Effect of Reduced Doses of Foramsulfuron (Equip®) and Different Nitrogen Rates on Weed Control in Corn (Zea mays L.)

To evaluate the effect of reduced doses of foramsulfuron and nitrogen rates on weed biomass in corn field، an experiment was conducted using split plots arrangement based on randomized complete block design with three replications at Research Field of Ferdowsi University of Mashhad، in 2011. Main plots were weed control levels comprising three reduced herbicide doses of foramsulfuron (50، 75، and 100% of recommended dose (2 lit. ha-1) 225، 337. 5 and 450 g ai. ha-1)، control treatment (no control of weed)، and completely weeded treatment and sub plots were nitrogen application rates (0، 115، 230، 345 kg ha-1). Results indicated that the highest amount of weed biomass refers to the highest level of nitrogen application (345kg. ha-1). Without nitrogen application، weed control percentage in 50 and 75% of recommended herbicide dose equal to application of 100% of recommended herbicide dose with 345 kg. ha-1 of nitrogen. When 230 kg. ha-1 nitrogen used، 75% of recommended herbicide dose needed to effectively control the weeds. Indeed، we can reduce foramsulfuron dose in corn with optimization of nitrogen application.