CN110583680B

CN110583680B - Compound weeding composition for corn field

Info

Publication number: CN110583680B
Application number: CN201810607193.5A
Authority: CN
Inventors: 王玉峰; 司永兵; 林永朋; 禹文静
Original assignee: Mengzhou Chuanqi Biotechnology Co ltd
Current assignee: Mengzhou Chuanqi Biotechnology Co ltd
Priority date: 2018-06-12
Filing date: 2018-06-12
Publication date: 2021-07-09
Anticipated expiration: 2038-06-12
Also published as: CN110583680A

Abstract

The invention discloses a compound weeding composition for a corn field, which comprises the following effective components of topramezone, flucarbazone-methyl and mesotrione in a weight ratio of topramezone: and (3) the fluocinosulfuron: mesotrione =1-9:1-25:1-64, and the weight percentage of the effective component in the composition is 4-85%. The compound weeding composition can be prepared into conventional formulations such as wettable powder, water dispersible granules, missible oil, dispersible oil suspending agents and the like, can simultaneously prevent and kill various weeds in corn fields, obviously improves the control effect on the weeds in the corn fields, has low using amount of effective components and low use cost, is safe for corn and succeeding crops, and is an ideal herbicide.

Description

Compound weeding composition for corn field

Technical Field

The invention belongs to the technical field of pesticides, and particularly relates to a herbicide composition which takes topramezone, flucarbazone-sodium and mesotrione as effective components and is used for preventing and removing annual weeds in a corn field.

Background

Corn is one of the main grain crops in China, the corn planting area is wide, and weeds in corn fields are common and various. The weeds in the corn field mainly comprise broadleaf weeds such as amaranthus retroflexus, chenopodium quinoa, bindweed, black nightshade, amaranth, piemarker, purslane, cocklebur, dayflower, bovine chickweed and the like; grassy weeds such as barnyard grass, large crabgrass, green bristlegrass herb, goosegrass herb and the like, and cyperaceae weeds such as cyperus rotundus and the like. The existence of weeds seriously affects the normal growth of corn in the seedling stage and even causes yield reduction, the current corn field herbicide varieties comprise atrazine, alachlor, acetochlor, metolachlor, nicosulfuron, trifluralin, 2,4-D and the like, wherein the consumption of the atrazine with long residual effect is too large, huge hidden danger exists, the weed control spectrum of most herbicides is limited, and the drug resistance of the weeds is easy to generate after long-term use, so that the development of herbicide mixed preparations for the corn field is emphasized, and the herbicide mixed preparations have better weed control effect and wider weed control spectrum.

Topramezone belongs to a triketone post-emergence stem and leaf treatment herbicide, is absorbed by roots, seedlings and leaves, is conducted to meristem towards the top and the base in plants, inhibits 4-HPPD (4-hydroxyphenylpyruvate dioxygenase), enables the biosynthesis of carotenoid and chlorophyll to be inhibited and disturbed in function, leads to the bleaching symptom of germinated sensitive weeds within 2-5 days, and leads to the death of the plants within 14 days. The topramezone has high activity and low required use amount, has the advantage of wide use suitable period due to the fact that the topramezone is a post-emergence herbicide, has the advantage of wide weed control spectrum, has good effect on preventing and removing annual weeds in corn fields, but has high single use cost, and is not beneficial to large-area popularization and use.

The flucarbazone-sodium is also named flucarbazone-sodium, belongs to a slightly toxic pesticide, is a novel sulfonylurea herbicide, and has the chemical name: n- (2-trifluoromethoxyphenyl sulfonyl) -4, 5-dihydro-3-methoxy-4-methyl-5-oxo-1H-1, 2, 4-triazolecarboxamide sodium salt. The mechanism of action of fluocinosulfuron is an inhibitor of acetolactate synthase (ALS), which prevents the biosynthesis of branched-chain amino acids by inhibiting ALS in plants, ultimately disrupting protein synthesis and interfering with DNA synthesis and cell division and growth. Absorbed by the stems and leaves of the weeds, the weeds are green and withered and die finally. The weeds which are sensitive to the flucarbazone-sodium and have the weeding effect of more than 85 percent comprise wild oat, wild shepherd's purse, Chinese gall grass, polygonum aviculare and the like. Because of long residual effect period, the pesticide damage to sensitive crops of the next crop or intercropping sensitive crops occurs in different degrees.

Mesotrione is also known as mesotrione, chemical name: 2- (4-methanesulfonyl) -2-nitrobenzoyl) cyclohexane-1, 3-dione. Has good control effect on annual broadleaf weeds and partial gramineous weeds such as abutilon, amaranth, chenopodium album, polygonum, cockspur grass, crab grass and the like in corn fields. But has poor control effect on copperleaf herb and some gramineous weeds. Mesotrione is a pre-emergent and post-emergent broad spectrum selective herbicide that inhibits the enzyme hydroxyphenylpyruvate dioxygenase (HPPD), which converts the amino acid tyrosine to a plastoquinone. Plastoquinone is a cofactor for phytoene desaturase and is a key enzyme in carotenoid synthesis. The emergence of yellowing symptoms in the meristems of plants within 3-5 days of mesotrione application causes subsequent blight, and after two weeks throughout the entire plant. Has weak acidity, can be tightly adsorbed on organic substances in most acidic soils, and exists in a non-absorbable anion form in neutral or alkaline soils. The compound is a novel triazolone herbicide, can be used for treating soil surface before seedling, can also be used for spraying stems and leaves after seedling, has quick response, has short residual period of mesotrione in soil, and is safe for succeeding crops. Meanwhile, the biological activity of the sulcotrione is more than 10 times that of sulcotrione, and the development potential and the competitiveness are better. Can effectively control main broad-leaved weeds and some gramineous weeds.

The inventor selects topramezone, flucarbazone-sodium and mesotrione with different herbicide types, different action mechanisms, different weed control spectrums and complementary advantages and disadvantages as effective components through a large number of experiments and reasonably matches the effective components, so that annual weeds in corn fields can be effectively prevented and removed, the dosage and the dosage times are reduced, the cost is reduced, and the labor force is saved.

Disclosure of Invention

The invention aims to provide a herbicide composition which has wide weed control spectrum, good weeding effect and safe use and is beneficial to the comprehensive control of weeds in a corn field according to the current situation of the current corn field herbicide and the occurrence situation of weeds in the corn field.

The invention is realized by adopting the following technical scheme:

the compound weeding composition for the corn field comprises the effective components of topramezone, flucarbazone-sodium and mesotrione, wherein the weight ratio of the topramezone to the flucarbazone-sodium to the mesotrione is as follows: 1-9:1-25:1-64, preferably in a weight ratio of: 3:5:8. The total weight of the topramezone, the flucarbazone-sodium and the mesotrione accounts for 4-85% of the total weight of the herbicide.

The compound weeding composition for the corn field can be prepared into any one of water dispersible granules, wettable powder, missible oil and dispersible oil suspending agents.

In the corn field compound weeding composition, in the water dispersible granules, the weight of the effective components accounts for 30-70% of the total weight of the herbicide; in the wettable powder, the weight of the effective component accounts for 20-85% of the total weight of the herbicide, and in the emulsifiable concentrate, the weight of the effective component accounts for 4-35% of the total weight of the herbicide; the weight of the active ingredients in the dispersible oil suspending agent accounts for 10-50% of the total weight of the herbicide.

The corn field compound weeding composition also contains one or more of auxiliary components which can be accepted in the agricultural pharmacy, such as an emulsifier, a wetting agent, a dispersing agent, a thickening agent, a disintegrating agent, a binder, a solvent, a carrier and the like.

The emulsifier is one or more of nonylphenol polyoxyethylene ether, nonylphenol polyglycol ether, benzylphenol polyoxyethylene ether, styrylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, fatty alcohol polyoxyethylene ether and calcium alkyl benzene sulfonate; the wetting agent is one or more of alkylphenol polyoxyethylene, sodium lauryl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether and octylphenol polyoxyethylene ether; the dispersant is one or more of lignin and sulfonate derivatives thereof, sodium fatty alcohol sulfate, naphthalene and alkyl naphthalene sulfonate formaldehyde condensate (dispersant NNO, dispersant MF and the like), alkylphenol polyoxyethylene ether phosphate and alkylphenol polyoxyethylene ether formaldehyde condensate sulfate; the thickening agent is one or more of xanthan gum, magnesium aluminum silicate, bentonite and Arabic gum; the disintegrating agent is one of sodium sulfate, sodium nitrate, sodium chloride, ammonium sulfate, etc.; the binder is one or more of hydroxyethyl cellulose, soluble starch, polyethylene glycol, methyl cellulose, dextrin, fructose or polyvinyl alcohol; the carrier is one or more of activated clay, kaolin, montmorillonite, diatomite, attapulgite and white carbon black; the solvent is one or more of n-heptane, hexane, octane, methyl stearate, methyl oleate, methyl linoleate, rosin-based vegetable oil, rapeseed oil, soybean oil and palm oil.

The corn field compound weeding composition has the beneficial effects that:

1. the weeding composition has high weeding activity, after the topramezone, the flucarbazone-sodium and the mesotrione are compounded, the advantages can be complemented, the weeding spectrum is expanded, all weed problems in a corn field can be solved by using the composition once, and the defects and limitations of using a single agent are overcome. Improve the weeding effect and the weeding speed and show obvious synergistic action.

2. In the weeding composition, the topramezone belongs to a triketone post-emergence stem-leaf treatment herbicide, the flucarbazone-methyl is a sulfonylurea herbicide, and the mesotrione is a triazolone herbicide, and has different action mechanisms, so that the occurrence and development of drug resistance and succession of field weed communities are delayed to the maximum extent.

Detailed Description

The present invention is further illustrated by the following examples, but the present invention is not limited thereto, and the preparation methods of the dosage forms in the examples are all conventional ones.

Formulation examples

Example 1: 30% topramezone-flucarbazone-sodium mesotrione water dispersible granule

Weighing 1% of topramezone, 5% of flucarbazone-methyl, 24% of mesotrione, 6% of alkylphenol polyoxyethylene, 8% of sodium fatty alcohol sulfate, 5% of ammonium sulfate, 3% of hydroxyethyl cellulose and diatomite to complement to 100%, uniformly mixing, passing through an airflow pulverizer, sieving materials with a 325-mesh sieve, mixing and stirring the materials in a mixer again, adding a proper amount of water for granulation, and drying to obtain the 30% topramezone-flucarbazone-mesotrione water dispersible granule.

Examples 2 to 4

Composition of matter	45％WDG	58％WDG	70％WDG
				Topramezone	3	3	6
Fluorobanuron-methyl	10	15	20
				Mesotrione	32	40	44
Wetting agent	4	6	5.5
				Dispersing agent	5	4	4
Disintegrating agent	4	4.5	3.5
				Binder	2	3	2.5
Carrier	Make up to 100%	Make up to 100%	Make up to 100%

In the embodiments 2-4, the wetting agent is one or more of alkylphenol polyoxyethylene, sodium lauryl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol polyoxyethylene, nonylphenol polyoxyethylene and octylphenol polyoxyethylene; the dispersant is one or more of lignin and sulfonate derivatives thereof, sodium fatty alcohol sulfate, naphthalene and alkyl naphthalene sulfonate formaldehyde condensate (dispersant NNO, dispersant MF and the like), alkylphenol polyoxyethylene ether phosphate and alkylphenol polyoxyethylene ether formaldehyde condensate sulfate; the disintegrating agent is one or more of sodium sulfate, sodium nitrate, sodium chloride, ammonium sulfate, etc.; the binder is one or more of hydroxyethyl cellulose, soluble starch, polyethylene glycol, methyl cellulose, dextrin, fructose or polyvinyl alcohol; the carrier is one or more of activated clay, kaolin, montmorillonite, diatomite, attapulgite and white carbon black.

Example 5: 20% wettable powder of topramezone, flucarbazone-sodium and mesotrione

Weighing 2% of topramezone, 2% of flucarbazone-methyl, 16% of mesotrione, 4% of octylphenol polyoxyethylene ether, 7% of sodium lignosulfonate, 4% of white carbon black and kaolin to complement to 100%, stirring and uniformly mixing, passing through an airflow pulverizer, and sieving with a 325-mesh sieve. And then mixing and stirring the materials in the mixer again to obtain 20% of topramezone-flucarbazone-mesotrione wettable powder.

Examples 6 to 8

In examples 6 to 8, the wetting agent is one or more of alkylphenol ethoxylate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, fatty alcohol ethoxylate, nonylphenol ethoxylate, and octylphenol ethoxylate; the dispersant is one or more of lignin and sulfonate derivatives thereof, sodium fatty alcohol sulfate, naphthalene and alkyl naphthalene sulfonate formaldehyde condensate (dispersant NNO, dispersant MF and the like), alkylphenol polyoxyethylene ether phosphate and alkylphenol polyoxyethylene ether formaldehyde condensate sulfate; the carrier is one or more of activated clay, kaolin, montmorillonite, diatomite, attapulgite and white carbon black.

Example 9: 4% topramezone-flucarbazone-sodium mesotrione emulsifiable concentrate

Weighing 1% of topramezone, 1% of flucarbazone-sodium and 2% of mesotrione, dissolving the weighed materials in 10% of turpentine-based vegetable oil, adding 12% of fatty alcohol-polyoxyethylene ether, and uniformly stirring and mixing to obtain a uniform and transparent topramezone-flucarbazone-mesotrione emulsifiable concentrate with the concentration of 4%.

Examples 10 to 12

Composition of matter	16％OF	28％OF	35％OF
				Topramezone	3	2	2
Fluorobanuron-methyl	5	10	12
				Mesotrione	8	16	21
Emulsifier	10	12	12
				Solvent(s)	12	15	18
Oleic acid methyl ester	Make up to 100%	Make up to 100%	Make up to 100%

The emulsifier is one or more of nonylphenol polyoxyethylene ether, nonylphenol polyglycol ether, benzylphenol polyoxyethylene ether, styrylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, fatty alcohol polyoxyethylene ether and calcium alkyl benzene sulfonate; the solvent is one or more of n-heptane, hexane, octane, methyl stearate, methyl oleate, methyl linoleate, rosin-based vegetable oil, rapeseed oil, soybean oil and palm oil.

Example 13: 10% topramezone-flucarbazone-sulfuron mesotrione dispersible oil suspension agent

Weighing 3% of topramezone, 9% of flucarbazone-sodium, 1% of mesotrione, 8% of castor oil polyoxyethylene ether, 5% of alkylphenol polyoxyethylene ether, 6% of fatty alcohol sodium sulfate, 0.5% of xanthan gum and methyl oleate, supplementing to 100%, uniformly mixing, and grinding or high-speed shearing and dispersing to obtain 10% of topramezone-flucarbazone-sulam-mesotrione dispersible oil suspension

Examples 14 to 16

Composition of matter	22％SC	41％SC	50％SC
				Topramezone	2	4	8
Fluorobanuron-methyl	4	15	12
				Mesotrione	16	22	30
Emulsifier	7	6	6.5
				Wetting agent	4	5	4
Dispersing agent	5	4.5	5.5
				Thickening agent	1	1.5	1.2
Oleic acid methyl ester	Make up to 100%	Make up to 100%	Make up to 100%

The emulsifier is one or more of nonylphenol polyoxyethylene ether, nonylphenol polyglycol ether, benzylphenol polyoxyethylene ether, styrylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, fatty alcohol polyoxyethylene ether and calcium alkyl benzene sulfonate; the wetting agent is one or more of alkylphenol polyoxyethylene, sodium lauryl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether and octylphenol polyoxyethylene ether; the dispersant is one or more of lignin and sulfonate derivatives thereof, sodium fatty alcohol sulfate, naphthalene and alkyl naphthalene sulfonate formaldehyde condensate (dispersant NNO, dispersant MF and the like), alkylphenol polyoxyethylene ether phosphate and alkylphenol polyoxyethylene ether formaldehyde condensate sulfate; the thickening agent is one or more of gelatin, xanthan gum, magnesium aluminum silicate, bentonite and Arabic gum;

b bioassay examples

1. Indoor bioassay test: determination of the type of combined action of the herbicidal compositions of the present invention.

(1) Designing test agents and dosages:

topramezone: 1. 3, 9g (a.i)/mu; 1, 5 and 25g (a.i)/mu of flucarbazone-sodium; mesotrione 1, 8, 32, 64g (a.i)/mu

(2) The tested weeds: the germination rate of seeds collected in the field is over 95 percent for the common weeds in corn fields of gramineous weeds (wild oat, goosegrass, cockspur grass and crab grass), broad-leaved weeds (amaranthus retroflexus, chenopodium album, abutilon and purslane) and cyperaceae weeds (cyperus rotundus).

(3) The test method comprises the following steps: the soil for the test is special soil for the test collected in a land without medicine, flowerpots with the same size are taken, the soil is filled to the height of 2/3, water is added until the soil is completely wetted, weed seeds which are forced to germinate and expose to white in a biochemical incubator are uniformly placed in the flowerpots, and each flowerpot is 100 seeds and cultured to the 3-4 leaf stage. The test agents are used for carrying out stem leaf spraying treatment on various weeds under different dosages, a spraying device is a 3WT-II type spraying tower, 3 times of repetition is set for each treatment, and a blank control is set.

The herbicidal activity after the combination is examined by the Colby method, i.e.

Wherein X is the survival rate of the weed of the herbicide A when the dosage is P; y is the survival rate of the weed of the herbicide B when the dosage is Q; z is the survival rate of the weed of the herbicide C when the dosage is W; e₀The theoretical weed survival rate of the herbicide (A + B + C) at the dosage of (P + Q + W); e is the actual weed survival rate for each treatment. According to the Colby method, when E₀-E>When the content is 10 percent, the mixed herbicide generates a synergistic effect; when E is₀-E<When the content is-10%, the mixed herbicide generates antagonism; when E is₀When the E value is +/-10%, the addition effect of the mixed herbicide is generated;

TABLE 1 judgement of the type of Combined action of topramezone, flucarbazone-methyl, mesotrione on grass weeds

TABLE 2 judgment of the type of Co-action of topramezone, flucarbazone-sodium and mesotrione on broadleaf weeds

TABLE 3 judgement of the type of combined action of topramezone, flucarbazone-sodium, mesotrione on sedge weeds

(4) Results and analysis of the experiments

As can be seen from tables 1 to 3, after the three effective substances of topramezone, flucarbazone-sodium and mesotrione are compounded, the weight ratio is (1-9): (1-25): (1-64) the mixed E0-E (%) is more than-10%, which shows that the compound weeding composition has additive or synergistic effect on weeds. Wherein topramezone: and (3) the fluocinosulfuron: survival rate of grass weeds E when weight ratio of mesotrione is 3:5:8₀-E ═ 15.6, survival rate on broadleaf weeds E₀-E ═ 10.8, survival rate for Cyperaceae weeds E₀-E ═ 14.4. Are all significantly higher than in the other combinations₀The value of E, so the combination of 3+5+8 is the optimal combination in terms of cost, control effect, herbicidal spectrum and formula balance, i.e. topramezone: and (3) the fluocinosulfuron: mesotrione is 3:5: 8.

2. And (3) pharmacodynamic test: test of field efficacy in preventing and killing weeds in corn field

(1) Test agent

16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (1: 5:8) 30 g/mu

② 16 percent of topramezone-flucarbazone-mesotrione emulsifiable concentrate (3: 1: 8) 30 g/mu

③ 16 percent of topramezone-flucarbazone-sodium mesotrione missible oil (3:5:8) 30 g/mu

Fourthly, 30 g/mu of 16 percent emulsifiable concentrate of topramezone, flucarbazone-sodium mesotrione (3: 25: 8)

16% topramezone-flucarbazone-mesotrione emulsifiable concentrate (9: 5:8) 30 g/mu

Sixthly, 30 g/mu of 16 percent emulsifiable concentrate of topramezone, flucarbazone-sodium mesotrione (3:5: 32)

Seventhly, 30 percent of topramezone suspending agent is 7 g/mu

Eighty percent (70%) flucarbazone-sodium water dispersible granule (5 g/mu)

Ninthly 10% mesotrione suspension concentrate 80 g/mu

Void in the red

(2) The test method comprises the following steps: the experiment is carried out by setting 10 treatments, each treatment is set to 4 times, the total number of the treatments is 40, the area of each treatment cell is 20 square meters, the treatments are randomly arranged in blocks, 30 kilograms of water is added into each mu, a 552C type sprayer (with the aperture of 0.7 mm) is adopted for uniform spraying, and the main weeds in the field comprise eleusine indica, green bristlegrass, crabgrass, piemarker, purslane, redroot amaranth, cyperus rotundus and the like.

(3) Purpose of the experiment

Safety: after the application, the growth and development conditions of the corn are observed, and the safety of the test agent to the corn is evaluated.

② weeding effect: 4 points are randomly selected in each plot, 1/4 square meters are investigated in each point, the weed condition is investigated 15 days and 30 days after the application, the species and the plant number of the weeds are respectively recorded, and the weed plant control effect is calculated.

(4) Test results

Safety: after the application of the herbicide, the corns in the herbicide treatment area grow normally, the plant height, the leaf color and the leaf age are basically consistent with those in the blank control area, and phytotoxicity symptoms such as whitening, dwarfing, malformation and the like are not found. The test agent is safe to use for corn under the recommended dosage.

② weeding effect: see tables 4 and 5

Table 4: weed control effect in corn field 15 days after pesticide application

Table 5: weed control effect in corn field 30 days after pesticide application

The field test result shows that: the herbicide composition has obvious control effect on weeds in corn fields 15 days after 16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (3:5:8) and 30 days after application, and the control effect is better than that of 16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (1: 5:8), 16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (3: 1: 8), 16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (3: 25: 8), 16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (9: 5:8), 16% of topramezone-flucarbazone-mesotrione emulsifiable concentrate (3:5: 32), more obviously better than that of a control agent of 7 g/mu of topramezone suspending agent, 5 g/mu of 70% flucarbazone water dispersible granules and 10% of mesotrione suspending agent of 80 g/mu; the ternary blending of the topramezone, the flucarbazone-sodium and the mesotrione can obviously improve the control effect in field application, reduce the application times, save the application cost and expand the weed control spectrum.

After the three components are mixed, the problems of poor control effect of the topramezone on cyperaceae weeds, poor control effect of the flucarbazone-sodium on part of broadleaf weeds and poor control effect of the mesotrione on gramineous weeds are solved, meanwhile, the quick action and the comprehensive control effect on the weeds in the corn field are greatly improved, and the medication cost is saved.

Claims

1. The compound weeding composition for the corn field is characterized by comprising the effective components of topramezone, flucarbazone-sodium and mesotrione, wherein the weight ratio of the topramezone to the flucarbazone-sodium to the mesotrione is 3:5: 8.

2. The compound weeding composition for corn fields according to claim 1, wherein the content of the active ingredients accounts for 4-85% of the total amount of the herbicide.

3. The compound herbicide composition for corn fields as claimed in any one of claims 1-2, wherein the herbicide composition can be made into any one of water dispersible granules, wettable powder, emulsifiable concentrate and dispersible oil suspension.

4. The compound weeding composition for corn fields according to claim 3, wherein in the water dispersible granules, the weight of the effective ingredients accounts for 30-70% of the total weight of the herbicide; in the wettable powder, the weight of the effective component accounts for 20-85% of the total weight of the herbicide, and the weight of the effective component in the missible oil accounts for 4-35% of the total weight of the herbicide; the weight of the active ingredients in the dispersible oil suspending agent accounts for 10-50% of the total weight of the herbicide.

5. The compound herbicide composition for corn fields as claimed in any one of claim 3, wherein the herbicide composition further comprises an agriculturally and pharmaceutically acceptable auxiliary ingredient, and the agriculturally and pharmaceutically acceptable auxiliary ingredient is one or more of an emulsifier, a wetting agent, a dispersant, a thickener, a disintegrant, a binder, a solvent and a carrier.

6. The compound weeding composition for corn fields according to claim 1, which is used for preventing and killing annual weeds in corn fields.