Control of net form of net blotch in barley from seed- and foliar-applied fungicides

Abstract

Net form of net blotch (NFNB), caused by Pyrenophora teres f. teres, is a major foliar disease of barley (Hordeum vulgare L.) worldwide that can cause grain yield and quality loss in susceptible varieties. Seed- and foliar-applied fungicides were evaluated in six field experiments infected with NFNB during 5 years, for suppression of NFNB severity and protection of grain yield and quality. Suppression of NFNB severity varied between treatments and experiments. Grain yield and quality improvements were recorded in two experiments. Foliar fungicide applications at stem elongation (Zadoks growth stage Z31) and flag leaf emergence (Z39) or ear emergence (Z55) significantly reduced NFNB severity, increased grain yield by up to 23%, and improved grain-quality measurements of retention, screenings and weight. The seed-applied fungicide fluxapyroxad provided significant reductions in NFNB severity, improvements in grain yield of up to 20%, and improved grain quality. Where NFNB was severe, none of the seed or foliar fungicide application strategies provided complete control of NFNB, indicating that more than two applications were necessary when conditions were favourable for disease development in susceptible varieties.