Exmond
ActiveLactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
NL
3 records
Diseases
Downy mildew of lettuce
Lactuca sativa L.
A fungal disease of lettuce caused by the obligate oomycete Bremia lactucae, characterized by high pathogen variability and the appearance of chlorotic angular spots with sporulation on the underside of leaves.
In the reference 2 007 varieties crop Lettuce, where this is mentioned in the description.
The disease is caused by the oomycete Bremia lactucae Regel, which exhibits high genetic variability. Pathogen populations include numerous physiological races, designated by the code Bl followed by a sequence number, the composition of which is constantly changing, making it difficult to maintain cultivar resistance.
Symptoms appear as chlorotic angular spots on the upper side of the leaf, restricted by veins. On the underside, a characteristic loose whitish, gray, or violet sporulation layer forms. Affected tissues become necrotic, leading to leaf desiccation and stunted seedling growth.
Breeding for resistance is based on the use of Dm-genes (Downy mildew) and quantitative trait loci (QTL). Cultivar resistance is determined by the ability to withstand specific races of the pathogen; however, the effectiveness of protection is limited due to the ability of local Bremia lactucae populations to overcome genetic resistance.
General information about the subject — on the page Downy mildew.
Varieties of Lettuce mentioned in the description
Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.
Afabila
ActiveLactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
NL
4 records
Ostria
ActiveLactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
NL
4 records
Redigo 3
ActiveLactuca sativa L. · Lettuce
Gautier Semences SAS (FR)
FR
2 records
Navela
ActiveLactuca sativa L. · Lettuce
MERIDIEM SEEDS S.L.
ES
2 records
Belgarde
ActiveLactuca sativa L. · Lettuce
Gautier Semences SAS (FR)
FR
2 records
Kalbelia
Application submittedLactuca sativa L. · Lettuce
Vilmorin-Mikado SAS (FR)
FR
2 records
Cassandra
ActiveLactuca sativa L. · Lettuce
Panora s.p.a.
NL
3 records
Rosny
TerminatedLactuca sativa L. · Lettuce
Graines Gautier SA (FR)
FR
3 records
Verdena
ActiveLactuca sativa L. · Lettuce
Panora s.p.a.
NL
2 records
Akre
ActiveLactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
NL
4 records
Manade
ActiveLactuca sativa L. · Lettuce
Graines Gautier SA (FR)
FR
3 records
Cydonia
TerminatedLactuca sativa L. · Lettuce
Gautier Semences SAS (FR)
FR
2 records
Gwendoline
ActiveLactuca sativa L. · Lettuce
Vilmorin-Mikado SAS (FR)
FR
2 records
Churruca
Application submittedLactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
NL
3 records
Modane
ActiveLactuca sativa L. · Lettuce
Vilmorin-Mikado SAS (FR)
FR
3 records
Tudor
ActiveLactuca sativa L. · Lettuce
Gautier Semences SAS (FR)
FR
2 records
Valvanera
ActiveLactuca sativa L. · Lettuce
RAMIRO ARNEDO, S.A.
ES
2 records
Mojito
TerminatedLactuca sativa L. · Lettuce
Shamrock Seed Co. Inc. (US)
FR
2 records
Yzarde
ActiveLactuca sativa L. · Lettuce
Gautier Semences SAS (FR)
FR
2 records
Picador
ActiveLactuca sativa L. · Lettuce
Gautier Semences SAS (FR)
FR
2 records
Falstaff
ActiveLactuca sativa L. · Lettuce
Panora s.p.a.
NL
2 records
Alecto
ActiveLactuca sativa L. · Lettuce
Enza Zaden Beheer B.V.
NL
4 records
Progreen 76
ActiveLactuca sativa L. · Lettuce
Syngenta Crop Protection AG
NL
2 records