Young shoots may be killed before they emerge. In wet weather, stem decay is soft and slimy and may quickly spread to a large part of the plant. Under dry conditions, the infected tissues become dry and shrivelled, but may only be noticeable on the underground portion of the stem. Tubers may be slightly discoloured at point of attachment to the main portion of the plant. It is at this end, where soft rot may develop and spread into the tuber.
Soft rot can affect tubers while in storage or in the soil before harvest.
The decay occurs after planting. Under dry conditions, there may be sunken areas that are dry and hard. Soft rotted potato flesh appears wet, cream to tan in colour with a soft, slightly granular appearance. There is also a definite break between healthy and infected tissue. It is usually odourless unless other decay organisms have already set in.