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
WESTERN AUSTRALIAN DEPARTMENT OF AGRICULTURE
Cucumis sativus L. · Cucumber
Monstanto Vegetable, NL
Poa pratensis L. · Kentucky bluegrass
JACKLIN SEED
Helianthus annuus L. · Sunflower
Saaten Union Romania, RO
Rosa L. · Rose
Reinhard Noack
Begonia x hiemalis Fotsch · Elatior Begonia
LUBBERTUS H.KOPPE
Helianthus annuus L. · Sunflower
MAS Seeds,FR
Helianthus annuus L. · Sunflower
MAS SEEDS
Cucumis melo L. · Melon
HAZERA SEEDS BV
Rubus L. · Blackberry
Scottish Crop Research Institute, GB
Helianthus annuus L. · Sunflower
Amelia Bertero
Brassica napus var. napus · Rapeseed
PIONEER OVERSEAS CORPORATION
Rosa L. · Rose
Rosaplants SCEA (FR)
Malus Mill. · Apple
Horticulture Research International
Helianthus annuus L. · Sunflower
MAS SEEDS
Helianthus annuus L. · Sunflower
Zhoel` Meun`er
Vitis vinifera L. · Common grape vine
The Regents of the University of California (US)
Brassica napus var. napus · Rapeseed
PRUVOT JEAN-CLAUDE
Pisum sativum L. · Pea
WAVEREN| van Waveren Saaten GmbH
Triticum aestivum L. · Bread wheat
Saaten Union Recherche SARL, Estrées-Saint -Denis FR
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Raggi Giordano, Marchetti Enrico, Musacchi Dario, Bernardini Danilo,
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Siboni Adriana, Raggi Giordano, Marchetti Enrico, Bernardini Danilo,
Cucurbita pepo L. · Field pumpkin
PETOSEED CO
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Vinson Peter Edward|Hernhill, GB / Warren Simon Peter|Hernhill, GB