Title: Study the efficacy of Solito (Pretilachlor + Pyrimax, EC 32%) as a new herbicide in paddy field weeds control
Author: Farzin Pouramir
Abstract: In order to evaluate the effectiveness of the new herbicide Solito (Pretilachlor + Pyrimax) in weed control of rice, research was conducted in the Rice Research Institute of Iran, in the laboratory, potted, and field conditions, during 2019 and 2020. In the laboratory, the reaction of barnyard grass to doses of zero, 0.01, 0.1, 1, 10 and 100% of the recommended amount of herbicides Solito (Pretilachlor + Pyrimax, EC 32%, 480 g.ai.ha-1), Rift (Pretilachlor, EC 50%, 875 g.ai.ha-1) and Pyrimax (Pyribenzoxim, EC 5%, 35 g.ai.ha-1) in Petri dish was investigated. The experiment was performed as a factorial experiment in a completely randomized design with three replications. In the greenhouse experiment, the reaction of 2–3-leaf seedlings of barnyard grass, susceptible and resistant sedge to herbicide at doses of zero, 50, 100, 150, and 200% of the recommended amount of Solito herbicide and the recommended doses of the nominee (Bispyribac-sodium, SC 10%, 25 g.ai.ha-1), Clean weed (Bispyribac-sodium, SC 40%, 40 g.ai.ha-1), Pyrimax and Basagran M60 (Bentazone + MCPA, SL 46%, 1150 g.ai.ha-1) herbicide was investigated. The experimental design was completely randomized with three replications. A field experiment was conducted in Gilan and Mazandaran provinces. Field experimental treatments, as well as the method of implementation, were different in the two provinces however, both experiments were performed as randomized complete blocks with 10 treatments and three replications. In Gilan, the treatments were; Basagran M60 + Proton (Pendimethalin, EC 33%, 1238 g.ai.ha-1) (BP), Basagran M60 + Saturn (Thiobencarb, EC 50%, 2750 g.ai.ha-1) (BT), Clean weed + Proton (CP), Clean weed + Saturn (CT), Rift + Londax (Bensulfuron-methyl, DF 60%, 30 g.ai.ha-1) (RL), Saturn + 50% of Solito (Solito-50) , Saturn + 100% of Solito (Solito-100), Saturn + 150% of Solito (Solito-150), Saturn + 200% of solito (Solito-200) and weedy control. The method of planting in Gilan was direct seeding and Rift, Londax, Saturn and Proton herbicides were used as soil-applied. The treatments used in Mazandaran were: Doses of 50, 100, 150, and 200% of Solito, recommended dose of Propanil (Stam F, SC 36%, 3960 g.ai.ha-1), Vejin (Bispyribac-sodium, SC 12.5%, 25 g.ai.ha-1), Nominee, Clean weed, two times of hand weeding and also weedy control. The cultivation method in Mazandaran was transplanting. The results of laboratory experiments showed that Solito herbicide in doses of 0.1% of the recommended amount and above, kills 100% of barnyard grass seedlings. However, the herbicide Rifit at doses of 1% and above controlled all barnyard grass, and the herbicide Pyrimax could not control all seedlings up to the recommended dose of 100%. The results of the pot experiment showed that the recommended and higher doses of Solito controlled sensitive and resistant sedge and barnyard grass, 98%≥, 92%≥ , and 96%≥, respectively. The results of field experiments in Gilan and Mazandaran showed that different doses of Solito herbicide up to twice the recommended amount have no toxic effects on rice. In Gilan, the application of the recommended dose of this herbicide after Saturn led to the efficiency of over 90% in the control of barnyard grass and an efficiency of over 70% in the control of sedge, although the 200% dose of the recommended amount controlled more than 95% of sedge in the field. This amount was higher than other herbicide treatments and shows the difference in the efficiency of different doses of Solito herbicide. Among the different doses of Solito, the dose of 200% had the highest yield of paddy (4620 kg/ha), although in this respect there was no significant difference between the doses of 100 (4386 kg/ha) and 150% (4176 kg/ha). The dose of 200% with the best herbicide treatment (CT treatment with 5493 kg/ha) did not differ significantly in terms of yield. In Mazandaran field experiments, different doses of Solito during different stages of evaluation had 40 to 94% efficiency in the control of barnyard grass and 37 to 90% efficiency on sedge. In Mazandaran, doses of 100, 150, and 200% of Solito along with Nominee and Clean weed with 5316, 5701, 5720, 5326, and 5392 kg/ha, respectively, had the highest paddy yield compared to weedy control (3608 kg/ha), Increased by about 47 to 59 percent. In general, the results of this study showed that use of Solito (Pretilachlor + Pyrimax, EC 32%, 480-720 g.ai.ha-1) in weeds 2- 4 leaves stage, followed by Saturn (Thiobencarb, EC 50%, 2750 g.ai.ha-1) as pre-emergence herbicide, has a very good performance in controlling important rice weeds and can be a good alternative to common foliar herbicides in paddy lands in the north of Iran.
Keywords: Dose-response, Foliar application, barnyard grass, sedge