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.
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Pyrus communis L. · European pear
Sumio FUKUI (US)
Cucurbita pepo L. · Field pumpkin
Gautier Semences SAS (FR)
Vitis vinifera L. · Common grape vine
INCONNU (FR)
Cucumis melo L. · Melon
Enza Zaden Beheer B.V.
Lactuca sativa L. · Lettuce
Vilmorin-Mikado S.A.S.
Helianthus annuus L. · Sunflower
APEX SARL
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Solanum lycopersicum L. · Tomato
Seminis Vegetable Seeds
Hordeum vulgare L. · Barley
Tomcsanyi Andras / Zsolnai Antalne / Leder Laszlo / Varga Ferenc
Triticum aestivum L. · Bread wheat
Kertesz Zoltan / Matuz Janos / Kertesz Zoltanne / Cseuz Laszlo / Pauk Janos / Beke Bela / Csoesz Laszlone / Papp Maria / Purnhauser Laszlo / Mesterhazy Akos
Rosa L. · Rose
Fryers Nurseries Ltd
Solanum lycopersicum L. · Tomato
Syngenta Seeds B.V.
Hordeum vulgare L. · Barley
Nordic Seed A/S
Triticum aestivum L. · Bread wheat
Institute of Plant Genetic Resources - Sadovo (BG)
Lactuca sativa L. · Lettuce
Enza Zaden Beheer
Cucumis sativus L. · Cucumber
Monsanto Vegetable IP Management B.V.
Malus domestica (Suckow) Borkh. · Apple
Institut Français des Productions Cidricoles (I.F.P.C.), Institut National de Recherche pour l'Agriculture l'Alimentation et l'Environnement (INRAE)
Cucumis sativus L. · Cucumber
Seminis Vegetable Seeds
Impatiens New Guinea Group · New Guinea Impatiens
Syngenta Crop Protection AG
Solanum lycopersicum L. · Tomato
ROB SCHAAREMEN
Hordeum vulgare L. · Barley
SECOBRA RECHERCHES S.A.S
x Triticosecale Wittm. ex A. Camus · Triticale
SEMILLAS BATLLE, S.A.
Triticum durum Desf. · Durum wheat
Florimond Desprez Veuve et Fils, FR