OCCURRENCE OF FUNGI AND MYCOTOXINS ASSOCIATED WITH FIELD MOLD DAMAGED SOYBEANS IN THE MIDWEST

Abnormally warm, humid weather from 18 September to 7 October 1986 resulted in a delayed soybean harvest throughout the northern half of Illinois and portions of Iowa, Michigan, Minnesota, Missouri and Wisconsin. Twenty-four soybean samples from Illinois, Iowa, and Michigan from soybean seed either refused or heavily discounted by grain elevators were analyzed for percent damage, fungal infection and germination, and oil and protein content; free fatty acid content in oil; and mycotoxins including diacetoxyscirpenol (DAS), deoxynivalenol (DON), HT-2 toxin, ochratoxin, T-2 toxin, zearalenone, zearalenol, and aflatoxins B-1, B-2, G(1), and G(2). The percent damage ranged from 4.7 to 25.8%, and germination ranged from 7.5 to 39.0%. Seeds were heavily infected with Alternaria alternata (6.3-63.0%), Fusarium graminearum (13.0-51.3%), and Phomopsis spp. (12.5-49.0%). Other fungi, including Cercospora kikuchii and Aspergillus spp., were identified in 2.0-15.5% of the seeds. Protein, oil, and free fatty acid content were in expected ranges. Zearalenone was detected in whole soybeans, hulls, meal, and oil. Zearalenol was detectable in hulls and meal. DON was detected in whole soybeans, hulls, meal, and oil. DAS was detected in whole soybeans, hulls, and meal. T-2 (primarily HT-2) was detected in whole soybeans, hulls, meal, and oil. Ochratoxin was not detected and aflatoxin B-1 was found in hulls of only three of 24 samples, with the greatest amount detected being 5.8 eta g/g.