Sclerotinia blight is similar to Southern stem rot in that both diseases are caused by soilborne fungi which attack plants at or near the soil surface. The distinct differences in appearance of the fungi that cause these diseases permit recognition in the field.
Sclerotinia minor has a cottony or fluffy appearance on stems under moist conditions.
This mold growth may disappear, however, when sunlight penetrates the leaf canopy and the morning dew evaporates. Entire limbs on plants may wilt and die as a result of the fungus decaying stems near the crown of plants. After the fungus has consumed all available food from a colonized stem, it produces small black, irregularly shaped survival structures called sclerotia. These sclerotia resemble mouse dung in size and appearance. Although diseased stems frequently show a light-tan color when affected by Sclerotinia blight, positive recognition requires that one find the black sclerotia of the causal fungus.