The relationship betweenVerticillium albo-atrum inoculum density and potato yield

Abstract

Population studies withVerticillium albo-atrum (microsclerotial form) have shown that a significant negative correlation exists between inoculum density in field soils determined before planting and yield of potatoes in some areas of Colorado but not in others. In Southern Weld and Morgan Counties where potatoes are planted early in sandy soils, reduced yield in Norgold Russet and Norchip cultivars occurred as inoculum densities increased. In Northern Weld County where potatoes are planted later in heavier soils, no such relationship was found. The significant relationship between inoculum density and reduced yield was associated with growing areas where conditions, particularly air temperature, appear to be favorable for verticillium wilt development when plants begin to mature.