Assessing the Efficacy and Safety of Preemergence Herbicides Applied Alone or in Combination with Superabsorbent Polymer, Soil Binding Agent, and Compost in Tomato (Solanum lycopersicum L.) Plasticulture Production

Preemergence herbicide application under plastic mulch is an effective way to manage weeds in tomato ( Solanum lycopersicum L.) production. Nonetheless, applying herbicides beneath plastic mulch in raised beds is associated with the inherent risk of crop phytotoxicity. This highlights the need to explore crop-safe methods for herbicide application in plastic mulch beds. The research aimed to evaluate the effectiveness of preemergence herbicides S -metolachlor and flumioxazin at the labeled rate (X) and reduced rate (0.5X, half of the labeled rate) either alone or in combination with a super absorbent polymer, soil binding agent, or compost to determine their ability to control weeds effectively in plastic mulched beds without causing negative effects on tomato crops. Two different experimental trials, trial 1 (Mar–Jun 2021) and trial 2 (Oct 2021–Jan 2022) were performed in the fields in Immokalee, FL, USA. The experimental design was a randomized complete block with five replications. S -metolachlor (X) plus soil binding agent and S -metolachlor (X) plus compost mix suppressed purple nutsedge density by >85% and approximately 68%, respectively, during trial II. Similarly, S -metolachlor (X), S -metolachlor (0.5X) plus super absorbent polymer, S -metolachlor (X) plus super absorbent polymer, S -metolachlor (X) plus soil binding agent, and S -metolachlor (X) plus compost caused reductions in purple nutsedge biomass by >50% compared with that of the nontreated control during trial II. Treatments did not significantly impact tomato crop vigor and chlorophyll contents during trials I and II. Moreover, treatments did not significantly affect tomato crop biomass and yield during both trials. In summary, using preemergence S -metolachlor (X) combined with soil binding agent or compost could be a viable option for suppressing purple nutsedge in plastic mulched tomato beds.