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.
Helianthus annuus L. · Sunflower
HIBRISOL S.L.
Cucumis sativus L. · Cucumber
Zeraim Gederta, Izrael
Hordeum vulgare L. · Barley
SAATZUCHT JOSEF BREUN GmbH&Co.KG
Triticum aestivum L. · Bread wheat
Hodowla Roslin Strzelce Sp z.o.o. Grupa IHAR
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
NUNZA BV, NL
Petroselinum crispum (Mill.) Nyman ex A. W. Hill · Parsley
Jan Draaistra
Avena sativa L. · Oat
Lochow-Petkus GmbH (DE)
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Simpson David
Daucus carota L. · Carrot
Vilmorin SA (FR)
Triticum durum Desf. · Durum wheat
SAATZUCHT DONAU GESMBH&COKG
Cucurbita pepo L. · Field pumpkin
Ralf Kuijpers
Cucumis sativus L. · Cucumber
Matthijs Groot
Triticum durum Desf. · Durum wheat
Saaten-Ring von Rümker KG
Cucumis melo L. · Melon
Nunhems, NL
Cucumis sativus L. · Cucumber
MORAVOSEED
Triticum aestivum L. · Bread wheat
DSV UK LTD
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel BV (NL)
Solanum lycopersicum L. · Tomato
SYNGENTA SEEDS B.V.
Solanum lycopersicum L. · Tomato
Syngenta Crop Protection AG
Cucumis sativus L. · Cucumber
RIJK ZWAAN ZAADTEELT EN ZAADHANDEL B.V.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
x Triticosecale Wittm. ex A. Camus · Triticale
Stephanie Franck