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.
Lolium perenne L. · Perennial ryegrass
DLF-TRIFOLIUM| DLF-Trifolium A/S
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
Luis Mullor Torres
Cucurbita pepo L. · Field pumpkin
Syngenta Seeds B.V.
Cucumis sativus L. · Cucumber
Südwestdeutsche Saatzucht GmbH & Co. KG Herrn Dr. Josef Gottwald
Triticum aestivum L. · Bread wheat
SAATEN UNION RECHERCHE
Triticum aestivum L. · Bread wheat
SELGEN A.S
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Beta vulgaris Sugar Beet Group · Sugar beet
Florimond Desprez Veuve et Fils, FR
Hordeum vulgare L. · Barley
SARL ADRIEN MOMONT ET FILS, FR
Rosa L. · Rose
INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE, FR
Triticum aestivum L. · Bread wheat
Sejet Planteforaedling I,S
Cucumis melo L. · Melon
SAKATA VEGETABLES EUROPE SAS
Pisum sativum L. · Pea
Sharpes International Seeds
Hordeum vulgare L. · Barley
SECOBRA RECHERCHES S.A.S
Triticum durum Desf. · Durum wheat
Südwestdeutsche Saatzucht GmbH&Co.KG
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Solanum lycopersicum L. · Tomato
Syngenta Seeds BV, Netherlands
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
VINSON PETER
Cucumis sativus L. · Cucumber
MAZEREEUW Jaap, NL
Malus domestica (Suckow) Borkh. · Apple
Roduit Aebischer C. (FR)
Hordeum vulgare L. · Barley
NICKERSON (UK)
Beta vulgaris Sugar Beet Group · Sugar beet
KWS SAAT SE & CO.KGAA
Helianthus annuus L. · Sunflower
Pablo Bergada