Reduction of deoxynivalenol (DON) contamination by improved fungicide use in wheat. Part 1. Dependence on epidemic severity and resistance level in small plot tests with artificial inoculation

Abstract

Fungicide control of FHB of wheat generally has poor efficacy and mostly susceptible cultivars are grown. Therefore, the toxin risk is high. We developed a more efficient control by combining an improved resistance with a more precise evaluation of fungicides. Small plot tests (5m2 ), along with artificial inoculation were used. Visual head symptoms (FHB), kernel infection (FDK) and DON content were evaluated (2009– 2012). Fungicide treatments were preventive at the full flowering stage with four isolates of F. graminearum and F. culmorum. The best fungicide decreased DON by 75% (variation between the four years: 60–93%), the least effective gave a 44% reduction (variation: 30– 59%). From medium to very high epidemic severity, smaller differences were observed in reduction (64– 68%), but the best reduction was seen at medium disease pressure. The medium susceptible GK Békés reduced DON from 5.86 mg/kg to 2.36–3.46 mg/kg for the fungicides used. The medium resistant GK-Fény varied for fungicides between 0.86–2.58 mg/kg, UTC: 3.90 mg/kg), the most susceptible GK-Kalász gave 1.07–5.32 mg/kg for fungicides (UTC: 10.01 mg/kg). The cumulative effect of fungicide/variety had a 91% reduction across years. The high reduction is not enough the DON content should also be lower than the 1.25 mg/ kg limit. Correlations between traits for fungicides were between r = 0.98–0.99 (p < 0.001), and DON gave the most reliable results. Beside fungicide efficacy, varietal resistance is an important component of effective control of FHB in the field. Susceptible cultivars should be withdrawn from production, but cultivars such as GK Fény can be grown without any serious food safety risk with a single preventive treatment. The fieldwork will be outlined in Part 2.

Keywords: Fusarium head blight, wheat, fungicide, cultivar resistance, deoxynivalenol, epidemic severity.

Abstract published in European Journal of Plant Pathology. DOI 10.1007/s10658-017-1350-2.