Aflatoxin development in preharvest corn

Typescript (photocopy).Aflatoxin development in corn prior to harvest can be a serious problem and it represents a production hazard that can have a significant monetary impact on corn producers. In 1980, silk-mediated kernel infection resulted in high levels of aflatoxin in preharvest corn. Hot, dry weather intensified silk-mediated kernel infection and subsequent toxin production, but reduced the period of susceptibility of silks to A. flavus infection. Silk and kernel infection occurred soon after silk emergence but significant aflatoxin production usually did not occur until 24 days after 50% silk. Cool, wet weather in 1981 resulted in very low aflatoxin levels in silk-inoculated corn. Plant stress resulting from southern corn leaf rust infection or plant defoliation caused marked increases in aflatoxin content of mechanically inoculated kernels. Southern corn leaf rust infection hastened plant maturity, probably resulting in a kernel moisture more favorable to A. flavus growth. Foliar application of the fungicide benomyl reduced aflatoxin levels in mechanically inoculated corn in 1979 and in both mechanically inoculated and silk inoculated corn in 1980. No effect was noted in 1981. Various commercial corn hybrids and 4 open pollinated races of Mexican corn all accumulated large amounts of aflatoxin when mechanically inoculated with A. flavus. ..