EFFECT OF DELAYED HARVEST ON CONTAMINATION OF PEARL-MILLET GRAIN WITHMYCOTOXIN-PRODUCING FUNGI AND MYCOTOXINS

The response to delayed harvest of fungal and mycotoxin contamination of grain of the pearl millet hybrid HGM 100 was examined in 1992 and 1 993. Samples of grain were assayed from seven plantings at locations n ear Tifton, Georgia, USA. Grain was harvested at 30, 40, and 50 days a fter anthesis and evaluated for infection by Fusarium species and Aspe rgillus flavus, and mycotoxin contamination. Mean isolation frequencie s of F. semitectum (35.6%) and F. chlamydosporum (17.2%) increased lin early with delayed harvest. Fusarium moniliforme and F. equisiti were infrequently isolated (<0.5%) and did not increase in the grain when h arvest was delayed. Low mean concentrations of zearalenone (0.17 ppm), nivalenol (0.42 ppm), and deoxynivalenol (0.01 ppm) were detected but were not affected by delayed harvest. Isolation frequencies of F. chl amydosporum and F. equiseti were correlated (P = 0.07) with levels of nivalenol. Aspergillus flavus was not isolated from the grain, and afl atoxin concentrations averaged 1.9 ppb.