The quality of the crop is seriously decreased, although the yield is almost unaffected. Affected potatoes usually store as well as healthy potatoes. There are no aboveground symptoms. This disease cannot infect tubers as they approach maturity, unless the tuber is wounded, for example, by insect feeding. These spots may grow together to make irregularly shaped patches.
Spots are usually tan to brown in color and are rough in texture.
The pitted spots may be invaded by scab gnats. If the tuber is sliced open, the flesh underneath the spot is straw colored and somewhat translucent. This is not usually evident under the russet scabs. Plant only disease-free tubers. A 4-year crop rotation which includes soybeans and alfalfa, can decrease disease severity.