Presprouting of seed tubers is a measure that is often recommended for organic potato growing. In on-farm field experiments the effect of presprouting was evaluated with respect to virus infection, yield and weed infestation. The effect of presprouting on yield was largely dependent on the year and on the late blight severity. Weeds were not affected significantly by presprouting. In most experiments virus incidence was higher in presprouted potatoes. Presprouting also had a suppressive effect on undesired regrowth after haulm destruction
