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
Robert Priieur
Malus Mill. · Apple
SEMPRA CARLO
Begonia x hiemalis Fotsch · Elatior Begonia
Hans Joachim Rohde (DE)
Hordeum vulgare L. · Barley
NORDIC SEED A/S
Triticum aestivum L. · Bread wheat
SEMUNDO SAATZUCHT GMBH
Clematis L. · Clematis
Uno Kivistik, Aili Kivistik
Vitis vinifera L. · Common grape vine
Dorothea Pospislova c/o VSSVVM n.o.
Hordeum vulgare L. · Barley
Lantmännen SW Seed
Triticum aestivum L. · Bread wheat
RAGT 2n
Hordeum vulgare L. · Barley
SVERIGES UTSÄDESFÖRENING SVALÖF
Vitis vinifera L. · Common grape vine
INCONNU (FR)
Triticum aestivum L. · Bread wheat
SINA ISABEL STRUBE
Malus domestica (Suckow) Borkh. · Apple
Prof. Dr. Christa Fischer / Dr. Andreas Peil im Inst. f. ZF an gartenb. Kulturen und Obst -Julius-Kühn-Institut-
Triticum aestivum L. · Bread wheat
W WEIBULL
Pisum sativum L. · Pea
Royal Sluis Vegetables BV (NL)
Pisum sativum L. · Pea
Royal Sluis Vegetables BV (NL)
Vitis vinifera L. · Common grape vine
PUOGET ROGER
Allium cepa L. · Onion
Martin Slot, John Pieter Schipper,
Hordeum vulgare L. · Barley
Limagrain Europe, FR
Pisum sativum L. · Pea
SLUIS & GROOT BV (NL)
Malus Mill. · Apple
BLAZEK J.
Triticum aestivum L. · Bread wheat
W. von Borries-Eckendorf GmbH & Co.KG
Malus domestica (Suckow) Borkh. · Apple
Information not available - Contact NL authorities
Ribes uva-crispa L. · Gooseberry
Sempra Praha a.s., CZ