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
MONSANTO VEGETABLE IP MANAGEMENT B.V.
Triticum aestivum L. · Bread wheat
Syngenta Seeds SAS, FR
Cucurbita pepo L. · Field pumpkin
ROYAL SLUIS
Lolium x hybridum Hausskn. · Hybrid ryegrass
DLF Seeds A-S, DK
Lolium x hybridum Hausskn. · Hybrid ryegrass
P.BREED.INT.CAMBRIDGE
Malus domestica (Suckow) Borkh. · Apple
Cucumis sativus L. · Cucumber
Nunhems B.V.
Hordeum vulgare L. · Barley
Claus Einfeldt
Solanum lycopersicum L. · Tomato
RIJK ZWAAN Zaadteelt en Zaadhandel B.V.
Triticum aestivum L. · Bread wheat
Nickerson International Research S.N.C.
Beta vulgaris Sugar Beet Group · Sugar beet
KWS SAAT SE & CO.KGAA
Cucumis sativus L. · Cucumber
ENZA ZADEN
Cucumis melo L. · Melon
Les Graines Caillard
Triticum aestivum L. subsp. spelta (L.) Thell. · Spelt
Hodowla Roslin Smolice Sp.z o.o Grupa IHAR
Triticum aestivum L. · Bread wheat
Selgen, a.s. Vyzkumne centrum SELTON, s.r.o.
Fragaria L. · Strawberry
Howard, Charles M.|deceased, late of Dover, FL, by Billie L. Howard, executor
Trifolium pratense L. · Red clover
Skriveri Research Centre
Cucumis sativus L. · Cucumber
PLANTICO ZIELONKI, SP. Z.O.O, PL
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
Yuksel Tohumculuk Tarim San. ve Tic. Ltd. Sti.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Triticum aestivum L. · Bread wheat
Sejet Planteforaedling I,S
Cucumis melo L. · Melon
Rijk Zwaan Zaadteelt en Zaadhandel BV (NL)