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.
Malus domestica (Suckow) Borkh. · Apple
Instytut Sadownictwa i Kwiaciarstwa im. Szczepana Pieniążka
Cucumis melo L. · Melon
SEMILLAS FITO, S.A.
Cucumis melo L. · Melon
Kees Reinink
x Triticosecale Wittm. ex A. Camus · Triticale
Stephanie Franck
Lactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
Hordeum vulgare L. · Barley
Lietuvos agrarinių ir miškų mokslų centras
Cucumis sativus L. · Cucumber
SEMILLAS FITO, S.A.
Triticum aestivum L. · Bread wheat
LEMAIRE DEFFONTAINES SEMENCES
Citrullus lanatus (Thunb.) Matsum. & Nakai · Watermelon
Origene Seeds, IL
Cucurbita pepo L. · Field pumpkin
JOLANDA KOUTERS
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Capsicum annuum L. · Bell pepper
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
BEJO ZADEN B.V.
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Rosa L. · Rose
Michel Adam (FR)
Cucumis melo L. · Melon
Enza Zaden Beheer B.V.
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Sinapis alba L. · White mustard
Michaela Schlathölter
Malus domestica (Suckow) Borkh. · Apple
ZOUK bvba, BE3800 Sint-Truiden
Hibiscus L. · Hibiscus
Hansen Hans A
Dianthus x allwoodii hort. · Allwood pink
Whetman John
Cucumis melo L. · Melon
Nunhems B.V.
Lagerstroemia indica L. · Crape myrtle
Fleming's Flower Fields Inc.
Phlox paniculata L. · Garden phlox
Verschoor Janus