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 B.V.
Malus domestica (Suckow) Borkh. · Apple
V.O.F. VANDEWALL
Glycine max (L.) Merr. · Soybean
MURESANU EUGEN
Cucumis sativus L. · Cucumber
Francisco Palomares
Lolium perenne L. · Perennial ryegrass
Teagasc
Lactuca sativa L. · Lettuce
ENZA ZADEN
Capsicum annuum L. · Bell pepper
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Prunus persica (L.) Batsch · Peach
Maillard Arsene|Elne, FR / Maillard Laurence|Elne, FR
Triticum durum Desf. · Durum wheat
S.I.S. SOCIETA' ITALIANA SEMENTI
Rosa L. · Rose
WARNERS ROSES
Cucumis melo L. · Melon
RIJK ZWAAN ZAADTEELT EN ZAADHANDEL B.V.
Cucumis sativus L. · Cucumber
KAMPE Eike, DE
Poa pratensis L. · Kentucky bluegrass
Novel AG, Inc. & Columbia River Seeds, LLC
Cucumis sativus L. · Cucumber
Seminis Vegetable Seeds
Pisum sativum L. · Pea
POP VRIEND BV
Capsicum annuum L. · Bell pepper
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis melo L. · Melon
Nunhems B.V.
Pisum sativum L. · Pea
Syngenta Seeds B.V.
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Brassica oleracea L. (Brussels Sprouts Group) · Brussels sprouts
Syngenta Seeds B.V.
Linum usitatissimum L. · Common flax
Linéa Semences de Lin G.I.E.