Effect of Doses, Application Dates, Adjuvants and Zinc Sulfate on Bromoxynil + Terbuthylazine + NicosulfuronWeed Control Efficacy and Maize Grain Yield in Mid-West Poland

It is possible to reduce herbicide doses while maintaining their high efficacy, provided they are applied with appropriately selected adjuvants and zinc sulphate in a split-dose system. The effect of multicomponent adjuvants and zinc sulphate on the efficacy of bromoxynil + terbuthylazine + nicosulfuron, applied once at full (144 + 400 + 40 mL ha−1) and in a split-dose system (herbicides applied twice, each time after new weed germination) at reduced doses (54 + 150 + 14 mL ha−1, on herbicide efficacy and grain yield was evaluated. At full dose, bromoxynil, terbuthylazine, and nicosulfuron greatly controlled lambsquarters (92–100%). Barnyard grass was controlled by 94–100%, at reduced 67–93%, with adjuvants in a split-dose system, as efficacy increased to 94–100%, and with zinc it increased to 88–91%. The efficacy of herbicides containing zinc sulphate and surfactant was 80–96%, with that of other adjuvants 97–99%. Regardless of the dose and application system, herbicide application increased grain yield by 11.4–13.9 t ha−1 compared to 4.8–5.0 from untreated check. The grain yield from split-dose treatments was comparable to that from plots with the recommended dose. The enhanced herbicide efficacy with adjuvants applied twice, despite higher treatment expenses, led to the development of maize plants and enhanced yields. This may ultimately translate into improved production profitability.