Seasonal variation and effects of wheat rotation on populations ofVerticillium dahliae Kleb. in Ohio potato field soils

摘要: Soil population levels ofVerticillium dahliae in Ohio were monitored from May–October, 1982–1985, 15 fields potato-wheat rotation and two potato monoculture. Population ranged 0 to 86 microsclerotia/10 g of air-dried soil with average values during each 6-month sampling period 9.7, 12.9, 9.6 19.6 for 1982, 1983, 1984 1985, respectively. In at least 2/3 the sampled year, populations ofV. peaked either July or August, regardless whether under wheat Of rotation, 13 showed a general pattern increased one both years following cropping potato. Among those 13, significantly higher (P < 0.05) observed field 1983 eight 1985. monoculture, consistently had 3–4 times than any other this study. Factors that may contribute periodic changes inV. populations, implications these interpreting data, usefulness managingV. are discussed.