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Root-Infecting Species of Fusarium in Soil and in the Roots, Rhizospheres, and Residues of Oats. H. L. Warren, Department of Plant Pathology, University of Minnesota, St. Paul 55101, Present address: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907; Thor Kommedahl, Department of Plant Pathology, University of Minnesota, St. Paul 55101. Phytopathology 63:1401-1403. Accepted for publication 8 May 1973. DOI: 10.1094/Phyto-63-1401.

Fusarium oxysporum, F. solani, and F. roseum were the principal Fusarium spp. isolated from oat roots, rhizosphere, plant residues, and soil in a field plot cropped annually to oats for a decade. Of Fusarium spp. isolated, F. oxysporum made up 72% in roots, 63% in the rhizosphere, and 58% in soil; F. solani comprised 19% in roots, rhizosphere, and soil; and F. roseum made up 7% in roots, 12% in the rhizosphere, and 16% in soil. Fusarium tricinctum, F. moniliforme, and F. episphaeria never exceeded 5% in prevalence for any substrate. Presence or absence of fertilizer or plant residues did not change these percentages appreciably during the 2-year test period. On oat residues, F. roseum was the most prevalent (54%), followed by F. oxysporum (33%) and F. solani (11%), and the percentages were lower in spring than in the preceding fall only when fertilizer was not applied. The rhizosphere to soil ratio was about 1:1 except for F. roseum, where it was 0.4 when plant residues were retained on the plot and 2.6 when residues were removed but fertilizer was applied.

Additional keywords: soil-borne fungi.