Ternary compound herbicide dispersible oil suspending agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of agriculture, in particular to a ternary compound herbicide dispersible oil suspending agent as well as a preparation method and application thereof. Comprising the following components in percentage by weight: 0.8%-1.2% of penoxsulam, 6.5%-7.5% of cyhalofop-butyl, 18%-22% of pretilachlor, 1.5%-3.0% of a block copolymer dispersant, 3.0%-6.0% of a polyether ester emulsifier, 0.3%-1.0% of an associative rheological additive, 0.5%-2.0% of an organic phosphate buffer, 1.0%-2.0% of organic bentonite, 1.5%-4.0% of propylene glycol and glycerol, 0.1%-0.5% of an antioxidant and the balance of water. The oil phase is a mixture of methyl oleate and isoparaffin, and the balance is supplemented to 100%. Three active compounds of penoxsulam, cyhalofop-butyl and pretilachlor with complementary action mechanisms are selected, but the three active compounds are different in physicochemical property, and the product stability is easily affected by acid-base hydrolysis, thermal decomposition or precipitation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of agriculture, and in particular to a ternary compound herbicide dispersible oil suspension concentrate, a preparation method and an application thereof. Background Art

[0002] As agricultural intensification continues, the demand for weed control continues to grow. To improve weed control efficiency, expand its scope of application, and reduce resistance, a variety of combination herbicide combinations are gradually emerging on the market. Among them, penoxsulam, cyhalofop-butyl, and pretilachlor, three herbicides with different mechanisms of action, each boasting broad-spectrum, fast-acting, and long-lasting effects, have the potential to achieve synergistic effects and reduce resistance through scientific combination.

[0003] Traditional herbicides are mostly formulated as emulsifiable concentrates (ECs), wettable powders (WPs), or water-dispersible granules (WDGs), often associated with high volatility, toxicity, environmental pollution, and poor stability. In recent years, dispersible oil concentrates (ODs), combining the advantages of both SCs and ECs, have become a trend in the development of highly effective, safe, and environmentally friendly formulations.

[0004] However, the three technical ingredients, especially cyhalofop-butyl, exhibit poor stability in the system and are prone to precipitation. Furthermore, the high pretilachlor content poses challenges to the system's dispersibility and low-temperature stability. Currently, most compounded oil suspension concentrates are limited to two-component systems, while ternary systems lack systematic solutions for adjuvant optimization, particle stability, oil phase selection, and low-temperature storage stability.

[0005] Therefore, there is an urgent need to provide a ternary compounded dispersible oil suspension composition and a preparation method thereof, which has good dispersion stability, storage stability, low foaming and synergistic herbicidal activity, and overcomes the shortcomings of the existing technology. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a ternary compound herbicide dispersible oil suspension concentrate, comprising the following components in percentage by weight:

[0007] Penoxsulam: 0.8%~1.2%,

[0008] Cyanosulfuron: 6.5% to 7.5%,

[0009] Pretilachlor: 18% to 22%,

[0010] Block copolymer dispersant: 1.5% to 3.0%,

[0011] Polyether ester emulsifier: 3.0% to 6.0%,

[0012] Associative rheological additive: 0.3% to 1.0%,

[0013] Organophosphate buffer: 0.5% to 2.0%,

[0014] Organic bentonite: 1.0% to 2.0%,

[0015] Propylene glycol and glycerin: total amount 1.5% to 4.0%,

[0016] Antioxidant: 0.1% to 0.5%,

[0017] The oil phase is a mixture of methyl oleate and isoparaffins, with the remainder making up to 100%.

[0018] As an embodiment of the present invention, the dispersant is Solsperse 22000 or a similar block copolymer thereof.

[0019] As an embodiment of the present invention, the emulsifier is a polyetherester structure with an HLB value of 10-13.

[0020] As an embodiment of the present invention, the buffer is urea phosphate or ethylenediaminetetramethylenephosphonic acid.

[0021] As an embodiment of the present invention, the oil phase is composed of methyl oleate and isomeric C13 alkanes in a mass ratio of 1:1 to 3:1.

[0022] As one embodiment of the present invention, the antioxidant is natural tocopherol.

[0023] As an embodiment of the present invention, the oil phase is methyl oleate and isomeric C13 alkanes in a mass ratio of 3:1.

[0024] A method for preparing the dispersible oil suspension comprises the following steps:

[0025] a) dissolving cyhalofop-butyl in the oil phase;

[0026] b) adding pretilachlor, penoxsulam technical and adjuvant in sequence, mixing and stirring;

[0027] c) Sand grinding at a temperature of 35°C ± 2°C to an average particle size D50 ≤ 2.5 μm;

[0028] d) Repackaging after passing the test.

[0029] As an embodiment of the present invention, the temperature during the sanding process is controlled at 35±2° C., and the sanding time is 1 to 2 hours.

[0030] As an embodiment of the present invention, the dispersible oil suspension is used for the simultaneous control of grass weeds and broadleaf weeds.

[0031] By adopting the above technical solution, the present invention has the following beneficial effects:

[0032] The present invention uses three technical drugs with complementary mechanisms of action: penoxsulam, cyhalofop-butyl, and pretilachlor. However, these three drugs have different physical and chemical properties and are easily affected by acid-base hydrolysis, thermal decomposition, or precipitation, which may affect the product stability.

[0033] To address the above problems, the present invention introduces an organophosphate buffer to stably control the pH of the system between 4.5 and 6.5, effectively inhibiting the sulfonylurea hydrolysis reaction of penoxsulam and the ester bond cleavage of cyhalofop-butyl, thereby preventing the degradation of ingredients from the source; at the same time, by adding a natural tocopherol antioxidant and combining it with a bio-based oil phase to construct a low-polarity, low-reactivity oil phase environment, the oxidation reaction can be significantly delayed and the degradation of active ingredients under high temperature conditions can be inhibited; after hot storage (54°C, 14 days) and low-temperature storage (0°C, 7 days) simulation tests, the system remained uniform and stable, without precipitation, stratification, or sedimentation, and the storage stability was superior to that of existing two-component oil suspension products.

[0034] The present invention uses a block copolymer dispersant with unique adsorption properties and a spatially stable structure, which can tightly wrap the surface of the pharmaceutical particles and significantly improve the uniformity and stability of the particle size distribution; at the same time, an associative polyurethane rheological additive is introduced to construct a dynamic micro-network structure under low shear conditions to form an "anti-sedimentation barrier"; the finished product prepared by the present invention has an average particle size D50 less than 3μm, D90 less than 5μm, a wet sieve pass rate ≥99%, and a suspension rate (24h) ≥95%, which is significantly superior to traditional calcium carbonate inorganic additive systems. DETAILED DESCRIPTION

[0035] The present invention will be further explained below with reference to specific embodiments.

[0036] Example 1

[0037] This embodiment provides a ternary compound herbicide dispersible oil suspension concentrate, comprising the following components in percentage by weight:

[0038] Penoxsulam: 1.0%,

[0039] Cyanosulfuron: 7.0%,

[0040] Pretilachlor: 20.0%,

[0041] Block copolymer dispersant Solsperse 22000: 2.5%,

[0042] Polyetherester emulsifier Atlox TM 4913: 5.0%,

[0043] Associative rheological additive Tafigel PUR-40: 0.6%,

[0044] Organophosphate buffer urea phosphate: 1.0%,

[0045] Organic bentonite: 1.5%,

[0046] Propylene glycol 2.0%,

[0047] Glycerin: 1.0%

[0048] Tocopherol antioxidant: 0.3%,

[0049] Methyl oleate: 25.0%,

[0050] Isomeric C13 alkanes, the remainder makes up to 100%.

[0051] The preparation process is as follows:

[0052] Cyhalofop-butyl is dissolved in a mixed oil phase of methyl oleate and isomeric C13 alkanes; pretilachlor and penoxsulam technical are subsequently added to the oil phase in sequence and stirred evenly; a block dispersant, an emulsifier, a buffer, and an antioxidant are added and stirred for pre-dispersion; organic bentonite, a rheological additive, and a low-temperature stabilizer are added and stirred evenly; the product is sent to a sand mill and sand milled for 1.5 hours at a temperature controlled at 35±2°C to an average particle size D50≤2.5μm; the product is filtered and tested and then packaged. The finished product has the appearance of a light yellow oily fluid and is well dilutable with water.

[0053] The following is a description based on specific embodiments.

[0054] Table 1 Compositions of various examples

[0055]

[0056]

[0057] Performance testing:

[0058] (1) Particle size test

[0059] The average particle size D50 and D90 were measured using a laser particle size analyzer. Reference standard: NY / T 2885-2015, “Quality Evaluation Methods for Pesticide Suspension Concentrates.”

[0060] Test steps:

[0061] Take about 0.5g of sample and add appropriate amount of deionized water for ultrasonic pre-dispersion; add the dispersed sample to the test cell of the laser particle size analyzer; set the refractive index (generally 1.52) and absorbance (default 0.1) and test three times; record the particle size D50 (median diameter) and D90 (90% particle size) and take the average value.

[0062] Judgment index: D50≤3μm, D90≤5μm is excellent; fluctuation no more than 10% is stable grinding.

[0063] (2) Suspension rate

[0064] The suspension rate of pesticide suspension concentrates was determined according to GB / T 14825-93. The suspension concentrates were allowed to stand at 25°C for 24 hours and the supernatant was used to calculate the suspension rate (%).

[0065] Test steps:

[0066] Accurately weigh 1.0 g of the preparation sample into a 100 mL graduated cylinder; add standard hard water at a temperature of 25±1°C to the scale line and plug the stopper; oscillate with a mechanical oscillator for 1 minute; after standing for 30 minutes, use a pipette to draw 50 mL from the top and pour it into a dry beaker; dry in an oven at 105°C to constant weight, calculate the residual weight of the suspended matter, and calculate the suspension rate S (%).

[0067] (3) Low temperature stability

[0068] The sample was placed in a constant temperature box at 0±2℃ for 7 days and observed for crystallization, precipitation or stratification.

[0069] (4) Thermal storage stability

[0070] The samples were placed at 54±2℃ for 14 days to detect changes in component content and the presence of precipitation and abnormal odor.

[0071] Table 2 Performance test results

[0072]

[0073]

[0074] Pesticide Field Efficacy Test Report

[0075] Test Name: Field efficacy test of 28% penoxsulam·cyhalofop-butyl·pretilachlor dispersible oil suspension concentrate for controlling gramineous weeds such as barnyardgrass and Leptochloa crus-galli in direct-seeded rice fields

[0076] Test crops: direct-seeded rice fields

[0077] Target of prevention and control: Grass weeds such as barnyard grass and Leptochloa crus-galli

[0078] Test agent:

[0079]

[0080]

[0081] Application method:

[0082] Stem and leaf spray method, water consumption is 450L / hm 2 .

[0083] Suitable time for application:

[0084] 15-20 days after direct seeding of rice, the seedlings are in the 2-4 leaf stage, while the chinensis and barnyard grass are in the 1-3 leaf stage.

[0085] Suitable dosage:

[0086] Active ingredient 336-504g / hm 2 (Preparation dosage 80-120ml / 667m 2 ).

[0087] How to use the medicine:

[0088] Drain the field before applying the pesticide, keep it moist, and add water 30L / 667m 2 Spray, keep the field moist for 2 days after application, then water it and carry out normal field management thereafter.

[0089] Drug safety:

[0090] The highest recommended dose (active ingredient 504g / hm 2 , preparation 120ml / 667m 2 ) application within the specified range is safe for direct-seeded rice, with no significant side effects. It significantly stabilizes yields. No adverse effects were observed on beneficial organisms, including major predatory (such as ladybugs, hoverflies, and spiders) and parasitic natural enemies in the field.

[0091] Field test report on the efficacy of 28% penoxsulam·cyhalofop-butyl·pretilachlor dispersible oil suspension concentrate in controlling gramineous weeds such as barnyardgrass and Leptochloa crus-galli in direct-seeded rice fields

[0092] 1. Purpose of the experiment

[0093] In 2015, with approval from the Ministry of Agriculture and Rural Affairs, field trials were conducted on the 28% penoxsulam-cyhalofop-butyl-pretilachlor dispersible oil suspension concentrate (OD) of Examples 1, 2, and Comparative Example 1 for controlling grass weeds such as barnyardgrass and Leptochloa crus-galli in direct-seeded rice fields. This trial, a continuation of the previous year's trial, further verified the product's actual field efficacy, dosage, and safety, providing a basis for its registration and application.

[0094] 2 Test conditions

[0095] 2.1 Crop and cultivar selection

[0096] The experimental crop was indica rice, and the variety was conventional rice (Huahang 31).

[0097] 2.2 Selection of test weeds

[0098] The main grass weeds in the experimental fields were Echinochloa crusgalli and Leptochloria chinesis. Cyperus weeds included Cyperus rira and C. difformis. Broadleaf weeds included Lindernia procumbens, Rotala indica, Sagittaria pygmaea, Monochoria vaginalis, and Edipta prostrata. As requested by the commission, this trial evaluated only the control efficacy against grass weeds such as Echinochloa crusgalli and Leptochloria chinesis.

[0099] 2.3 Cultivation conditions

[0100] The experimental field was located at the Ningxi Teaching Base of South China Agricultural University in Zengcheng District. Double-cropping rice is cultivated year-round. Weed infestation is moderate, soil organic matter content and pH have not been measured, and soil fertility is moderate. Tillage standards are high. Compound fertilizer is regularly applied as a base fertilizer. Each plot is separated by a 10 cm x 15 cm field bed. 20 cm wide irrigation and drainage ditches are installed within the plot, separating irrigation and drainage. Protected rows are installed within the experimental area.

[0101] 2.4 Other conditions

[0102] Routine management of the experimental fields, field fertilizer and water management, and consistent varieties.

[0103] 3 Experimental design and arrangement

[0104] 3.1 Pharmacy

[0105] 3.1.1 Test Agents

[0106] Penoxsulam·cyhalofop-butyl·pretilachlor, dispersible oil suspension concentrate (OD), active ingredient content 28%, Examples 1, 2, and Comparative Example 1.

[0107] 3.1.2 Control Agents

[0108] Penoxsulam, dispersible oil suspension (OD), 25 g / L, Dow AgroSciences, USA. Cyhalofop-butyl, emulsifiable concentrate (EC), 10%, Dow AgroSciences, USA. Pretilachlor, emulsifiable concentrate (EC), 300 g / L, Zhejiang Shenghua Biotech Co., Ltd. (PD20131228).

[0109] Manual weeding and blank control treatments were set.

[0110] 3.1.3 Test design of test agents

[0111] The test drug is determined by the client, and the control drug is determined by the technical person in charge based on the purpose of the trial.

[0112] Table 4 Experimental design of test agents

[0113]

[0114] 3.2 Community Arrangement

[0115] 3.2.1 Cell Arrangement

[0116] The experimental site was divided into 4 blocks, each block was divided into 8 plots, and the treatments were randomly arranged. Plot area and replication.

[0117] Area of ​​each plot: 25-30m 2 , repetitions: 4 times.

[0118] 3.3 Application method

[0119] 3.3.1 Usage

[0120] Rice seeds were soaked and germinated and then sown directly on July 2, 2016. On July 16, the field experiment was designed, and the blocks and plots were divided. Markers were inserted and the pesticides were applied. After application, the field was kept moist for 2 days and then watered to maintain a water layer of 3-5 cm. After natural drying, the field was managed normally. The required amount of medicine was accurately measured with a pipette (the control agent 25g / L penoxsulam OD and 300g / L pretilachlor EC were accurately weighed with a balance), prepared with clean water, mixed thoroughly, and sprayed from low to high dosages. The nozzle was placed 30-40cm above the ground, and the spray angle was adjusted to be parallel to the direction of human movement. The swing direction of the nozzle was perpendicular to the direction of human movement and sprayed evenly. No missed spraying and no repeated spraying.

[0121] 3.3.2 Pesticide application equipment

[0122] The sprayer is a knapsack sprayer (WS-16P, Shandong Weishi Plant Protection Machinery Co., Ltd.) using a Teejet series 8002VS fan nozzle with an operating pressure of approximately 3 kg / cm 2 , the flow rate of the liquid medicine is about 700-800ml / min.

[0123] 3.3.3 Application time and frequency

[0124] On July 16, apply the pesticide once.

[0125] 3.3.4 Usage

[0126] Spray liquid volume 30L / 667m 2 .

[0127] 3.3.5 Information on pesticides for controlling pests, diseases, and non-target weeds

[0128] The experimental fields were previously early rice fields, and no herbicides were applied within three months of the experiment. No other herbicides were sprayed during the experiment. Cyperaceae and broadleaf weeds were manually weeded throughout the field (including the CK plots) on the day of application and 40 days afterward. Conventional methods were used to control planthoppers and rice blast during the mid-to-late rice growth period.

[0129] 4 Investigation, recording and measurement methods

[0130] 4.1 Meteorological and field management data

[0131] 4.1.1 Meteorological data

[0132] The pesticide was applied on the afternoon of July 16. The temperature on that day was sunny to cloudy, 26-34℃, with no sustained wind direction ≤ level 3, and no rainfall within 2 days after the application.

[0133] 4.1.2 Field management information

[0134] During the experiment, water and fertilizer management was carried out according to routine requirements. Insecticides and fungicides were sprayed according to routine requirements to prevent insects and treat diseases.

[0135] 4.2 Survey methods, time and frequency

[0136] 4.2.1 Survey time and frequency

[0137] A total of three surveys were conducted, namely on the day of spraying (July 16), 20 days after spraying (August 5), and 39 days after spraying (August 24), to investigate the number of surviving weeds and calculate the efficacy of the spray.

[0138] 4.2.2 Weed Survey

[0139] Cyhalofop-butyl is a systemic herbicide from the aromatic oxyphenoxypropionic acid class. It is absorbed by the leaves and sheaths of plants, conducted through the phloem, and accumulated in the meristematic zone of the plant. It inhibits acetyl-CoA carboxylase (ACCase), halting fatty acid synthesis, preventing normal cell growth and division, and damaging lipid-containing structures such as membranes, ultimately leading to plant death. Penoxsulam is a triazolopyrimidine sulfonamide post-emergence herbicide that works by inhibiting acetolactate synthase (ALS). Pretilachlor belongs to the hormone-type quinoline carboxylic acid herbicide class, and its weed poisoning symptoms are similar to those of auxins. In this experiment, the main symptoms of weed poisoning after application were discoloration and shrinkage of young shoots, growth inhibition, and gradual death of plants. Older leaves showed minimal changes and gradual death. Weeds in the control area germinated and grew normally.

[0140] The base number of weeds was investigated before treatment, and the efficacy of the pesticide was investigated 20 and 39 days after application. One fixed point was selected in the east, west, south and north directions of each plot, for a total of four points. With the mark as the center, a square iron frame with a side length of 0.5m was placed on the fixed point. The number of weeds at each point was counted 0.25m. 2The number of main surviving target grasses within the range of (0.5m×0.5m). After 39 days, in addition to investigating the number of surviving grasses, all surviving target weeds in the point were pulled out, washed free of mud and sand, wiped dry and weighed after fresh weight.

[0141] 4.3 Calculation method of drug efficacy

[0142] The efficacy was calculated according to the guidelines for pesticide field efficacy test GB / T 17980.40-2000. The test results were statistically analyzed using the Duncan's new multiple range test (DMRT method, p = 0.05) using SAS software package.

[0143]

[0144] 4.4 Crop Survey

[0145] 4.4.1 Survey Methods

[0146] Observe the leaf color and growth of rice seedlings in the treated areas 1, 3, and 7 days after application. Detailed records should be kept of any abnormalities. Visually inspect the crop damage rate (%) in each treated area 10 and 20 days after application (same as the control = 0%). Measure rice plant height 39 days after application. For the plant height survey, randomly select 10 points in each plot (I, II, III, IV), each with an area of ​​0.25 m2. 2 (0.5m×0.5m), measure each point (0.25m 2 ) The highest plant height of rice was taken as its plant height, and the average value was taken to compare the differences among the treatments.

[0147] 4.4.2 Survey time and frequency

[0148] Observe once 1, 3, 7, 10, 20, and 39 days after spraying.

[0149] 4.5 Impact on other organisms

[0150] When observing pesticide damage and visually estimating the pesticide damage rate, observe whether each treatment with the test agent has any abnormal effects on non-target organisms (especially the main predatory and parasitic natural enemies in the field), and record them in detail if necessary.

[0151] 4.6 Crop Yield and Quality

[0152] On November 2, sampling and yield measurement were carried out. Four points were surveyed in each replicate (plot), and the area of ​​each point was 0.25m 2 , calculate and accumulate 4 points (the actual survey area of ​​each repetition is 1.0m 2 ) effective number of ears (ears / m 2 ), and the rice at the four points was harvested, threshed, dried, blown and weighed, and the yield (kg / m 2 ) Estimated rice yield (kg / hm2) 2), evaluate the effect of the agent on yield.

[0153] Results and Analysis

[0154] The results of plant control efficacy and fresh weight control efficacy 20 days and 39 days after application of the pesticide in this test are listed in Table 5, Table 6 and Table 7. Table 5 28% penoxsulam·cyhalofop-butyl·pretilachlor OD control of grass weeds in direct-seeded rice fields Plant control efficacy (%) - 20 days

[0155]

[0156] Note: CK is the number of surviving weeds (plants / m 2 ), and the rest of the treatment data are for prevention effect. The comparison of significant differences does not include CK.

[0157] Table 6 Control effect of 28% penoxsulam·cyhalofop-butyl·pretilachlor OD on grass weeds in direct-seeded rice fields (%) 39 days

[0158]

[0159]

[0160] Note: CK is the number of surviving weeds (plants / m 2 ), and the rest of the treatment data are for prevention effect. The comparison of significant differences does not include CK.

[0161] Table 7 Control efficacy of 28% penoxsulam·cyhalofop-butyl·pretilachlor OD on fresh weight of grass weeds in direct-seeded rice fields (%) 39 days

[0162]

[0163] Note: CK is the fresh weight of surviving weeds (g / m 2 ), and the rest of the treatment data are for prevention effect. The comparison of significant differences does not include CK.

[0164] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ternary compound herbicide dispersible oil suspension concentrate, characterized in that: The composition comprises the following components in weight percentage: Penoxsulam: 0.8%~1.2%, Cyanosulfuron: 6.5% to 7.5%, Pretilachlor: 18% to 22%, Block copolymer dispersant: 1.5% to 3.0%, Polyether ester emulsifier: 3.0% to 6.0%, Associative rheological additive: 0.3% to 1.0%, Organic phosphate buffer: 0.5% to 2.0%, Organic bentonite: 1.0% to 2.0%, Propylene glycol and glycerin: total amount 1.5% to 4.0%, Antioxidant: 0.1% to 0.5%, The oil phase is a mixture of methyl oleate and isoparaffins, with the remainder making up to 100%.

2. The dispersible oil suspension according to claim 1, characterized in that The dispersant is Solsperse 22000 or a similar block copolymer thereof.

3. The dispersible oil suspension according to claim 1, characterized in that The emulsifier is a polyetherester structure with an HLB value of 10-13.

4. The dispersible oil suspension according to claim 1, characterized in that The buffer is urea phosphate or ethylenediaminetetramethylenephosphonic acid.

5. The dispersible oil suspension according to claim 1, characterized in that The oil phase consists of methyl oleate and isomeric C13 alkanes in a mass ratio of 1:1 to 3:

1.

6. The dispersible oil suspension according to claim 1, characterized in that The antioxidant is natural tocopherol.

7. The dispersible oil suspension according to claim 5, characterized in that The oil phase is methyl oleate and isomeric C13 alkanes in a mass ratio of 3:

1.

8. A method for preparing the dispersible oil suspension according to claim 1, characterized in that: The following steps are involved: a) dissolving cyhalofop-butyl in the oil phase; b) adding pretilachlor, penoxsulam technical and adjuvant in sequence, mixing and stirring; c) Sand grinding at a temperature of 35°C ± 2°C to an average particle size D50 ≤ 2.5 μm; d) Repackaging after passing the test.

9. The method according to claim 8, characterized in that During the sanding process, the temperature is controlled at 35±2° C., and the sanding time is 1 to 2 hours.

10. The dispersible oil suspension according to claim 1, characterized in that Used for simultaneous control of grass weeds and broadleaf weeds.

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