Pre- and Postemergence Herbicides for Row Middle Weed Control in Vegetable Plasticulture Production Systems

In plasticulture vegetable production systems, broadleaf weeds and grasses emerge in the crop planting holes and between the raised beds. Weeds emerging on the bare ground between the raised beds can be the most difficult to control. Experiments were conducted in the spring and fall of 2014 at the Gulf Coast Research and Education Center in Balm, FL, to evaluate a range of herbicides for use in row middles in vegetable crops. Weed counts and control ratings did not differ over time and as a result are averaged across 2, 4, and 8 wk after treatment. In the absence of PRE herbicides, carfentrazone did not differ from the nontreated control, whereas paraquat reduced total weed density by 67 and 61% in the spring and fall, respectively. In the fall, carfentrazone tank-mixed with flumioxazin, S-metolachlor + flumioxazin, or paraquat tank-mixed with flumioxazin, S-metolachlor, metribuzin, or S-metolachlor + flumioxazin had 81 to 90% fewer broadleaf weeds than the nontreated control. Total weed density was 70 to 90% lower than the nontreated control when carfentrazone was tank-mixed with flumioxazin or S-metolachlor+flumioxazin or paraquat was tankmixed with flumioxazin, S-metolachlor, oxyfluorfen, metribuzin or S-metolachlor + flumioxazin. Similar trends occurred in the spring. A tank mix of a soil residual herbicide and POST burn-down herbicides tended to have a greater reduction in weed numbers compared to the POST treatment alone. The most consistent row middle tank-mixes were paraquat tank-mixed with flumioxazin, S-metolachlor + flumioxazin, or S-metolachlor + oxyfluorfen.