Improving cole crop safety and weed control response with chloroacetamide and oxyfluorfen herbicide combinations

Abstract In 2022, trials were carried out in New Jersey and New York to assess the efficacy of weed management and the response of two cole crops to various herbicide combinations and rates. The experiments involved the application of S -metolachlor and microencapsulated (ME) acetochlor either alone or combined with oxyfluorfen. Different application timings of oxyfluorfen were tested in greenhouse and field studies. Results from the greenhouse trials show that substituting S –metolachlor with ME acetochlor in over-the-top applied mixes with oxyfluorfen caused 15% to 22% less crop injury and increased seedling biomass by 33%. In field studies, nontreated plots exhibited significant weed growth, reaching up to 71% coverage 28 d after transplanting (DATr), whereas herbicide-treated plots exhibited weed cover at or below 10% by 28 DATr. Mixtures or sequential applications of oxyfluorfen and chloroacetamides achieved excellent control (≥99%) of the weed species complex compared to single applications of oxyfluorfen or chloroacetamides. However, applying both oxyfluorfen and a chloroacetamide posttransplanting, either as a tank mixture or in sequence, resulted in ≥19% injury. Despite the effective weed control achieved with herbicide treatments, mixing herbicides posttransplanting reduced relative commercial yield by 46% to 94% compared to oxyfluorfen applied alone or followed by chloroacetamides. The findings from these experiments will inform regional crop safety guidelines and support potential modifications to oxyfluorfen labels regarding sequential applications with chloroacetamides.