fungus known to attack the leaves and stems of African Violets. The most distinct symptom of Rhizoctonia is the oval or peanut-shaped spots which the fungus produces on the leaves. These spots have a distinct outline and are mottled yellow within. If left untreated, Rhizoctonia can be fatal. More information.

A fungus which rots plant roots.

Rhizoctonia disease of potato, often referred to as black scurf, is caused by the fungus Rhizoctonia solani . R. solani is a very common soilborne pathogen and is found in most potato-producing areas of the world. There are two phases of the disease: the stem and stolon phase, and the tuber phase. The first occurs early in the growing season in the form of lesions on the growing tips of sprouts, stems or stolons. The second and most noticeable phase is the formation of sclerotia on tubers. These sclerotia give the name black scurf and look like "dirt that doesn't wash off." The longer the potatoes remain in the soil after vine kill, the more sclerotia will be formed on the tubers. The fungus overwinters as sclerotia (spores) and mycelium (vegetative growth) on infected tubers, in plant residue, or in infested soils.