Submitted to: Corn Dry Milling Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/30/1997
Publication Date: N/A
Technical Abstract: A commercially available CIBA (now Novartis) Bt line expressing high levels of crystal protein in green tissues only was examined for ear insect and mycotoxigenic molds in natural field conditions in Illinois in 1996. At harvest, incidence of insect damage that occurred at milk stage in the Bt hybrid was half that of the nonBt hybrid, and half as many kernels were damaged when insects were present. Less than 1% of the Bt ears had greater than 10 kernels per ear molded with Fusarium, as compared to 9% of the nonBt ears. In studies with a CIBA Bt inbred that expressed the protein throughout the plant, ECBs were added one week after silking, followed by a mixed inoculum of F. proliferatum and A. flavus a week later in Illinois. No ECB damage, negligible mold and 10% BGYF was seen in the Bt inbred in 1995 as compared to 53% ECB damage, 37% mold and 47% BGYF for the nonBt line. In 1996 with a 1/2 1995 Bt level inbred, ECB damage was reduced by 3X and mold incidence on kernels was reduced by four-fold in the Bt vs. non Bt inbred. Studies by Pioneer Hi-Bred in Puerto Rico and Hawaii indicated for four corresponding Bt and nonBt hybrids, average kernel loss was reduced from 20% to 6%, and average ear mold was reduced from 54% to 28%. This trend for lower ear mold levels on Bt hybrids has been evident in several other trials. Under more normal insect pressure, the difference between Bt and non-Bt kernel damage and moldy ears on Bt hybrids is more apparent.