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 Mill. · Apple
Sandidge, Jr., Charles R.|5618 Entiat River Rd., Entiat, WA 98822
Raphanus sativus L. var. sativus · Radish
Vilmorin SA (FR)
Cucumis melo L. · Melon
Nunhems Netherlands B.V.
Cucurbita pepo L. · Field pumpkin
Qi Zhang
Glycine max (L.) Merr. · Soybean
Patrice Jeanson
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V. 2025243007
Prunus persica (L.) Batsch · Peach
Cucumis melo L. · Melon
HAZERA SEEDS BV
Rosa L. · Rose
DE RUITER'S NIEUWE ROZEN
Hordeum vulgare L. · Barley
Graminor A.S
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Vitis vinifera L. · Common grape vine
INCONNU (FR)
Cucumis melo L. · Melon
Syngenta Crop Protection AG, CH
Hordeum vulgare L. · Barley
W WEIBULL
Lactuca sativa L. · Lettuce
MORAVOSEED
Beta vulgaris Sugar Beet Group · Sugar beet
Dietrich Hauer, Madlaina Peter,
Triticum aestivum L. · Bread wheat
W WEIBULL
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Triticum aestivum L. · Bread wheat
RAGT 2N S.A.S
Secale cereale L. · Rye
Monsanto Saaten GMBH
Beta vulgaris Sugar Beet Group · Sugar beet
SUGAR BEET RESEARCH INSTITUTE
Cucumis sativus L. · Cucumber
PlantiCo Hodowla i Nasiennictwo Ogrodnicze Golebiew sp. z o.o.
Capsicum annuum L. · Bell pepper
Syngenta Crop Protection AG
Ribes nigrum L. · Blackcurrant
Trajkovski, Viktor