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.
Spinacia oleracea L. · Spinach
SVS, NL
x Triticosecale Wittm. ex A. Camus · Triticale
INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE, FR
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
HENK VAN KOOTEN
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Hydrangea L. · Hydrangea
HORN HEINZ| Heinz Horn
x Triticosecale Wittm. ex A. Camus · Triticale
Danko Hodowla Roslin Sp.z.o.o.
Triticum aestivum L. subsp. spelta (L.) Thell. · Spelt
Universität Hohenheim Landessaatzuchtanstalt 720
Triticum aestivum L. · Bread wheat
Tapio Juuti 65%, Hans Küüts 10%, Anne Ingver 10%, Reine Koppel 10%, Mati Koppel 5%
Glycine max (L.) Merr. · Soybean
Lidea France S.A.S
Lactuca sativa L. · Lettuce
Johannes Simon Petrus Nannes.
Citrullus lanatus (Thunb.) Matsum. & Nakai · Watermelon
Cora Seeds SRL, I
Lactuca sativa L. · Lettuce
Rijk Zwaan, NL
Lactuca sativa L. · Lettuce
BEJO ZADEN
Cucumis melo L. · Melon
Syngenta Seeds B.V.
Hordeum vulgare L. · Barley
Limagrain Europe S.A.S
Cucurbita pepo L. · Field pumpkin
SAKATA SEED SUDAMERICA LTDA
Triticum aestivum L. · Bread wheat
Nickerson International Research S.N.C.
Hordeum vulgare L. · Barley
Limagrain Europe S.A.S
Cucumis melo L. · Melon
Nehama, Shulamit
Cucumis sativus L. · Cucumber
MORAVOSEED
Hordeum vulgare L. · Barley
Unisigma GIE (FR)/Societe Europeenne de Semences NV/SA (BE)
Cucumis melo L. · Melon
Kees Reinink
Pisum sativum L. · Pea
W BROTHERTON SEED CO INC