Herbicide and Erratic Emergence Peanut Notes No. 111 2020

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Paraquat and Erratic Emergence

Peanut emergence within a significant number of fields across North Carolina has varied widely. This is mainly due to replanting areas of fields. This type of situation almost always creates challenges with weed control. Recently I was asked how to control 4 to 8 inch tall Palmer amaranth in a field with peanuts that had been up for 3 to 4 weeks versus peanuts that had not emerged. While paraquat could still be applied in this field, paraquat at the rates we use after peanuts emerge is unlikely to kill Palmer amaranth this large. One quart/acre or more as a burndown would kill these weeds but generally not 8 or 11 oz/acre. I recommended that the grower shift to Cobra or Ultra Blazer (assuming ALS resistance in this weed in all fields). The residual from these herbicides in negligible and there is a greater chance that these herbicides will kill Palmer amaranth this large than paraquat. Paraquat followed by Cobra or Ultra Blazer would be a possibility, especially if more weeds emerge. But the follow up would need to come relatively soon, and if the sequence is made in a short period of time, that could cause more injury on the emerged peanuts.