Effects of Chemical Weed Control on Forage Yield of Sorghum (Sorghum bicolor L.)

This study was performed to evaluate the efficacy of some previous or recently registered herbicides for chemical weed control on forage sorghum in Mashhad (Iran) during 2010. The experiment was conducted in RCBD with four replications. Treatments were consisted of Mesotrion+S-Metolacholor+Terbuthlazine (Lumax 3 and 4 l ha-1 post and pre-emergence), Cinosulfuron (Setoff 250 and 375 g ha-1, pre-emergence), Oxadiagyl (Topstar 3 and 4 l ha-1, pre-emergence), Trifluralin (Treflan 1 l ha-1), Trifluralin+Atrazin (2 l ha-1+1.5 Kg ha-1), 2,4-D+Banvel+Atrazine (Dialant 1 l ha-1+Atrazine 1kg ha-1), along with weed free and weed infested controls. The results showed that Lumax, Treflan, Treflan+Atrazine and Atrazine+Dialan with 85-95 percent reduction were the most successful in weed suppression while Setoff and Topstar with35% reduction were relatively unsuccessful. Also, the mention treatments were the most efficient to saving forage yield of sorghum while it was decreased in post emergence application of Setoff 375 gr ha-1 and Lumax 4 l ha-1. Application of Lumax caused a temporary injury symptoms early season in sorghum.The most important weeds were Amaranthus retroflexus, Chenopodium album, Portulaca oleracea, Convolvulus arvensis and Solanum nigrum.