Evaluation of Preemergence Herbicides for Purple Nutsedge (Cyperus rotundus) Control in Tomato

Purple nutsedge is a problematic weed in plasticulture vegetable production due to its ability to penetrate the plastic mulch. Experiments were conducted in the fall 2013 and spring 2014 at the Gulf Coast Research and Education Center in Balm, FL, to evaluate a range of PRE herbicides for 'Charger' and 'Florida 47' tomato cultivars tolerance and herbicide efficacy on nutsedge. Fall-applied herbicides did not stunt nor damage either tomato cultivar. Tank mixes applied in the spring that contained EPTC as well as the fomesafen + S-metolachlor + napropamide tended to stunt Charger. The EPTC + fomesafen, the EPTC + fomesafen + S-metolachlor, and the fomesafen + S-metolachlor + napropamide stunted Florida 47. Crop damage in the spring was consistently higher where tank mixes were applied that contained EPTC. In the fall of 2013, S-metolachlor and fomesafen + S-metolachlor reduced nutsedge density by 84 to 90% compared to the nontreated control; in the fall of 2014, napropamide + S-metolachlor reduced nutsedge density by 88% compared to the nontreated control. In the spring of 2013 halosulfuron and a tank mix of EPTC + S-metolachlor reduced nutsedge density by 25% compared to the nontreated control. None of the herbicide treatments had a consistent effect on yield, although Florida 47 yields tended to be lower where tank mixes containing EPTC were applied.