Worldwide distribution of potato-cyst nematodes and their importance in crop production.

The potato-cyst nematodes Heterodera rostochiensis and H. pallida are important pathogens of potatoes, a basic food crop. When soil populations of either species are high, potato yields are often less than the seed planted. Apparently, these nematodes originated in the Andean mountains of South America, the home of the potato. One or both species have spread from this region to approximately 47 countries. The two species may occur together or separately in potato-growing areas. Although these nematodes can be spread in numerous ways, contaminated soil associated with seed potatoes, farm machinery, and reusable containers is among the most important. An integrated control program used in the U.S.A. is described.