Topramezone derivative for preventing and controlling stubborn resistant weeds in paddy field and application of topramezone derivative

Abstract

The invention discloses a topramezone derivative for preventing and controlling stubborn resistant weeds in a paddy field and application of the topramezone derivative, accurately overcomes the two core pain points of'seedling injury by herbicide 'and'incapability of preventing weeds' confronted by current paddy field weeding, expands the application scene of the herbicide, promotes the product structure upgrading of the industry from'applicability to single crops' to'adaptation to multiple crops', and improves the application prospect. The market vitality is further activated. From the perspective of agricultural sustainable development, the characteristics of BZ01 highly meet the requirements of modern green agriculture. From the level of grain safety strategy, the BZ01 can simultaneously solve the two threats of'weed fertilizer competition 'and'herbicide phytotoxicity' in the paddy field: the BZ01 not only can efficiently remove weeds and reduce nutrient loss, but also can ensure the safe growth of the rice, provides technical support for stable and high yield of the rice, and indirectly assists the construction of a national grain safety guarantee system.

Description

Technical Field

[0001] This invention relates to benzoxazine derivatives for the control of stubborn resistant weeds in paddy fields and their applications. It belongs to the field of pesticide compound technology. Background Technology

[0002] Rice, a vital food crop in my country, is planted on over 450 million mu (approximately 30 million hectares) nationwide, serving as a crucial cornerstone for national food security. Weed infestation in paddy fields is a significant factor affecting stable and high rice yields. Among these, barnyard grass, goosegrass, and weedy rice are notoriously difficult to control in paddy fields across the country, causing annual rice losses exceeding 2 billion jin (approximately 1 billion kg). In recent years, changes in farming systems and cultivation techniques, along with frequent inter-regional crop rotation, have led to significant changes in the weed composition of paddy fields. Barnyard grass and goosegrass have developed into stubborn and noxious weeds in major rice-producing areas, with the area affected by perennial weeds increasing year by year. Upland weeds have gradually become dominant species in paddy fields, making control increasingly difficult. Song Baoan, an academician of the Chinese Academy of Engineering and president of Guizhou University, pointed out that barnyard grass, goosegrass, and barnyard grass cause a reduction of 9.5 million tons of crop yield annually, resulting in economic losses exceeding 250 billion yuan. Applying herbicides is a relatively economical and widespread method for addressing weed problems in paddy fields. There is an urgent need in the market for new herbicides that can effectively control resistant weeds in rice paddies, are safe for rice crops, and are friendly to the aquatic environment.

[0003] Currently, rice paddy weed control faces a dual dilemma: herbicide damage to seedlings and inability to control weeds. On the one hand, although the traditional pyrazolone-based HPPD-targeted herbicide benzoxazole is widely used in cornfields, it has never been approved for use in rice paddies because most rice varieties have poor tolerance to it, and normal use easily leads to rice damage and yield reduction. Benzoxazole can cause slight whitening of rice at a dose of only 15g ai / ha, and severe growth inhibition and whitening occur at a dose of 30g ai / ha. On the other hand, in recent years, due to changes in cropping systems, cultivation techniques, and inter-regional crop transfers, the weed composition in rice paddies has changed dramatically. Barnyard grass and Echinochloa crus-galli have become stubborn and noxious weeds in major producing areas, the damage caused by perennial weeds has expanded, and weeds in dryland areas have invaded, making control much more difficult. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a benzoxam derivative for the control of stubborn resistant weeds in paddy fields and its application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: 1. A benzalkonium derivative or an agriculturally chemically acceptable salt thereof for the control of stubborn resistant weeds in paddy fields, wherein the benzalkonium derivative is 4-(3-(4,5-dihydroisoxazo-3-yl)-2-methyl-4-(methanesulfonyl)benzoyl)-1-methyl-1H-pyrazole-5-yl diethylcarbamate, i.e., BZ01, with the molecular formula C 21 H 26 N4O6S, chemical structural formula as follows: .

[0006] 2. A pharmaceutical composition comprising the aforementioned benzoxazine derivative or an agriculturally chemically acceptable salt thereof.

[0007] 3. Application of the aforementioned benzalkonium derivatives or their agriculturally chemically acceptable salts in the control of stubborn resistant weeds in paddy fields.

[0008] As one of the preferred technical solutions, weed control methods include: barnyard grass, Echinochloa crus-galli, Crataegus pinnatifida, and Eleusine indica.

[0009] 4. Application of the aforementioned drug composition in the control of stubborn resistant weeds in paddy fields.

[0010] As one of the preferred technical solutions, weed control methods include: barnyard grass, Echinochloa crus-galli, Crataegus pinnatifida, and Eleusine indica.

[0011] 5. Pesticides used for the control of stubborn resistant weeds in paddy fields, wherein the active ingredient is the aforementioned benzoxazine derivative or its agriculturally chemically acceptable salt.

[0012] 6. A pesticide for controlling stubborn resistant weeds in paddy fields, comprising the aforementioned drug composition.

[0013] As a further preferred technical solution, the pesticide formulation is selected from any of the following: water dispersible agent, dispersible liquid, wettable powder, soluble powder, suspension, water emulsion, microemulsion, suspension emulsion, microcapsule suspension, emulsifiable concentrate, granules.

[0014] The beneficial effects of this invention are: This invention provides a benzoxam derivative BZ01 for the control of stubborn resistant weeds in paddy fields and its application.

[0015] On the one hand, even with a dosage of BZ01 as high as 120g ai / ha, the two rice varieties were still able to grow normally, breaking through the technical bottleneck that most rice varieties have poor tolerance to benzoxazole and that the use of benzoxazole leads to rice damage and yield reduction.

[0016] On the other hand, BZ01 is more effective than benzoxazole in controlling stubborn weeds such as barnyard grass, goosegrass, crabgrass, and goosegrass in paddy fields, and is 2 to 4 times more effective than benzoxazole. Ultimately, it achieves the dual guarantee of "efficient weed control" and "crop safety", effectively solving the current problem of weed control in paddy fields.

[0017] In summary, BZ01 precisely addresses the two core pain points of current rice paddy weed control: "herbicide damage to seedlings" and "inability to control weeds." It expands the application scenarios of herbicides, promotes the industry's product structure upgrade from "suitable for single crops" to "suitable for multiple crops," and further revitalizes the market.

[0018] From the perspective of sustainable agricultural development, BZ01's characteristics are highly compatible with the needs of modern green agriculture. BZ01 is far safer than benzoxazine in terms of its safety to aquatic environments (especially algae and duckweed) and mammals, significantly reducing the risks of water pollution and human health associated with herbicide use. This aligns with the policy orientation of various countries towards low-toxicity, low-risk pesticides, making it easier to obtain policy support and market acceptance.

[0019] From the perspective of food security strategy, BZ01 can simultaneously solve the two major threats of "weeds competing for fertilizer" and "herbicide damage" in paddy fields: it can not only efficiently remove weeds and reduce nutrient loss, but also ensure the safe growth of rice, providing technical support for stable and high rice yields, and indirectly contributing to the construction of the national food security system. Attached Figure Description

[0020] Figure 1 This is the proton spectrum of BZ01; Figure 2 This is the proton spectrum of CCXN-2-001; Figure 3 This is the hydrogen spectrum of CCXN-2-002. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its content.

[0022] Example 1 Preparation of BZ01 300 g of benzoxazine (825.56 mmol) (purchased from Dezhou Hanhua Pharmaceutical Chemical Co., Ltd.) and 1.5 L of dioxane were added sequentially to a 5 L reaction flask. 117 g of triethylamine (1.16 mol) and 6 g of DMAP (4-dimethylaminopyridine, 49.11 mmol) were added with stirring at room temperature. After stirring until dissolved, 146 g of diethylcarbamoyl chloride (1.07 mol) (CAS: 88-10-8) was added. The mixture was heated to approximately 75 °C and reacted for 16 h. The reaction was monitored by TLC until completion. After cooling, the mixture was concentrated to dryness under reduced pressure. 2 L of dichloromethane and 500 mL of water were added and stirred for 30 min. The mixture was separated, and the organic phase was concentrated to dryness under reduced pressure. 1 L of methanol was added, and the mixture was heated to 60–65 °C and stirred for 1 h. The mixture was then cooled to 0–10 °C and stirred until a large amount of solid precipitated. The mixture was filtered, washed with 100 mL of methanol, and dried to obtain 315 g of the product, with a yield of 82.5%.

[0023] 1 H NMR (400 MHz, DMSO) δ (ppm): 7.97 (d, J = 8.1 Hz, 1H), 7.87 (s, 1H), 7.64 (d, J = 8.1 Hz, 1H), 4.47 (t, J = 10.0 Hz, 2H), 3.66 (s, 3H),3.34–3.29(m, 2H), 3.26 (s, 3H), 3.21 – 3.02 (m, 4H), 2.16(s, 3H), 1.03 (dt, J = 14.3,7.1 Hz, 6H).C 21 H 26 N4O6S[M+H + =463.1646. Figure 1 ) The reaction formula is as follows: .

[0024] Comparative Example 1 Preparation of CCXN-2-001

[0025] In a 1L three-necked flask, add benzoxazine (21g, 57.8mmol) and 600ml acetonitrile (white, insoluble). While stirring, add potassium carbonate (16g, 115.8mmol) (yellow, insoluble). Then, while stirring at room temperature, add 1-chloroethyl methyl carbonate (CAS: 80196-03-8) (24g, 173.2mmol) and potassium iodide (0.96g, 5.78mmol). After the addition is complete, heat to 85℃ and react for 5 hours. TLC analysis showed the reaction was complete (PE:EA = 1:1, v / v). Concentrate under reduced pressure, add 400ml DCM (dichloromethane) and 400ml water, extract separately, dry the organic phase with anhydrous sodium sulfate, concentrate under reduced pressure, and perform column chromatography (PE:EA = 1:1, v / v) to give 22.5g of a white solid. Yield: 84%.

[0026] 1H NMR (400 MHz, DMSO-d6), δ (ppm): 8.012 (d, J=8, 1H), 7.681 (d, J=8.4, 1H), 7.496 (s, 1H), 6.535 (m, 1H), 4.473 (t, C 20 H 23 N3O8S [M+H + =466.1297. Figure 2 ) The reaction formula is as follows: .

[0027] Comparative Example 2 Preparation of CCXN-2-002

[0028] Add 10.00 g (27.5 mmol) of benzoxazine and 100 ml of DCM (dichloromethane) to a 250 ml three-necked flask and stir. Add 5.01 g (49.5 mmol) of triethylamine and 3.65 g (30.3 mmol) of pentanoyl chloride at room temperature and stir for 3 h. Monitor the reaction by TLC (DCM:MeOH = 10:1, v / v). Once the reactants have reacted completely, add 30 ml of water and wash once. Separate the solutions. Wash the organic phase once with 30 ml of saturated brine, dry the organic phase with anhydrous sodium sulfate, filter, and concentrate the mother liquor to obtain a yellow oily liquid. Add n-hexane to the yellow oily liquid; a small amount of white solid precipitates. Concentrate to obtain a pale yellow solid. Add 40 ml of n-hexane, sonicate for 5 min, and slurry at room temperature for 16 h. Filter, wash with 10 ml of n-hexane, and dry to obtain 11.8 g of white solid, yield 96%.

[0029] 1 H NMR (400 MHz, CDCl3), δ (ppm): 8.070 (d, J=8.4, 1H), 7.570 (d, J=8, 2H), 4.586 (t, J=10.0,2H), 3.716 (s,3H), 3.377 (br,2H) 3.206 (s,3H), 2.289 (s,3H), 1.367 (s,9H). C 21 H 25 N3O6S [M+H + =448.1436. Figure 3 ) The reaction formula is as follows: .

[0030] Test case 1. Herbicidal activity test Test basis: Refer to the Indoor Bioassay Test Guidelines for Pesticides, Herbicides, Part 4: Activity Test, Foliar Spray Method, NY / T 1155.4-2006.

[0031] Weeds tested: barnyard grass, Echinochloa crus-galli, Crataegus pinnatifida, and Eleusine indica Experimental conditions: The soil used in the experiment consisted of top 20cm loam mixed with the culture medium at a volume ratio of 3:1. The experimental weeds were cultivated in a glass greenhouse at a temperature of 25–35℃ under natural light.

[0032] Planting and management of the tested weeds and crops: A fixed amount of barnyard grass, goosegrass, crabgrass, foxtail grass, and goosegrass seeds were sown in plastic pots with a diameter of 9 cm, covered with 1-2 mm of soil, and placed in an enamel dish filled with water. Watering was carried out by bottom drip irrigation. After the water seeped to the soil surface, the pots were transferred to a glass greenhouse for later use.

[0033] Dosage and solution preparation: Five dosages were set for both BZ01 and the control pesticide benzoxazine: 3.75, 7.5, 15, 30, and 60 g active ingredient / ha, respectively, plus a blank control. Accurately measure the required amount of pesticide and add it directly to water, then dilute to the desired dosage using a doubling dilution method.

[0034] Efficacy investigation method and calculation formula: Fresh weight of each treatment was investigated 14 days after application. The fresh weight efficacy was calculated according to the following formula: Fresh weight efficacy (%) = (Control fresh weight - Treatment fresh weight) ÷ Control fresh weight × 100.

[0035] The control efficacy of BZ01 and benzoxazine against barnyard grass, Echinochloa crus-galli, Crataegus pinnatifida, and Eleusine indica is shown in Tables 1-4.

[0036] Table 1. Control efficacy of BZ01 and benzoxazole against barnyardgrass (post-emergence)

[0037] Table 2. Control efficacy of BZ01 and benzoxazine against Echinochloa crus-galli (post-emergence)

[0038] Table 3. Control efficacy of BZ01 and benzoxazole against barnyardgrass (post-emergence).

[0039] Table 4. Control efficacy of BZ01 and benzoxazine against goosegrass (post-emergence) 2. Indoor safety testing of rice Test crops: Two rice varieties: Japonica rice Longjing 31; Indica rice Y Liangyou 900 Planting and management of the test crop: A fixed quantity of rice seeds was sown in plastic pots with a diameter of 15 cm, covered with 2-3 cm of soil, and placed in an enamel dish filled with water. Watering was carried out by bottom drip irrigation. After sowing, the plants were moved to a glass greenhouse for cultivation and growth until ready for use.

[0041] Dosage and preparation of pesticide solution: In the rice safety test, four dosages were set for compound BZ01 of this invention, similar compounds CCXN-2-001 (Comparative Example 1) and CCXN-2-002 (Comparative Example 2), and the control pesticide benzoxazole, respectively: 15, 30, 60, and 120 g active ingredient / ha (four times the herbicidal dosage). A blank control was also added. The required amount of pesticide was accurately measured, dissolved in an appropriate amount of emulsifier and organic solvent, and then diluted with a certain amount of water using a double-dilution method to the required dosage for later use.

[0042] Treatment Design and Arrangement: Uniform foliar spraying of rice at the 3-4 leaf stage. Indoors, an ASS-3 type automatic control spraying system with fan-shaped nozzles was used for pesticide spraying. The spraying pressure and flow rate were adjusted according to the actual spraying area (1.1 m²). 2 Spray 50 mL of pesticide solution (equivalent to 30 L of water per acre), adjust the operating speed, and evenly arrange the plastic basins to be treated on the spraying platform for uniform spraying. Spray pressure: 0.35 MPa; fan-shaped nozzle flow rate: 800 mL / min. Spray from low to high dosage sequentially. Repeat each treatment 3 times. Apply the pesticide once. After spraying, allow to dry for one day, then place in a glass greenhouse and water regularly to keep it moist.

[0043] Crop survey: After application, investigate whether rice in each treatment shows any phytotoxicity symptoms. If so, record the symptoms and severity in detail. Twenty days after application, measure the fresh weight of rice in each treatment and calculate the fresh weight efficacy to determine the safety of the test agent to rice. Fresh weight efficacy (%) = (control fresh weight - treatment fresh weight) ÷ control fresh weight × 100. The safety of the test agent to rice decreases as the fresh weight efficacy value increases.

[0044] The effects of compounds BZ01 and benzoxazine on the fresh weight of japonica rice Longjing 31 are shown in Tables 5-1 and 5-2.

[0045] The effects of compounds BZ01 and benzoxazine on the fresh weight of indica rice Y Liangyou 900 are shown in Tables 6-1 and 6-2.

[0046] The effects of compound CCXN-2-001 on the fresh weight of japonica rice Longjing 31 and indica rice Y Liangyou 900 are shown in Tables 7-1 and 7-2.

[0047] The effects of compound CCXN-2-002 on the fresh weight of japonica rice Longjing 31 and indica rice Y Liangyou 900 are shown in Tables 8-1 and 8-2.

[0048] As can be seen from Tables 5-2 and 6-2, a dose of only 15 g ai / ha of benzoxazine can cause slight whitening in rice, while a dose of 30 g ai / ha can cause severe growth inhibition and whitening.

[0049] As can be seen from Tables 7-1 and 7-2, a dose of only 15g ai / ha of CCXN-2-001 can cause slight whitening in rice, while a dose of 30g ai / ha can cause severe whitening or slight deformity.

[0050] As can be seen from Tables 8-1 and 8-2, a dose of only 15g ai / ha of CCXN-2-002 can cause slight whitening and slight deformity in rice, while a dose of 30g ai / ha can cause severe whitening.

[0051] As can be seen from Tables 5-1 and 6-1, even with a dosage of BZ01 as high as 120 g ai / ha, the two rice varieties can still grow normally, breaking through the technical bottleneck that most rice varieties have poor tolerance to benzoxazole and that the use of benzoxazole leads to rice damage and yield reduction.

[0052] Therefore, compared with benzoxazine, CCXN-2-001, and CCXN-2-002, the compound BZ01 of this invention has better safety for rice.

[0053] Table 5-1 Effect of compound BZ01 on the fresh weight of rice (Japonica rice Longjing 31)

[0054] Table 5-2 Effects of benzoxazine on the fresh weight of rice (Japonica rice Longjing 31)

[0055] Table 6-1 Effects of compound BZ01 on the fresh weight of rice (Y Liangyou 900, an indica rice variety).

[0056] Table 6-2 Effects of benzoxazine on the fresh weight of rice (Y Liangyou 900 indica rice)

[0057] Table 7-1 Effect of CCXN-2-001 on the fresh weight of rice (Japonica Longjing 31)

[0058] Table 7-2 Effects of CCXN-2-001 on the fresh weight of rice (Y Liangyou 900, indica rice).

[0059] Table 8-1 Effects of CCXN-2-002 on the fresh weight of rice (Japonica Longjing 31)

[0060] Table 8-2 Effects of CCXN-2-002 on the fresh weight of rice (Indica rice Y Liangyou 900)

[0061] 3. Environmental safety assessment test Safety data of benzoxazine on aquatic organisms show that its toxicity varies among different aquatic organisms, with algae being more sensitive and fish and water fleas having relatively low toxicity. Specific data are as follows (benzoxazine, Pesticide Science and Management 2011, 32(6)) (Zhao Fangfang, Study on the toxic mechanism of herbicide benzoxazine on Chlorella, Zhejiang University of Technology, Master's thesis, 2017): Toxicity to fish: Rainbow trout 96-hour LC50 50 (Median lethal concentration) >100mg / L, which is classified as low toxicity according to the pesticide toxicity classification standards for fish.

[0062] Toxicity of Daphnia zebrina: 48-hour LC50 of Daphnia zebrina 50 >100mg / L, which is also considered low toxicity, indicates that benzoxazine has relatively weak acute toxicity to Daphnia magna.

[0063] Toxicity to algae: Green algae 96-hour EC50 50 The half-maximal effective concentration (HEC) was 17.2 mg / L⁴. Other studies have shown that the EbC of *Novoidea* after 96 hours... 50 The concentration was 47.0 mg / L². In Chlorella treated with low concentrations of benzoxazine (0.01 mg / L and 0.1 mg / L), growth inhibition was not obvious in the early stages of cultivation, but gradually became apparent over time. By day 7, the growth inhibition rates reached 25.34% and a relatively high level, respectively. In the 100 mg / L treatment group, the growth inhibition rate was as high as 85.62% by day 7. Furthermore, the study found that benzoxazine leads to the accumulation of reactive oxygen species in Chlorella cells, inducing oxidative stress, damaging the antioxidant system, significantly increasing malondialdehyde content, impairing cell membrane structure and function, reducing photosynthetic pigment content, downregulating the expression of photosynthesis-related genes, and affecting the photosynthetic process.

[0064] Toxicity of duckweed: Duckweed 7-day ErC 50 The half-maximal effective concentration (HMC) is 0.125 mg / L, EbC 50 The concentration was 0.009 mg / L, indicating that benzoxazine has relatively high toxicity to duckweed, especially its effect on its growth and reproduction.

[0065] Safety data from studies on aquatic organisms using BZ01 indicate that its toxicity varies among different aquatic organisms. It is more sensitive to algae, while its toxicity to fish and water fleas is relatively low. Specific data are as follows: Toxicity to fish: Zebrafish 96-hour LC50 50 (Median lethal concentration) >100mg / L, which is classified as low toxicity according to the pesticide toxicity classification standards for fish.

[0066] Toxicity to Daphnia: Daphnia macrocarpa 48-hour EC50 50 >100mg / L, according to the pesticide toxicity classification standard for Daphnia magna, it belongs to low toxicity.

[0067] Toxicity to algae: Chlorella 72-hour EC50 50 (Half-maximal effective concentration) > 100 mg / L. According to the pesticide toxicity classification standard for algae, it belongs to low toxicity.

[0068] Toxicity of duckweed: Duckweed 7-day ErC 50 (Half-maximal effective concentration) > 100 mg / L. According to the pesticide toxicity classification standard for duckweed, it belongs to low toxicity.

[0069] BZ01 is significantly safer than benzoxazine in aquatic environments.

[0070] Each test was conducted in accordance with the following standards: GB / T 31270.12-2014 "Test Guidelines for Environmental Safety Evaluation of Chemical Pesticides Part 12: Acute Toxicity Tests for Fish", GB / T 31270.13-2014 "Test Guidelines for Environmental Safety Evaluation of Chemical Pesticides Part 13: Acute Activity Inhibition Tests for Daphnia", GB / T 31270.14-2014 "Test Guidelines for Environmental Safety Evaluation of Chemical Pesticides Part 14: Algal Growth Inhibition Tests", and NY / T 3090-2017 "Test Guidelines for Inhibition of Duckweed Growth by Chemical Pesticides".

[0071] 4. Toxicity in mammals Test basis: GB / T 15670.2-2017 Acute oral toxicity test for pesticide registration toxicology Acute oral toxicity of BZ01 in rats: Suspensions with a concentration of 500 mg / mL were prepared using olive oil. Rats were administered a single oral dose of 5000 mg / kg of BZ01 suspension by gavage. After one exposure and two consecutive days of observation, no obvious abnormalities were observed in the rats. At the end of the observation period, surviving rats underwent necropsy, and no gross lesions were found in the major organs. LD50 50 >5000mg / kg. According to the acute oral toxicity classification standard in the "Regulations on Pesticide Registration Data", the acute oral toxicity of BZ01 rat is classified as slightly toxic.

[0072] Acute oral toxicity of benzoxazine in rats: LD50 50 >2000mg / kg.

[0073] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A benzoxam derivative or its agriculturally chemically acceptable salt for the control of stubborn resistant weeds in paddy fields, characterized in that, The benzoxazolone derivative is 4-(3-(4,5-dihydroisoxazo-3-yl)-2-methyl-4-(methanesulfonyl)benzoyl)-1-methyl-1H-pyrazole-5-yl diethylcarbamate, i.e., BZ01, with the molecular formula C 21 H 26 N4O6S, chemical structural formula as follows: 。 2. A pharmaceutical composition, characterized in that, It includes the benzoxazine derivative of claim 1 or an agriculturally chemically acceptable salt thereof.

3. The application of the benzoxazine derivative of claim 1 or its agriculturally chemically acceptable salt in the control of stubborn resistant weeds in paddy fields.

4. The application according to claim 3, characterized in that, Weeds that can be controlled include: barnyard grass, Echinochloa crus-galli, Crataegus pinnatifida, and Eleusine indica.

5. The application of the pharmaceutical composition according to claim 2 in the control of stubborn resistant weeds in paddy fields.

6. The application according to claim 5, characterized in that, Weeds that can be controlled include: barnyard grass, Echinochloa crus-galli, Crataegus pinnatifida, and Eleusine indica.

7. A pesticide for controlling stubborn resistant weeds in paddy fields, characterized in that, Its active ingredient is the benzoxazine derivative of claim 1 or its agriculturally chemically acceptable salt.

8. A pesticide for controlling stubborn resistant weeds in paddy fields, characterized in that, It comprises the pharmaceutical composition of claim 2.

9. The pesticide according to claim 8, characterized in that, The formulation of the pesticide is selected from any of the following: water dispersible agent, dispersible liquid, wettable powder, soluble powder, suspension, water emulsion, microemulsion, suspension emulsion, microcapsule suspension, emulsifiable concentrate, granules.

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