quenty

Active

Lactuca sativa L. · Lettuce

Vilmorin-Mikado S.A.S.

5 records

Rawley

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

6 records

Pursuit

Active

Lactuca sativa L. · Lettuce

Vilmorin-Mikado S.A.S.

6 records

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Diseases

Powdery mildew 33 570
Fusarium wilt and blight 29 887
Viral mosaic diseases 22 022
Leaf spot diseases 15 926
Rust 14 859
Verticillium wilt 12 175
Scab 12 064
Grey mold 7 316

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Text source

This summary is compiled from the publications listed in the sources and verified by an editor. It contains no legally significant information; it provides agronomic context for registry data rather than the registry data itself.