Preemergence (PRE) herbicides are often banded over the entire top of raised beds for broadleaf and grass control in plasticulture vegetable production systems. However, broadleaf and grass weeds only emerge from the planting holes and tears in the plastic mulch. Banded application results in herbicides applied where no holes occur and therefore where they are not needed. Our objective is to identify herbicides that do not harm transplanted crops when directed at transplant holes post-transplant (POST) with the aim to reduce off-target applications. Therefore, we evaluated tomato and pepper tolerance to PRE herbicides applied to transplant holes 2 weeks after transplant and the subsequent effects on crop tolerance and weed density. Halosulfuron, S-metolachlor, metribuzin, and pendimethalin did not injure tomato transplants, reduce height, or reduce yield. Fomesafen caused some tomato injury (7%) but had no effect on other measured parameters in Trial I. All PRE herbicides injured peppers (≥19%) though no effect on yield was observed. Overall, halosulfuron, S-metolachlor, metribuzin, and pendimethalin can be safely applied to tomato transplant holes two weeks after transplant with no significant crop injury nor effects on final yield, but none of the evaluated herbicides are safe for use in pepper.

Postemergence herbicides to control weeds in the space between raised, plastic-covered beds in plasticulture production systems are typically banded and herbicides are applied to weeds as well as where weeds do not occur. To reduce the incidence of off-targeted applications, the University of Florida developed smart spray technology for row middles in plasticulture systems. The technology detects weed categories and applies herbicides only where they occur. Field experiments were conducted at the Gulf Coast Research and Education Center in Balm, FL, in the Fall 2021 and Spring 2022. The objective was to evaluate the efficacy of postemergence applications of diquat and glyphosate in row middles in jalapeno pepper fields when banded or applied with smart spray technology. The overall precision of the weed detection model was 0.92 and 0.89 for fall and spring respectively. The actuation precision achieved was 0.86 and 1 for fall and spring respectively. No significant differences were observed between banded and targeted applications either with glyphosate or diquat in terms of broadleaf, grass, and nutsedge weed density. No significant pepper damage was observed with either herbicides or application techniques. The smart spray technology reduced herbicide application volume by 26% and 42% for fall and spring respectively, with no reduction in weed control or pepper yield compared to a banded application. Overall, the smart spray technology reduced the herbicide volume applied with no reductions in weed control and no significant effects on crop yield.