Submitted to: Plant Health Progress
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/25/2006
Publication Date: 3/24/2006
Citation: Bruns, H.A., Abbas, H.K. 2006. Effects of glufosinate - ammonium and urea on aflatoxin and fumonisin levels in corn.. Plant Health Progress. doi:10.1094/PHP-2006-0324-01-RS Interpretive Summary: Aflatoxin and fumonisin are potent cancer causing chemicals (mycotoxins) produced by the grain molds Aspergillus flavus, and Fusarium verticillioides, respectively, and can contaminate corn grain before it is harvested. Glufosinate-ammonium, sold as the herbicide “Liberty”, has been found in laboratory research to suppress the growth of A. flavus and urea, a common nitrogen fertilizer, is used to control certain fungal plant diseases. In a field experiment done from 2002 to 2004, at the Jamie Whitten Delta States Research Center in Stoneville, MS, neither “Liberty” nor urea suppressed aflatoxin or fumonisin contamination in corn grain. Although “Liberty” may have reduced aflatoxin in laboratory tests, and urea controls other fungi, they were ineffective as potential control agents for aflatoxin and fumonisin in field grown corn.
Technical Abstract: A study was conducted to determine if glufosinate-ammonium [2-amino-4-(hydroxymethylphosphinyl)-ammonium salt] (G-A) or urea [CO(NH2)2] would chemically suppress fungal growth of Aspergillus flavus Link ex Fries, which produces the mycotoxin aflatoxin, and Fusarium verticillioides (Sacc.) Nirenberg. (synonym =. F. moniliforme J. Sheld.), which produces the mycotoxin fumonisin, in pre-harvest corn (Zea mays L.). Four commercial corn hybrids, two genetically modified to be resistant to G-A and two non-genetically modified, were planted at Stoneville, MS in a randomized complete block with a split-plot arrangement of treatments replicated four times in 2001, 2002, 2003, and 2004. The experiment was furrow irrigated. Individual experimental units were two rows 30 feet long, spaced 40 inches apart, and included one of the following treatments: 1) untreated non-inoculated check, 2) untreated inoculated check, 3) 0.23 % v:v G-A:water, 4) 1.13% v:v G-A:water, and 5) 0.075 molar solution of urea. Twenty ears selected at random in each sub-plot were inoculated with a pin bar, using a culture of F3W4 A. flavus. Fusarium verticillioides was allowed to infect naturally. Among years, inoculated ears averaged 153.6 ppb to 257.3 ppb more aflatoxin than non-inoculated ears. Neither G-A nor urea reduced aflatoxin or fumonisin contamination. Hybrids did not differ in yield or aflatoxin contamination but one brand had less fumonisin (3.7 ppm and 2.3 ppm) than the other (7.5 ppm and 6.9 ppm). Grain yields were less in 2004 (110.4 bu/A) than 2001 (140.7 bu/A) or 2002 (143.6 bu/A).