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.
Hordeum vulgare L. · Barley
SECOBRA RECHERCHES S.A.S
Malus domestica (Suckow) Borkh. · Apple
Tupy Jaroslav
Triticum aestivum L. · Bread wheat
Výzkumné Centrum Selton s.r.o., Selgen A.S.
Helianthus annuus L. · Sunflower
Saaten Union, RO
Pisum sativum L. · Pea
NICKERSON S.A.
Cucumis sativus L. · Cucumber
Paul Degreef
Hordeum vulgare L. · Barley
SAATZUCHT JOSEF BREUN GmbH&Co.KG
Hordeum vulgare L. · Barley
SARL ADRIEN MOMONT ET FILS, FR
Pisum sativum L. · Pea
GSN Semences SAS (FR)
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Marionnet S.A.S
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Marionnet S.A.S
Rosa L. · Rose
HANS JURGEN EVERS (T)
Rosa L. · Rose
HCA de Groot
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Rosa L. · Rose
Weeks Roses Inc (US)
Euonymus fortunei (Turcz.) Hand.-Mazz. · Wintercreeper
Waldvogel, Karel
Rosa L. · Rose
Jarrel van Dam
Vitis vinifera L. · Common grape vine
Simone Diego Castellarin^^^Guido Cipriani^^^Gabriele Di Gaspero^^^Michele Morgante^^^Enrico Peterlunger^^^Raffaele Testolin
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Fresh Forward Holding BV, Netherlands
Pisum sativum L. · Pea
Seminis Vegetable Seeds
Cucumis sativus L. · Cucumber
Nunhems, NL
Brassica napus L. var. napobrassica (L.) Rchb. · Rutabaga
PGG Wrightson Seeds
x Triticosecale Wittm. ex A. Camus · Triticale
STRENG ENGELEN