Weed control and the response of yield and yield components to Sulfonyl Urea Herbisides in Corn (Zea mays L.)

To investigate the effect of post emergence sulfonyl urea herbicides on weed population of maize, an experiment was conducted in a randomized block design with 8 treatments and 3 replications in Arak region, Iran, in 2012. The treatments were including rimsolfuron + once hand weeding, nicosolfuron + once hand weeding, nicosolfuron + rimsolfuron + once hand weeding, twice hand weeding and weedy check. The most important weeds in this experiment were common lambsquarters (Chenopodium album), field bindweed (Convolvulus arvensis) and bermudagrass (Cynodon ductylon). Results showed that average weed dry matter for the treatment of weedy check was 40.18 g.m-2 and nicosolfuron + rimsolfuron + once hand weeding was the most effective treatment, because it had the lowest weed dry matter with 88.96% reduction in comparison with weedy check. The treatment of 40 g.ha-1 rimsolfuron had the lowest affectivity by controlling only 58.57% of the weeds. Even though none of the treated herbicide showed crop injury, but nicosolfuron + rimsolfuron +once hand weeding with 4514 kg.ha-1 and the weedy check with 1209.25 kg.ha-1 grain yields produced the highest and the lowest amount of yields, respectively. Thereby, yield reduction of weeds in corn cost 27% in comparison with weed free treatments.