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.
Cucumis melo L. · Melon
LARRY A.
Triticum aestivum L. · Bread wheat
Secobra Recherches, F
Triticum aestivum L. · Bread wheat
Zoltán Bedő^^^László Láng^^^Ottó Veisz^^^Gyula Vida^^^Ildikó Karsai^^^Mariann Rákszegi^^^Klára Mészáros
Rosa L. · Rose
WERNER NOACK
Poa pratensis L. · Kentucky bluegrass
Pickseed USA, Inc. and Rutgers, The State University of New Jersey
Cucumis sativus L. · Cucumber
Matthijs Groot
Cucumis sativus L. · Cucumber
Monsanto Vegetable IP Management B.V.
Triticum aestivum L. · Bread wheat
PHILIPPE MOMONT
Rosa L. · Rose
Wilhelm Kordes, W. Kordes' Sohne Rosenschulen GmbH & Co KG
Hordeum vulgare L. · Barley
KWS Lochow
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Pisum sativum L. · Pea
Sharpes International Seeds
Cucurbita pepo L. · Field pumpkin
Ralf Kuijpers
Hordeum vulgare L. · Barley
SAATZUCHT STRENG-ENGELEN GMBH&CO. KG
x Triticosecale Wittm. ex A. Camus · Triticale
LEMAIRE DEFFONTAINES S.A.S.
Cucumis sativus L. · Cucumber
Paul Degreef
Hordeum vulgare L. · Barley
Syngenta Seeds, F
Rosa L. · Rose
ZARY| Dr. Keith Zary c/o Bear Creak Gardens, Inc.
Rosa L. · Rose
Wilhelm Kordes,Tim-Hermann Kordes,Margarita Kordes
Rosa L. · Rose
Warriner, William A.|Tustin, CA
Malus domestica (Suckow) Borkh. · Apple
STATION FEDERALE RAC
Cucumis melo L. · Melon
Ralf Kuijpers
Beta vulgaris Sugar Beet Group · Sugar beet
Miroslaw Lakomy
Cucurbita pepo L. · Field pumpkin
SVS HOLLAND BV , NL