Seed degeneration is the gradual loss in productivity of a potato crop during successive multiplication cycles as a result of growth of seed borne diseases. These diseases include viruses such as potato leaf roll virus (PLRV) and bacterial diseases such as wilt. Seed degeneration is significant when seed potatoes are used in several subsequent seasons without special measures to control seed borne diseases (e.g. in ware potato production).
To control seed degeneration, farmers need to replace their seed stocks regularly with healthy seed potato. It is also important for farmers to practice Positive Seed selection (PSS) when they are not replacing their seed stock.
Source: Seed Potato Production and Certification Guidelines from KEPHIS, Dec 2016