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.
Pisum sativum L. · Pea
WEBSTER DAVID
Rosa L. · Rose
Rosen Tantau KG
Lolium x hybridum Hausskn. · Hybrid ryegrass
DLF Seeds A/S, Dansk Planteforedling (DK)
Daucus carota L. · Carrot
Vilmorin SA (FR)
Pisum sativum L. · Pea
Seminis Vegetable Seeds
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Spinacia oleracea L. · Spinach
Henk Driessen
Vitis vinifera L. · Common grape vine
Gabriele Di Gaspero^^^Guido Cipriani^^^Michele Morgante^^^Enrico Peterlunger^^^Simone Diego Castellarin^^^Raffaele Testolin
Lactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
Daucus carota L. · Carrot
Raphael Van-Hyfte
Malus domestica (Suckow) Borkh. · Apple
SANDIDGE JR. - CHARLES R.
Triticum aestivum L. · Bread wheat
Caussade Semences, F
Cucumis sativus L. · Cucumber
RIJK ZWAAN Zaadteelt en Zaadhandel B.V.
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Malus domestica (Suckow) Borkh. · Apple
VÝZKUMNÝ A ŠLECHTITELSKÝ ÚSTAV OVOCNÁŘSKÝ HOLOVOUSY s.r.o. (CZ)
Malus domestica (Suckow) Borkh. · Apple
Spinacia oleracea L. · Spinach
Bejo Zaden, NL
Rosa L. · Rose
POULSEN ROSER A/S
Rosa L. · Rose
Poulsen Roser A/S
Triticum aestivum L. · Bread wheat
Institut za ratarstvo i povrtarstvo, Novi Sad
Daucus carota L. · Carrot
SAKATA VEGETABLES EUROPE SAS
Hordeum vulgare L. · Barley
W WEIBULL
Pisum sativum L. · Pea
Syngenta Seeds B.V.
Fragaria x ananassa Duchesne ex Rozier · Garden strawberry