A Study of Aspergillus flavus/parasiticus in Iowa Crop Fields: 1988–1990. J. F. Shearer, Research Associate, Iowa State University, Ames 50011. L. E. Sweets, N. K. Baker, and L. H. Tiffany. Plant Pathologist, Pillsbury Green Giant, LeSueur, MN 56058; Laboratory Technician, and Professor of Botany, Iowa State University, Ames 50011. Plant Dis. 76:19-22. Accepted for publication 30 July 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0019.

Fungi belonging to the Aspergillus flavus/parasiticus group were consistently isolated from soil collected in fields of corn (Zea mays) and other crops in Iowa over a 3-yr period. The population recovered declined from an estimated 1,231 colonies per gram of dry soil in fall 1988 to 396 colonies per gram in fall 1990. Aflatoxin-producing isolates declined from 65% in 1988 to 14% in 1990, whereas sclerotia-producing isolates increased from 23 to 68% over the same period. Similar trends were observed in the isolates obtained from corn debris sampled from the fields in 1988 and 1990.