4 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.
2-Aminobutyric Acid as a Chemical Marker for the Detection of Sulfonylurea Herbicides
- Yun-Zein Li, Ching-Yuh Wang
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- Journal:
- Weed Technology / Volume 19 / Issue 1 / March 2005
- Published online by Cambridge University Press:
- 20 January 2017, pp. 176-182
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The objective of this study was to evaluate the feasibility of using 2-aminobutyric acid (2-aba) as a chemical marker for the detection of sulfonylurea (SU) herbicides in crop and soil environments. A bioassay, on the basis of the injury index to vegetable seedlings, showed that both field mustard and Chinese mustard were more sensitive to bensulfuron, imazosulfuron, and pyrazosulfuron than lettuce and cabbage in winter. In a similar study, field mustard was found to be the most sensitive species among six summer vegetables. After foliar application of bensulfuron at 0.487 μM, 2-aba accumulation reached the maximum in field mustard within 6 to 12 h, before any visible symptoms appeared, and this high level was maintained up to 72 h. Among all vegetables tested for differential SU sensitivities, maximum accumulation of 2-aba occurred, in coincidence with the onset of injury, in field mustard. The accumulation of 2-aba in field mustard showed a linear regression to the log-transformed concentrations, ranging from 10−2 to 102 μM, of each of the three SUs. However, no such relationship between the applied rate, especially at the lower rates, and the residue content of SUs in field mustard plant was found. In addition, with the extract of SU-treated paddy soil sprayed on field mustard, the accumulation of 2-aba in this plant was found to reflect indirectly the amount of SU residues in the soil.
Weeds and Weed Management of Rice in Karnataka State, India
- Adusumilli Narayana Rao, Suhas P. Wani, Mugalodi Ramesha, Jagdish K. Ladha
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- Journal:
- Weed Technology / Volume 29 / Issue 1 / March 2015
- Published online by Cambridge University Press:
- 20 January 2017, pp. 1-17
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Rice is one of the staple food crops of India, and Karnataka is one of the major rice-producing states. The primary method of rice establishment in Karnataka is transplanting, but farmers are opting to shift to direct-seeding of rice. Weed management is critical for realizing optimal yield of direct-seeded rice (DSR). The objective of this review was to synthesize the published literature on weeds and weed management in rice in Karnataka, identify improved weed-management technologies for delivery to farmers, and suggest research needs. Some 98 weed species are reported to be associated with rice in Karnataka. Weed control to date in Karnataka has mostly been based on herbicides. Hand-weeding was found to be effective in all methods of rice establishment. However, it is time-consuming, tedious, and costly because labor is becoming scarce and unavailable, and labor wages are higher. Several PRE and POST herbicides that were effective in other Asian countries were also found to be effective in managing weeds in rice established by different methods in Karnataka. Bensulfuron plus pretilachlor and pyrazosulfuron in aerobic rice and pendimethalin, thiobencarb, bispyribac-sodium, cyhalofop, fenoxaprop plus chlorimuron plus metsulfuron, and fenoxaprop plus ethoxysulfuron in dry-DSR were found effective in managing weeds. In wet-DSR, butachlor plus safener and pretilachlor plus safener were effective. Thiobencarb, pendimethalin, pretilachlor, azimsulfuron plus metsulfuron, bispyribac-sodium, butachlor, cinosulfuron, oxadiazon, and quinclorac were found promising for weed management in transplanted rice. Integration of herbicides with hand-weeding or intercultivation was found to be effective in rice established by different methods. Options that were found economical in managing weeds varied across the different rice-establishment methods. The need for developing location-specific, sustainable, integrated weed management and extension of available technologies for the farming community in Karnataka is emphasized.
Herbicide Options for Weed Control in Dry-Seeded Aromatic Rice in India
- Gulshan Mahajan, Bhagirath S. Chauhan
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- Journal:
- Weed Technology / Volume 27 / Issue 4 / December 2013
- Published online by Cambridge University Press:
- 20 January 2017, pp. 682-689
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The looming water crisis and shortage of labor during rice transplanting in northwest India have led researchers to develop alternative methods to transition away from puddled transplanted rice. In this context, dry-seeded rice (DSR) is emerging as an efficient production technology to replace puddled transplanted rice. Weeds, however, are the main biological constraints to its success. A study comprising 12 treatments was conducted to evaluate the efficacy of PRE (pendimethalin and pyrazosulfuron) and POST herbicides (bispyribac, penoxsulam, and azimsulfuron) applied either alone or in a sequence for weed control in dry-seeded fine rice cv. ‘Punjab Mehak 1’. Results indicated that the single application of pendimethalin (750 g ai ha−1) PRE, pyrazosulfuron (15 g ai ha−1) PRE, bispyribac-sodium (25 g ai ha−1) POST, penoxsulam (25 g ai ha−1) POST, and azimsulfuron (20 g ai ha−1) POST reduced total weed biomass by 75, 68, 73, 70, and 72%, respectively, compared with the nontreated control at flowering stage of the crop. Azimsulfuron POST and pyrazosulfuron PRE proved effective against purple nutsedge and crowfootgrass, respectively. Chinese sprangletop, large crabgrass, and junglerice were effectively controlled with pendimethalin PRE. POST application of bispyribac-sodium and penoxsulam provided effective control of rice flatsedge. Compared to the nontreated control, grain yield following the single application of pendimethalin PRE, pyrazosulfuron PRE, bispyribac-sodium POST, penoxsulam POST, and azimsulfuron POST increased by 149, 119, 138, 124, and 144%, respectively. The sequential application of herbicides proved better than single applications. The lowest weed biomass was observed with the sequential application of pendimethalin PRE followed by azimsulfuron POST, and rice yielded 228% more than the nontreated control following this treatment. The results of this study are important for farmers growing DSR in making decisions regarding the application of POST herbicides, according to existing weed flora in the field.