JP3289735B2 - Rice herbicide with reduced phytotoxicity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a herbicide for paddy rice, and more particularly, to a herbicide for paddy rice with reduced phytotoxicity to paddy rice.

[0002]

BACKGROUND OF THE INVENTION Methyl 2- [3- (4,6-dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate (Code No .: DPX-84 / Generic Name: Bensulfonmethyl or Bensulfuronmethyl)
(R) -1- (α-methylbenzyl) -3- (p-tolyl) urea and (S) -1- (α-methylbenzyl) -3-
Herbicides containing an equivalent mixture (racemic) with (p-tolyl) urea are widely used as herbicides for paddy rice.

Although this herbicide has an excellent herbicidal effect and has reduced phytotoxicity such as inhibition of root growth of paddy rice and the like, it has not completely eliminated phytotoxicity. The present inventors have conducted intensive studies to further reduce the phytotoxicity while maintaining the excellent herbicidal effect of the herbicide. As a result, the (R) -1-form of the R-isomer, which is an isomer constituting the racemic form, was obtained. (Α-methylbenzyl) -3- (p-tolyl) urea and S-form of (S) -1- (α-methylbenzyl) -3-
Among the (p-tolyl) ureas, the herbicide in which the S-form is blended with the above-mentioned benzulfonemethyl or the like maintains excellent herbicidal effect and does not inhibit root growth of paddy rice and the like. And completed the invention of the present application.

[0004] Among the two isomers constituting the racemic form, the R-form of (R) -1- (α-methylbenzyl)-
Although 3- (p-tolyl) urea has a better herbicidal effect on weeds of the Cyperaceae family than S-form (S) -1- (α-methylbenzyl) -3- (p-tolyl) urea, ,
As for the phytotoxicity reduction effect, the R-form is inferior to the S-form.

Further, a herbicide obtained by blending an R-form of (R) -1- (α-methylbenzyl) -3- (p-tolyl) urea with a sulfonylurea compound such as the above-mentioned benzulfonemethyl is used. Although excellent herbicidal effects are maintained, phytotoxicity is hardly reduced.

[0006] Conventionally, 1- (α, α-dimethylbenzyl) -3- (p-tolyl) urea (trade name: Daimlon) has been used for cyperaceae weeds such as paddy beetle, firefly, pine bee, horned beetle and kuroguwai. It has been widely used as a herbicide for these weeds because it shows an excellent herbicidal effect against rice flour and fly, and herbicides in which this "Dimron" is blended with the above "bensulfonemethyl" are already known. . However, this herbicide has an excellent herbicidal effect and has phytotoxicity such as inhibiting root growth of paddy rice and the like, and although phytotoxicity has been reduced, it has not completely eliminated phytotoxicity.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems associated with the prior art as described above, and to provide a herbicide for paddy rice which has an excellent herbicidal effect and has significantly reduced phytotoxicity to rice. It is an object.

[0008]

SUMMARY OF THE INVENTION The herbicide for paddy rice according to the present invention comprises a sulfonylurea compound and a (S) -1- (α-methylbenzyl) -3-phenylurea compound represented by the following formula [1]: In [1], R ¹ and R ² represent an alkyl group, halogen or hydrogen, and R ¹ and R ² may be the same or different.)

[0009]

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... [1] is characterized by being blended. The sulfonylurea-based compound is preferably methyl 2- [3- (4,6-dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate, ethyl 5- [3- (4,6-dimethoxypyrimidine-2-yl). Ill)
Ureidosulfonyl] -1-methylpyrazole-4-carboxylate, 3- (4,6-dimethoxy-1,3,5-triazin-2-yl) -1- [2- (2-methoxyethoxy)
-Phenylsulfonyl] urea, N- (2-chloroimidazole [1,2-a] pyridin-3-yl-sulfonyl) -N '-(4,6-dimethoxy-2-pyrimidyl) urea, and among them methyl 2- [3- (4,6-Dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate is particularly preferably used.

[0011] Further, (S) -1-
As the (α-methylbenzyl) -3-phenylurea compound, (S) -1- (α-methylbenzyl) -3- (p-tolyl) urea is preferably used.

Such a herbicide is excellent in herbicidal effect, and has remarkably little phytotoxicity such as not inhibiting root growth of rice.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the rice herbicide according to the present invention will be described in detail. The herbicide for paddy rice according to the present invention is a sulfonylurea-based compound, wherein the (S) -1- (α-methylbenzyl) -3-phenylurea-based compound (R ¹ , R ² represents an alkyl group, halogen or hydrogen, and R ¹ and R ² may be the same or different.)

[0014]

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.. [1] is blended. Examples of the sulfonylurea-based compound include the following compounds.

Methyl 2- [3-- represented by the following formula (A)
(4,6-Dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate:

[0017]

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(A) Ethyl 5- [3- (4,6-dimethoxypyrimidin-2-yl) ureidosulfonyl] -1- represented by the formula (b)
Methylpyrazole-4-carboxylate:

[0019]

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(B) 3- (4,6-dimethoxy-1,3) represented by the formula (c)
3,5-Triazin-2-yl) -1- [2- (2-methoxyethoxy) -phenylsulfonyl] urea:

[0021]

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(C) N- (2-chloroimidazole [1,2-a] pyridin-3-yl-sulfonyl) -N'- represented by the formula (d)
(4,6-dimethoxy-2-pyrimidyl) urea:

[0023]

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(D) 2-chloro-N- (4-methoxy-6methyl-1,3,5-triazin-2-yl-aminocarbonyl) benzenesulfonamide, methyl 2- [3- (4- Methoxy-6-methyl
-1,3,5-Triazin-2-yl) ureidosulfonyl] benzoate, methyl 2- [3- (4,6-dimethylpyrimidin-2-yl) ureidosulfonyl] benzoate, ethyl 2- [3- (4- Chloro-6-methoxypyrimidin-2-yl) ureidosulfonyl] benzoate,
1- (4,6-dimethoxypyrimidin-2-yl) -3- (3
-Ethylsulfonyl-2-pyridylsulfonyl) urea, 3- (6-methoxy-4-methyl-1,3,5-triazin-2-yl) -1- [2- (2-chloroethoxy) phenylsulfonyl] urea , Methyl 2- [3- (4-methoxy
-6-methyl-1,3,5-triazin-2-yl) -3-methylureido-sulfonyl] benzoate, methyl 3-
[3- (4-methoxy-6-methyl-1,3,5-triazine
-2-yl) ureidosulfonyl] thiophen-2-carboxylate, 1- (4,6-dimethoxypyrimidine-2-
Yl) -3- (3-trifluoromethyl-2-pyridinylsulfonyl) urea, 2- (4,6-dimethoxypyrimidin-2-yl-carbamoylsulfamoyl) -N, N-dimethylnicotinamide, -[3- (4,6-bis (difluoromethoxy) -pyrimidin-2-yl) ureidosulfonyl] -benzoic acid methyl ester, methyl 2-[(4-ethoxy-6-methylamino-1,3,5 -
Triazin-2-yl) carbamoylsulfamoyl] benzoate.

Among such sulfonylurea compounds, sulfonylurea compounds represented by the above formulas (a) to (d) are preferred, and methyl 2- [3- (4) , 6-Dimethoxypyrimidine-
2-yl) ureidosulfonylmethyl] benzoate is preferably used for paddy rice. In addition, such a sulfonylurea-based compound may be used alone or in combination of two or more.

The (S) -1- (α-methylbenzyl) -3-phenylurea compound represented by the above formula (1)
R ¹ and R ² represent an alkyl group, halogen or hydrogen,
R ¹ and R ² may be the same or different. Specifically, the following compounds may be mentioned.

(S) -1- represented by the following formula [1-a]
(Α-methylbenzyl) -3- (p-tolyl) urea:

[0028]

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... [1-a] (S) -1- (α-methylbenzyl) -3- (o-tolyl) urea represented by the formula [1-b]:

[0030]

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... [1-b] (S) -1- (α-methylbenzyl) -3- (m-tolyl) urea represented by the formula [1-c]:

[0032]

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... [1-c], (S) -1- (α-methylbenzyl) -3-phenylurea, (S) -1- (α-methyl-p-methylbenzyl) -3-
(P-tolyl) urea, (S) -1- (α-methylbenzyl) -3- (p-halogenated phenyl) urea and the like.

Among such (S) -1- (α-methylbenzyl) -3-phenylurea-based compounds, the above-mentioned formula [1]
-A] represented by (S) -1- (α-methylbenzyl)-
3- (p-Tolyl) urea is preferably used. Such a herbicide in which the S-form is blended with the above-mentioned sulfonylurea compound is excellent in herbicidal effect, and has remarkably little phytotoxicity such that growth of rice root is not inhibited.

Such an (S) -1- (α-methylbenzyl) -3-phenylurea compound can be easily prepared by a conventionally known method. For example, (S) -1-
(Α-Methylbenzyl) -3- (p-tolyl) urea is prepared as follows.

That is,

[0037]

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(S) -1-methylbenzylamine p-tolylphenyl isocyanate

[0039]

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The herbicide for paddy rice according to the present invention contains 1 part by weight of the sulfonylurea compound as described above.
(S) -1- (α-methylbenzyl) -3-phenylurea compound is used in an amount of 10 to 250 parts by weight, preferably 15 to 250 parts by weight.
It is blended in an amount of up to 200 parts by weight.

Such a herbicide for paddy rice can be prepared by applying a conventionally known technique for formulating agrochemicals, for example, various kinds of preparations such as emulsions, wettable powders, granules, flowables, granular wettable powders and microcapsules. Used in molds.

This herbicide applied in various dosage forms has an application amount of the sulfonylurea compound as described above of 10
0.5 to 10 g per are, preferably 1 to 5 g per 10 are, and the amount of (S) -1- (α-methylbenzyl) -3-phenylurea compound sprayed is 10 are The amount is 0.5 to 2500 g per 10 ares, preferably 0.3 to 2000 g per 10 ares.

Such herbicides include bensulfuron-methyl, pyrazosulfuron-ethyl, sinosulfuron, N- (2-chloroimidazo [1,2-a] pyridine-3
-Ylsulfonyl) -N '-(4,6-dimethoxy-2-pyrimidinyl) urea, pyrazolate, pyrazoxifene, benzofenap, and the like. The herbicide containing such a compound may be: , Azena, Hera-modaka and so on, and a high herbicidal effect on perennial hard-to-control weeds such as Urikawa, Omodaka and Krogwai.

[0044]

The herbicide for paddy rice according to the present invention contains (S) -1- (α) in addition to the sulfonylurea compound as described above.
(Methylbenzyl) -3-phenylurea compound is included, so that it has excellent herbicidal effect and has extremely little phytotoxicity to paddy rice, such as not inhibiting root growth of rice.

[0045]

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

[0046]

Example 1 Wetting agent [(S) -1- (α-methylbenzyl) -3- (p-tolyl)
Synthesis of Urea] Optically active α-methylbenzyl urea compound [(S) -1- (α-methylbenzyl) -3- () in which one of the two methyl groups at the benzyl position of Daimulon is replaced with hydrogen p-tolyl) urea] was synthesized by the following method.

That is,

[0048]

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(S) -1-methylbenzylamine p-tolylphenyl isocyanate

[0050]

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(S) -1- (α-) synthesized by the above method
15 parts by weight of methylbenzyl) -3- (p-tolyl) urea and methyl 2- [3-
(4,6-dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate (generic name: bensulfuronmethyl) 0.2 part by weight, clay 73.8 parts by weight, white carbon 3 parts by weight, and ligninsulfonic acid 5 parts by weight of soda and 3 parts by weight of sodium alkylnaphthalenesulfonate were mixed and pulverized to obtain a uniform wettable powder.

[0052]

Example 2 Granules 15 parts by weight of (S) -1- (α-methylbenzyl) -3- (p-tolyl) urea synthesized by the above method, 0.2 parts by weight of benesulfonemethyl, 30 parts by weight of bentonite, 2 parts by weight of sodium dodecylbenzenesulfonate, and 3 parts by weight of sodium ligninsulfonate are mixed, and the water is mixed with about 18 parts by weight.
After adding the parts by weight and kneading with a kneader, the mixture was granulated with a granulator and then dried to obtain granules.

[0053]

Test Example 1 With respect to the herbicide for paddy rice according to the present invention, the herbicidal effect on cyperaceae weeds and the phytotoxicity-reducing effect on inhibition of rice root elongation were examined by the following methods.

(1a) Test Method Rice seeds (Nipponbare) selected in salt water were added to 70% ethanol
After immersion for 0 minutes, it was washed with water. The seeds were germinated at 25 ° C. for 3 hours, and 10 seeds of each were seeded on a petri dish with filter paper.
A chemical solution adjusted to a predetermined concentration was injected into them, and 10 days after immersion, the root length of rice seeds was measured, and the growth rate (%) was calculated.

(1b) Result (S) -1- (α-methylbenzyl) -3- (p-tolyl) urea [hereinafter abbreviated as (S) -DM]. Table 1 shows the effect of bensulfuron-methyl on the inhibition of rice root elongation by the addition of

[0056]

[Table 1]

In addition, the herbicidal effect on weeds of Cyperaceae was tested by the following method. (2a) Test Method Paddy field soil was filled in a 1/2000 arel Wagner pot, and after entering and flushing, the water depth was kept at 3 cm. The next day, the dog fireflies and tamayatsuri were sown. For the chemical treatment, a predetermined amount was sprayed on the water surface 5 days after sowing so as to be uniform in the Wagner pot. The test was performed in a glass greenhouse at 23 ° C to 30 ° C. In the survey, the herbicidal effect was evaluated 28 days after the treatment according to the following criteria. (2b) Results Table 2 shows the results of examining the herbicidal effect on cyperaceae paddy field weeds.

However, in the table, 5: complete inhibition to 0: no effect. (S) -DM is the same as above, and (R) -DM
DM is an abbreviation for (R) -1- (α-methylbenzyl) -3- (p-tolyl) urea. The same applies hereinafter.

[0059]

[Table 2]

[0060]

[Comparative Test Example 1] The above-mentioned Examples 1 and 2
In place of (S) -1- (α-methylbenzyl) -3- (p-tolyl) urea, R-form (R) -1- (α-methylbenzyl)-prepared by the following method is used. 3- (p-tolyl)
A wettable powder and granules were prepared in the same manner as in Example 1 and Example 2 except that urea was used, and a comparative test was performed.

[(R) -1- (α-methylbenzyl) -3-
Synthesis of (p-tolyl) urea] An optically active α-methylbenzylurea compound in which one of two methyl groups at the benzyl position of Daimlon is replaced with hydrogen [(R) -1-)
(Α-methylbenzyl) -3- (p-tolyl) urea] was synthesized by the following method.

That is, in the first embodiment, (S) -1-
The procedure of Example 1 was repeated, except that (R) -1-methylbenzylamine was used instead of methylbenzylamine.
[(R) -1- (α-methylbenzyl) -3- (p-tolyl)
Urea] was synthesized.

Test Method The herbicide for paddy rice was then examined for herbicidal effect on cyperaceae weeds and alleviation of phytotoxicity on inhibition of rice root elongation in the same manner as in "Test Example 1".

That is, the test was performed according to the test method (1a). Results Table 3 shows the effect of addition of (R) -1- (α-methylbenzyl) -3- (p-tolyl) urea [(R) -DM] on inhibition of rice root elongation by bensulfuron-methyl.

[0065]

[Table 3]

[0066]

Comparative Test Example 2 Test Method A test was performed in the same manner as in the above test method (1a). or,
According to the equation shown in Table 4 below, the Modified Saf
The enner Index was calculated.

[0067]

[Table 4]

Results Changes in the Modified Safener Index with respect to inhibition of rice root growth by bensulfuron-methyl were determined.

Table 5 shows the results.

[0070]

[Table 5]

Claims (4)

(57) [Claims] (1) a sulfonylurea compound represented by the following formula (1): (S) -1- (α-methylbenzyl) -3-phenylurea compound (in the formula [1],
R ¹ and R ² represent an alkyl group, halogen or hydrogen,
R ¹ and R ² may be the same or different. ) ... [1] A herbicide for paddy rice, characterized in that: 2. The sulfonylurea compound is methyl 2- [3- (4,6-dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate, ethyl 5- [3- (4,6-dimethoxypyrimidine-2). -Yl) ureidosulfonyl] -1-methylpyrazole-4-
Carboxylate, 3- (4,6-dimethoxy-1,3,5-triazin-2-yl) -1- [2- (2-methoxyethoxy) -phenylsulfonyl] urea, and N- (2-chloroimidazole [1,2-a] pyridin-3-yl-sulfonyl) -N′-
The herbicide for paddy rice according to claim 1, wherein the herbicide is one kind or two or more kinds selected from (4,6-dimethoxy-2-pyrimidyl) urea. 3. The (S) -1- (α) represented by the above formula [1].
-Methylbenzyl) -3-phenylurea compound
The herbicide for paddy rice according to claim 1 or 2, which is (S) -1- (α-methylbenzyl) -3- (p-tolyl) urea. 4. The sulfonylurea compound is methyl 2
The herbicide for paddy rice according to claim 3, which is-[3- (4,6-dimethoxypyrimidin-2-yl) ureidosulfonylmethyl] benzoate.