Above ground symptoms on sweetpotato plants include stunting and yellowing of the growing three months in foilage. In severe cases plants may die or produce no yield. The tips of fibrous roots are rotted. Numerous black lesions of varying size occur on fibrous roots as well as on the underground stem. As the lesions develop, they turn black and have distinct margins.
Storage roots exhibit sunken lesions that are black and crusty.
One to several pox lesions can appear in rows and are usually associated with the lateral roots. The affected sweetpotato will be misshapen and roots can be severely constricted or indented in one or more places. Pox lesions can be confused with circular spot caused by Sclerotium rolfsii . Circular spot lesions are usually not associated with lateral roots and tends to be light brown, round with distinct borders, and bitter to the taste. With both diseases the lesions do not enlarge following harvest.