Effects of fungicide treatments on scald (Rhynchosporium secalis (Oud.) J. Davis) infection and yield of barley in Western Australia.

Abstract

Application of fungicides (benomyl and triadimefon) to early sown barley (cv. Clipper) in 1979 and 1980 reduced the incidence of scald and greatly increased grain yield. Fungicide applied to the young crop 4-6 weeks after sowing was ineffective but applications at 10 and 12 weeks indicated that economic returns from the use of fungicides could be obtained. In subsequent experiments on cv. Stirling, an application at the 6-7 leaf stage gave the most consistent grain yield increase, ranging from 15 to 48% (225-937 kg/ha). Triadimefon was found to be more effective in reducing scald than was benomyl but gave no greater yield increases. Controlling scald by multiple application of fungicide increased harvest dry weight, number of heads/m2, number of grains/head and 100-seed weight, and prevented lodging in at least two trials. A single application, though it may be economic, offers only partial control of scald, and resistant cultivars are therefore necessary to achieve full yield potential in scald-prone areas.