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.
Cucurbita pepo L. · Field pumpkin
Syngenta Crop Protection AG
Hordeum vulgare L. · Barley
Agri-Obtentions S.A.
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Instytut Ogrodnictwa - Państwowy Instytut Badawczy
Cucumis sativus L. · Cucumber
UNITED GENETICS SEEDS CO
Cucumis melo L. · Melon
Graines Gautier SA (FR)
Cucumis sativus L. · Cucumber
Monsanto Vegetable IP Management B.V.
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel BV (NL)
Cucumis sativus L. · Cucumber
Syngenta Seeds B.V.
Cucumis melo L. · Melon
Tezier SA (FR)
Solanum lycopersicum L. · Tomato
Enza Zaden Beheer B.V.
Cucumis sativus L. · Cucumber
Syngenta Seeds B.V.
Beta vulgaris Sugar Beet Group · Sugar beet
SAS Florimond Desprez Veuve & Fils
Triticum aestivum L. · Bread wheat
RAGT CZECH S.R.O.
Cucumis melo L. · Melon
Enza Zaden Beheer B.V.
Solanum lycopersicum L. · Tomato
Enza Zaden Beheer B.V.
Cucumis melo L. · Melon
SEMILLAS FITO, S.A.
Solanum lycopersicum L. · Tomato
Syngenta Seeds B.V.
Cucumis melo L. · Melon
Gautier Semences SAS (FR)
Solanum lycopersicum L. · Tomato
Syngenta Seeds B.V.
Vitis vinifera L. · Common grape vine
Reisch, Bruce I.|Geneva, NY / Pool, Robert M.|Geneva, NY / Watson, John P.|Phelps, NY / Remaily, George W.|Hammondsport, NY / Einset, John|deceased, late of Geneva, NY, by Hjordis Einset, executrix
Vitis vinifera L. · Common grape vine
Jorg Wolf, D
Citrullus lanatus (Thunb.) Matsum. & Nakai · Watermelon
SEMILLAS FITO, S.A.
Cucumis sativus L. · Cucumber
Kees Broersen Zaden
Triticum aestivum L. · Bread wheat
Unisigma G.I.E., Limagrain Europe S.A.S.