Efficacies of fungicides for control of stem rust of wheat

Abstract

The potential commercial use of fungicides for control of stem rust (Puccinia graminis) of wheat was assessed in field experiments at two sites. Foliar sprays containing either triadimefon or propiconazole were the most effective in reducing disease severity. Chlorothalonil was effective only when applied at an early stage of disease development and where stem rust was not severe in control plots. Dichlone, fenarimol, nuarimol and 2-(thiocyanomethylthio) benzothiazole did not significantly reduce stem rust severity at either site. Even though treatments were applied at an early stage ofthe disease epidemic at one site, disease control on heads, peduncles and sheaths did not exceed 63,36 and 19%, respectively, with any treatment. Increases in grain yield and density, of up to 0.27 t/ha and 8.6 kg/hectolitre, respectively, were barely sufficient to cover the cost of treatment.