A herbicidal composition for synergistically controlling broadleaf weeds in tobacco fields

Abstract

The present application relates to the technical field of pesticide compounding, and specifically discloses a kind of weed control composition for synergistically preventing broadleaf weeds in tobacco field, comprising sulfosulfuron and Aspergillus versicolor D5 strain fermentation liquor extract, and the mass ratio of the two is 1:1 to 1:12; the present application improves the overall control effect on broadleaf weeds in tobacco field by compounding sulfosulfuron and Aspergillus versicolor D5 fermentation liquor extract, especially shows the control ability to persistent weeds such as spilanthes acmella-muller and solanum nigrum, while greatly reducing the dosage of single chemical agent, on the basis of effectively controlling weeds, the risk of phytotoxicity to tobacco plants is reduced, and crop safety is improved.

Description

Technical Field

[0001] This invention belongs to the field of pesticide compound technology, specifically relating to a herbicidal composition for synergistic control of broadleaf weeds in tobacco fields. Background Technology

[0002] In tobacco cultivation, weed infestation has always been a significant factor affecting tobacco yield and labor costs. Weeds in tobacco fields not only compete with tobacco plants for nutrients, water, and sunlight, but can also become intermediate hosts for pests and diseases, hindering tobacco growth and reducing yield. Currently, weed control in tobacco fields mainly relies on chemical herbicides; however, long-term, single-use of chemical agents can easily lead to herbicide resistance in weeds, potentially causing phytotoxicity to tobacco growth and resulting in environmental pollution.

[0003] Sulfadiazon, a sulfonylurea herbicide, exhibits good control efficacy against various broadleaf weeds and some grassy weeds. However, in practical applications, its use alone presents challenges such as limited efficacy, high dosage requirements, and potential phytotoxicity to tobacco. Meanwhile, with increasing emphasis on green agriculture, the need for developing environmentally friendly herbicides is becoming increasingly urgent.

[0004] In recent years, microbial herbicides have received widespread attention due to their environmental friendliness and low likelihood of developing resistance. Aspergillus versicolor D5, a microorganism with herbicidal activity, exhibits inhibitory effects on various weeds through its fermentation broth extract. However, microbial herbicides generally suffer from slow onset of action and unstable efficacy, limiting their effectiveness when used alone. Summary of the Invention

[0005] The purpose of this invention is to provide a herbicidal composition for synergistic control of broadleaf weeds in tobacco fields, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A herbicidal composition for synergistic control of broadleaf weeds in tobacco fields comprises sulfadiazine and a fermentation broth extract of Aspergillus versicolor D5 strain, in a mass ratio of 1:1 to 1:12.

[0008] Preferably, it also contains the following components in weight percentage: 3-8% emulsifier, 5-10% dispersant, 1-5% wetting agent, 0.1-1% stabilizer, 0.5-2% thickener, and the balance being vegetable oil.

[0009] Preferably, the percentage content of the sulfadiazine technical is 1-5%, and the percentage content of the Aspergillus versicolor D5 fermentation broth extract is 10-25%.

[0010] Preferably, the emulsifier is alkyl aryl polyoxyethylene ether, the dispersant is sodium methyl dinaphthalene sulfonate, the wetting agent is sodium dodecyl sulfate, the stabilizer is BHT, and the thickener is magnesium aluminum silicate.

[0011] Preferably, the Aspergillus versicolor D5 fermentation broth extract is prepared by the following method:

[0012] a) Inoculate the D5 strain into PDB liquid medium and culture at 28°C and 175 rpm for 7 days with shaking.

[0013] b) Extract the bacterial culture three times with 2 times the volume of ethyl acetate, combine the extracts and concentrate to dryness;

[0014] c) After the bacterial cells were broken up, they were extracted with a 1:1 mixture of dichloromethane and methanol for 24 h, and then concentrated to dryness after ultrasonic treatment.

[0015] d) Combine the extracts from steps b and c to obtain the fermentation broth extract.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] (1) By combining sulfadiazine with Aspergillus versicolor D5 fermentation broth extract, the overall control efficacy against broadleaf weeds in tobacco fields was improved, especially the control ability against stubborn weeds such as purslane and black nightshade. At the same time, the dosage of single chemical agents was greatly reduced. The compound solution effectively controlled weeds, reduced the risk of phytotoxicity to tobacco plants, and improved crop safety.

[0018] (2) Taking into account both environmental friendliness and the sustainability of agricultural production, the introduction of microbial components not only slows down the development of herbicide resistance in weeds, but also reduces the chemical load on the soil ecosystem. While ensuring high weed control efficiency, it helps to promote healthy tobacco growth and improve tobacco yield and quality. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the fermentation broth extract of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1:

[0022] Aspergillus versicolor D5 strain preserved on slant culture was inoculated into PDA medium and activated at 28°C for 12 h. A 1% inoculum was then transferred to PDB liquid medium and cultured at 28°C with shaking at 175 rpm for 24 h to obtain a seed culture. 40 mL of the seed culture was inoculated into 1 L of PDB medium and fermented under the same conditions for 7 days. After fermentation:

[0023] The bacterial culture was extracted three times with 2 volumes of ethyl acetate. The organic phases were combined and concentrated to dryness under reduced pressure at 40°C.

[0024] The bacterial cells were disrupted using a cell disruptor, soaked in a mixed solvent of dichloromethane:methanol (1:1 v / v) for 24 h, extracted by ultrasonication for 30 min, and concentrated to dryness by rotary evaporation at 40℃.

[0025] The two extracts were combined to obtain a brownish-red powdery D5 fermentation broth extract (yield: 1.8 g / L fermentation broth).

[0026] Example 2:

[0027] The test target was *Amaranthus retroflexus* (4-5 leaf stage).

[0028] Treatment groups were set up: sulfadiazine single agent, D5 extract single agent, and compound agents (mass ratio 1:1, 1:2, 1:4, 1:6, 1:8, 1:10, 1:12), with concentration gradients of 0.1, 0.5, 1.0, 5.0, and 10.0 mg / mL. Each treatment was repeated 5 times, with 1 mL sprayed per pot. Fresh weight inhibition rate was measured after 7 days.

[0029] Specifically, 2-3 weeks in advance, plant 30 seeds of *Amaranthus retroflexus* in 10 cm pots. Prepare solutions of sulfadiazine and *A. retroflexus* D5 fermentation broth extract at ratios of 1:0, 0:1, 1:1, 1:2, 1:4, 1:6, 1:8, 1:10, and 1:12, with concentrations of 0.1, 0.5, 1.0, 5.0, and 10.0 mg / mL, respectively. When the *Amaranthus retroflexus* reaches a certain size (approximately 4-5 leaves), spray 1 mL of the prepared solution evenly onto the plants. Use water as a control. Repeat each treatment 5 times. After one week, observe the degree of wilting of the weeds and record their fresh weight, as shown in Table 1.

[0030] Table 1. Toxicity determination and co-toxicity coefficient of sulfadiazine and D5 fermentation broth extract combined with Amaranthus retroflexus.

[0031]

[0032] Wherein, toxicity index = standard reagent EC 50 Value / Reagent EC 50Value × 100; Actual Toxicity Index (ATI) = Standard EC 50 EC value / mixture 50 Value × 100;

[0033] Theoretical toxicity index (TTI) = toxicity index of A × content of A in the mixture (%) + toxicity index of B × content of B in the mixture (%).

[0034] Cotoxicity coefficient (CTC) = Actual toxicity index (ATI) / Theoretical toxicity index (TTI) × 100;

[0035] A co-toxicity coefficient (CTC) value of less than 80 indicates an antagonistic effect, between 80 and 120 indicates an additive effect, greater than 120 indicates a synergistic effect, and greater than 200 indicates a significant synergistic effect.

[0036] Table 1 shows that sulfadiazine and D5 fermentation broth extract alone have a significant effect on the EC5 of Amaranthus retroflexus. 50 The values ​​were 45.10 mg / L and 155.60 mg / L, respectively, and the EC was prepared by mixing the two in different proportions. 50 The lowest value was 33.27 mg / L (sulforaphane:D5 fermentation broth extract = 1:6) and the highest was 91.40 mg / L (sulforaphane:D5 fermentation broth extract = 1:12), according to EC. 50 The values ​​are sorted as follows: 1:6 < 1:4 < 1:2 < 1:8 < 1:1 < 1:10 < 1:12. The co-toxicity coefficients of the two compounds in different proportions are all greater than 120, indicating a synergistic effect. Among them, the co-toxicity coefficients of 1:6, 1:4, 1:2, and 1:8 are greater than 200, showing a significant synergistic effect.

[0037] Therefore, the compounding ratios of sulfadiazine, which has strong toxicity to Amaranthus retroflexus, and D5 fermentation broth extract are 1:6, 1:4, 1:2, and 1:8.

[0038] Example 3:

[0039] Treatment groups were set up with sulfadiazine single agent (250 mg / L), D5 extract single agent (1 g / L), and compound agent (1:1 to 1:10). These were sprayed on Yunyan 87 seedlings, and the phytotoxicity level was determined after 30 days (Level 1: no phytotoxicity; Level 2: mild inhibition).

[0040] Specifically, an indoor potted plant experiment was conducted. 1 g / L D5 fermentation broth extract and 250 mg / L sulfadiazine were sprayed separately, while the control was sprayed with an equal amount of water. One month later, Yunyan 87 seeds were introduced. After the control seeds germinated and grew, the germination rate and fresh weight of the tobacco seedlings were observed and recorded, as shown in Table 2.

[0041] Table 2 Safety test results of the combination of sulfadiazine and D5 fermentation broth extract with tobacco.

[0042]

[0043] As shown in Table 2, based on the experimental results of indoor biological herbicides, D5 fermentation extract and sulfadiazine, when used alone, had a slight inhibitory effect on tobacco growth, with a phytotoxicity level of 2. When sulfadiazine and D5 fermentation extract were mixed in different proportions, the inhibition rate of fresh weight of tobacco decreased. Among them, when the mixing ratio of sulfadiazine and D5 fermentation extract was 1:1, 1:2, 1:4, and 1:6, no phytotoxicity was caused to tobacco, while the mixing ratios of 1:8 and 1:10 caused slight phytotoxicity.

[0044] Example 4:

[0045] Preparation of compound oil suspension

[0046] The formulation consists of 3% of the active ingredient sulfadiazine technical grade and 18% of D5 fermentation broth extract; adjuvants include 8% sodium methyl dinaphthalenesulfonate (dispersant), 3% sodium dodecyl sulfate (wetting agent), 5% alkyl aryl polyoxyethylene ether (emulsifier), 0.5% BHT (stabilizer), and 1% magnesium aluminum silicate (thickener); the carrier is soybean oil to bring the total to 100%.

[0047] Weigh out the proportions of sulfadiazine and D5 fermentation broth extract in the formula, and add them to vegetable oil along with emulsifier, dispersant, wetting agent, stabilizer, and thickener. Mix them evenly by high-speed shearing in a shearing kettle, and grind them to a particle size d90≤5μm using a sand mill. Filter the mixture to obtain a stable dispersible oil suspension.

[0048] Example 5:

[0049] Experimental design: The location was a tobacco field in Liangshan Prefecture, Sichuan Province. Groups were set up: T1 (no herbicide applied), T2 (12% sulfadiazine oil suspension 12 mL / mu), T3 (D5 fermentation broth 100 mL / mu), and T4 (formulation of Example 4 42 mL / mu). The tobacco was sprayed with 30 kg / mu of water during the vigorous growth period.

[0050] Specifically, two medium-fertility tobacco fields were selected in Liangshan Prefecture, each about half an acre in size, without duplication. Each field had four treatments, each about 75 square meters (i.e., about 120-130 tobacco plants). Each treatment was sprayed with 30 kg / acre of water. Sulfadiazine and D5 fermentation broth extract were applied during the vigorous growth period of the tobacco seedlings.

[0051] Fifteen days after application, 3-4 sites were surveyed for each treatment. Each site covered an area of ​​0.25 square meters (0.5 meters long x 0.5 meters wide). The types and number of weeds at each site were recorded, and the plants were weighed. The plant control efficacy and fresh weight control efficacy were calculated. Weed plant control efficacy = (number of weeds in the control group - number of weeds in the treatment group) / number of weeds in the control group × 100%. Weed fresh weight control efficacy = (fresh weight of weeds in the control group - fresh weight of weeds in the treatment group) / fresh weight of weeds in the control group × 100%. The flue-cured tobacco leaves from each treatment were stored separately for yield calculation, and economic traits were statistically analyzed, as shown in Tables 3-5.

[0052] Table 3. Fresh weight control efficacy of sulfadiazine and D5 fermentation broth extract combined with the control of weeds in the first tobacco field (unit: %)

[0053]

[0054] Different letters indicate significant differences between data processed in different ways;

[0055] Table 3 shows that in the first experimental field, the total plant control efficacy of each treatment against weeds ranged from 65.44% to 80.87%, and the total fresh weight control efficacy ranged from 68.53% to 89.30%, all demonstrating strong weed control capabilities. The fermentation broth of *A. versicolor* D5 and its combination with sulfadiazine showed the highest total control efficacy against tobacco weeds, with plant control efficacy and fresh weight control efficacy reaching 80.87% and 89.30%, respectively, higher than that of *A. versicolor* D5 fermentation broth and sulfadiazine alone. It also showed synergistic effects against broadleaf weeds such as *Amaranthus tricuspidata*, *Vigna angularis*, *Eclipta prostrata*, *Portulaca oleracea*, *Cyperus rotundus*, and *Solanum nigrum*.

[0056] Specifically, A. versicolor D5 fermentation broth and its combination with sulfadiazine exhibit excellent control effects against purslane, black nightshade, and spatholobus in tobacco fields, with fresh weight control efficacy exceeding 90%, which is no less than that achieved by applying A. versicolor D5 fermentation broth or sulfadiazine alone. The control efficacy against purslane and black nightshade reaches 100%. It also shows moderate control efficacy against vetch, sedge, and ironweed in tobacco fields, with fresh weight control efficacy exceeding 80%. The control efficacy against vetch and sedge is no less than that achieved by applying A. versicolor D5 fermentation broth or sulfadiazine alone, but the control efficacy against ironweed is lower than that achieved by applying A. versicolor D5 fermentation broth alone, but higher than that achieved by applying sulfadiazine alone. The control efficacy against barnyard grass and crabgrass is moderate, with fresh weight control efficiencies of 63.52% and 63.43%, respectively, both lower than that achieved by applying sulfadiazine alone but higher than that achieved by applying A. versicolor D5 fermentation broth alone.

[0057] Table 4. Fresh weight control efficacy of sulfadiazine and D5 fermentation broth extract combined with the second tobacco field (unit: %)

[0058]

[0059] Different letters indicate significant differences between data processed in different ways;

[0060] Table 4 shows that in the second experimental field, the total plant control efficacy of each treatment against weeds in the tobacco field ranged from 72.38% to 83.48%, and the total fresh weight control efficacy ranged from 71.13% to 91.76%, all demonstrating strong weed control capabilities. The fermentation broth of *A. versicolor* D5 and its combination with sulfadiazine showed the highest total control efficacy against tobacco weeds, with plant control efficacy and fresh weight control efficacy reaching 83.48% and 91.76%, respectively, which were higher than those achieved by applying *A. versicolor* D5 fermentation broth or sulfadiazine alone. It also showed a synergistic effect against broadleaf weeds such as *Vigna oleifera*, *Eclipta prostrata*, *Portulaca oleracea*, *Solanum nigrum*, and *Solanum nigrum*.

[0061] Specifically, the A. versicolor D5 fermentation broth and its combination with sulfadiazine achieved 100% control efficacy against purslane and black nightshade, and exhibited excellent control efficacy against *Trichoderma repens*, with a fresh weight control efficacy exceeding 90%, comparable to or higher than that of A. versicolor D5 fermentation broth and sulfadiazine alone. It also showed moderate control efficacy against *Eclipta prostrata* in tobacco fields, with a fresh weight control efficacy exceeding 80%, comparable to or higher than that of A. versicolor D5 fermentation broth and sulfadiazine alone. Furthermore, it demonstrated good control efficacy against *Vigna edulis*, *Digitaria sanguinalis*, and *Amaranthus trifasciata* in tobacco fields, with a fresh weight control efficacy exceeding 70%. The A. versicolor D5 fermentation broth significantly enhanced the fresh weight control efficacy of sulfadiazine against *Vigna edulis* and *Amaranthus trifasciata*. However, its control efficacy against barnyardgrass was moderate, with a fresh weight control efficacy of 68.11%, lower than that of sulfadiazine alone but higher than that of A. versicolor D5 fermentation broth alone.

[0062] Table 5. Effects of sulfadiazine and D5 fermentation broth extract combination on tobacco agronomic traits.

[0063]

[0064] Different letters indicate significant differences between data processed in different ways;

[0065] As shown in Table 5, there were no differences in plant height, stem circumference, maximum leaf length, and number of effective leaves among the tobacco plants after herbicide treatment. However, the maximum leaf width of tobacco plants was significantly increased in plot 1. In terms of yield, the combined use of A. versicolor D5 fermentation liquid and sulfadiazine, as well as the A. versicolor D5 fermentation liquid treatment, resulted in higher yields per acre than the sulfadiazine treatment.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A herbicidal composition for synergistic control of broadleaf weeds in tobacco fields, characterized in that, It includes sulfadiazine and Aspergillus versicolor D5 strain fermentation broth extract, with a mass ratio of 1:1 to 1:

12.

2. The herbicidal composition for synergistic control of broadleaf weeds in tobacco fields according to claim 1, characterized in that, It also contains the following components by weight percentage: emulsifier 3-8%, dispersant 5-10%, wetting agent 1-5%, stabilizer 0.1-1%, thickener 0.5-2%, and the balance being vegetable oil.

3. The herbicidal composition for synergistic control of broadleaf weeds in tobacco fields according to claim 2, characterized in that: The percentage content of the sulfadiazine technical material is 1-5%, and the percentage content of the Aspergillus versicolor D5 fermentation broth extract is 10-25%.

4. The herbicidal composition for synergistic control of broadleaf weeds in tobacco fields according to claim 2, characterized in that, The emulsifier is alkyl aryl polyoxyethylene ether, the dispersant is sodium methyl dinaphthalene sulfonate, the wetting agent is sodium dodecyl sulfate, the stabilizer is BHT, and the thickener is magnesium aluminum silicate.

5. The herbicidal composition for synergistic control of broadleaf weeds in tobacco fields according to claim 1, characterized in that, The Aspergillus versicolor D5 fermentation broth extract was prepared by the following method: a) Inoculate the D5 strain into PDB liquid medium and culture at 28°C and 175 rpm for 7 days with shaking. b) Extract the bacterial culture three times with 2 times the volume of ethyl acetate, combine the extracts and concentrate to dryness; c) After the bacterial cells were broken up, they were extracted with a 1:1 mixture of dichloromethane and methanol for 24 h, and then concentrated to dryness after ultrasonic treatment. d) Combine the extracts from steps b and c to obtain the fermentation broth extract.

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