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Seasonal Formation of Aflatoxins in Cottonseed Produced in Arizona and California. T. E. Russell, Associate Research Scientist, Department of Plant Pathology, University of Arizona, Tucson 85721. L. S. Lee, and S. Buco. Research Chemist, Southern Regional Research Center, USDA, ARS, P.O. Box 19687, New Orleans, LA 70179; and Biometrician, Southern Region, Department of Experimental Statistics, Louisiana State University, Baton Rouge 70803. Plant Dis. 71:174-177. Accepted for publication 21 July 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1987. DOI: 10.1094/PD-71-0174.

Open cotton bolls were hand-harvested at 10- to 15-day intervals throughout two consecutive growing seasons and assayed for aflatoxins. In both years, the percentages of total toxins (70.43% the first year and 78.97% the second year) and toxin levels were highest in seed maturing before 1 September. These toxins were detected in 67% of the total seed harvested the first year and in 55% of the seed harvested the second year. A 500-fold variation in toxin levels was observed in one field between seasons. Maximum field-to-field variation was 230-fold. Levels of toxin were less in early-flowering, second-year, perennial cotton than in annual cotton grown in parallel plots. The critical period for toxin formation was a 30- to 45-day interval commencing about the date of initial boll opening.

Keyword(s): Aspergillus flavus.