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.
Hordeum vulgare L. · Barley
Secobra, F
Cucumis melo L. · Melon
NUNHEMS ZADEN
Cucumis sativus L. · Cucumber
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
MONSANTO HOLLAND BV , NL
Brassica oleracea L. (Broccoli Group) · Broccoli
Jean-Marie Boussac
Cucumis sativus L. · Cucumber
ROBERT SWINKELS
Malus domestica (Suckow) Borkh. · Apple
Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, France
Ribes nigrum L. · Blackcurrant
Research Institute of Horticulture (Instytut Ogrodnictwa) / Research Institute of Horticulture (Instytut Ogrodnictwa)
Pisum sativum L. · Pea
Syngenta UK Ltd
Cucurbita pepo L. · Field pumpkin
Saatzucht Gleisdort, A
Daucus carota L. · Carrot
Robert Oostveen, Nunhems B.V.
Hordeum vulgare L. · Barley
Secobra, F
Triticum aestivum L. · Bread wheat
Serasem, FR
Daucus carota L. · Carrot
Paul Degreef
Hordeum vulgare L. · Barley
SAS FLORIMOND DESPREZ VEUVE and FILS
Brassica oleracea L. (Cauliflower Group) · Cauliflower
Rijk Zwaan, NL
Rosa L. · Rose
HANS JURGEN EVERS (T)
Rosa L. · Rose
Terra Nigra Holding b.v
Rosa L. · Rose
Rosen-Tantau Mathias Tantau Nachfolger
Prunus persica (L.) Batsch · Peach
Maillard Arsene / Maillard Laurence
Pisum sativum L. · Pea
Rogers Brothers Seed Co., JD 83711-0727
Pisum sativum L. · Pea
Seminis Vegetable Seeds
Cucumis melo L. · Melon
P.DEGREEF
Rosa L. · Rose
Poulsen Roser ApS