EFFECT OF HARVEST DATE ON AFLATOXIN CONTAMINATION OF COTTONSEED

In 1987 and 1988, aflatoxin in cottonseed was three to 12 times higher in seed harvested at the Yuma Valley Agricultural Center near the end of the commercial harvest season than at the beginning in the Yuma Valley of Arizona. Most toxin was detected in seed from tight locks and locks with lint exhibiting bright green-yellow fluorescence. Evidence from laboratory experiments confirmed observations on field-grown cotton that aflatoxin levels may increase in fully mature cottonseed both before and after harvest. Toxin increases occurred over a broad range of temperatures (16-37 C) if the relative humidity was 93% or greater. Early harvest is recommended to improve management of aflatoxin contamination of Arizona cottonseed.