Impacts of herbicides and potassium fertilizer or seed treatments and seaweed extract on chickpea health in Saskatchewan

An emerging health issue, with symptoms including leaflet edge bleaching, apical or upper branch chlorosis or necrosis, wilting and plant death, has been seen in chickpea in Saskatchewan. Pre-emergence Group 14 herbicides and/or post-emergence metribuzin are both suspected contributors, whose impacts may be additive. Field trials in 2022 and 2023 near Swift Current and Hodgeville, Saskatchewan, sought to test the above theory and the hypothesis that potassium chloride (KCl) fertility could reduce symptoms. Separate experiments at the same sites and years aimed to test the hypothesis that synthetic or natural product seed treatments, or seaweed extracts, would reduce this health issue, potentially synergistically. However, symptoms consistent with the chickpea emerging health issue – leaflet or upper plant discoloration, wilting or death – were not observed, suggesting that sulfentrazone and metribuzin herbicides are insufficient to induce this issue. However, the impacts of the treatments in both experiments on emergence, ascochyta blight, weed control and yield were evaluated. Metribuzin improved weed control only in combination with KCl and increased ascochyta blight. Sulfentrazone controlled weeds better than an alternative, ethalfluralin, only in Swift Current in 2022. KCl, as a main effect, did not alter any parameter measured. Synthetic seed treatment increased stand density, weed control and yield, but also increased Ascochyta blight. Saponin seed treatment increased stand density in one site-year. Seaweed extract had no impacts. While this study does not pinpoint cause(s) of the chickpea emerging health issue, it provides valuable insights into the impacts of management options for chickpea growers.