Diseases

White Mold of Lettuce

Lactuca sativa L.

A dangerous fungal disease of lettuce caused by the pathogens Sclerotinia sclerotiorum and Sclerotinia minor, manifested by wilting, watery stem rot, and the formation of dense white mycelium with black sclerotia.

In the reference 8 varieties crop Lettuce, where this is mentioned in the description.

The disease is caused by fungi of the genus Sclerotinia. The species S. sclerotiorum is a broad-spectrum pathogen, while S. minor has a narrower host range. There is no clear classification into races or pathotypes, although significant intraspecific variability among isolates is observed regarding aggressiveness and oxalic acid production.

Primary symptoms include wilting and yellowing of the lower leaves in contact with the soil, followed by the appearance of watery, light-brown spots at the base of the stem. A diagnostic feature is the development of abundant white mycelium, in which sclerotia are formed: small in S. minor and larger in S. sclerotiorum.

There is no immunity to this disease in lettuce, and resistance is a quantitative polygenic trait. Scientific studies have identified QTLs (loci qLDR1.1 and qLDR5.1) associated with the level of resistance; however, breeding is difficult due to the correlation of these traits with undesirable characteristics, such as premature bolting.

General information about the subject — on the page White mold.

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.