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Reduction in Fusarium Populations in Soil by Oilseed Meal Amendments. Michael A. Zakaria, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824, Present address: Department of Botany, Bogor Agricultural University, Bogor, Java, Indonesia; John L. Lockwood, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Phytopathology 70:240-243. Accepted for publication 13 September 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-240.

Natural loamy sand, artificially infested with Fusarium oxysporum and F. solani was amended with 10 kinds of plant or animal residues, each at 1% (w/w), and incubated in closed plastic containers. Linseed, cottonseed, and soybean meals reduced Fusarium chlamydospore populations from ~105 per gram of soil to 102 or fewer per gram in 45 wk. Crab shell reduced populations to 104 per gram, but six other amendments were ineffective. The oilseed meals were effective at concentrations at least as low as 0.25% (w/w). Soybean meal reduced Fusarium populations about equally in soil held at 15, 30, 50, or 100% of water-holding capacity (WHC) (approximately equivalent to 3.0, 0.2, 0.03, and 0 bars water potential, respectively). Linseed and cottonseed meals were most effective at 100% of WHC. Once reduced, Fusarium populations remained low for at least 4 wk. Total numbers of fungi, actinomycetes, and bacteria were not reduced as greatly by the oilseed meal amendments as were the fusaria. Severity of pea root rot in soil amended with oilseed meal was proportional to the surviving population of F. solani f. sp. pisi. Soil treated with linseed or cottonseed meal was phytotoxic to pea and soybean, whereas soil treated with soybean meal was not. The oilseed meals also reduced Fusarium populations in Capac loam, but not in Brookston loam. The rate of reduction in Capac loam was slower than that in loamy sand.

Additional keywords: biological control.