Method for controlling weeds

The present invention relates to a method for controlling weeds in corn field which comprises applying a herbicidal composition comprising 2-[2-chloro-4-fluoro-5-{3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydropyrimidin-1-yl}phenoxy]propionic acid ester as an active ingredient to corn fields after seeding corn.According to the present method, kinds of weeds in corn fields can be controlled widely and no problematic phytotoxicity to corn is caused.

FIELD OF THE INVENTION

The present invention relates to a method for controlling weeds in corn fields.

BACKGROUND ARTS

Many herbicidal composition have been commercially available, and used for controlling weeds in corn fields. There are, however, many species of weeds to be controlled and their growth extends over a long time. For this reason, requested are herbicides with higher herbicidal activity, wide herbicidal spectrum, and safety to corns.

DISCLOSURE OF THE INVENTION

The present inventor has intensively studied under such a circumstance. As a result, he has found that various weeds growing in corn fields can be controlled and no problematic phytotoxicity can be caused by applying a composition comprising 2- 2-chloro-4-fluoro-5- 3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydropyrimidin-1-yl phenoxy propionic acid ester as an active ingredient to corn fields after seeding corns, and he has accomplished the present invention.

Therefore, the present invention provides a method for controlling weeds in corn fields by applying a composition comprising 2- 2-chloro-4-fluoro-5- 3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydropyrimidin-1-yl phenoxy propionic acid ester (hereinafter, referred to as the present compound) as an active ingredient (referred to as the present herbicidal composition) to corn fields after seeding corns (hereinafter, referred to as the present method).

The production example of the present compound is shown below.

PRODUCTION EXAMPLE 1

In 70 ml of N,N-dimethylformamide, 6.7 g of 3-(4-chloro-2-fluoro-5-hydroxyphenyl)-1-methyl-6-trifluoromethyl-2,4-(1H,3H)-pyrimidindione (produced according to a method described in U.S. Pat. No. 4,859,229) was dissolved, and 4.2 g of potassium carbonate and 3.3 ml of methyl 2-chloropropionate were added thereto. The mixture was stirred at room temperature for 1 hour and at 100 C. for 45 minutes. After that, the reaction mixture was added into water and extracted with ethyl acetate. The organic layer was washed with saturated saline, dried over anhydrous magnesium sulfate and then, concentrated. The residue was subjected to silica gel column chromatography (eluent, hexane/ethylacetate 3/1) to give 5.82 g of methyl 2- 2-chloro-4-fluoro-5- 3-methyl-2,6-dioxo-4-(trifluoromethyl)-1,2,3,6-tetrahydropyrimidin-1-yl phenoxy propionate (hereinafter, referred to as Compound A).

Each of objective present compounds can obtained by conducting the same method as described in the above production example except that the reaction reagents described in the following table 1 are used in replace of methyl 2-chloropropionate.

Physical properties of some of the present compounds are shown below.

Compound A

Compound H

Compound K

Compound L

According to the present method, the following kinds of weeds which cause problems in corn fields can be controlled.

The present herbicidal composition can be usually formulated by mixing each of the present compounds with solid or liquid carriers or diluents, if necessary, surfactants, and/or other formulation auxiliary agents to become emulsifiable concentrates, wettable powders, flowables, and granules, and used.

These formulations may contain any of the present compounds as an active ingredient at an amount of 0.5% to 90% by weight, preferably 1% to 80% by weight, based on the total weight of the formulation.

The present herbicidal composition may be applied to weeds as such, or after diluted with water or the like. The present herbicidal composition may also be used in admixture with other herbicides, in which case the herbicidal activity can be expected to be enhanced. The present herbicidal composition can also be used together with insecticides, bactericides, fungicides, plant growth regulators, fertilizers, safener, soil conditioners, or other agents.

The application amount of the present compound, although it may vary with formulation types, application times, application places, and weeds to be controlled, is usually in the range of 1 to 200 g, more preferably 2 to 100 g, further preferably 5 to 80 g per hectare

The present composition can be applied in corn fields after seeding corns, preferably at 2 leaf stage of corn or later.

Hereinafter, formulation examples are explained. In the examples, part(s) represents part(s) by weight .

Formulation Example 1

Eighty (80) parts of compound A, compound B, compound C, compound D, compound E, compound F, compound G, compound H, compound I, compound J, compound K, compound L or compound M, 3 parts of calcium ligninsulfonate, 2 parts of sodium laurylsulfate, and 15 parts of synthetic hydrated silicon dioxide are well pulverized and mixed, to obtain wettable powders.

Formulation Example 2

Fifty (50) parts of compound A, compound B, compound C, compound D, compound E, compound F, compound G, compound H, compound I, compound J, compound K, compound L or compound M, 3 parts of polyoxyethylene sorbitan monooleate, 3 parts of CMC (carboxymethylcellulose), and 44 parts of water are mixed and wet pulverized until the particle size comes to 5 microns or smaller to give flowables.

Formulation Example 3

Ten (10) parts of compound A, compound B, compound C, compound D, compound E, compound F, compound G, compound H, compound I, compound J, compound K, compound L or compound M, 3 parts of polyoxyethylene sorbitan monooleate, 3 parts of CMC (carboxymethylcellulose), and 84 parts of water are mixed and wet pulverized until the particle size comes to 5 microns or smaller to give flowables.

Formulation Example 4

Fifty (50) parts of compound A, compound B, compound C, compound D, compound E, compound F, compound G, compound H, compound I, compound J, compound K, compound L or compound M, 3 parts of calcium ligninsulfonate, 2 parts of sodium laurylsulfate, and 45 parts of synthetic hydrated silicon dioxide are well pulverized and mixed, to obtain wettable powders.

Formulation Example 5

Ten (10) parts of compound A, compound B, compound C, compound D, compound E, compound F, compound G, compound H, compound I, compound J, compound K, compound L or compound M, 3 parts of calcium ligninsulfonate, 2 parts of sodium laurylsulfate, and 85 parts of synthetic hydrated silicon dioxide are well pulverized and mixed, to obtain wettable powders.

Next, test examples are explained.

The herbicidal activity was evaluated at 11 levels with indices of 0 to 10, i.e., designated by the numeral 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 or 10 wherein 0 means that there was no or little difference in the degree of germination or growth between the treated and the untreated tested plants at the time of examination, and 10 means that the test plants died completely or their germination or growth was completely inhibited. The evaluation of phytotoxicity is as follows:

No harm: Phytotoxicity is hardly seen.

Slight: Slight phytotoxicity which does not affect the growth of corn is seen.

Light: Light phytotoxicity and light growth inhibition of corn are seen.

Middle: Middle phytotoxicity and growth inhibition of corn are seen.

Serious: Serious phytotoxicity and serious growth inhibition of corn are seen.

Test Example 1

Plastic pots having a diameter of 11 cm and a depth of 8 cm were filled with upland soil, and seeded with common lambsquarters ( Chenopodium album ), ivyleaf morningglory ( Ipomoea hederacea ), velvetleaf ( Abutilon theophrasti ), and corn. The test plants were grown in a greenhouse for 7 days. After that, other corn was further seeded in each of the above pots and the test plants were grown in the greenhouse for further 19 days. Emulsifiable concentrate comprising compound A obtained by well mixing 5 parts of compound A, 6 parts of Sorpol 3005X (produced by Toho Chemical Industry, Co., Ltd.) and 89 parts of xylene was diluted with prescribed amount of water, and the dilution was applied over the test plants uniformly using a small sprayer. The leaf stage of the corns grown for 26 days and 19 days were 2-leaf stage and 1-leaf stage, respectively. After the application, the test plants were grown in the greenhouse for 10 days and then, herbicidal activity and phytotoxicity to corn were examined. The results are shown in Table 2.

Plastic pots having a diameter of 11 cm and a depth of 8 cm were filled with upland soil, and seeded with common cocklebur ( Xanthium strumarium ) . The test plants were grown in a greenhouse for 5 days. After that, corn was further seeded in each of the above pots and the test plants were grown in the greenhouse for further 16 days. Emulsifiable concentrate comprising compound A or Comparative compound obtained by well mixing 5 parts of compound A or Comparative compound, 6 parts of Sorpol 3005X (produced by Toho Chemical Industry, Co., Ltd.) and 89 parts of xylene was diluted with prescribed amount of water, and the dilution was applied over the test plants uniformly using a small sprayer. The leaf stage of the corns grown for 16 days were 2-leaf stage. After the application, the test plants were grown in the greenhouse for 10 days and then, herbicidal activity and phytotoxicity to corn were examined. The results are shown in Table 3.

According to the present method, kinds of weeds in corn fields can be controlled widely and no problematic phytotoxicity to corn is caused.