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.
Triticum aestivum L. · Bread wheat
KWS UK LTD
Rosa L. · Rose
R.G.JELLY
Hordeum vulgare L. · Barley
Station Van Heverlee (BE)
Solanum lycopersicum L. · Tomato
Enza Zaden Bikhir B.V.
Rosa L. · Rose
W.KORDES'SOHNE
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Daucus carota L. · Carrot
Кees Reinink
Triticum aestivum L. · Bread wheat
SELGEN, a.s. (CZ)/Vyzkumne centrum SELTON, s.r.o.
Rosa L. · Rose
W.KORDES'SOHNE
Hordeum vulgare L. · Barley
SAATZUCHT STRENG-ENGELEN GMBH&CO. KG
Malus domestica (Suckow) Borkh. · Apple
Ústav experimentální botaniky AV ČR, v.v.i. (CZ)
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Beta vulgaris Sugar Beet Group · Sugar beet
U DIECKMANN
Cucumis melo L. · Melon
Syngenta Seeds B.V.
Malus domestica (Suckow) Borkh. · Apple
Cucurbita pepo L. · Field pumpkin
Saatzucht Gleisdorf
Ribes uva-crispa L. · Gooseberry
Vitis vinifera L. · Common grape vine
Prof. Dr. H. Becker
Cucumis sativus L. · Cucumber
Petr Horal
Triticum aestivum L. · Bread wheat
Nickerson International Research S.N.C.
Rosa L. · Rose
R HARKNESS and CO LTD
Cucumis sativus L. · Cucumber
Harris Moran Seed (US)
Fragaria L. · Strawberry
Sanford, John C.|Geneva, NY / Ourecky, Donald K.|Lauderdale Lakes, FL / Reich, Jack E.|II, Geneva, NY
Solanum lycopersicum L. · Tomato
HM.Clause S.A.S.