Effects of quinone outside inhibitor fungicides on Fusarium head blight, deoxynivalenol, and Fusarium graminearum biomass in soft red winter wheat
D. D’ANGELO (1), K. Willyerd (1), A. Cabrera (1), L. Madden (1), P. Paul (1). (1) The Ohio State University, Wooster, OH, U.S.A.
Quinone Outside Inhibitors (QoIs) are effective fungicides against foliar diseases of wheat, but are usually not recommended for Fusarium head blight (FHB) and deoxynivalenol (DON) management. This is largely because they have been shown to increase DON in the grain, but reasons such a response are largely unknown. Field and greenhouse experiments were conducted to determine whether DON response to QoIs varied with active ingredients (AIs) and application timing, and whether it was associated with an increase in grain fungal biomass (FBM). Treatments consisted of two QoIs (azoxystrobin [AZO] and pyraclostrobin [PYR]) and a Demethylation Inhibitor (tebuconazole + prothioconazole) applied at Feekes 8, 10, and 10.5.1, plus an untreated check. All plants were inoculated with a spore suspension of <i>F. graminearum</i> at anthesis. FHB index (IND) was rated three weeks after anthesis, and a sample of grain from each treatment was assayed for DON and FBM. Treatments applied at Feekes 10.5.1 resulted in significantly lower IND than the check. Depending on the AI, Feekes 8 and 10 treatments had comparable or lower IND than the check. In general, mean DON and FBM were highest in QoI treatments applied at Feekes 8 and 10, even though mean IND was relatively low in some of those same treatments. Among the QoI treatments, AZO tended to result in higher DON than the check at all growth stages. For PYR, only the Feekes 8 treatment tended to result in higher DON than the check.
View Presentation |
