Lettuce Drop
Lettuce drop
Common name
Lettuce drop
Causal agent
Lettuce drop is caused by two members of the genus Sclerotinia. These white mold fungi affect the foliage and stems of the plants, especially lettuce causing the premature drop.
Scientific name
Sclerotinia sclerotiorum
Sclerotinia minor
Symptoms & Signs
The fungi first affect the lower leaves in contact with the soil. The leaves turn brown, wilt, and drop off the stem. It gradually spreads to the inner leaves until the whole plant is infected. The leaves show white mold along with fruiting bodies called sclerotia. Mature plants have a higher risk of collapsing than younger plants.
Transmission
Cool, moist conditions favor the growth of fruiting bodies and the spread of the spores. The spores travel to other plants through the wind. However, the spores can survive in the sclerotia for a few years, even without a host.
Time of concern
Early spring to summer
Common hosts
Onion
Garlic
Cabbage
Lettuce
Cucumber
Squash
Potato