STORABILITY OF WHEAT INFECTED WITH FUSARIUM HEAD BLIGHT

Abstract

The effect of scab (Fusarium head blight) on storability of three varieties of hard red spring wheat (Triticumaestivum) grown in several locations and in two years was studied. Samples of scab-infected hard red spring wheat werecollected from west-central and northwest Minnesota after harvest in 1994 and 1995. Half of each sample was passedover a gravity table twice to remove as many of the scab-infected kernels as possible. Carbon dioxide evolution fromcleaned and uncleaned samples was then used to determine dry matter loss during storage at 16, 18, and 20% moisture(wet basis) and 20C. Several quality factors and U.S. grade number were determined before and after storage, and thetime required to reach 0.5% dry matter loss was determined. The storage time to reach 0.5% dry matter changed from1.6% to +43.3% for samples that had been cleaned to remove scab-infected kernels compared to samples that had notbeen cleaned. There was no consistent trend in levels of the mycotoxin deoxynivalenol (DON) during storage of 1994wheat, but in most cases, there were significant increases in the levels of DON during storage of 1995 wheat. In all cases,DON levels were lower after storage tests in samples that had been cleaned on the gravity table compared to samples thathad not been cleaned. Wheat stored at 16% moisture deteriorated at a much slower rate than would be expected for corn(Zea mays) stored under similar conditions, and a wheat variety that is somewhat resistant to the fungi that cause scabdeteriorated more slowly than varieties that are susceptible to scab fungi. There were large, unexplained differences instorability for wheat grown in the two years of the study. In both years, however, the 0.5% dry matter loss criterion that isused to determine allowable storage time for corn seemed to be too high for use with wheat.