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United States Department of Agriculture

Agricultural Research Service


item Jaime Garcia, Ramon
item Cotty, Peter

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2003
Publication Date: 9/1/2003
Citation: Jaime-Garcia, R., Cotty, P.J. 2003. Aflatoxin contamination of commercial cottonseed in South Texas. Phytopathology. 93:1190-1200.

Interpretive Summary: Aflatoxins are toxic metabolites produce by several members of Aspergillus section flavi. U.S. Federal regulations limit the use of cottonseed contaminated with aflatoxin. Cottonseed with aflatoxin content of 20 ppb (parts per billion) or higher may not enter the profitable dairy market. In order to establish area-wide control measures, we need to determine the distribution of aflatoxin contamination in the area as well as the factors influencing contamination. We studied the distribution of aflatoxin contamination of cottonseed in South Texas during 1997 through 2001. Specific areas of high vulnerability to contamination were identified. Rainfall after cotton bolls are open was found to be the most important environmental factor predisposing the crop to contamination. Cottonseed harvested earlier had lower levels of contamination. The results suggest growers can limit contamination by harvesting early to avoid rain on the mature crop. Recurrent patterns of areas with either low or high aflatoxin contamination of cottonseed were detected. Specific areas of South Texas where aflatoxin management would be most cost effective were identified. This information will be very useful for the cotton industry in South Texas.

Technical Abstract: Aflatoxins are toxic fungal metabolites produced by several members of Aspergillus section flavi. U.S. Federal regulations limit the use of aflatoxin-contaminated cottonseed. Cottonseed with aflatoxin content of 20 ng/g or higher may not enter the profitable dairy market. Between 4,472 and 9,949 truckloads of cottonseed from 31 to 35 gins in South Texas were analyzed for aflatoxin content each year from 1997 to 2001 upon receipt at the Valley Co-op Oil Mill in Harlingen, Texas. Highest levels of contamination occurred in 1999 with an average aflatoxin content of 112 and 66% of the cottonseed truckloads exceeding 20 ng/g. Years 1997 and 2000 had the lowest aflatoxin levels averaging 24 ng/g. The lowest incidence (16%) of the truckloads exceeding 20 ng/g occurred in 1997. In general, aflatoxin contamination increased as the ginning season progressed. Rainfall after boll opening correlated highly with aflatoxin content, with rainfall in July explaining over 50% of the observed variability in aflatoxin content. South Texas was divided into four regions: Rio Grande Valley, Coastal Bend, Upper Coast and Winter Garden. Geostatistical analyses revealed recurrent patterns of high and low contamination. Greatest contamination occurred from the central Coastal Bend region through the southern Upper Coast region. The Rio Grande Valley region experienced the least contamination during the study period.

Last Modified: 09/19/2017
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