Integrated Use of Tebuconazole and Fusarium Head Blight–Resistant Barley Genotypes

Abstract

All malting barley (Hordeum vulgare L.) cultivars adapted for production in the upper midwestern USA are susceptible to Fusarium head blight (FHB), incited primarily by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein)]. Quality of FHB‐infected barley is reduced due to a mycotoxin called deoxynivalenol (DON) that is produced by the pathogen. Malting barley buyers severely discount or refuse to purchase barley with DON concentrations >0.5 mg kg−1. Individually, use of genetic resistance or fungicides has not successfully reduced DON concentrations to acceptable limits. The objective of this research was to determine if the integrated use of the fungicide tebuconazole (α‐[2‐(4‐chlorophenyl) ethyl]‐α‐(1,1‐dimethylethyl)‐1H‐1,2,4‐triazole‐1‐ethanol) and barley genotypes with partial FHB resistance could reduce DON to acceptable concentrations. Field research, using two rates of tebuconazole (0 and 118 mL a.i. ha−1) and 13 barley genotypes with varying levels of FHB resistance, was conducted in North Dakota from 2000 to 2002. No supplemental inoculum or irrigation was used in any of the environments. Data for FHB severity, DON concentration, foliar disease severity, and kernel color were collected and analyzed. Deoxynivalenol was detected in all environments at concentrations >0.5 mg kg−1. Overall, the response of the FHB‐resistant and moderately resistant genotypes to tebuconazole was inconsistent for FHB severity and DON accumulation. Furthermore, tebuconazole applied to FHB‐resistant or moderately resistant genotype did not consistently result in DON concentration of ≤0.5 mg kg−1 in any of the environments. Thus, the integrated use of FHB‐resistant or moderately resistant genotypes and tebuconazole will not reduce DON.