Soil-Applied Glyphosate and Peanuts (by Dr. Eric Prostko)
I received a few questions recently about the use of glyphosate prior to planting or shortly after planting peanuts. Many of you have remembered (surprisingly!) what Dr. Culpepper has said about the potential residual effects of higher rates of glyphosate on crops such as transplanted squash, broccoli, and collards. Despite what most of us learned in school many years ago, glyphosate does have soil residual properties but it all depends upon the crop and the application rate. Fortunately, peanut is not a crop that is overly sensitive to glyphosate residues. In 2020, I conducted a field study to prove this point. In this study, I applied Roundup PowerMax II 5.5SL at rates ranging from 32 oz/A to 160 oz/A. Applications were made preplant (6 DBP) or preemergence (1 DAP). Results indicated that glyphosate had no effect on peanut density, height, width, or yield. I do not think that a grower should ever use a 160 oz/A rate (5X) but it does prove a point.
