Control of take-all in soft white spring wheat with seed and soil treatments

Abstract

The root disease take-all, caused by the fungus Gaeumannomyces graminis var. tritici, is a serious problem in irrigated fields of soft white spring wheat (Triticum aestivum) in southern Alberta. A 2-year field study examined the efficacy of ammonium sulfate or manganese sulfate alone and in combination with the seed treatment fungicide triadimenol for take-all control in soft white spring wheat. When take-all was severe early in the growing season, triadimenol alone or in combination with either ammonium sulfate or manganese sulfate usually reduced disease severity at anthesis and the mid-dough stage and increased yield relative to the take-all-inoculated check treatment. However, combining either ammonium sulfate or manganese sulfate with triadimenol did not further enhance the efficacy of the fungicide in reducing take-all severity or improving yield. Separate application of manganese sulfate did not reduce take-all severity or the percentage of whiteheads in comparison to the inoculated check treatment, while ammonium sulfate had an inconsistent effect on these factors. Reductions in take-all severity were directly associated with lower percentages of whiteheads. A concurrent field study examined the effect of broadcasting copper sulfate and then incorporating it into the soil to reduce take-all severity in wheat. The application of copper sulfate did not improve take-all control or increase yield. Both studies were conducted at sites where available manganese and copper were sufficient for normal wheat growth.