Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/5/1999
Publication Date: N/A
Technical Abstract: Fusarium head blight (FHB), also known as wheat head scab, causes extensive damage to wheat throughout the world. In North America, the primary causal agent of FHB is Gibberella zeae (anamorph=Fusarium graminearum). Biological control of FHB is promising since wheat cultivars with a high degree of resistance are not currently available, and chemical control measures can have residue and cost concerns. In this work, microbial antagonists, previously discovered in our research, were tested for their ability to reduce the severity of scab of wheat when coinoculated with any of three different isolates of G. zeae. Additionally, the effect of applying antagonist inoculum to wheat heads at various times before or after the arrival of pathogen inoculum was studied. Antagonists were effective in controlling all isolates of G. zeae tested. In assays against G. zeae isolate Z3639, six antagonists reduced disease as indicated by increased 100 kernel weights of microbially treated wheat heads (P<0.05). Three antagonists decreased disease severity. Bacterial strains AS 43.3, AS 43.4, and yeast strain OH 182.9 reduced disease severity by >77%, 93%, and 56%, respectively. Five antagonists increased 100 kernel weight of plants inoculated with G. zeae isolate DOAM. All antagonists except one increased 100 kernel weights, and five of seven antagonists reduced disease severity (P<0.05) when tested against G. zeae isolate Fg-9-96. In spray inoculation experiments, all antagonists significantly reduced disease severity, regardless of the sequence, timing, and concentration of inoculum application (P<0.05), though 100 kernel weights did not always increase when antagonists were applied 4 h after inoculum of G. zeae. Biological control shows great promise as part of an IPM program for managing FHB.