Symptoms appear as wilting and a slow or rapid collapse of the plant. The roots can appear brown and water-soaked instead of white. A water-soaked lesion can often appear at the base of the stem. Affected plants should be rogued out and discarded. Stem rot, Sclerotinia sclerotiorum.
Individual stalks begin to collapse and wilt.
The interior of dead stems frequently reveals small, irregularly-shaped black structures called sclerotia. Since the fungus lives in the soil, a two-year rotation with nonsusceptible plants, such as corn, to prevent the buildup of pathogenic organisms rotation can reduce the incidence of disease. Botrytis blight , Botrytis cinerea. Botrytis blight occurs on many different kinds of herbs. The disease appears when plants are grown under conditions of high humidity, such as in a terrarium.