Diseases
Peronosporaceae
Downy mildew is a dangerous plant disease caused by oomycetes under high humidity conditions. It manifests as a characteristic growth on the underside of leaves and spotting, which leads to rapid death of vegetative mass and yield reduction.
Mentioned in descriptions 16 384 varieties reference book.
Downy mildew is a group of diseases caused by specialized oomycetes. The disease manifests as the appearance of yellowish or brown angular spots on the upper side of the leaves, delimited by veins. On the underside of the leaf, under humid conditions, a characteristic grey-violet, white, or bluish fuzzy growth forms. Pathogen development leads to yellowing and drying of leaves, stunting of plants, and deformation of fruits, which, in the case of high pathogen aggressiveness, can lead to crop death in a short period.
Disease development depends directly on meteorological conditions and agronomic practices. The pathogen prefers a cool, humid environment, with critical risk factors being heavy dew, fog, prolonged rain, high air humidity, and crop density. Optimal conditions for infection include nighttime temperatures in the range of +13…+20°C and the presence of droplet moisture on the leaf surface for more than 6 hours.
Assessment of variety resistance during variety testing is based on phytopathological recording of the degree of leaf damage, specialized screening of collection samples, and molecular analysis methods using DNA markers to find genetic donors of resistance. In production, a distinction is made between genetically resistant varieties possessing specific Dm-genes and tolerant forms capable of maintaining yield under infection due to active vegetative mass formation. Since new pathogen races can overcome genetic resistance, varieties require regular monitoring and renewal.
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.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Helianthus annuus L. · Sunflower
MAS SEEDS
Cucumis melo L. · Melon
Nehama, Shulamit
Glycine max (L.) Merr. · Soybean
Semences Prograin Inc
Helianthus annuus L. · Sunflower
Limagrain Europe, FR
Pisum sativum L. · Pea
W BROTHERTON SEED CO INC
Lactuca sativa L. · Lettuce
Nunza BV (NL)
Petroselinum crispum (Mill.) Nyman ex A. W. Hill · Parsley
Jan Draaistra
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis melo L. · Melon
Nunhems B.V.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Cucumis sativus L. · Cucumber
HAZERA (1939)
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel BV (NL)
Helianthus annuus L. · Sunflower
Nicolae Boaghe, Elena Andreea Teodorescu
Lactuca sativa L. · Lettuce
Victor Segura Juan
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Lactuca sativa L. · Lettuce
Sakata Vegetables Europe S.A.S
Helianthus annuus L. · Sunflower
Gabriel State
Helianthus annuus L. · Sunflower
Euralis Semences
Lactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
Lactuca sativa L. · Lettuce
Rijk Zwaan, NL
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.