Evaluation tank-mixing foramsulfuron with nicosulfuron by the addition of ammonium-sulfate to control of barnyardgrass (Echinochloa crus-galli (L) Beauv) in maize (Zea mays L.)

of the basic strategies in this context. In order to evaluate the effect of foramsulfuron and nicosulfuron combination without and with ammonium sulfate as an adjuvant on barnyardgrass (Echinochloa crus-galli (L) Beauv) control in maize, a study was conducted in three separate experiments, in Ferdowsi University of Mashhad during 2011 2012. The first experiment was conducted separately for each plant of barnyardgrass to determine optimum dose for foramsulfuron and nicosulfuron in greenhouse conditions, based on the dose-response experiments. The second experiment conducted to evaluate the effect of different mixture ratio of two herbicides (75% foramsulfuron 25% nicosulfuron, 50% foramsulfuron 50 nicosulfuron, 25% foramsulfuron 75% nicosulfuron) based on the results of the first experiment. The third experiment included the second experiment treatments plus ammonium sulfate as adjuvant. Results showed that both herbicides without ammonium sulfate and at high doses controlled barnyardgrass. Sulfonylurea herbicides mixture without ammonium sulfate by application of 75% foramsulfuron% nicosulfuron among others, had the most damage to the barnyardgrass and herbicides mixture effect was additive. Combination of sulfonylurea herbicides together by adding ammonium sulfate showed synergistic effects for controlling barnyardgrass, so that its dry matter reduced by application of lower doses of herbicides in comparison with herbicides applied alone. Also combination of these two herbicides alone and by addition of ammonium sulfate to them showed no undesirable effect on maize.