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 sativus L. · Cucumber
SUNSEEDS
Solanum lycopersicum L. · Tomato
RIJK ZWAAN Zaadteelt en Zaadhandel B.V.
Cucumis melo L. · Melon
Ralf Kuijpers
Malus domestica (Suckow) Borkh. · Apple
Prof. Dr. Hanna Schmidt / Dr. Jutta Krüger in Bundesforschungsanstalt für gartenbauliche Pflanzenzüchtung
Cucumis melo L. · Melon
De Ruiter Zonen (HR)
Hordeum vulgare L. · Barley
YNGVE HÖRBERG & PER LUNDIN
Malus domestica (Suckow) Borkh. · Apple
SEMPRA PRAHA A S
hybrids between Solanum lycopersicum L. and S. habrochaites S. Knapp & D.M. Spooner
Enza Zaden Beheer B.V.
Capsicum annuum L. · Bell pepper
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Citrullus lanatus (Thunb.) Matsum. & Nakai · Watermelon
Syngenta Crop Protection AG
Cucumis melo L. · Melon
Ralf Kuijpers
Lactuca sativa L. · Lettuce
Enza Zaden Beheer B.V. / Enza Zaden Beheer B.V.
Capsicum annuum L. · Bell pepper
Syngenta Seeds B.V.
Triticum durum Desf. · Durum wheat
RAGT 2N S.A.S
Linum usitatissimum L. · Common flax
GIE Linea Semences de lin (FR)
Cucumis sativus L. · Cucumber
Nunhems B.V.
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis melo L. · Melon
Syngenta Seeds B.V.
Triticum aestivum L. · Bread wheat
Strube Research GmbH&Co KG
Solanum lycopersicum L. · Tomato
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Triticum aestivum L. · Bread wheat
RAGT 2n
x Triticosecale Wittm. ex A. Camus · Triticale
ISEA S.R.L
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Avena sativa L. · Oat
Selgen a.s., CZ