2 results
Herbicides for monochoria (Monochoria vaginalis) control in transplanted rice
- Zahra Hazrati, Bijan Yaghoubi, Pershang Hosseini, Bhagirath Singh Chauhan
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- Journal:
- Weed Technology / Volume 37 / Issue 6 / December 2023
- Published online by Cambridge University Press:
- 04 September 2023, pp. 598-605
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In Iran, monochoria is a noxious weed in fields of transplanted rice. Two field experiments were conducted to assess the efficacy of soil-applied and foliar-applied herbicides to control monochoria in transplanted rice. Prepackaged herbicides (triafamone plus ethoxysulfuron applied at 40 g ai ha−1, pyrazosulfuron-ethyl plus pretilachlor applied at 382.5 g ai ha−1, and pendimethalin plus clomazone applied at 1,200 g ai ha−1) reduced monochoria biomass by 100%, 100%, and 14%, respectively; and a single application of flucetosulfuron at 30 g ai ha−1, pendimethalin at 990 g ai ha−1, thiobencarb at 2,750 g ai ha−1, and pretilachlor at 1,000 g ai ha−1 reduced monochoria biomass by 100%, 99%, 75%, and 56%, respectively, compared with a nontreated control. Tank-mixed bensulfuron-methyl at 45 g ai ha−1 applied with pretilachlor, thiobencarb, or pendimethalin provided 100% control of monochoria. Rice height, and straw and grain yield were greater after herbicide treatments than those of the nontreated and hand-weeded controls, indicating the advantages of chemical control of monochoria over manual weeding. Full-season monochoria interference reduced rice grain yield by 32%. In the second study, the herbicides triafamone plus ethoxysulfuron, flucetosulfuron, 2,4-D at 1,080 g ai ha−1, dicamba plus 2,4-D at 928 g ai ha−1, bispyribac-sodium at 31.25 g ai ha−1, bentazon plus MCPA at 1,150 g ai ha−1, pyribenzoxim at 30 g ai ha−1, and propanil at 5,400 g ai ha−1 applied to foliage at 4- to 5-leaf seedlings of monochoria provided ≥97% control and prevented 100% of its regrowth, with the exception of propanil. This study shows that monochoria control can be achieved by using a variety of residual and foliar-applied herbicides with different mechanisms of action.
Performance of different herbicides on pondweed (Potamogeton nodosus) in rice
- Bijan Yaghoubi, Hashem Aminpanah, Bhagirath Singh Chauhan
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- Journal:
- Weed Technology / Volume 36 / Issue 2 / April 2022
- Published online by Cambridge University Press:
- 15 March 2022, pp. 270-275
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Pondweed is a rhizomatous perennial weed of aquatic habitats that recently adapted to rice ecosystems in northern Iran. Two field experiments were conducted at the Rice Research Institute of Iran to determine the impact of pondweed on rice yield and identify effective herbicides for pondweed control. The focus of the first study was to evaluate the herbicides commonly used in Iranian rice, including butachlor, pretilachlor, oxadiargyl, pendimethalin, thiobencarb, and bensulfuron-methyl. None of these herbicides effectively controlled pondweed, except bensulfuron, which reduced pondweed biomass by ≥95% and produced 26% higher rough rice grain yield than the nontreated plots. The second experiment evaluated the performance of acetolactate synthase–inhibiting herbicides on pondweed control, rough rice yield, and pondweed regrowth. Herbicide efficacy on pondweed varied from 36% to 100%. Five preemergence herbicides, bensulfuron at 45 g ai ha−1, flucetosulfuron at 30 g ai ha−1, triafamone plus ethoxysulfuron at 40 g ai ha−1, and metsulfuron-methyl at 15 g ai ha−1, provided ≥98% control of pondweed. Use of postemergence herbicides penoxsulam at 35 g ai ha−1, bispyribac-sodium at 30 g ai ha−1, and pyribenzoxim at 35 g ai ha−1 provided 36%, 89%, and 93% pondweed control, respectively. Rough rice yields ranged from 107% to 124% in herbicide-treated plots compared with the nontreated plots. Soil-applied herbicide treatments produced higher (≥119%) yield than the hand-weeded control or foliar-applied herbicides. Pondweed regrowth was affected by herbicides and was variable. Soil-applied residual herbicides metazosulfuron, flucetosulfuron, and metsulfuron provided complete control of pondweed and prevented regrowth. In contrast, pondweed regrowth in other soil- and foliar-applied herbicide treatments occurred, indicating their lesser translocation to underground vegetative rhizomes. This study shows that although most sulfonylurea herbicides can control pondweed effectively to achieve high rough rice yield, only a few soil-applied herbicides were able to prevent pondweed regrowth.