VIEW ARTICLE

Disease Control and Pest Management

Effect of Triadimenol Seed Treatment on Powdery Mildew Epidemics on Winter Wheat. J. A. Frank, Research plant pathologist, ARS, USDA, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; J. E. Ayers, professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 76:254-257. Accepted for publication 17 September 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/Phyto-76-254.

Triadimenol seed treatment reduced powdery mildew disease severity on the winter wheat cultivar Hart in Pennsylvania in field experiments conducted in 1981-1983. Powdery mildew severity was assessed in the spring at four growth stages (GS-7, 9, 10.1, and 10.53, Feekes scale). In each year, and at all assessment periods, triadimenol generally reduced disease severity compared to the untreated controls. However, the yield of plots planted with triadimenol-treated seeds was increased only in 1982 and 1983. The area under the disease progress curve (AUDPC) provided a better estimation of the powdery mildew epidemic than the actual disease severity values or the apparent infection rates. Based on the AUDPC, the triadimenol seed treatment reduced disease severity in all 3 yr compared to untreated controls or seed treatments with either phenylmercury ammonium acetate or a carboxin-thiram combination. Triadimenol was the only seed treatment that contributed to an increase in yield.