Investigating the efficacy of bispyribac sodium SC42% herbicide in rice (Oryza sativa L.) weeds control

To evaluate the efficacy of bispyribac sodium SC42% herbicide (Rissin) on rice weeds control in transplanting method and comparing it with some registered herbicides, an experiment was carried out in two regions, Guilan (Rasht) and Mazandaran (Sari), Iran, in 2019. Treatments consisted as bispyribac sodium SC42% at four doses (50, 54, 58 and 62 ml.ha-1), bispyribac sodium OF10% at 250 ml.ha-1, bispyribac sodium SC40% at 65 ml.ha-1, oxadiargyl EC30% at 3.5 L.ha-1, triafamon + ethoxysulfuron WG30% at 150 g.ha-1, pertilachlor EC50% at 2  L.ha-1, together with two check treatments (weed free and unweeded treatment). The experiment was performed in randomized complete block design with three replications. The results showed that Rissin had good efficacy on weed control and did not cause rice damage even at the highest used dose. The efficacy of Rissin for weed control at three doses of 54, 58 and 62 ml.ha-1 was 85-91% for barnyardgrass (Echinochloa crus galli L.), 66-90% for nutsedges (Cyperus difformis L.) and 95-97% for crowngrass (Paspalum distichum L.) in Sari and 60-93% for barnyardgrass, 60-100% for nutsedges and 30-77% for crowngrass in Rasht. Weed biomass in the experimental field in Sari was lower than in Rasht, which explains the reason of the different control results. Rissin at the three higher doses had similar efficacy to commercial doses of the registered herbicides for weed control and in term of rice yield components (such as tiller and panicle number, biological yield and grain yield), the best result was obtained at 62 ml.ha-1 of Ressin and was similar to weed free treatment.