Risk factors

Stem canker in potatoes is favoured by a cool climate after planting as well as by any other factor that slows emergence. 

This increases the period of susceptibility of the plant to the disease: for example, avoid early deep planting in cold soil with unsprouted and unheated seed tubers.

Short rotations greatly favour infection, as does a long delay between haulm destruction and the harvest for black scurf on tubers.