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Ecology and Epidemiology

Occurrence of Fusarium Species in Roots and Stalks of Symptomless Corn Plants During the Growing Season. Thor Kommedahl, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108; Carol E. Windels(2), and R. E. Stucker(3). (2)Associate scientist, Department of Plant Pathology, University of Minnesota, St. Paul 55108; (3)Professor, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108. Phytopathology 69:961-966. Accepted for publication 21 March 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-961.

The same Fusarium spp. were isolated throughout two seasons (1974-1975) from roots and stalks of three corn hybrids differing in resistance to root lodging. Whereas Fusarium spp. infected 90% of the plants sampled by July and 100% by mid-August, they were isolated infrequently from stalks in July until after silking. By early September, about 90% of the stalks were infected, even though no symptoms of stalk rot were apparent. As the season progressed, often more than one Fusarium spp. was isolated from a single stalk and as many as five species were isolated from some stalks by mid-October. Fusarium oxysporum and F. solani were isolated from roots more frequently than from stalks, and F. moniliforme and F. tricinctum were isolated from stalks more frequently than from roots. F. roseum appeared more frequently in roots than in stalks until the end of August when it occurred more frequently in stalks. Of F. roseum populations, those in the cultivar Equiseti predominated followed by Acuminatum; Graminearum was only occasionally isolated from roots or stalks. When cornstalk stubble was sampled from the same plot in spring 1976, the Fusarium spp. were the same as those isolated the previous fall, except that F. moniliforme was absent.