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.
Cucurbita moschata Duchesne · Butternut squash
Sakata Vegetables Europe S.A.S
Rosa L. · Rose
Meilland International
Rosa L. · Rose
Meilland Alain A.|Antibes, FR
Rosa L. · Rose
HANS JURGEN EVERS (T)
Malus domestica (Suckow) Borkh. · Apple
STATION FEDERALE RAC
Rosa L. · Rose
Wilhelm Kordes, W. Kordes' Sohne Rosenschulen GmbH & Co KG
Vitis vinifera L. · Common grape vine
Martinez Manuel Tornel,Espin Juan Carreno
Lactuca sativa L. · Lettuce
ZONNEVELD OLAF
Rosa L. · Rose
interplant b.v.
Lactuca sativa L. · Lettuce
Nunhems B.V., 6083 AB Nunhem
Clematis L. · Clematis
RAYMOND J. EVISON|Josephine Hill
Pisum sativum L. · Pea
MICROTEC SRL
Festuca rubra L. · Red fescue
Euro Grass Breeding GmbH Co. KG
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Katalin Monika Pakozdi Carlos D. Fear Alessandra Lillo, Driscoll's, Inc.
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Suiker Marcel
Lactuca sativa L. · Lettuce
NUNHEMS
Cucumis sativus L. · Cucumber
Bejo Zaden, NL
Vitis vinifera L. · Common grape vine
NO DECLARADOS
Vitis L. · Grapevine
VI¥A DEL DEPARTAMENTO DE AGRICULTURA DE LOS EEUU DE ACA. EN EL SERVICIO DE INV. AGRICOLA
Verbena L. · Vervain
Yomo, Y.
Rosa L. · Rose
HANS JURGEN EVERS (T)
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Rosa L. · Rose
Meilland Alain A.
Vitis vinifera L. · Common grape vine
David W. Cain, PhD.