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Association of Fusarium Species With Picnic Beetles on Corn Ears. Carol E. Windels, Assistant Scientist, Department of Plant Pathology, University of Minnesota, St. Paul 55108; Mark B. Windels(2), and Thor Kommedahl(3). (2)Scientist, Department of Entomology, Fisheries and Wildlife, University of Minnesota, St. Paul 55108; (3)Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Phytopathology 66:328-331. Accepted for publication 2 October 1975. DOI: 10.1094/Phyto-66-328.

All corn ears buried by tillage operations in the fall of 1971 and 1973 were infested with picnic beetles, Glischrochilus quadrisignatus, and Fusarium spp. in July 1972 and 1974. More than 90% of the kernels from buried ears were colonized by Fusarium spp. From kernels of buried ears in the 2 years, F. solani grew from 66-84%, F. moniliforme from 25-39%, and F. oxysporum from 12-14%. These three Fusarium spp. also were isolated from larvae (85% internally in 1972; 96% externally and 82% internally in 1974), pupae (63% externally and 13% internally in 1974), and from newly emerged beetles (68% externally and 11% internally in 1974). In addition, F. roseum ‘Equiseti’ was isolated from pupae and newly emerged beetles. Beetles collected from ears on plants harbored more species and in greater frequency than beetles newly emerged from buried ears in 1972 and 1974 and included F. oxysporum, F. tricinctum, F. moniliforme, F. solani, and F. roseum ‘Acuminatum’, ‘Avenaceum’, ‘Equiseti’, ‘Gibbosum’, and ‘Graminearum’. Geotrichum candidum was isolated from kernels and from all insect stages in both years and from 13 of 14 fields in 1974. Buried ears may, therefore, serve as inoculum sources for ear-infecting Fusarium spp. through the activities of the picnic beetle.