Abstract

Barnyard grass (Echinochloa crus-galli) is an annual plant from grass family, which is one of the most problematic weed in tomato production. Herbicide programs are the first highly effective practice for weed control in tomato and have been used in Shahriar from long ago. Field trials were performed over the fall of 2016 and spring of 2017 at the experimental area of the state farm Safadasht, Shahriar region, Iran to survey postemergence and pre-emergence herbicide program to control barnyard grass in tomato production. Pre-emergence herbicide treatment metribuzin and S-metolachlor were not effective when applied alone, and did not reduce barnyard grass plants compared to the weedy control. Post-emergence transplanting application of halosulfuron did not significantly affect barnyard grass plants at 8 weeks after treatment (WAT) in the fall of 2016, but treatment favorably reduced the density of barnyard grass at 12 WAT in both seasons. Barnyard grass control was greater by preemergence transplanting application of metribuzin or S-metolachlor plus postemergence halosulfuron, and barnyard grass numbers were eventually diminished in both seasons. Experimental treatments did not negatively affect tomato height and yields. Multiple herbicide programs could prove effective in higher barnyard grass control compared to the lone application of pre and post herbicides. The herbicides were selected due to routine use by tomato producers in the area. Using herbicidis from the different herbicide families with different modes of action could facilitate effective management of herbicide-resistant barnyard grass in tomato fields.