A herbicidal composition and its preparation method and application

Abstract

The present invention discloses a herbicide composition, its preparation method, and application. The composition comprises clomazone and either flufenacet or mefenacet. The weight ratio of clomazone to flufenacet is 1:0.27-4.44, and the weight ratio of clomazone to mefenacet is 1:1.11-17.78. The herbicide composition of the present invention can effectively control weeds in wheat and rice fields, effectively killing different weed groups. When used in combination, it exhibits a significant synergistic effect against malignant grass weeds in wheat and rice fields, significantly reducing herbicide dosage and improving safety for wheat and rice. The components of the combined agents complement each other in their herbicidal spectrum. When mixed, the herbicidal spectrum effectively covers a variety of common weeds in wheat and rice fields, extending the duration of action after application. The composition is highly active against resistant weeds that are extremely difficult to control in wheat and rice fields, and has significant market potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of agriculture, and in particular relates to a weed control composition and application thereof. Background Art

[0002] China is the world's largest producer of rice and wheat. Weeds are one of the major biological hazards faced by rice and wheat cultivation. Currently, herbicide use remains the most important means of controlling weeds in rice and wheat fields. Herbicide usage is increasing annually, placing increasing costs on growers. Therefore, efficient and safe weed control to ensure stable rice and wheat yields and quality safety is a fundamental task in my country's crop production.

[0003] At present, there are 13 herbicide-resistant weeds that have been clearly reported in China's wheat fields, including Beckmannia syzigachne, Japanese foxtail grass (Alopecurus japonicus), foxtail grass (Alopecurus aequalis), Polypogon fugax, Gunn's false grass (Sclerochloa kengiana), Galium aparine, Vicia sativa, Shepherd's purse (Capsella bursa-pastoris), Lithospermum marvense, Descurainia sophia, Myosoton aquaticum, Stellaria media, Rorippa indica); the herbicides involved in these resistant weeds are mainly acetyl-CoA carboxylase (ACCase) inhibitors, including aryloxyphenoxypropionates such as fenoxaprop-butyl and clodinafop-butyl, neophenylpyrazolines such as pinoxaden, and acetolactate synthase (ALS) inhibitors, including sulfonylureas such as bensulfuron-methyl and mesosulfuron-methyl, and triazolopyrimidine sulfonamides such as florasulam and pyrifos. These herbicides are all foliage treatment agents (also known as post-emergence herbicides, which are sprayed on the stems and leaves of weeds after they emerge, and are mainly absorbed by the stems and leaves to kill the weeds). Weeds in rice fields, including Echinochloa spp., Leptochloa chinensis, Digitaria sanguinalis, Monochoria korsakowii, Sagittaria trifolia, Cyperus difformis, and Ammannia arenaria, have developed resistance to a variety of herbicides. The most serious resistance targets include the quinolinecarboxylic acid herbicide quinclorac, the ALS inhibitors bensulfuron-methyl, pyrazosulfuron-methyl, and penoxsulam, and the ACCase inhibitor cyhalofop-butyl, all of which are foliar herbicides. Therefore, there is an urgent need for more practical herbicides to be introduced into production to effectively and safely address weed infestations while delaying the emergence of resistance to existing agents.

[0004] In general, rice and wheat weeds have a low level of resistance to soil treatment agents. Soil treatment agents, also known as pre-emergence herbicides, are sprayed on the soil surface before or during weed emergence, forming a film that is absorbed by the roots, stems, and leaves of the weeds. They primarily kill weeds during emergence and their early seedlings. Early weed seedlings are extremely vulnerable to environmental stresses, and the film in the soil persists for a long time. Therefore, it is extremely difficult for soil treatment agents to develop resistance. In most cases, failures in weed control after soil treatment are due to insufficient active ingredient content due to factors such as uneven distribution of the film and excessive degradation. Reducing the use of chemical pesticides has become a national commitment in my country. The continuous development of efficient, safe, and low-risk herbicides for rice and wheat soil treatment not only meets national needs but also reflects market development trends.

[0005] Clomazone is a systemic oxazolone herbicide, a deoxy-D-xylulose phosphate synthase (DOXP) inhibitor. It is primarily absorbed through plant roots and seedlings. By inhibiting DOXP, it disrupts the biosynthesis of plastidial isoprenoids and hinders the synthesis of carotenoids, resulting in the inability of susceptible plants to photosynthesize normally. The plants turn white, yellow, or lose their green color, and eventually stop growing and die. Clomazone is relatively safe and has a long-lasting effect. It is primarily used to control broadleaf weeds such as shepherd's purse, artemisia selengensis, chickweed, schizonepeta tenuifolia, speedwell, and speedwell. However, prior art clomazone primarily targets broadleaf weeds, requiring high dosages for wheat and rice field weeds. Its effectiveness against common and serious grass weeds in China's rice and wheat fields is limited. Summary of the Invention

[0006] Purpose of the invention: In order to solve the above-mentioned technical problems, the present invention aims to provide an efficient and safe herbicide composition for controlling weeds in wheat fields. The composition comprises diclofenac and any one of flufenacet and mefenacet, which solves the technical problem of the lack of control agents for resistant and difficult-to-control grass weeds, and has high weed control efficiency and low usage dosage.

[0007] The invention also provides a preparation method and application of the herbicidal composition.

[0008] Technical solution: In order to achieve the above-mentioned purpose, the herbicidal composition of the present invention comprises dichloroisothiazolin and any one of flufenacet and mefenacet.

[0009] Furthermore, the composition is clomazone and flufenacet, and the weight ratio thereof is 1:0.27-4.44.

[0010] Furthermore, the composition is clomazone and flufenacet, and the weight ratio thereof is 1:0.56-2.22.

[0011] More preferably, the preferred weight ratio of clomazone to flufenacet in the composition is 1:0.56-1.11.

[0012] Most preferably, the preferred weight ratio of clomazone and flufenacet in the composition is 1:1.11.

[0013] Furthermore, the composition is clomazone and mefenacet, and the weight ratio thereof is 1:1.11-17.78.

[0014] Furthermore, the composition is clomazone and mefenacet, and the weight ratio thereof is 1:2.22-8.89.

[0015] More preferably, the composition is a composition in which the preferred weight ratio of clomazone to mefenacet is 1:2.22-4.44.

[0016] Most preferably, the preferred weight ratio of clomazone to mefenacet in the composition is 1:4.44.

[0017] The preparation method of the herbicidal composition of the present invention comprises the following steps: mixing clomazone and any one of flufenacet and mefenacet.

[0018] The herbicidal composition of the present invention is used in preventing and controlling weeds or resistant weeds in wheat fields and rice fields.

[0019] Furthermore, the weeds are any one of grass weeds, broadleaf weeds and sedge weeds.

[0020] Furthermore, the resistant weeds are any one of Alopecurus macrostachya, Alopecurus macrostachya, Lolium multiflorum, Echinochloa crusgalli, Leptochloa chinensis or Echinochloa crusgalli.

[0021] Among them, the weeds are grass weeds and broad-leaved weeds, including but not limited to common weeds and difficult-to-control weeds in wheat fields and rice fields such as foxglove, giant alopecuroides, multiflora ryegrass, Japanese alopecuroides, chickweed, shepherd's purse, sophora flavescens, barnyard grass, kiwi fruit, and crabgrass.

[0022] Furthermore, when the herbicidal composition is a compound of clomazone and flufenacet, the dosage range is 27 to 216 g ai / hm 2 30~240g ai / hm 2 When the herbicidal composition is a mixture of clomazone and mefenacet, the dosage range is 27 to 108 g ai / hm 2 、120~480g ai / hm 2 .

[0023] Preferably, the dosage range of the combination of clomazone and flufenacet is 54 to 216 g a.i. / hm 2 、60~240g ai / hm 2 .

[0024] Preferably, the dosage range of the combination of clomazone and mefenacet is 54 to 108 g a.i. / hm 2 、240~480g ai / hm 2 .

[0025] More preferably, the dosage of the combination of clomazone and flufenacet is 54+60g ai / hm 2 .

[0026] More preferably, the dosage of the combination of clomazone and mefenacet is 54+240 g a.i. / hm 2 .

[0027] Furthermore, the application process is to control weeds in wheat fields and rice fields by spraying, mixing with fertilizer or mixing with sand.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0029] (1) The composition of the present invention has a synergistic effect. The two agents can effectively kill different groups of weeds, and the combination has a significant synergistic effect.

[0030] (2) The two agents have complementary herbicidal spectra. When used together, they can effectively cover grass and broad-leaved weeds, including common weeds in wheat fields such as gramineous weed, giant alopecuroides, multiflora ryegrass, Japanese alopecuroides, chickweed, shepherd's purse, sow's wormwood, barnyard grass, and chinensis.

[0031] (3) The composition of the present invention significantly reduces the dosage of flufenacet and improves the safety to wheat and rice.

[0032] (4) It can be used to control resistant weeds. At present, weeds in wheat and rice fields have not developed resistance to diclofenac and flufenacet. The combination of the two agents can effectively control various herbicide-resistant weeds that cause disasters in the fields.

[0033] (5) It can be used to control the currently difficult-to-control malignant grass weeds such as Japanese foxtail millet, Japanese foxtail millet, giant foxtail millet, multiflora ryegrass, barnyard grass, and Leptochloa chinensis, which are resistant to pesticides and thus alleviate the urgent need for the prevention and control of resistant and difficult-to-control grass weeds. DETAILED DESCRIPTION

[0034] Unless otherwise specified, the materials and reagents used in the following examples are all commercially available. Experimental methods without specific conditions specified in the examples are generally performed under conventional conditions or the conditions recommended by the manufacturer.

[0035] The present invention includes methyldisulfuron-methyl and pinoxaden-resistant Alopecurus japonicus, Alopecurus truncatus resistant to pinoxaden, Leptochloa chinensis resistant to cyhalofop-butyl, and Echinochloa crus-galli resistant (Progress in research on the mechanism of weed resistance to herbicides, Zhang Lingling et al., Journal of Pesticide Science, 2024, 26(4): 703-715); pinoxaden-resistant multiforum ryegrass (Study on the resistance of multiforum ryegrass (Lolium multiforum) to fenoxaprop-butyl in wheat fields and its control, Zhang Pei, 2018, Nanjing Agricultural University, doctoral dissertation); conventional Alopecurus japonicus, conventional Alopecurus truncatus, conventional multiforum ryegrass, conventional Leptochloa chinensis, and conventional Echinochloa crus-galli. All the above materials are preserved and provided by the laboratory of the College of Agriculture of Yangzhou University.

[0036] Example 1

[0037] Screening test on the formula ratio of diclofenac-flufenacil combination.

[0038] In order to screen the optimal formulation ratio of clomazone and flufenacet, a series of whole-plant bioassays were conducted in an artificial climate chamber.

[0039] 1.1 Test weeds: Alopecurus serrata, Alopecurus macrostachya, Lolium multiflorum, and Leptochloa chinensis. These four weed species are representative of major grass weeds that currently cause serious damage in wheat and rice fields. Significant populations of these four weed species have developed resistance to wheat foliar herbicides, primarily ACCase and ALS inhibitors. Resistance to flufenacet has not been reported.

[0040] 1.2 Binary compound formulation ratio screening test dosage setting:

[0041] 1) The dosage settings for each single dose are as follows:

[0042] Targeting weeds in wheat fields:

[0043] Clomazone (A): 0 (A0), 13.5 (A13.5), 27 (A27), 54 (A54) g ai / hm 2 ;

[0044] Flufenacet (B): 0 (B0), 15 (B15), 30 (B30), 60 (B60) g ai / hm 2 .

[0045] Targeting rice field weeds:

[0046] Clomazone (A): 0 (A0), 6.75 (A6.75), 13.5 (A13.5), 27 (A27) g ai / hm 2 ;

[0047] Flufenacet (B): 0 (B0), 7.5 (B7.5), 15 (B15), 30 (B30) g ai / hm 2 .

[0048] 2) The dosage setting of the binary compound formulation ratio screening is shown in Table 1:

[0049] Table 1 Binary compound formulation ratio screening dosage setting table

[0050]

[0051] 1.3 Test methods

[0052] Square plastic pots (7 × 7 × 7 cm) were filled with herbicide-free organic soil (pH 6.5, 2.4% organic matter content) and saturated with water. Full-grained seeds of sedgegrass, alopecuroides, ryegrass, and Leptochloa chinensis were selected, with 20 seeds sown per pot. A layer of fine soil (approximately 3 mm thick) was applied to the seeds in the pots. Before sowing, sedgegrass seeds were rubbed between the palms of both hands to rupture the air sacs attached to the seeds and promote germination. The pots were placed in a 44 × 33 × 10 cm thickened plastic transfer box (pre-filled with 2 cm of clean water) and cultured in an artificial climate chamber. The wheat field weeds (sedgegrass, alopecuroides, and Leptochloa chinensis) were cultured under the following conditions: 15°C light for 12 h, 10°C dark for 12 h; the rice field weed Leptochloa chinensis was cultured under the following conditions: 30°C light for 12 h, 20°C dark for 12 h. During the experiment, a 0.5cm to 1cm water layer was maintained in the transfer box to keep the soil in the small white box moist through water absorption. Each treatment was repeated in four small pots. When the weed seedlings in the test pots reached the 0.5-1 leaf stage, they were treated with herbicides by spraying, while the control group was sprayed with an equal amount of water. Spraying was carried out using a walking type pressure-stabilized spray tower with a spray height of 20cm, a flat fan nozzle with a spray width of 50cm, and a pressure of 200kPa. The spray liquid volume corresponds to a field spray volume of 45L water / hm2. 2 45 days after the weed treatment in the wheat field and 30 days after the weed treatment in the rice field, the fresh weight of the aboveground part of the test weeds in each small flower pot was collected and weighed.

[0053] The fresh weight inhibition rate (E) and theoretical fresh weight inhibition rate (E0) of weeds in different treatments of single agent and binary combination herbicide were calculated. The Gowing method was used to evaluate the joint action type of binary combination herbicides by comparing E and E0 values.

[0054] Measured fresh weight inhibition rate (E) = (fresh weight of control group – fresh weight of treatment group) ÷ fresh weight of control group × 100%

[0055] Theoretical fresh weight inhibition rate (E0) = (X + Y – XY) × 100%

[0056] Wherein, E0 is the theoretical fresh weight inhibition rate of the combination of clomazone and flufenacet, X is the measured fresh weight inhibition rate of clomazone alone, and Y is the measured fresh weight inhibition rate of flufenacet alone.

[0057] When E–E0>10%, it indicates that the two herbicides have a synergistic effect; when E–E0<-10%, it indicates that the two herbicides have an antagonistic effect; and when the E–E0 value is between -10% and 10%, it indicates an additive effect.

[0058] 1.4 Test results

[0059] 1) Combined effects of clomazone and flufenacet on sedge grass

[0060] Table 2 The measured fresh weight inhibition rate E (%) of diclofenac-flufenacil mixtures with different ratios on sedge grass

[0061]

[0062] Table 3 Theoretical fresh weight inhibition rate E0 (%) of diclofenac-flufenacil mixtures with different ratios on sedge grass

[0063]

[0064] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0065] Table 4 The combined effect values ​​of different ratios of clomazone and flufenacet on Euphrasia officinalis [(E–E0)×100]

[0066]

[0067] Note: E–E0>10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0068] As shown in Table 2, the inhibitory effect of clomazone alone on sedge grass was low; the inhibitory effect of flufenacet alone at 60 g ai / hm2 was 2 45 days after treatment, the fresh weight inhibition rate of clomazone was only 43%, and the single dose of clomazone 54g ai / hm 245 days after treatment, the fresh weight inhibition rate of cypermethrin was only 9.4%, while the combined inhibition rate of the two herbicides at the same dose reached 83.73%, a significant improvement. The theoretical inhibition rate of the two herbicides combined was calculated based on this, as shown in Table 3. By comparing the measured inhibition rates and theoretical inhibition rates of the two herbicides in different combinations, the combined effect of the two herbicides on cypermethrin was further investigated, as shown in Table 4. The results showed that clomazone and flufenacet had a significant combined effect, with clomazone at 13.5 to 54 g·i. / hm2. 2 With flufenacet 15-60g ai / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, demonstrating a very significant synergistic effect.

[0069] 2) Combined effects of clomazone and flufenacet on Alopecurus serrata

[0070] Table 5 The measured fresh weight inhibition rate E (%) of diclofenac-flufenacil combination at different ratios on Alopecurus macrostachya

[0071]

[0072] Table 6 Theoretical fresh weight inhibition rate E0 (%) of dichloroisothiazolinone-flufenacet combination at different ratios on Alopecurus macrostachya

[0073]

[0074] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0075] Table 7 Combined effect values ​​of different ratios of clomazone and flufenacet on Alopecurus macrostachya [(E–E0)×100]

[0076]

[0077] Note: E–E0>10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0078] As shown in Table 5, the inhibitory effect of clomazone alone on Alopecurus macrostachya was poor; the inhibitory effect of flufenacet alone at 60 g a.i. / hm2 on Alopecurus macrostachya was poor; 2 45 days after treatment, the fresh weight inhibition rate of Alopecurus macrostachya was only 30%, and a single dose of clomazone 54g ai / hm 245 days after treatment, the fresh weight inhibition rate of Alopecurus serrata was only 7.61%, while the combined inhibition rate of the two herbicides at the same dose reached 72.48%, a significant improvement. The theoretical inhibition rate of the two herbicides combined was calculated based on this, as shown in Table 6. By comparing the measured inhibition rates and theoretical inhibition rates of the two herbicides in different combinations, the combined effect of the two herbicides on Alopecurus serrata was further investigated, as shown in Table 7. The results showed that there was a significant combined effect between clomazone and flufenacet, with clomazone at 13.5-54 g ai / hm2. 2 With flufenacet 15-60g ai / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, demonstrating a very significant synergistic effect.

[0079] 3) Combined effects of clomazone and flufenacet on Lolium multiflorum

[0080] Table 8 Measured fresh weight inhibition rate E (%) of diclofenac-flufenacil combination at different ratios on multifloral ryegrass

[0081]

[0082] Table 9 Theoretical fresh weight inhibition rate E0 (%) of diclofenac-flufenacil combination at different ratios on multifloral ryegrass

[0083]

[0084] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0085] Table 10 The combined effect values ​​of different ratios of clomazone and flufenacet on multiflora ryegrass [(E–E0)×100]

[0086]

[0087]

[0088] Note: E–E0>10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0089] As shown in Table 8, a single dose of clomazone 54g ai / hm 2 The inhibition rate of flufenacet on multifloral ryegrass was only 11%; the inhibitory effect of flufenacet on multifloral ryegrass was poor, and 60g ai / hm 245 days after treatment, the fresh weight inhibition rate of multifloral ryegrass was only 32%, while the combined inhibition rate of the two herbicides at the same dose reached 80.74%, a significant improvement. The theoretical inhibition rate of the two herbicides combined was calculated based on this, as shown in Table 9. By comparing the measured inhibition rates and theoretical inhibition rates of the two herbicides in different combinations, the combined effect of the two herbicides on multifloral ryegrass was further investigated, as shown in Table 10. The results showed that clomazone and flufenacet had a significant combined effect, with clomazone at 13.5-54 g ai / hm2. 2 With flufenacet 15-60g ai / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, demonstrating a very significant synergistic effect.

[0090] 4) Combined Effect of Clomazone and Flufenacet on Leptochloa chinensis

[0091] Table 11 Inhibition rate E (%) of different ratios of clomazone-flufenacil combination on the measured fresh weight of Leptochloa chinensis

[0092]

[0093] Table 12 Theoretical fresh weight inhibition rate E0 (%) of dichloroisothiazolinone-flufenacet combination at different ratios on Leptochloa chinensis

[0094]

[0095] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0096] Table 13 The combined effect values ​​of different ratios of clomazone and flufenacet on Leptochloa chinensis [(E–E0)×100]

[0097]

[0098] Note: E–E0>10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0099] As shown in Table 11, a single dose of 27 g ai / hm2 of clomazone 2 Thirty days after treatment, the inhibition rate on Leptochloa chinensis was only 29%; a single dose of flufenacet 30 g ai / hm 2The inhibition rate of the fresh weight of Leptochloa chinensis was only 47% when the two herbicides were used in combination at the same dose, while the inhibition rate reached 97.12% at the same dose, which was a significant improvement. The theoretical inhibition rate of the two herbicides was calculated based on this, as shown in Table 12. By comparing the measured inhibition rate and theoretical inhibition rate of the two herbicides in different combinations, the combined effect of the two herbicides on Leptochloa chinensis was investigated, as shown in Table 13. The results showed that there was a significant combined effect of clomazone and flufenacet, with clomazone at 6.75-27 g ai / hm2. 2 With flufenacet 7.5-30g ai / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, demonstrating a very significant synergistic effect.

[0100] 1.6 Test Conclusion

[0101] The four weeds selected in this study are all resistant and difficult-to-control grass weeds that cause serious damage to wheat or rice fields. The above research results show that the combination of diclofenac and flufenacet has outstanding inhibitory effects and combined synergistic effects on various weeds.

[0102] Further analysis of the ratio of diclofenac and flufenacet in the formula showed that the content of diclofenac was 6.75-54 g.i. / hm. 2 With flufenacet 15-60g ai / hm 2 or clomazone 6.75-27 g ai / hm 2 With flufenacet 7.5-30g ai / hm 2 The different dosage combinations all showed synergistic effects. Therefore, the weight ratio of clomazone and flufenacet is in the range of clomazone: flufenacet = 1: (0.27-4.44).

[0103] Clomazone 27~54g ai / hm 2 With flufenacet 30-60g ai / hm 2 or clomazone 13.5-27 g ai / hm 2 With flufenacet 15-30g ai / hm 2 The combined effect values ​​(E–E0) of various combinations were all above 30%. Therefore, the optimized ratio range of clomazone and flufenacet was: clomazone:flufenacet = 1:(0.56~2.22).

[0104] Clomazone 54g ai / hm 2 With flufenacet 30-60g ai / hm 2 or clomazone 27g a.i. / hm2 With flufenacet 15-30g ai / hm 2 The combined effect values ​​(E–E0) of various combinations were significantly higher than those of other combinations. Therefore, the optimal weight ratio of clomazone to flufenacet is: clomazone:flufenacet = 1:(0.56-1.11). The preferred dosage ranges of clomazone and flufenacet are 54-216 g ai / hm, respectively. 2 、60~240g ai / hm 2 The most preferred dosage for both is 54+60g ai / hm 2 .

[0105] Example 2

[0106] Safety assessment of clomazone-flufenacil combination on wheat and rice

[0107] To determine the safety of a combination of clomazone and flufenacet on wheat and rice, a series of whole-plant bioassays were conducted in an artificial climate chamber. Based on the results of Example 1, a combination of clomazone and flufenacet at a ratio of 1:1.11 was used for wheat and rice safety testing. The results showed that clomazone + flufenacet had a significant effect on the safety of wheat and rice at 54 + 60 g ai / hm2. 2 The highest inhibition effect on wheat field weeds was achieved under the treatment and the synergistic effect was good. The diclofenac + flufenacet at 27+30ga.i. / hm 2 Under the treatment, the highest inhibitory effect on rice field weeds was achieved and the synergistic effect was good. Therefore, if double and quadruple the dosage of this dosage combination is used to treat wheat or rice field weeds and it is still safe for wheat and rice fields, it proves that this series of compound agents has excellent safety and great potential.

[0108] 2.1 Test crops: Yangmai 23, Jimai 22, japonica rice (Nanjing 9108), and indica rice (Yongyou 2640).

[0109] 2.2 Dosage setting:

[0110] Safety test dose for wheat:

[0111] Clomazone+flufenacil: 0+0, 108+120g ai / hm 2 、216+240a.i. / hm 2

[0112] Safety test dose for rice:

[0113] Clomazone+flufenacil: 0+0, 54+60g ai / hm 2、108+120g ai / hm 2

[0114] 2.3 Test method:

[0115] The safety of a combination of clomazone and flufenacet was tested on wheat at the 0.5- to 1-leaf stage and rice at the 4- to 5-leaf stage. Herbicide-naive organic soil (pH 6.5, 2.4% organic matter content) was placed in plastic boxes measuring 22 × 15 × 10 cm. The soil layer within each box was approximately 8 cm high, and holes were punched in the bottom of the box to facilitate water absorption. The boxes were placed in a 44 × 33 × 10 cm thickened plastic transfer box (pre-filled with 2 cm of clean water) and incubated in an artificial climate chamber. During the experiment, a water layer of approximately 0.5 cm was maintained in the transfer box to ensure the soil remained moist through water absorption. Four replicates were used for each treatment. Wheat seedlings were cultured under the following conditions: 15°C light for 12 h, 10°C dark for 12 h; rice seedlings were cultured under the following conditions: 30°C light for 12 h, 20°C dark for 12 h. Wheat was sprayed at the 0.5- to 1-leaf stage, and rice at the 4- to 5-leaf stage. The control group was sprayed with an equal amount of water. A 200 kPa spray tower was used for spraying. The spray height was 20 cm, the fan-shaped nozzle had a spray width of 50 cm, and the pressure was 200 kPa. The spray volume corresponded to a field spray volume of 45 L water / hm2. 2 Thirty days after application, the fresh weight of the aboveground part of the wheat in each plastic box was collected and weighed. The inhibition rate of the fresh weight of the aboveground part of the wheat under different treatments was calculated.

[0116] Fresh weight inhibition rate = (fresh weight of control group – fresh weight of treatment group) ÷ fresh weight of control group × 100%

[0117] 2.4 Test results

[0118] The effects of the combination of clomazone and flufenacet on the fresh weight of wheat and the aboveground part of wheat under different dosage treatments are shown in Table 11. The results show that the combination of clomazone and flufenacet in a ratio of 1:1.11 has good safety for wheat at various dosages, and the fresh weight inhibition rates of wheat and rice are both <10%.

[0119] Table 14 Inhibition rate of diclofenac-flufenacil combination on the fresh weight of aboveground parts of wheat and rice (%).

[0120]

[0121] *: The dosage is that of clomazone+flufenacil.

[0122] 2.5 Test Conclusion

[0123] As shown in Table 14, the mixture of clomazone and flufenacet was prepared at a ratio of 1:1.11 at a concentration of 114-228 g ai / hm2. 2 The treatment has good safety to rice. The compounding ratio of clomazone and flufenacet is 1:1.11 and the concentration is 228-456g ai / hm 2 It has good safety to wheat under treatment.

[0124] Example 3

[0125] Determination of the inhibitory effect of clomazone-flufenacil combination on resistant weeds

[0126] To determine the inhibitory effect of a combination of clomazone and flufenacet on herbicide-resistant weeds that cause severe damage in wheat and rice fields, a series of whole-plant bioassays were conducted in an artificial climate chamber.

[0127] 3.1 Test weeds: Mesosulfuron-methyl and pinoxaden-resistant Alopecurus sutchuenensis, Alopecurus sutchuenensis-resistant, Lolium multiflorum-resistant, Leptochloa crusgalli-resistant, Echinochloa crusgalli-resistant, conventional Alopecurus sutchuenensis, conventional Alopecurus sutchuenensis, conventional Lolium multiflorum-resistant, conventional Leptochloa crusgalli, and conventional Echinochloa crusgalli. Mesosulfuron-methyl and bensulfuron-methyl are sulfonylurea ALS inhibitors, while pinoxaden is a neophenylpyrazoline ACCase inhibitor. Mesosulfuron-methyl and pinoxaden are the most widely used and widely used herbicides for foliar treatment of grass weeds in wheat fields. Metamifop is an ACCase inhibitor and is currently an important herbicide for controlling Leptochloa crusgalli and Echinochloa crusgalli in rice fields. On the other hand, ragwort, foxtail millet, and multiflora ryegrass are the most severely herbicide-resistant weeds in my country's wheat fields, while barnyardgrass and clematis chinensis are the most severely herbicide-resistant weeds in my country's rice fields. Therefore, this example uses these resistant weed populations as test subjects and conventional populations as controls to further investigate the potential of clomazone / flufenacet for controlling resistant weeds in wheat and rice fields.

[0128] 3.2 Herbicide dosage setting:

[0129] Clomazone + flufenacet: 108 + 120g ai / hm 2 、216+240g ai / hm 2

[0130] Mesosulfuron: 15.75 g ai / hm2 2 , the upper limit of the dosage of mesosulfuron registered for use in wheat fields in China.

[0131] Pinoxaden: 75g ai / hm 2 , the upper limit of the dosage of pinoxaden registered for use in wheat fields in China.

[0132] Metamifop: 120g ai / hm 2 , the upper limit of the dosage of oxadipamide registered for use in rice fields in China.

[0133] 3.3 Test method:

[0134] Plastic plant pots with a diameter of 9 cm and a height of 10 cm were filled with herbicide-free organic soil (pH 6.5, organic matter content 2.4%) and watered until saturated. Weed seeds with plump seeds were selected for testing, and 20 seeds were sown in each pot. After sowing, a layer of fine soil (approximately 3 mm thick) was covered on the seeds. The pots were placed in a 44×33×10 cm thickened plastic transfer box (pre-filled with 2 cm of clean water) and cultured in an artificial climate chamber. During the experiment, a 0.5 cm layer of water was maintained in the transfer box to keep the soil inside the small white box moist through water absorption. Each treatment was replicated in four pots. The artificial climate chamber for cultivating sedge grass, giant alopecuroides, and multiflora ryegrass was set at 15°C for 12 hours of light and 10°C for 12 hours of darkness; the artificial climate chamber for cultivating barnyard grass and Leptochloa chinensis was set at 30°C for 12 hours of light and 20°C for 12 hours of darkness.

[0135] The test weeds treated with mesosulfuron, pinoxaden, and oxadix were transplanted into each small flower pot at the 2-3 leaf stage, and 10 best-growing seedlings were retained in each small flower pot. The herbicides were treated with stem and leaf spray at the 3-5 leaf stage, and the control group was sprayed with an equal amount of water. The test weeds treated with clomazone + flufenacet were treated with a spray method at the 0.5-1 leaf stage, and the control group was sprayed with an equal amount of water. The spray was carried out using a walking type pressure-stabilizing spray tower with a spray height of 20 cm, a flat fan nozzle with a spray width of 50 cm, and a pressure of 200 KPa. The spray liquid volume corresponds to a field spray volume of 45 L water / hm2. 2 30 days after application, the aboveground fresh weight of the test plants in each plastic box was collected and weighed, and the inhibition rate of the aboveground fresh weight of the different treatments was calculated.

[0136] Fresh weight inhibition rate = (fresh weight of control group – fresh weight of treatment group) ÷ fresh weight of control group × 100%

[0137] 3.4 Test results

[0138] The effects of the combination of clomazone and flufenacet on the fresh weight of the aboveground parts of the test weeds under different dosages are shown in Tables 15 and 16. The results show that the inhibition rates of the combination of clomazone and flufenacet on the resistant weed populations under each treatment were consistent with those of the corresponding sensitive populations, and all the test weeds were effectively killed.

[0139] Table 15 Inhibition rate of aboveground fresh weight of grass weeds in resistant and conventional wheat fields by different herbicides (%)

[0140]

[0141] Table 16 Inhibition rate of aboveground fresh weight of grass weeds in resistant and conventional rice fields by different herbicides (%)

[0142]

[0143] 3.5 Test conclusion

[0144] Dichloroisothiazolin-flufenacil can be used to control resistant weeds in wheat and rice fields. It can not only be used for the prevention and control of conventional weeds, Alopecurus macrostachya, Lolium multiflorum, Echinochloa crus-galli, and Leptochloa chinensis, but can also be used for the prevention and control of related resistant populations.

[0145] Example 4

[0146] Screening test on the formula ratio of diclofenac and mefenacet combination.

[0147] In order to screen the optimal formulation ratio of clomazone and mefenacet, a series of whole-plant bioassays were conducted in an artificial climate chamber.

[0148] 4.1 Test Weeds: Echinochloa crus-galli, Leptochloa chinensis, and Digitaria sanguinalis. These three weed species are representative of serious and malignant grass weeds that currently infest wheat and rice fields. Significant populations of these weeds have developed resistance to foliar herbicides primarily consisting of ACCase and ALS inhibitors in rice fields. However, no populations have been reported to be resistant to mefenacet.

[0149] 4.2 Binary compound formulation ratio screening test agent dosage setting:

[0150] 1) The dosage settings for each single dose are as follows:

[0151] Clomazone (A): 0 (A0), 6.75 (A6.75), 13.5 (A13.5), 27 (A27) g ai / hm 2 ;

[0152] Mefenacet (B): 0 (B0), 30 (B30), 60 (B60), 120 (B120) g ai / hm 2 .

[0153] 2) The dosage setting for the binary compound formulation ratio screening is shown in Table 17:

[0154] Table 17 Binary compound formulation ratio screening dosage setting table

[0155] <h2 style=";text-align:left;direction:ltr">A0B0 <h2 style=";text-align:left;direction:ltr"> A6.75B0 <h2 style=";text-align:left;direction:ltr"> A13.5B0 <h2 style=";text-align:left;direction:ltr"> A27B0 <h2 style=";text-align:left;direction:ltr"> A0B30 <h2 style=";text-align:left;direction:ltr"> A6.75B30 <h2 style=";text-align:left;direction:ltr"> A13.5B30 <h2 style=";text-align:left;direction:ltr"> A27B30 <h2 style=";text-align:left;direction:ltr"> A0B60 <h2 style=";text-align:left;direction:ltr"> A6.75B60 <h2 style=";text-align:left;direction:ltr"> A13.5B60 <h2 style=";text-align:left;direction:ltr"> A27B60 <h2 style=";text-align:left;direction:ltr"> A0B120 <h2 style=";text-align:left;direction:ltr"> A6.75B120 <h2 style=";text-align:left;direction:ltr"> A13.5B120 <h2 style=";text-align:left;direction:ltr"> A27B120

[0156] 4.3 Test methods

[0157] Square plastic plant pots measuring 7 x 7 x 7 cm were filled with herbicide-free organic soil (pH 6.5, 2.4% organic matter content) and watered to saturation. Full-grained seeds of Echinochloa crus-galli, Leptochloa chinensis, and Digitaria sanguinalis were selected and 20 seeds were sown per pot. A layer of fine soil (approximately 3 mm thick) was applied over the seeds in the pots. The pots were placed in a 44 x 33 x 10 cm thickened plastic transfer box (pre-filled with 2 cm of clean water) and incubated in an artificial climate chamber at 15°C for 12 hours of light and 10°C for 12 hours of darkness. During the experiment, a 0.5 cm to 1 cm layer of water was maintained in the transfer box to allow the soil in the small white box to remain moist through water absorption. Four replicate pots were used for each treatment. When the weed seedlings in the test pots reached the 0.5- to 1-leaf stage, they were sprayed with herbicides. The control group was sprayed with an equal amount of water. The spraying is carried out using a walking type pressure-stabilized spray tower, with a spray height of 20cm, a flat fan nozzle with a spray width of 50cm, and a pressure of 200KPa. The spray liquid volume corresponds to a field spray volume of 45L water / hm2. 2 Thirty days after application, the fresh weight of the aboveground parts of the test weeds in each small flower pot was collected and weighed.

[0158] The fresh weight inhibition rate (E) and theoretical fresh weight inhibition rate (E0) of weeds in different treatments of single agent and binary combination herbicide were calculated. The Gowing method was used to evaluate the joint action type of binary combination herbicides by comparing E and E0 values.

[0159] Measured fresh weight inhibition rate (E) = (fresh weight of control group – fresh weight of treatment group) ÷ fresh weight of control group × 100%

[0160] Theoretical fresh weight inhibition rate (E0) = (X + Y – XY) × 100%

[0161] Wherein, E0 is the theoretical fresh weight inhibition rate of the combination of clomazone and mefenacet, X is the measured fresh weight inhibition rate of clomazone alone, and Y is the measured fresh weight inhibition rate of mefenacet alone.

[0162] When E–E0>10%, it indicates that the two herbicides have a synergistic effect; when E–E0<-10%, it indicates that the two herbicides have an antagonistic effect; and when the E–E0 value is between -10% and 10%, it indicates an additive effect.

[0163] 4.4 Test results

[0164] 1) Combined effects of clomazone and mefenacet on barnyardgrass

[0165] Table 18 Measured fresh weight inhibition rate E (%) of dichloroisothiazolinone-mefenacet combination at different ratios on barnyardgrass

[0166]

[0167] Table 19 Theoretical fresh weight inhibition rate E0 (%) of dichloroisothiazolinone-mefenacet combination at different ratios on barnyardgrass

[0168]

[0169] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0170] Table 20 The combined effect values ​​of clomazone and mefenacet at different ratios on barnyardgrass [(E–E0)×100]

[0171]

[0172] Note: E–E0>10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0173] As shown in Table 18, the inhibitory effect of clomazone alone on barnyard grass was low; the inhibitory effect of clomazone alone at 27 g a.i. / hm2 on barnyard grass was low; 2 Thirty days after treatment, the fresh weight inhibition rate of barnyardgrass was only 20.69%. 2 Thirty days after treatment, the fresh weight inhibition rate of the test barnyardgrass was only 36%, while the combined use of the two herbicides at the same dose achieved an inhibition rate of 86.93%, a significant improvement. The theoretical inhibition rate of the combined use of the two herbicides was calculated based on this, as shown in Table 19. By comparing the measured inhibition rates and theoretical inhibition rates of the two herbicides in different combinations, the combined effect of the two herbicides on barnyardgrass was further investigated, as shown in Table 20. The results showed that clomazone and mefenacet had a significant combined effect, with clomazone at 6.75-27 g ai / hm2. 2 With mefenacet 30-120g ai / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, that is, a synergistic effect was shown.

[0174] 2) Combined effects of clomazone and mefenacet on Leptochloa chinensis

[0175] Table 21 Inhibition rate (E) of different ratios of clomazone-mefenacet combination on the measured fresh weight of Leptochloa chinensis

[0176]

[0177] Table 22 Theoretical fresh weight inhibition rate E0 (%) of dichloroisothiazolinone-mefenacet combination at different ratios on Leptochloa chinensis

[0178]

[0179] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0180] Table 23 The combined effect values ​​of different ratios of clomazone and mefenacet on Leptochloa chinensis [(E–E0)×100]

[0181]

[0182] Note: E–E0 > 10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), indicating no combined effect.

[0183] As shown in Table 21, a single dose of 27 g ai / hm2 of clomazone 2 Thirty days after treatment, the inhibition rate on Leptochloa chinensis was only 29%; a single dose of mefenacet at 120 g ai / hm2 2 Thirty days after treatment, the fresh weight inhibition rate of Leptochloa chinensis was only 44%, while the combined inhibition rate of the two herbicides at the same dose reached 96.28%, a significant improvement. The theoretical inhibition rate of the two herbicides combined was calculated based on this, as shown in Table 22. By comparing the measured inhibition rates and theoretical inhibition rates of the two herbicides in different combinations, the combined effect of the two herbicides on Leptochloa chinensis was investigated, as shown in Table 23. The results showed that clomazone and mefenacet had a significant combined effect, with clomazone at 6.75-27 g ai / hm2. 2 With mefenacet 30~120g a.i. / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, that is, a synergistic effect was shown.

[0184] 3) Combined Effect of Clomazone and Mefenacet on Crabgrass

[0185] Table 24 Measured fresh weight inhibition rate E (%) of dichloroisothiazolinone-mefenacet combination at different ratios on crabgrass

[0186]

[0187] Table 25 Theoretical fresh weight inhibition rate E0 (%) of dichloroisothiazolinone-mefenacet combination at different ratios on crabgrass

[0188]

[0189] “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), and there is no combined effect.

[0190] Table 26 The combined effect values ​​of different ratios of clomazone and mefenacet on crabgrass [(E–E0)×100]

[0191]

[0192] Note: E–E0 > 10% indicates a synergistic effect. “ / ”: The theoretical fresh weight inhibition rate (E0) under single-dose treatment is equal to the measured fresh weight inhibition rate (E), indicating no combined effect.

[0193] As shown in Table 24, the inhibitory effect of clomazone alone on crabgrass was poor. 2 Thirty days after treatment, the inhibition rate of crabgrass was only 23.28%; a single dose of mefenacet 120g ai / hm 2 Thirty days after treatment, the fresh weight inhibition rate of crabgrass was 38%, while the inhibition rate of the combined use of the two herbicides at the same dose reached 88.57%, a significant improvement. The theoretical inhibition rate of the combined use of the two herbicides was calculated based on this, as shown in Table 25. By comparing the measured inhibition rate and theoretical inhibition rate of the two herbicides in different combinations, the combined effect of the two herbicides on crabgrass was investigated, as shown in Table 26. The results showed that clomazone and mefenacet had a significant combined effect, with clomazone at 6.75-27 g a.i. / hm2. 2 With mefenacet 30-120g ai / hm 2 The different dosage combinations all showed that the measured inhibition rate exceeded the theoretical inhibition rate by more than 20%, that is, a synergistic effect was shown.

[0194] 4.6 Test Conclusion

[0195] The three weeds selected in this study are all resistant and difficult-to-control grass weeds that cause serious damage to rice fields. The above research results show that the combination of diclofenac and mefenacet has outstanding inhibitory effects and combined synergistic effects on various weeds.

[0196] Further analysis of the ratio of diclofenac and mefenacet in the formula showed that diclofenac was 6.75-27 g ai / hm2. 2 With mefenacet 30-120g ai / hm 2 The different dosage combinations all showed synergistic effects. Therefore, the ratio range of clomazone and mefenacet is: clomazone: mefenacet = 1: (1.11-17.78).

[0197] Clomazone 13.5~27g ai / hm 2 With mefenacet 60-120g ai / hm 2 The combined effect values ​​(E–E0) of various combinations were all above 30%. Therefore, the optimized ratio range of diclofenac to mefenacet was: diclofenac: mefenacet = 1:(2.22~8.89).

[0198] Clomazone 27g ai / hm 2 With mefenacet 60-120g ai / hm 2 The combined effect values ​​(E–E0) of various combinations were significantly higher than those of other combinations. Therefore, the optimal ratio of clomazone to mefenacet was: clomazone: mefenacet = 1:(2.22-4.44). The optimal dosage ranges of clomazone and mefenacet were 54-108 g ai / hm, respectively. 2 、240~480g ai / hm 2 The most preferred dosage for both is 54+240g ai / hm 2 . .

[0199] Example 5

[0200] Safety assessment of clomazone-mefenacet combination on rice

[0201] To determine the safety of a clomazone / mefenacet combination on wheat, a series of whole-plant bioassays were conducted in a climatic chamber. Based on the previous results, a clomazone:mefenacet ratio of 1:4.44 was used for the wheat safety test.

[0202] 5.1 Test crops: Japonica rice (Nanjing 9108) and Indica rice (Yongyou 2640).

[0203] 5.2 Dosage setting:

[0204] Clomazone+mefenacet: 0+0, 27+120, 54+240, 108+480g ai / hm 2

[0205] 5.3 Test method:

[0206] The safety of the combination of clomazone and mefenacet on rice at the 4th to 5th leaf stage was tested respectively.

[0207] Plastic boxes measuring 22 × 15 × 10 cm were filled with herbicide-free organic soil (pH 6.5, organic matter content 2.4%). The soil layer within each box was approximately 8 cm high, and holes were punched in the bottom of the box to facilitate water absorption. The boxes were placed in a 44 × 33 × 10 cm thickened plastic transfer box (pre-filled with 2 cm of clean water) and incubated in an artificial climate chamber with a 12-hour light cycle at 30°C and a 12-hour dark cycle at 20°C. During the experiment, a 0.5 cm water layer was maintained within the transfer box to maintain moisture within the box through water absorption. Four replicates were used for each treatment. Treatments were sprayed when rice plants were at the 4th to 5th leaf stage, while the control group was sprayed with an equal amount of clean water. Spraying was performed using a row-type, pressure-stabilized spray tower with a spray height of 20 cm, a flat fan nozzle with a spray width of 50 cm, and a pressure of 200 kPa. The spray volume corresponded to a field spray volume of 45 L of water / hm2. 2 Thirty days after application, the fresh weight of the aboveground part of the wheat in each plastic box was collected and weighed. The inhibition rate of the fresh weight of the aboveground part of the wheat under different treatments was calculated.

[0208] Fresh weight inhibition rate = (fresh weight of control group – fresh weight of treatment group) ÷ fresh weight of control group × 100%

[0209] 5.4 Test results

[0210] The effects of the combination of clomazone and mefenacet on the fresh weight of the aboveground part of rice under different dosage treatments are shown in Table 27. The results show that the combination of clomazone and mefenacet in a ratio of 1:4.44 has good safety for wheat at various dosages, and the fresh weight inhibition rates of wheat and rice are both <10%.

[0211] Table 27 Inhibition rate of dichloroisothiazolin-mefenacet combination on fresh weight of aboveground parts of wheat and rice (%).

[0212]

[0213] *: The dosage is the dosage of clomazone+mefenacet.

[0214] 5.5 Test conclusion

[0215] The mixture of clomazone and mefenacet is 1:4.44, with a concentration of 147-588 g ai / hm2. 2 The treatment has good safety to rice in the 4-5 leaf stage.

[0216] Example 6

[0217] Determination of the inhibitory effect of clomazone-mefenacet combination on resistant weeds

[0218] To determine the inhibitory effect of a combination of clomazone and mefenacet on herbicide-resistant weeds that are serious pests in rice fields, a series of whole-plant bioassays were conducted in an artificial climate chamber.

[0219] 6.1 Test Weeds: Metamifop-resistant Leptochloa chinensis, Metamifop-resistant Echinochloa crusgalli, conventional Echinochloa crusgalli, and conventional Leptochloa chinensis. Metamifop is an ACCase inhibitor herbicide and is currently an important herbicide for controlling Leptochloa chinensis and Echinochloa crusgalli in rice fields. On the other hand, Echinochloa crusgalli and Leptochloa chinensis are the most severely herbicide-resistant weeds in rice fields in my country. Therefore, this example used the above-mentioned weed-resistant populations as test subjects and conventional populations as controls to further investigate the potential of clomazone-mefenac for controlling resistant weeds in rice fields.

[0220] 6.2 Herbicide dosage setting:

[0221] Clomazone+mefenacet: 54+240, 108+480g ai / hm 2

[0222] Metamifop: 120g ai / hm 2 , the upper limit of the dosage of oxadipamide registered for use in rice fields in China.

[0223] 6.3 Test method:

[0224] Fill a plastic plant cultivation pot with a diameter of 9 cm and a height of 10 cm with organic soil (pH 6.5, organic matter content 2.4%) that has not been used with herbicides, and add water until saturated. Select test weed seeds with full seeds and sow 20 seeds in each small flower pot. After sowing, cover the seeds with a layer of fine soil (about 3 mm thick). Put the small flower pot into a 44×33×10 cm thickened plastic transfer box (pre-added with 2 cm deep clean water) and cultivate it in an artificial climate chamber. The artificial climate chamber is set to 30°C for 12 hours of light and 20°C for 12 hours of darkness. During the test, a water layer of about 0.5 cm was maintained in the transfer box so that the soil in the small white box could remain moist through water absorption. Each treatment was repeated in 4 small flower pots.

[0225] The weeds to be treated with oxadiazon were transplanted into each small flower pot at the 2-3 leaf stage, and 10 best-growing seedlings were retained in each small flower pot. The weeds were treated with the herbicide by foliar spraying at the 3-5 leaf stage, and the control group was sprayed with an equal amount of water. The weeds to be treated with clomazone+mefenac were treated with the herbicide by spraying at the 0.5-1 leaf stage, and the control group was sprayed with an equal amount of water. The spray was carried out using a walking type pressure-stabilizing spray tower with a spray height of 20 cm, a flat fan nozzle with a spray width of 50 cm, and a pressure of 200 kPa. The spray liquid volume corresponds to a field spray volume of 45 L water / hm2. 230 days after application, the aboveground fresh weight of the test plants in each plastic box was collected and weighed, and the inhibition rate of the aboveground fresh weight of the different treatments was calculated.

[0226] Fresh weight inhibition rate = (fresh weight of control group – fresh weight of treatment group) ÷ fresh weight of control group × 100%

[0227] 6.4 Test results

[0228] The effects of the combination of clomazone and mefenacet on the fresh weight of the aboveground part of the tested weeds under different dosages are shown in Tables 12 and 13. The results showed that the combination of clomazone and mefenacet at 54+240, 108+480, g.i. / hm 2 The inhibition rates of the resistant weed populations under the different dose treatments were consistent with those of the corresponding sensitive populations, and all of them were able to effectively kill the tested weeds.

[0229] Table 28 Inhibition rate of aboveground fresh weight of grass weeds in resistant and conventional rice fields by different herbicides (%)

[0230]

[0231]

[0232] 6.5 Test conclusion

[0233] Dichloroisothiazolin-mefenacet can be used to control resistant weeds in rice fields. It can not only be used for the prevention and control of conventional barnyard grass and loblolly nut, but also for the prevention and control of related resistant populations.

Claims

1. A use of a herbicidal composition for controlling weeds or resistant weeds in wheat and rice fields, wherein the herbicidal composition comprises clomazone and flufenacet, or clomazone and mefenacet; when the herbicidal composition is a combination of clomazone and flufenacet, the dosage range is 27 to 216 g ai / hm 2 、30~240 g ai / hm 2 When the herbicidal composition is a mixture of clomazone and mefenacet, the dosage range is 27~108 g.i. / hm 2 、120~480 g ai / hm 2 .

2. The use according to claim 1, characterized in that The weeds are any one of grass weeds, broadleaf weeds and sedge weeds.

3. The use according to claim 1, characterized in that The resistant weeds are any one of: Alopecurus macrostachya, Alopecurus macrostachya, Lolium multiflorum, Echinochloa crusgalli, Leptochloa chinensis or Echinochloa crusgalli.

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