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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.

Sources8

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.

Lactuca sativa L. · Lettuce

Syngenta UK Ltd

NL
9 records

Lactuca sativa L. · Lettuce

Nunhems B.V.

NL
9 records

Kiribati

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel BV (NL)

FR
8 records

Poplar

Active

Lactuca sativa L. · Lettuce

NUNHEMS

NL
10 records

Lactuca sativa L. · Lettuce

Nunhems B.V.

NL
10 records

Gitanas

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

ES NL
8 records

Estony

Active

Lactuca sativa L. · Lettuce

Enza Zaden B.V.

HR NL
6 records

Tudela

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

ES NL
7 records

Lactuca sativa L. · Lettuce

Nunhems B.V.

NL
8 records

Radian

Active

Lactuca sativa L. · Lettuce

Syngenta, NL

NL
8 records

Lactuca sativa L. · Lettuce

NUNHEMS

NL
15 records

Izanas

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

NL
10 records

Exwatch

Active

Lactuca sativa L. · Lettuce

RIJK ZWAAN ZAADTEELT EN ZAADHANDEL B.V.

NL
9 records

Centore

Active

Lactuca sativa L. · Lettuce

Syngenta Seeds BV (NL)

ES FR HR NL
7 records

Amadeus

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

ES NL
7 records

Saula

Active

Lactuca sativa L. · Lettuce

Enza Zaden Beheer B.V.

NL
8 records

Klausia

Terminated

Lactuca sativa L. · Lettuce

Novartis Seeds BV (NL)

ES FR HU NL
7 records

Tralex

Active

Lactuca sativa L. · Lettuce

Rijk Zwaan, NL

NL
9 records

Lactuca sativa L. · Lettuce

Rijk Zwaan Zaadteelt en Zaadhandel B.V.

NL
9 records

Bataille

Active

Lactuca sativa L. · Lettuce

P.DEGREEF

NL
9 records

Lactuca sativa L. · Lettuce

NUNHEMS

NL
9 records

Matador

Active

Lactuca sativa L. · Lettuce

ISI SEMENTI SPA

FR NL
6 records

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