VIEW ARTICLE

Disease Control and Pest Management

Effects of Fall Infection by Gaeumannomyces graminis var. tritici and Triadimenol Seed Treatment on Severity of Take-All in Winter Wheat. W. W. Bockus, Assistant professor, Department of Plant Pathology, Kansas State University, Manhattan 66506; Phytopathology 73:540-543. Accepted for publication 27 October 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-540.

Treatment of winter wheat seed with the systemic fungicide triadimenol at 14.8 and 29.6 ml a.i./45.4 kg of seed reduced take-all under artificially and naturally infested field conditions. Yield losses due to take-all were reduced 60- 75% depending on rate of triadimenol applied. In greenhouse experiments, the treatments protected seedling roots from infection by Gaeumannomyces graminis var. tritici (Ggt) for 4 and 8 wk, respectively. In the field, the lower rate of fungicide delayed infection by Ggt approximately 6 wk during the fall. Conversely, increases in the incidence of infection by Ggt during the winter and spring were virtually the same for plants derived from treated or nontreated seed. In six fields with known take-all levels, the high correlations for incidence of Ggt and percentage of whiteheads obtained when incidence was measured 4 or 8 wk after planting indicated that fall infections by Ggt strongly influenced the amount of take-all yield loss in conducive soils under Kansas conditions. Seed treatment with triadimenol protects wheat plants from Ggt during this critical period resulting in control.