%D 2012 %0 In-Process %T Effect of growth stage on the efficacy of postemergence herbicides on four weed species of direct-seeded rice . %J ScientificWorldJournal %V 2012 %P 123071 %A Chauhan BS %A Abugho SB %M pub22619576 %X The efficacy of bispyribac-sodium , fenoxaprop + ethoxysulfuron , and penoxsulam + cyhalofop was evaluated against barnyardgrass , Chinese sprangletop , junglerice , and southern crabgrass when applied at four- , six- , and eight-leaf stages . When applied at the four-leaf stage , bispyribac-sodium provided greater than 97% control of barnyardgrass , junglerice , and southern crabgrass ; however , it was slightly weak ( 74% control ) on Chinese sprangletop . Irrespective of the weed species , fenoxaprop + ethoxysulfuron provided greater than 97% control when applied at the four-leaf stage . At the same leaf stage , penoxsulam + cyhalofop controlled 89 to 100% barnyardgrass , Chinese sprangletop , and junglerice and only 54% of southern crabgrass . The efficacy of herbicides was reduced when applied at the eight-leaf stage of the weeds ; however , at this stage , fenoxaprop + ethoxysulfuron was effective in controlling 99% of Chinese sprangletop . The results demonstrate the importance of early herbicide application in controlling the weeds . The study identified that at the six-leaf stage of the weeds , fenoxaprop + ethoxysulfuron can effectively control Chinese sprangletop and southern crabgrass , penoxsulam + cyhalofop can effectively control Chinese sprangletop , and bispyribac-sodium can effectively control junglerice .