Effects of Glufosinate-Ammonium and Urea on Aflatoxin and Fumonisin Levels in Corn

Abstract

Glufosinate-ammonium [butanoic acid, 2-amino-4-(hydroxymethylphosphinyl)-ammonium salt] (G-A) and urea [CO(NH2)2] were evaluated as foliar treatments for suppression of pre-harvest aflatoxin and fumonisin contamination in corn (Zea mays). The experiment was conducted in Stoneville, MS as a randomized complete block split-plot design replicated four times. The whole plots were four commercial hybrids, two genetically modified to be resistant to G-A and two nonmodified. Twenty randomly-selected ears in each sub-plot were inoculated with a culture of F3W4 Aspergillus flavus using a pin bar. Infection by Fusarium verticillioides (= F. moniliforme) occurred naturally. The sub-plot treatments were applied as an aqueous solution (0.23 % v:v G-A, 1.13% v:v G-A, and 0.075 M urea) 60 days after silking. The experiment also included untreated controls with and without inoculation of A. flavus. Sub-plots were two rows 30 ft long, spaced 40 inches apart. The experiment was repeated four times starting in 2001 and ending in 2004. 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 concentrations. Hybrids did not differ in yield or aflatoxin concentration. Fumonisin concentrations among hybrids ranged from 2.3 ppm to 7.5 ppm. Grain yields were less in 2004 (110 bu/acre) than 2001 (140 bu/acre) or 2002 (144 bu/acre). Accepted for publication 25 January 2006. Published 24 March 2006.