Title: Study the efficacy of Metazosulfuron 33% WG on paddy rice weed control
Author: Bijan Yaghoubi
Abstract: Potted and field experiments were carried out to study the efficacy of metazosulfuron herbicide (Ginga, WG 33%) in weed control and its selectivity on rice at the Rice Research Institute of Iran in 2019 and 2020. In the pot test, the recommended dose of metazosulfuron (250 g/ha) in comparison with the herbicides flucetosulfuron, triafamone + ethoxysulfuron, pyrazosulfuron ethyl + pretilachlor, pretilachlor and thiobencarb in the control of weeds, Bolboschoenus planiculmis, Paspalum distichum, Monochoria vaginalis, Alisma plantago aquatica, Echinochloa oryzoides, and Potamogeton nodosus were investigated. The results showed that metazosulfuron had ≥98% efficiency in controlling all of the above weeds and provided similar or higher efficiency compared to other registered herbicides. In the second experiment, the efficacy of 0, 50, 100, 150 and 200% of the recommended dosage of metazosulfuron in comparison with pretilachlor + bensulfuron methyl, thiobencarb + bensulfuron methyl, triafamone + ethoxysulfuron, bensulfuron methyl, thiobencarb, and hand weeded control in the research field of Rice Research Institute of Iran in Rasht and Amol was investigated. The results showed that the density and biomass of weeds of barnyardgrass and bulrush as well as tiller, biomass, and yield of rice were affected by the location of the experiment, treatment, and the interaction effect of the treatments. Comparison of means showed that weed density in the critical stage of weed control in Guilan was about 10 to 15 times higher than Mazandaran. The efficiency of all herbicide treatments in Mazandaran was similar in most sampling stages and was about 95% or more. Rice tiller and biomass were not significantly different in most of the studied treatments. The efficacy of metazosulfuron in Guilan (90%) was always similar or higher than other herbicides (except 50% of recommended dosage). The economic yield loss of weeds in control treatment compared to hand weeded in Mazandaran and Guilan were 30 and 79%, respectively. Rice yield in Mazandaran was statistically similar in all studied treatments except weedy control. The yield of paddy in Guilan in different dosages of metazosulfuron (except 50% dose) is statistically similar to hand weeded control, pretilachlor + bensulfuron, triafamone + ethoxysulfuron, less than thiobencarb + bensulfuron and more than sole application of bensulfuron or thiobencarb. Increasing the dosages of metazosulfuron up to twice the recommended amount had no adverse effect on paddy and biological yield of rice, which indicates good selectivity of this herbicide or good tolerance of rice to this herbicide. According to the present study and regression models fitted to the trend of biomass changes and density of two important paddy weeds, bulrush and barnyardgrass had much higher tolerance to metazosulfuron than the perennial pizzeria and the dose required for 95% of sorghum control during the critical period of weed control (6). The week after herbicide treatment was about three times that of pizzeria. Therefore, for the control of perennial sedges and barnyardgrass, 100 and 250 g of commercial metazosulfuron per hectare are recommended, respectively. Cultivation was higher than one culture striped stem borer infestation and lower yield.
Keywords: Chemical control, grass, sedge, paddy, sulfonylurea