Spray carrier water cations can affect most postemergence herbicides activity on weeds. Foramsulfuron is newly registered for corn weed in Iran so it is needed to determine the effect of water quality on its performance. Greenhouse and field experiments were carried out in the experimental greenhouse and field of University of Tehran during 2010 and 2011. The effect of different adjuvants on offsetting adverse effects of cations of spray carrier water on foramsulfuron performance in controlling Chenopodium album L. (common lambsquarters) and Sorghum halepense (L.) Pers. (Johnsongrass) in greenhouse and whole weed species in corn field were evaluated. Treatments were various doses of herbicides in companying with adjuvants urea-ammonium nitrate (UAN), ammonium sulfate (AMS) and mutilated seed oil (MSO) which were used with water fortified with calcium and Fe ions. Experimental design was a completely randomized design with four replications. Treatments were a factorial combination of foramsulfuron rates, adjuvants and spray carrier water. The results of this study revealed that Fe was more efficient than Ca in reducing foramsulfuron toxicity to weed species. All used adjuvants increased herbicide efficacy regardless of spray solution salts. Adding MSO to nitrogen additives further enhanced weed control. The best adjuvant for control of common lambsquarters was UAN while for johnsongrass adding AMS was the best adjuvant. In general AMS was most effective adjuvant in enhancing foramsulfuron performance.
