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.
Rosa L. · Rose
VAN DE LAAK (NL)
Vitis vinifera L. · Common grape vine
Prof. V. Kraus
Hydrangea macrophylla (Thunb.) Ser. · Bigleaf hydrangea
Information regarding the breeder received in the contribution to CPVO :Kientzler
Rosa L. · Rose
MEILLAND ALAIN| Alain Meilland
Rosa L. · Rose
Marie Louise Meilland (FR)
Rosa L. · Rose
SNC Meilland (FR)
Cucumis sativus L. · Cucumber
Royal Sluis BV (NL)
Rosa L. · Rose
Marie Louise Meilland (FR)
Rosa L. · Rose
MEILLAND ALAIN ANTOINE
Triticum aestivum L. · Bread wheat
KWS MOMONT RECHERCHE SARL, FR
Rosa L. · Rose
KORDES' SOEHNE| W. Kordes' Soehne Rosenschulen GmbH & Co KG
Lactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
Triticum aestivum L. · Bread wheat
SARL ADRIEN MOMONT ET FILS, FR
Triticum aestivum L. · Bread wheat
Výzkumné Centrum Selton s.r.o., Selgen A.S.
Begonia L. · Begonia
SIEGFRIED MERHOLZ
Humulus lupulus L. · Common hop
Franz Gmelch / Herbert Ehrmaier
Rosa L. · Rose
Werner Kordes / Reimer Kordes / Wilhelm Kordes
Brassica napus L. · Rapeseed
BASF AGRICULTURAL SOLUTIONS US LLC
Cucurbita pepo L. · Field pumpkin
Enza Zaden Beheer B.V.
Hordeum vulgare L. · Barley
LOCHOW-PETKUS
Fragaria L. · Strawberry
Sort ie suspil`nym nadbanniam
Cucumis sativus L. · Cucumber
Semenarna Ljubljana, SI
Begonia x hiemalis Fotsch · Elatior Begonia
ROHDE-RIEGER MARGARETE| Begonien-Rieger, Margarete Rohde-Rieger
Rosa L. · Rose
Iris Helga Hetzel