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.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Rosa L. · Rose
Rosen Tantau KG
Spinacia oleracea L. · Spinach
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Lactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
Lactuca sativa L. · Lettuce
Vilmorin-Mikado SAS (FR)
Linum usitatissimum L. · Common flax
Linéa Semences de Lin G.I.E.
Hordeum vulgare L. · Barley
Cultivari Getreidezüchtungsforschung Darzau gGmbH
Lolium perenne L. · Perennial ryegrass
Christof Böhm in Fa. Saatzucht Steinach GmbH und Co KG
Cucumis melo L. · Melon
HM.Clause S.A.S.
Hordeum vulgare L. · Barley
SECOBRA RECHERCHES S.A.S
Hordeum vulgare L. · Barley
Syngenta Crop Protection AG
Cucumis melo L. · Melon
Syngenta Seeds B.V.
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry
Walther Faedi^^^Gianluca Baruzzi^^^Paolo Sbrighi^^^Pierluigi Lucchi
Cucumis sativus L. · Cucumber
Nunhems B.V.
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel BV (NL)
Hordeum vulgare L. · Barley
Saatzucht Donau GmbH & Co.KG
Cucumis melo L. · Melon
Syngenta Seeds BV (NL)
Triticum aestivum L. · Bread wheat
Syngenta Participations AG
Fragaria L. · Strawberry
Mr. Jimmy Haig Bagdasarian
Avena sativa L. · Oat
SW Semundo Limited (GB)
Cucumis sativus L. · Cucumber
Monsanto Vegetable IP Management B.V.
Daucus carota L. · Carrot
MONSANTO VEGETABLE IP MANAGEMENT B.V.
Cucumis sativus L. · Cucumber
HAZERA (1939)
Triticum aestivum L. · Bread wheat
Syngenta Participations AG| CH