- Presented at the 70th Annual Meeting of the Western Society of Weed Science.
- Research continues to find low-cost, triazine-free weed control options in non-transgenic sweet corn production in W OR. Tolpyralate is a relatively new HPPD herbicide developed by ISK with selectivity in corn and possibly vegetable crops. Crop safety and efficacy of tolpyralate were evaluated in several sweet corn experiments from 2012 to 2016 in Western OR. Tolpyralate applied in 2012 to 6 corn varieties (including shrunken (SH2), sugar enhanced (SE), and sugary (SU) types), at 5 rates (from 0.018 to 0.071 lb ai/A), and with and without chlorpyrifos T-banded at planting, had no effect on corn color or growth. In 2013, tolpyralate was applied again at the same rates to the varieties Coho (SE), Captain (SU), Devotion (SH2 white), and Owatonna (SH2 yellow) at the V4 growth stage and again no differences were noted in phyto after application or crop height at tasseling. In 2014, common purslane control with tolpyralate at 0.026 lb ai/A without atrazine but with MSO and UAN was 88%. In contrast, mesotrione at 0.094 ai/A plus COC and UAN had no effect on common purslane. In 2015, treatments with tolpyralate at 0.026 lb ai/A without atrazine applied to sweet corn (var. Mint, SH2) yielded as much or more than treatments of tembotrione, topramezone, and mesotrione. The most recent trial was placed in a grower’s field in 2016, and weed control with tolpyralate at 0.026 lb ai/A when applied without atrazine was significantly better than tembotrione, topramezone, bicyclopyrone, and mesotrione.