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 sativus L. · Cucumber
RIJK ZWAAN ZAADTEELT EN ZAADHANDEL BV, NL
Linum usitatissimum L. · Common flax
Wiersum Plantbreeding B.V. (NL)
Triticum aestivum L. · Bread wheat
SAATEN UNION RECHERCHE
Pisum sativum L. · Pea
Paul Degreef
Hordeum vulgare L. · Barley
Syngenta UK Ltd
Cucumis sativus L. · Cucumber
SEMO a.s
Cucumis sativus L. · Cucumber
Paul Degreef
Triticum durum Desf. · Durum wheat
Saatzucht Donau GmbH & Co.KG
Linum usitatissimum L. · Common flax
Van de Bilt Zaden en Vlas B.V.
Beta vulgaris Sugar Beet Group · Sugar beet
Betaseed GmbH (DE)
Hordeum vulgare L. · Barley
Graminor AS, N-2322 Ridabu
Trifolium pratense L. · Red clover
SELGEN A.S
Triticum aestivum L. · Bread wheat
Secobra Recherches, F
Triticum aestivum L. · Bread wheat
Sarl Adrien Momont et Fils, F
Cucumis sativus L. · Cucumber
SEMO a.s
Cucumis sativus L. · Cucumber
Matthijs Groot
Cucumis melo L. · Melon
Vilmorin SA (FR)
Hordeum vulgare L. · Barley
Syngenta UK Ltd
Capsicum annuum L. · Bell pepper
SYNGENTA SEEDS B.V.
x Triticosecale Wittm. ex A. Camus · Triticale
RAGT SA (FR)
Triticum aestivum L. · Bread wheat
LEMAIRE DEFFONTAINES S.A.S.
Cucurbita pepo L. · Field pumpkin
Syngenta Seeds B.V.
Petroselinum crispum (Mill.) Nyman ex A. W. Hill · Parsley
Jan Draaistra
Triticum aestivum L. · Bread wheat
Verneuil Recherche SA (FR)