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.
Malus domestica (Suckow) Borkh. · Apple
ARC INFRUTEC NIETVOORBIJ
Rosa L. · Rose
Weeks Roses
Rosa L. · Rose
Weeks Roses
Verbena L. · Vervain
Yomo Yasunori
Hibiscus moscheutos L. · Crimson-eyed rose mallow
Tan Alain
Rosa L. · Rose
Spek Rose Breeding International B.V.
Malus domestica (Suckow) Borkh. · Apple
Takao Takano
Vitis L. · Grapevine
LABORATORIO DE INVESTIGACION DE CULTIVOS HORTICOLAS DEL SERVICIO DE INVESTIGACION AGRICOLA
Impatiens New Guinea Group · New Guinea Impatiens
SATO CHIHIRO
Calibrachoa Cerv. · Calibrachoa
UI AKINOBU|FUYAMA MICHIYOSHI
Rosa L. · Rose
De Ruiter's Nieuwe Rozen B.V.
Rosa L. · Rose
William J. Radler
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Fresh Forward Holding B.V., 6851 ET Huissen
Rosa L. · Rose
Sean Arkinstall, Bright Future Investments Pty Ltd
Cercis canadensis L. · Eastern redbud
Werner Dennis James / Snelling Layne Karlton
Rosa L. · Rose
Meilland International
Rosa L. · Rose
MEILLAND ALAIN ANTOINE
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Whitehouse Adam Barrie,Simpson David William,Johnson Abigail
Rosa L. · Rose
MEILLAND ALAIN ANTOINE
Rosa L. · Rose
Meilland International
Rosa L. · Rose
Wilhelm Kordes^^^Tim-Hermann Kordes^^^John Vincent Kordes
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes