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Fertilization and Wheat Refuse Effects on Fusarium Species Associated with Wheat Roots in Minnesota. H. L. Warren, Department of Plant Pathology, University of Minnesota, St. Paul 55101; Thor Kommedahl, Department of Plant Pathology, University of Minnesota, St. Paul 55101. Phytopathology 63:103-108. Accepted for publication 26 July 1972. DOI: 10.1094/Phyto-63-103.

Isolations from roots, soil, rhizosphere, and crop residues of wheat (Triticum aestivum ‘Chris’) in field plots yielded six species of Fusarium: F. oxysporum, F. solani, F. roseum, F. tricinctum, F. moniliforme, and F. episphaeria. Fusarium oxysporum was dominant, followed by F. solani and F. roseum. Seedling blight caused by Fusarium spp. averaged 1-2% when fertilizer and residues were present, and 11-14% when both were absent. Fertilizer alone gave a lower blight incidence, lower root disease indices, and fewer Fusarium-infected roots than did residue alone. In a year when seedling blight was severe, Fusarium roseum comprised 90% of the Fusarium isolates from roots, followed by F. oxysporum and F. solani. Of the F. roseum cultivars, Graminearum comprised 70%, followed by Avenaceum and Culmorum with 15% each. The removal of wheat residue (mainly surface) resulted in greater survival of F. oxysporum and less survival of F. roseum and F. solani in soil.