|Munkvold, Gary - IOWA STATE UNIVERSITY|
|Shoewrs, William - RETIRED|
|Rice, Marlin - IOWA STATE UNIVERSITY|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 1996
Publication Date: N/A
Technical Abstract: Infection of maize kernels by toxigenic Gibberella species is often associated with insect damage. This research investigates whether maize plants transformed with a gene encoding for a Bacillus thuringiensis (Bt) toxin are less susceptible to fungal contamination compared with non transformed maize plants. In 1994 and 1995, Bt maize plants and near isogenic non-Bt maize plants were established in field plots. Three-way factorial RCB design was used with the following treatments: maize variety, Bt and non-Bt; insecticide applications, twice and none; ECB infestations, manual and natural. Plants were evaluated for ECB damage to leaf and kernel tissue, Fusarium and Gibberella ear rot symptoms, and kernel infection by G. fujikuroi and G. zeae. In both years, Bt maize plants had significantly lower Fusarium ear rot symptoms than non-Bt maize plants. Mean symptomatic kernels per ear were reduced from 11.7 to 0.45 (1994) and from 7.2 to 1.5 (1995) in Bt vs. non-Bt plants. Kernel infection by G. fujikuroi was reduced from 64% to 37% (1994) and from 77% to 45% (1995). Disease severity and kernel infection were positively correlated with kernel damage by ECB. Insecticidal treatments reduced G. fujikuroi symptoms and infection. G. zeae symptoms and kernel infection were not reduced in transgenic genotypes or by insecticides. This research shows that Bt maize reduces insect damage and simultaneously ear rot symptoms, thus reducing mycotoxin in maize making it a safer product for consumers.