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.
Hordeum vulgare L. · Barley
Vitis vinifera L. · Common grape vine
Ribes nigrum L. · Blackcurrant
Ceratonia siliqua L. · Carob
Humulus lupulus L. · Common hop
Hordeum vulgare L. · Barley
Cucumis sativus L. · Cucumber
Vitis vinifera L. · Common grape vine
Cucurbita pepo L. · Field pumpkin
Pan American Seed Co. (US)
Vitis vinifera L. · Common grape vine
Humulus lupulus L. · Common hop
Hordeum vulgare L. · Barley
Lotus corniculatus L. · Bird's-foot trefoil
Cucumis sativus L. · Cucumber
Cucumis sativus L. · Cucumber
Cucumis melo L. · Melon
Cichorium intybus L. (Witloof Chicory Group) · Witloof chicory
Solanum lycopersicum L. · Tomato
Cucumis sativus L. · Cucumber
Cucumis sativus L. · Cucumber
Beta vulgaris Sugar Beet Group · Sugar beet
Cucumis sativus L. · Cucumber
Vitis L. · Grapevine
Lactuca sativa L. · Lettuce