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.
Vitis vinifera L. · Common grape vine
Vivai Cooperativi Rauscedo, I
Rosa L. · Rose
SCHREURS PETRUS NICOLAAS JOHANNES
Pisum sativum L. · Pea
Syngenta Seeds B.V.
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
Nunhems, NL
Solanum lycopersicum L. · Tomato
Syngenta Seeds B.V.
Ocimum basilicum L. · Basil
Jan Draaistra
Rosa L. · Rose
Meilland Alain A.|Antibes, FR
Rosa L. · Rose
HANS JURGEN EVERS (T)
Malus domestica (Suckow) Borkh. · Apple
KVITSCHAL Marcus Vinicius (BR)/CRESTANI HAWERROTH Maraisa (BR)/DENARDI Frederico (BR)
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Solanum lycopersicum L. · Tomato
Nunhems B.V.
Pisum sativum L. · Pea
Van Waveren Saaten GmbH
Rosa L. · Rose
Wilhelm Kordes, W. Kordes' Sohne Rosenschulen GmbH & Co KG
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Pisum sativum L. · Pea
Sue Kennedy / Elsoms Seeds Limited
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Triticum aestivum L. · Bread wheat
Selgen, CZ
Rosa L. · Rose
Willian A. Warrimer
Dahlia Cav. · Dahlia
Verwer, Aad|Lisse, Netherlands
Trifolium pratense L. · Red clover
SELGEN A.S
Malus domestica (Suckow) Borkh. · Apple
VAN LEUVEN MYLES
Triticum aestivum L. · Bread wheat
Michael Winzeler