Diseases
Erysiphales
Powdery mildew is a fungal disease manifesting as a white web-like coating on plant organs, leading to tissue necrosis, fruit deformation, and significant crop losses.
Mentioned in descriptions 33 570 varieties reference book.
Powdery mildew is caused by ectoparasitic fungi of the order Erysiphales, which develop primarily on the surface of leaves, shoots, and fruits. The initial white web-like coating eventually densifies into "powdery" cushions, upon which fungal fruiting bodies may form as dark spots. As a result of the infection, tissues turn yellow and become necrotic, fruits may crack, and leaves drop prematurely.
The intensity of disease development depends on a complex of factors: high relative humidity, moderate temperatures, the presence of dense canopy, and excessive nitrogen nutrition. Risks increase with alternating dry and wet weather. The harmfulness of the disease is expressed in a reduction of the leaf assimilation area, deterioration of crop quality, and a decrease in the general winter hardiness of crops.
Assessment of variety resistance is conducted under field conditions at various stages of vegetation, most often during the full heading phase. To classify the degree of infection, scoring systems or intensity scales in percentages are used, where varieties with up to 10% infection are considered highly resistant (R), 11 to 40% as moderately resistant (M), and more than 41% as susceptible (S). Variety resistance is ensured by genetic mechanisms that prevent colonization by the pathogen or limit the development of its mycelium.
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.
Triticum durum Desf. · Durum wheat
Südwestdeutsche Saatzucht GmbH&Co.KG
Solanum lycopersicum L. · Tomato
Syngenta Crop Protection AG
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Stewart Philip J.|Watsonville, CA, US / Madesko Martin P.|Aptos, CA, US / Coss JoAnne F.|Pebble Beach, CA, US / Mowrey Bruce D.|Watsonville, CA, US
Lolium multiflorum Lam. ssp. italicum (A. Br.) Volkart · Italian ryegrass
STELLING DIETER
Rosa L. · Rose
Société Nouvelle Pépinières et Roseraies Georges Delbard S.A.S.
Cucumis sativus L. · Cucumber
Seminis Vegetable Seeds
Cucumis melo L. · Melon
HM Clause,France
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Triticum durum Desf. · Durum wheat
Florimond Desprez Veuve et Fils, FR
Triticum durum Desf. · Durum wheat
S.I.S. SOCIETA' ITALIANA SEMENTI / SYNGENTA FRANCE S.A.S.
Triticum aestivum L. · Bread wheat
DSP Delley Samen und Pflanzen AG
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
RIJK ZWAAN ZAADTEELT EN ZAADHANDEL B.V.
Cucumis sativus L. · Cucumber
Remzi Dogan
Poa pratensis L. · Kentucky bluegrass
Novel AG
Lactuca sativa L. · Lettuce
Vilmorin, F
x Triticosecale Wittm. ex A. Camus · Triticale
SAS Lemaire-Deffontaines
Brassica oleracea L. (Broccoli Group) · Broccoli
Syngenta Crop Protection AG
Lolium multiflorum Lam. · Italian ryegrass
Semillas Biscayart S.A.
Hordeum vulgare L. · Barley
Sejet Planteforaedling, DK-8700 Horsens
Rosa L. · Rose
David C H Austin (GB)/Patricia J Austin (GB)
Cucumis melo L. · Melon
HM CLAUSE, FR
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Poa pratensis L. · Kentucky bluegrass
Pickseed USA