Factors Affecting Control of Take-All of Spring Wheat by Seed Treatment with Sterol Biosynthesis-Inhibiting Fungicides. Celsa Garcia, Department of Plant Pathology, Montana State University, Bozeman 59717. D. E. Mathre, Department of Plant Pathology, Montana State University, Bozeman 59717. Plant Dis. 71:743-746. Accepted for publication 2 April 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0743.

Eight sterol biosynthesis-inhibiting fungicides, nuarimol, imazalil, prochloraz, triadimenol, bitertanol, propiconazol, etaconazole, and diniconazole, were tested in vitro against Gaeumannomyces graminis var. tritici (G. g. var. tritici). All were strongly inhibitory at 10 µM, and imazalil and prochloraz were effective at 0.01 µM. Field tests of five of these compounds applied as seed treatments on Pondera spring wheat when inoculum was placed with the seed indicated a difference in efficacy in reducing symptom severity and increasing grain yield. Triadimenol and prochloraz were the most effective at rates above 0.3 g a.i./kg. Studies in the field and greenhouse on inoculum location vs. efficacy of triadimenol seed treatment showed that this compound is most effective in reducing infection when the inoculum is below the seed.