Method for preventing and controlling weeds in paddy field

Abstract

The invention relates to the technical field of pesticides, and discloses a paddy field weed control method, which comprises the step of applying a weeding composition of dithiopyr and disulfuron to a paddy field. The weeding composition provided by the invention is used for preventing and removing weeds such as paddy field barnyard grass, leptochloa chinensis, digitaria sanguinalis, green bristlegrass, eleusine indica, monochoria vaginalis, lindernia procumbens, ammannia baccifera, polygonum lilac, arrowhead, cyperus difformis, cyperus iria, fimbristylis miliacea, scirpus planiculmis, eleocharis yokoscensis, scirpus juncoides and the like, and has a surprising and unexpected synergistic effect; the weeding activity is more remarkable than the expected sum of the activity of a single herbicide, the synergistic effect is more remarkable under the condition of low dosage, the dosage can be reduced, the pollution to the environment is reduced, the use cost is reduced by reasonable compounding, the adaptability of the product to high temperature is improved, the lasting period of the product to high temperature is prolonged, and the weeding composition has a better application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticides, and in particular to a method for preventing and controlling weeds in rice fields. Background Art

[0002] In rice production, weeds are a major factor affecting rice yield and quality, and herbicides are currently the most effective weed control method. Weeds in rice fields persist for a long time, occur in large numbers, and cause severe damage. A "one seal, one kill" strategy is generally adopted for weed control in rice fields. Under favorable climatic conditions, soil sealing treatments are performed using agents such as pretilachlor, bensulfuron-methyl, and their combinations. A second application of weed treatments is typically performed when weeds reach the 2- to 4-leaf stage, using agents such as cyhalofop-butyl and penoxsulam for foliar treatment, combined with pretilachlor and butachlor for sealing, achieving a combined sealing and killing effect. However, the continuous use of conventional foliar treatments such as cyhalofop-butyl and penoxsulam has led to a rapid increase in weed resistance in recent years, resulting in a significant number of unprotected fields. Amide herbicides such as pretilachlor and butachlor are currently the most commonly used sealing herbicides in rice fields, and resistance levels are increasing year by year. They also suffer from issues such as a short duration of action and increased safety risks to rice at low temperatures. Therefore, new weed control solutions are urgently needed in the market.

[0003] Dithiopyr, internationally known as Dithiopyr, CAS number: 97886-45-8, chemical formula: C15H16F5NO2S2, chemical name: S,S-dimethyl-2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinethiodicarboxylate. This product acts as a mitotic inhibitor. It is absorbed primarily through stems, leaves, and roots, blocking the formation of spindle microtubules, shortening them and preventing normal spindle formation. This prevents cells from undergoing mitosis, leading to weed growth arrest and death. It is effective against annual grass weeds, some broadleaf weeds, and sedges.

[0004] Flusulfinam, internationally known as Flusulfinam, CAS number: 2428458-82-4; molecular formula: C14H13F4N3O3S, chemical name: 2-Fluoro-N-(5-methyl-1,3,4-oxadiazol-2-yl)-3-propylsulfinyl-4-(trifluoromethyl)benzamide. Developed by Qingyuan Agro-Crown, this product is a systemic, selective, stem-and-leaf treatment agent for HPPD inhibitors. It is absorbed through the stems and leaves of plants and effectively controls grass weeds such as barnyardgrass, crabgrass, and Leptochloa crus-galli, as well as some broadleaf and sedge weeds in rice fields. Its stem-and-leaf activity is superior to that in the soil, making it safe for rice.

[0005] Patent CN112741097B discloses a herbicide composition containing N-(1,3,4-oxadiazol-2-yl)arylformamide compounds and their use. The patent discloses that a combination of flusulfoxetine and dithiopyr can be used for weed control. However, the examples only disclose that the combined effect on stem and leaf treatment of Alisma orientalis is synergistic. The application of the composition in rice fields is not described. There is no mention of the combined effect of the composition on weeds during closed treatment, nor is there any mention of the type of combined effect on the malignant weeds Echinochloa crus-galli and Leptochloa chinensis in rice fields.

[0006] The present invention is primarily used for rice. The combination can reduce the dosage of flusulfoxam, improving safety. It has a wide application window and can be used from the needle-forming stage onwards. It significantly enhances the effectiveness of barnyardgrass and Leptochloa chinensis at different leaf ages, has a long-lasting effect, and is adaptable to varying temperature conditions. This combination significantly outperforms conventional combinations of insecticides, and uses a lower dosage, offering the advantages of safety, efficiency, and environmental protection. Summary of the Invention

[0007] The first aspect of the present invention is to provide a method for controlling weeds in rice fields, comprising applying a herbicidal composition of disulfiram and flusulfuron to the rice fields, wherein the flusulfuron is an R-type herbicidal composition having the following structural formula:

[0008]

[0009] The second aspect of the present invention is to provide a method for applying the herbicidal composition described in the first aspect, wherein the herbicidal product of the present invention is applied before or after transplanting rice, or after direct-seeded rice has established its needles, by spraying, swishing, bottle-throwing, broadcasting of granules, poisoned soil method (mixing with soil or fertilizer), or broadcasting of pesticides and fertilizers. The application method can be manual application, aerial application, or mechanical spraying.

[0010] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0011] The herbicidal composition provided by the present invention has good safety to rice and can be used before or after transplanting rice fields, as well as after direct-seeded rice has established needles. It has a synergistic effect on malignant weeds in rice fields such as barnyard grass, loblolly chinensis, duckweed, and sedge, has a broad weed control spectrum, a long lasting effect, and can adapt to different environmental temperature conditions.

[0012] The herbicidal composition of the present invention can be used directly with the active ingredient, or the composition containing the target active ingredient can be formulated, or the active ingredients can be formulated separately and then mixed. Other herbicides can also be added for mixed use. During application, the active ingredients of the present invention can be applied separately or simultaneously, providing flexibility and convenience. DETAILED DESCRIPTION

[0013] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0014] The first aspect of the present invention provides a method for controlling weeds in a rice field, comprising applying a herbicidal composition of disulfiram and flusulfuron to the rice field, wherein the flusulfuron is an R-type and has the following structural formula:

[0015]

[0016] In some embodiments of the present invention, the herbicidal composition is used to control weeds in rice fields, where the planting methods of the rice fields include direct seeding rice and transplanting rice.

[0017] In some embodiments of the present invention, the weeds are grass weeds, broadleaf weeds and / or sedges.

[0018] In some embodiments of the present invention, the grass weeds are selected from at least one of Echinochloa crus-galli, Leptochloa chinensis, Digitaria sanguinalis, Setaria viridis, and Eleocharis chinensis.

[0019] In some embodiments of the present invention, the broad-leaved grass is selected from at least one of Commelina tongue grass, Lycopodiella vulgaris, Amaranthus water spinach, Polygonum multiflorum, and Sagittaria sagittifolia.

[0020] In some embodiments of the present invention, the sedge is selected from at least one of Cyperus difformis, Cyperus angustifolia, Cyperus rotundus, Cyperus scutellaria, Cyperus ox-hair felt, and Cyperus rotundus.

[0021] The second aspect of the present invention provides a method for applying the herbicidal composition described in the first aspect, wherein the herbicidal composition of the present invention is applied before or after transplanting rice, or after direct-seeded rice needles have established, by spraying, swishing, bottle-throwing, broadcasting of granules, poisoned soil method (mixing with soil or fertilizer), broadcasting of pesticides and fertilizers, and can be applied manually, by aircraft, or by mechanical spraying.

[0022] In some embodiments of the present invention, the weight ratio between disulfiram and flusulfocaine is 0.13 to 8.0:1, preferably 1.0 to 3.0:1, and more preferably 1.5 to 2.4:1.

[0023] In some embodiments of the present invention, the mass ratio of disulfiram and flusulfuron can be but not limited to 0.13:1, 0.15:1, 0.2:1, 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 6:1, 7:1 or 8:1, or any ratio between (0.13 and 8):1.

[0024] In order to achieve the desired control effect on different weeds, in some specific embodiments, the mass ratio of disulfiram to flusulfuron is (0.3-3.2):1.

[0025] In order to achieve different weed control effects, in some specific embodiments, the mass ratio of disulfiram to flusulfuron is (0.13-1.60):1.

[0026] In order to achieve different weed control effects, in some specific embodiments, the mass ratio of disulfiram to flusulfuron is (0.8-8):1.

[0027] In some embodiments of the present invention, the application rate of the active ingredient of the herbicidal composition is 117-198 g ai / ha, preferably 135-180 g ai / ha.

[0028] In some embodiments of the present invention, dithiopyr is applied at a rate of 72-108 g ai / ha, preferably 90-108 g ai / ha.

[0029] In some embodiments of the present invention, the application rate of formosan is 45-90 g ai / ha, preferably 45-72 g ai / ha.

[0030] In some embodiments of the present invention, the herbicidal composition of disulfiram and flusulfoxam can be formulated in the form of any one of a dispersible oil suspension, an aqueous suspension, a suspoemulsion, a wettable powder, an emulsifiable concentrate, a water-dispersible granule, an aqueous emulsion, a microemulsion, a soluble liquid or a microcapsule sustained-release agent.

[0031] In some embodiments of the present invention, the active ingredient of the herbicidal combination of disulfiram and flusulfoxam accounts for 0.05-80% of the total weight of the herbicidal composition, for example, 0.05%, 1%, 3%, 10%, 20%, 33%, 50%, 60%, 70%, 80%, and any value within the range of any two of the above values, preferably 5-15%.

[0032] In some embodiments of the present invention, the herbicidal composition of dithiopyralid and flusulfocaine further comprises an adjuvant acceptable to pesticides.

[0033] In some embodiments of the present invention, the pesticide-acceptable adjuvant includes one or more of a dispersant, a wetting agent, a thickener, an antifreeze agent, a defoaming agent, a preservative, and a solvent.

[0034] In some embodiments of the present invention, the dispersant is selected from one or more of alkylnaphthalene sulfonates, methacrylate copolymers, lignin sulfonates, and polycarboxylates.

[0035] In some embodiments of the present invention, the wetting agent is selected from one or more of sodium alkyl sulfate, calcium alkylbenzene sulfonate, sodium alkylbenzene sulfonate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether and polyoxyethylene ether phosphate and salts thereof.

[0036] In some embodiments of the present invention, the antifreeze agent is selected from one or more of ethylene glycol, propylene glycol, glycerol and urea.

[0037] In some embodiments of the present invention, the thickener is selected from one or more of white carbon black, magnesium aluminum silicate, sodium carboxymethyl cellulose, xanthan gum, gelatin and gum arabic.

[0038] In some embodiments of the present invention, the defoaming agent is selected from one or more of silicones, polyethers and fatty alcohols.

[0039] In some embodiments of the present invention, the preservative is selected from isothiazolin-3-one preservatives, preferably one or more selected from 1,2-phenylisothiazolin-3-one, 5-chloro-2methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.

[0040] In some embodiments of the present invention, the solvent is selected from one or more of water, aromatic hydrocarbons, alcohols, ketones, amides and esters, preferably water.

[0041] Among them, in specific use, the application methods of disulfiram and flusulfuron include applying disulfiram and flusulfuron separately or applying disulfiram and flusulfuron together.

[0042] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] The present invention is specifically implemented through greenhouse potting method and field plot test. The pesticides and their sources are shown in Table 1.

[0044] Table 1 Test agents and their sources

[0045] Serial number Medicine name source 1 95% dithiopyr technical Produced by Max (Rudong) Chemical Co., Ltd. 2 Flusulfoxam technical (R type) Prepared according to CN112741097B 3 300g / L Pretilachlor EC Syngenta (Suzhou) Crop Protection Co., Ltd. 4 60% Butachlor EC Zhejiang Zhongshan Chemical Industry Group Co., Ltd. 5 40% cyhalofop-butyl water-dispersible oil suspension concentrate Qingdao Qingyuan Agricultural Crown Resistance Weed Control Co., Ltd.

[0046] (1) Determination method and standard of herbicidal activity

[0047] 1. Bioassay test method:

[0048] Refer to the Ministry of Agriculture and Rural Affairs' "Guidelines for Indoor Bioassay Tests of Pesticides. NY / T 1155.3-2006" Herbicides Part 3: Activity Determination Test Soil Spray Method and "Guidelines for Indoor Bioassay Tests of Pesticides. NY / T 1155.4-2006" Herbicides Part 4: Activity Determination Test Stem and Leaf Spray Method.

[0049] Drug solution preparation: The preparation in Table 1 was prepared into a 1% stock solution, which was diluted with distilled water to a test dose according to the set dose for treatment; the original drug was diluted with dimethylformamide (DMF) to a 1% stock solution, which was diluted with distilled water containing 0.1% Tween-80 to a test dose according to the set dose for treatment.

[0050] 2. Evaluation criteria for herbicidal activity by visual inspection

[0051] The herbicidal activity was visually assessed based on the degree of plant damage symptoms (inhibition, deformity, yellowing, and albinism). 0 indicates no herbicidal effect, and 100% indicates complete kill of the weeds. The visual assessment criteria are shown in Table 2.

[0052] Table 2 Evaluation criteria for herbicidal activity by visual inspection

[0053]

[0054] The calculation formula of fresh weight inhibition rate is as follows:

[0055]

[0056] The experimental data were analyzed by variance analysis using DPS 7.05 statistical analysis software and Duncan's new multiple range method to determine the significance of the differences in the effects of different treatments (α = 0.05).

[0057] (2) Combined effect evaluation test

[0058] Test targets: Echinochloa crus-galli (L.), Leptochloa chinensis (L.) Nees

[0059] The test method was a greenhouse potted test. Sandy loam soil collected from untreated plots was mixed with a nutrient medium (1.5% organic matter, pH 7.2) in a 1:2 ratio by volume. Pots with a diameter of 6.5 cm and a depth of 5.5 cm were filled to 3 / 4 of their height. After the soil was thoroughly moistened with water, weed seeds were sown in the pots, ensuring 10-20 seeds per weed species, with a germination rate of 50-90%. After sowing, the pots were covered with approximately 0.2 cm of a 1:1 ratio of loess to vermiculite. Water was added to the bottom of the pots until the soil was saturated with water, and the pots were then incubated in a greenhouse, maintaining 100% soil moisture content. The temperature in the greenhouse was maintained between 20°C and 30°C, and the air humidity was above 60%.

[0060] Weeds were sprayed in the soil after sowing and before seedlings emerged, or on the stems and leaves after the weeds reached the two-leaf stage. The spray was then applied according to the designed dosage in a vertical intelligent spray tower (HCL-500). Each weed was sprayed four times at a height of 50 cm, a pressure of 0.2 MPa, and a water volume of 600 liters per hectare. Thirty days after application, weeds were visually inspected, and the fresh weight of the aboveground parts of each treatment was measured. The fresh weight inhibition rate (%) was calculated.

[0061] The herbicidal activity of two herbicides mixed was tested using the Gowing method. The mixture effect was calculated as: E0 = X + Y – XY / 100, where X represents the weed control efficacy of herbicide A at a dosage of P; Y represents the weed control efficacy of herbicide B at a dosage of Q; and E0 represents the theoretical control efficacy of the herbicides (A + B) at a dosage of (P + Q). According to the Gowing method, a value of E - E0 > 10% indicates a synergistic effect between the herbicides; a value of E - E0 < -10% indicates an antagonistic effect; and a value between ±10% indicates an additive effect. E represents the actual control efficacy (%) of each treatment.

[0062] In the following table, number A represents disulfiram, number B represents flusulfuron, and A:B represents the mass ratio.

[0063] Table 3 Evaluation test results of the combined effect of disulfiram + flusulfuron on barnyardgrass (pre-emergence)

[0064]

[0065] Table 4 Evaluation results of the combined effect of disulfiram + flusulfuron on barnyardgrass (2-leaf stage)

[0066]

[0067]

[0068] Table 5 Evaluation results of the combined effect of disulfiram + flusulfamide on Leptochloa crus (pre-emergence)

[0069]

[0070]

[0071] Tables 3-5 show the herbicidal activity and combined effects of fluthiopyral and flusulfoxam combinations against the major grass weeds Echinochloa crusgalli and Leptochloa chinensis in rice fields. The results indicate that the combined weed control efficacy of the two agents was significantly higher than that of either agent alone, significantly enhancing herbicidal activity. Evaluation of the combined effects of the combinations revealed that the actual control efficacy (E) of fluthiopyral and flusulfoxam combination was greater than the theoretical control efficacy (E0) for most ratios. For pre-emergence Echinochloa crusgalli, the E0 values ranged from 0.3 to 3.2, for two-leaf stage Echinochloa crusgalli, from 0.8 to 8.0, and for pre-emergence Leptochloa chinensis, the E0 values were all greater than 10%. The combined effects were synergistic for the combination, while additive for the remaining ratios, with no antagonism observed.

[0072] (3) Comparative test of greenhouse herbicidal activity and safety

[0073] 1. Safety and herbicidal activity test on direct-seeded rice

[0074] Using the greenhouse potting method, approximately 10 target weed seeds were sown on the soil surface in plastic pots filled with a fixed amount of soil. Covered with 0.5-1 cm of fine soil, the target weeds were then cultured in the greenhouse. Spraying was performed when the target weeds reached the appropriate leaf age. Each treatment was repeated four times. After treatment, the target weeds were cultured in the greenhouse, and their growth was regularly observed. The fresh weight of the aboveground part was measured 30 days after application, and the fresh weight inhibition rate (%) was calculated.

[0075] In the rice safety test, rice seeds were soaked, germinated, and then sown after whitening. The spray treatment was applied at the needle-standing, one-leaf, two-leaf, and three-leaf stages. After treatment, the rice seeds were cultured in a greenhouse, simulating field soil moisture management for direct-seeded rice. The rice growth was regularly observed. The fresh weight of the aboveground portion was measured 30 days after application, and the fresh weight inhibition rate (%FW) was calculated. The results are shown in Table 6.

[0076] Table 6 Safety and herbicidal activity test of disulfiram+flusulfuron on direct-seeded rice

[0077]

[0078]

[0079] Different lowercase letters in the same column indicate significant differences (P<0.05).

[0080] Results showed that fluthiopyr was safe against rice from the bud to the third leaf stage and had good activity against pre-emergence barnyardgrass, but activity decreased significantly with increasing leaf age. A low dose of 45 gai / ha (45 gai / ha) was safe for rice from the bud to the third leaf stage, but increasing the dose to 90-180 gai / ha was only safe for rice from the third leaf stage and not for rice from the bud to the second leaf stage. A fluthiopyr-fluthiopyr herbicide combination showed high activity against the grass weed barnyardgrass from the pre-emergence to the third leaf stage, with fresh weight inhibition rates ranging from 95.6% to 100%. It was also safe for rice, with fresh weight inhibition rates ranging from -1.3% to 8.9%. The fluthiopyr-fluthiopyr combination demonstrated high weed control efficacy against both pre-emergence and post-emergence weeds and was safe for rice at all leaf stages, achieving a balanced weed control and rice safety. Its application was significantly superior to single-agent treatments of fluthiopyr and fluthiopyr, and the application dose was significantly reduced.

[0081] 2. Comparative test of activity at different temperatures

[0082] This test method was the same as in 1. After treatment, the plants were placed in light-incubators at different temperatures for plant growth. The incubator temperatures were 25°C and 35°C, respectively. The specific results are shown in Table 7. The results showed that the herbicidal activity of both single-agent treatments decreased with increasing temperature. However, the combination of dithiopyralid and flusulfoxam maintained high herbicidal activity against both pre- and post-emergence barnyardgrass at both 25°C and 35°C. The effect of application at 35°C was significantly better than that of the two single-agent treatments, indicating that the temperature effect of the combination was significantly improved.

[0083] Table 7 Comparative test of herbicidal activity of disulfiram+flusulfuron at different temperatures

[0084]

[0085] Different lowercase letters in the same column indicate significant differences (P<0.05).

[0086] 3. Comparative test of duration of efficacy

[0087] This test method was the same as in 1. Herbicidal activity against barnyardgrass was assessed at various times after treatment. The results are shown in Table 8. The results showed that the dithiopyr + flusulfoxam combination maintained high herbicidal activity against pre-emergence and two-leaf barnyardgrass 15 and 30 days after application. The two single agents maintained high activity against two-leaf or pre-emergence barnyardgrass 15 days after application, but activity decreased significantly after 30 days. The combination exhibited significantly longer-lasting activity than the single agent treatments.

[0088] Table 8 Evaluation test of disulfiram+flusulfuron-pyraclostrobin's effective period

[0089]

[0090] Different lowercase letters in the same column indicate significant differences (P<0.05).

[0091] (3) Field plot test

[0092] 1. Direct-seeded rice

[0093] The test was conducted using a field plot method in accordance with the national standard "GB / T 17980.40-2000 Guidelines for Field Efficacy Tests of Pesticides (I) Herbicides for Control of Weeds in Paddy Fields." The test was conducted in Xuyu Village, Huangmei County, Hubei Province. The experimental field was flat, with complete irrigation and drainage facilities, consistent field management, uniform medium fertility, loam soil, and a neutral pH. Land preparation was performed on May 31st using a small tractor-assisted land preparation machine. The rice variety was a local, conventional indica rice variety, and sown manually on June 2nd at a fixed rate of 10 jin / mu. The primary weeds in the experimental field were barnyardgrass and sedge grass, which occurred evenly.

[0094] The experimental plots were arranged in random blocks, with a plot area of 21m 2 The plots were rectangular, with three replicates per treatment. Treatments were applied after the rice needles had established and at the two-leaf stage. Application was by spraying, using a boom sprayer to evenly apply spray to the stems and leaves, with a watering rate of 30 L / mu. Weed control efficacy was assessed approximately 30 days after application, using visual inspection. Yield was measured in each plot at harvest time.

[0095] 1.1 Field efficacy test during direct seeding

[0096] The safety and herbicidal activity of the dithiopyral + flusulfamide combination during the seeding stage of direct-seeded rice are shown in Table 9. The results showed that the dithiopyral + flusulfamide combination at 90 gai / ha and 45 gai / ha was safe during the seeding stage of direct-seeded rice and significantly increased yield. It also demonstrated high control efficacy against barnyardgrass and sedge, surpassing the two single-dose controls and the conventional agent pretilachlor.

[0097] Table 9 Application results of disulfiram + flusulfuron combination in rice needle-standing period

[0098]

[0099]

[0100] Different lowercase letters in the same column indicate significant differences (P<0.05).

[0101] 1.2 Field efficacy test at the 2-leaf stage of direct seeding

[0102] Table 10 shows the safety and herbicidal activity of the dithiopyral + flusulfoxam combination at the two-leaf stage for direct-seeded rice. The results showed that the dithiopyral + flusulfoxam combination (108 g ai / ha + 72 g ai / ha) was safe at the two-leaf stage for direct-seeded rice and significantly increased yield. It also demonstrated high control efficacy against barnyardgrass, cyperus vaginalis, and Cyperus diversiformis, surpassing the two single-dose controls and the conventional combination of butachlor + cyhalofop-butyl.

[0103] Table 10 Application results of disulfiram + flusulfuron combination at rice 2-leaf stage

[0104]

[0105] Different lowercase letters in the same column indicate significant differences (P<0.05).

[0106] 2. Transplanting rice

[0107] The test was conducted using a field plot method in accordance with the standard "GB / T 17980.40-2000 Guidelines for Field Efficacy Tests of Pesticides (I) Herbicides for Control of Weeds in Paddy Fields." The test was conducted in Fuyang City, Zhejiang Province. The experimental field was flat, with complete irrigation and drainage facilities, consistent field management, uniform medium fertility, loam soil, and a neutral pH. Land preparation was performed on June 13th, and rice seedlings were transplanted on June 17th. Land preparation was performed using a harrow and rotary tiller. A local, conventional rice variety was used. The main weeds in the experimental field were Echinochloa crus-galli, Leptochloa chinensis, and Dalbergia tongue grass, which were evenly distributed.

[0108] The experimental plots were arranged in random blocks. Each plot was separated by dikes and equipped with independent water inlets and outlets to prevent water contamination between different treatments. Each plot was watered before drug application. The plot area was 22.5m 2 The plots were rectangular, with three replicates per treatment. Treatments were applied seven days after rice transplanting, using a boom sprayer for uniform application. The water content was 30 L / mu. Detailed weather information was recorded on the day of application, including minimum and maximum temperatures, wind speed, and precipitation. No other herbicides or crop regulators were applied during the trial. Insecticide and fungicide treatments were applied uniformly to all plots.

[0109] Weed control efficacy and rice growth were assessed 25 and 50 days after treatment. Visual inspection was used to assess weed control efficacy. Yield measurements were taken for each plot at harvest time. The results are shown in Table 11.

[0110] Table 11 Application results of disulfiram + flusulfuron combination in transplanted rice

[0111]

[0112] Different lowercase letters in the same column indicate significant differences (P<0.05).

[0113] Test results showed that a combination of dithiopyral + flusulfamide (108 g / ha + 45 g / ha) demonstrated excellent safety for transplanted rice and demonstrated high control efficacy against barnyardgrass, Leptochloa chinensis, and Dalbergia vaginalis, with a duration of effect exceeding 50 days. This control efficacy was significantly superior to the single-dose controls of dithiopyral and flusulfamide, and also to the combination of pretilachlor and flusulfamide. This combination demonstrates its safety for rice and high weed control efficacy, demonstrating promising application prospects.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling weeds in rice fields, characterized in that: The method comprises applying a herbicidal composition of disulfiram and flusulfuron to a rice field, wherein the flusulfuron structural formula is as follows:

2. The method according to claim 1, characterized in that The weight ratio of disulfiram to flusulfuron is 0.13 to 8.0:1, preferably 1.0 to 3.0:1, and more preferably 1.5 to 2.4:

1.

3. The method according to claim 1, characterized in that The weeds are grass weeds, broadleaf weeds and / or sedges.

4. The method according to claim 3, characterized in that The grass weeds are at least one of barnyard grass, chinensis, crabgrass, foxtail grass, and goosegrass; the broad-leaved grass is at least one of duckweed, moss, water amaranth, lilac, and arrowhead; the sedge is at least one of cyperus dimorphus, cyperus angustifolia, sunshine-blooming grass, flat-stemmed scabious grass, cow hair felt, and firefly rush.

5. A method for applying a disulfiram and flusulfuron herbicide combination for controlling weeds in rice fields, characterized in that: Apply before or after transplanting rice and after direct-seeded rice needles have established.

6. The application method according to claim 5, characterized in that The application methods include spraying, swishing, bottle throwing, granule spreading, soil mixing, fertilizer mixing, pesticide and fertilizer spreading, manual application, aircraft application or mechanical spraying.

7. The application method according to claim 5, characterized in that The application amount of dithiopyr is 72-108 g ai / ha; the application amount of flusulfuron is 45-90 g ai / ha; preferably, the application amount of dithiopyr is 90-108 g ai / ha, and the application amount of flusulfuron is 45-72 g ai / ha.

8. The method according to claim 1, characterized in that The herbicidal composition of dithiopyralid and flusulfocaine further comprises an adjuvant acceptable in pesticides.

9. The method according to claim 1, characterized in that The herbicidal composition of dithiopyralid and flusulfocaine is in the form of any one of a dispersible oil suspension, an aqueous suspension, a suspoemulsion, a wettable powder, an emulsifiable concentrate, a water dispersible granule, an aqueous emulsion, a microemulsion, a soluble liquid or a microcapsule sustained-release agent.

10. The method according to claim 1, characterized in that Disulfiram and flusulfuron can be applied simultaneously or separately.

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