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.
Daucus carota L. · Carrot
Vilmorin & Cie
Cucumis sativus L. · Cucumber
Enza Zaden Beheer B.V.
Cucurbita pepo L. · Field pumpkin
Syngenta Seeds BV (NL)
Cucumis sativus L. · Cucumber
Nunhems Netherlands B.V.
Hordeum vulgare L. · Barley
Syngenta Participations AG
Begonia L. · Begonia
Man, Jan|Lisse, Netherlands
Vitis vinifera L. · Common grape vine
INCONNU (FR)
Lolium multiflorum Lam. · Italian ryegrass
FORSCHUNGSANSTALT AGROSCOPE RECKENHOLZ
Avena sativa L. · Oat
Hodowla Roslin Strzelce Sp z.o.o. Grupa IHAR
Solanum lycopersicum L. · Tomato
Kees Konst
Cucumis melo L. · Melon
Golden West Seed Co.
Cucumis melo L. · Melon
SEMILLAS FITO, S.A.
Hordeum vulgare L. · Barley
SEMILLAS BATLLE, S.A.
Citrullus lanatus (Thunb.) Matsum. & Nakai · Watermelon
Clause (FR)
Hordeum vulgare L. · Barley
PERSSON GÖRAN
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Lolium multiflorum Lam. · Italian ryegrass
ILVO PLANT(APPLIED GENETICS+BREEDING)
Rosa L. · Rose
Marie Louise Meilland (FR)
Cucumis melo L. · Melon
Syngenta Crop Protection AG
Cucumis melo L. · Melon
Nunhems BV (NL)
Triticum aestivum L. · Bread wheat
PIONEER HI-BRED INTERNATIONAL
Rosa L. · Rose
MEILLAND ALAIN| Alain Meilland
Beta vulgaris Sugar Beet Group · Sugar beet
SESVanderhave NV
Vitis vinifera L. · Common grape vine
INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE, FR