Monoculture can lead to reduced yields due to pressure from biotic or abiotic sources. This pressure may be reduced by rotating crops. In the first year, a 0.5-ha of a Bernow fine-loamy, siliceous, thermic Glossic Paleudalf soil was planted to peanuts at Lane, Okla. In each of the following 5 years, the area was subdivided in to four rotations that were replicated four times. Bell pepper, cucumber, navy bean and cabbage were planted after 1, 2, or 3 years of peanuts. The first vegetable planting in each rotation was followed by either vegetables or peanuts, and these crops were planted in 3 of the 6 years in each rotation. Half of each plot was treated with soil fungicides, and half of the peanut plots were treated with foliar fungicides. Sclerotia, likely in the genera Sclerotia and Sclerotinia, were counted in the spring of each year starting in the second year. Peanut yields in the first year were 6.6 Mg·ha–1 but were <2.5 Mg·ha–1 thereafter. Yields of vegetables planted to follow 1 or 2 years of peanuts were normal for this location. Yields in later vegetable plantings in these rotations were reduced by 50%, and yields of vegetables planted after 3 years of peanuts were significantly less than vegetables planted after 1 or 2 years of peanuts. Numbers of sclerotia fluctuated over time, but numbers in the spring of the second year were the same as in the spring of the sixth year. The vegetables tested here should not be planted after >2 years of peanuts at this location.
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