PATHOLOGY AND CONTROL OF SOIL-BORNE FUNGAL PATHOGENS OF POTATO

Several soil-borne fungal pathogens continue to cause problems in pota to production worldwide. The reasons for these problems are illustrate d by reference to the pathogens Verticillium dahliae, Rhizoctonia sola ni, Spongospora subterranea and a group normally considered to be tube r-borne, including Colletotrichum coccodes, Helminthosporium solani an d Fusarium species. Generally, the long-term persistence of survival s tructures, the difficulties in reducing inoculum and lack of good sour ces of resistance hinder attempts to improve control of soil-borne fun gal pathogens. Post-harvest fungicide treatment of seed or ware potato es does not entirely alleviate storage problems. In the foreseeable fu ture there is no alternative to the use of integrated measures from th e time of planting seed to movement from storage. Key research areas t hat arise as a means of better controlling most of these pathogens are : the role of intraspecific variation in pathogenesis and ecology, pro blems of detecting and quantifying inoculum, and the need for improved methods for biological control.