JPH0446921B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a herbicidal composition, particularly to a herbicidal composition having excellent herbicidal activity against paddy field weeds. Herbicides for paddy fields in Japan are roughly divided into three categories based on the timing of use: early-season herbicides, mid-season herbicides, and late-season herbicides, but the first two account for the majority of usage. . As initial herbicides, 2, 4, 6
-trichlorophenyl-4-nitrophenyl ether and 2,4-dichlorophenyl-4-nitro-3-methoxyphenyl ether, and as medium-term herbicides S-(4-chlorobenzyl)-
N,N-diethylthiol carbamate and 2-methylthio-4,6-bis(ethylamino)-S-
Mixture with triazine, S-ethyl-N,N-hexamethylenethiol carbamate and 2-methylthio-4,6-bis(ethylamino)-S-triazine and γ-(2-methyl-4-chlorophenoxy) a mixture with butyric acid ethyl ester, and 3-
Examples include isopropyl-1H-2,1,3-benzothiadiazine-(4)-3H-one-2,2-dioxide. Early stage herbicides are extremely effective when used at the beginning of weed emergence, but are significantly less effective when used at the peak of weed emergence. On the other hand, intermediate herbicides are effective from the beginning of weed emergence to the growth stage, but if used during the germination stage, they cause significant damage to paddy rice, and the period of use is limited to when the growth of paddy rice is considerably advanced. Furthermore, these herbicides are not sufficiently effective against perennial weeds, and furthermore, it is often seen that their effectiveness decreases or that they cause chemical damage to paddy rice depending on conditions such as temperature, soil, and water management. In recent years, in order to save labor in agricultural work, there has been a desire for a herbicide that can control all weeds, including perennial weeds, with a single treatment, has a wide range of suitable application periods, and is harmless to paddy rice. There is. However, existing herbicides cannot be said to satisfy these requirements. The purpose of the present invention is to provide a herbicidal composition that meets these demands and has an accurate control effect when used at any time from the start of weed emergence to the growing season immediately after rice planting, and is harmless to paddy rice. It is said that The present invention relates to α-(2-naphthoxy)propionanilide (hereinafter referred to as "Compound A"), 2-benzothiazol-2-yloxy-N-methylacetanilide (hereinafter referred to as "Compound B") and N-
The present invention relates to a herbicidal composition for rice fields containing (α,α-dimethylbenzyl)-α-bromotertiarybutylacetamide (hereinafter referred to as "compound C") as an active ingredient. Compounds A, B, and C are represented by the following chemical structural formulas (), (), and (), respectively. All the compounds contained in the composition according to the present invention are known compounds described in the following literature. JP-A-46-14077, JP-A-54-154762, JP-A-55-43014, JP-A-56-
Publication No. 110655, Japanese Patent Publication No. 48-35454. However, when each of the active compounds is used alone, the herbicidal activity is not always fully satisfactory, the grass species and suitable season for use are limited, and phytotoxicity to paddy rice is often observed. For example, Compound A shows a remarkable effect on annual broad-leaved weeds and Japanese grass, but has little effect on barnyard grass, a grass weed. Compound B is highly effective against barnyard grass, but less effective against perennial weeds and broad-leaved weeds. Compound C is highly effective against firefly, a weed of the Cyperaceae family, but less effective against barnyard grass and perennial weeds, and there is concern about chemical damage to paddy rice depending on the time of use. The herbicide composition according to the present invention not only complements weeds that are difficult to control with each individual active compound, but also has a synergistic herbicidal effect of each compound, which can be used to control small amounts of weeds that cannot be completely controlled by each active compound alone. At a given dosage, it has a remarkable control effect not only on annual weeds but also on perennial weeds, which have recently become more common, and there is no chemical damage to paddy rice during the entire period from immediately after rice planting to the growing season. Although the herbicidal compositions according to the invention exhibit a particularly strong synergistic effect in certain composition ratios, the mixing proportions of the three active compounds may vary within a fairly wide range. In particular, it is desirable to use 2 to 0.2 parts by weight of compound B and 2 to 0.2 parts by weight of compound C to 1 part by weight of compound A. The herbicidal composition of the present invention is most effective when formulated into granules for use. That is, a method in which the amount of the active compound is increased using bentonite, clay, talc, limestone, etc., a binder such as sodium ligninsulfonate, polyvinyl alcohol, or sodium alkylbenzenesulfonate is added, kneaded with water, extrusion granulated, and then dried; It is most desirable to formulate a granule by dissolving it in an appropriate solvent and uniformly adsorbing it onto granular diatomaceous earth, permiyukilite, or the like. In addition to granules, the formulation may be formulated into a wettable powder or powder, diluted with water, and then sprayed, or directly sprayed. Furthermore, it is also possible to use them in combination with insecticides, fungicides, or other herbicides, or to formulate formulations, if necessary. Next, examples of the herbicide composition of the present invention will be given, but the present invention is not limited thereto. In addition, all the mixing ratios in the examples are weight ratios. Example 1 Granules After mixing 7% compound A, 3.5% compound B, 5% compound C, 60% bentonite, 21.5% talc, 2% alkylnaphthalene sulfonic acid condensate, and 1% dioctyl sulfone succinate, add an appropriate amount of water. are added, kneaded, and granulated using a granulator in the usual manner to obtain granules. Hereinafter, the herbicidal effect of the composition of the present invention will be specifically explained using test examples. Test example 1 Weeding test at the beginning of weed germination Paddy field soil was placed in an R/2.000 Wagner pot, and 1 g each of N, P ₂ O ₅ and K ₂ O was added to it.
Apply a chemical fertilizer containing 30% to the entire layer, add an appropriate amount of water, and stir thoroughly to create a water-filled condition. Two paddy rice seedlings (leaf chill 2.5) grown in advance in a greenhouse were used as one plant, and the two plants were planted per pot at a depth of 3 cm, and seeds of Japanese millet, bulrush, and Helaomodaka were sown into these. In addition, tubers of Urikawa were transplanted to this and grown in a greenhouse while maintaining the water depth at 3 cm. After 10 days from the seedlings, at the beginning of weed emergence, a predetermined amount of the test compound was treated using granules prepared according to the method shown in the above example. After treatment, water leakage of 1 cm per day was given. One month after the chemical treatment, the herbicidal effect and chemical damage to paddy rice were investigated. The results are shown in Table 1 below. In this table, the herbicidal effects and phytotoxicity of each grass species are evaluated on a scale of 10 from "0" to "9" according to the evaluation criteria below.
The degree of chemical damage to paddy rice is expressed using numerical values, and the display categories are ``severe damage,'' ``major damage,''``poisoning,'' and ``slight damage.''
There were six levels: "slight harm" and "harmless." Evaluation criteria 0 Remaining grass amount to untreated ratio 85 or more (wt%) 1 71-84 2 56-70 3 41-55 4 31-40 5 21-30 6 11-20 7 6- 10 8 〃 1-5 9 〃 0 Harmless: No symptoms of chemical damage Minor harm: Significant recovery Minor harm: Expected decrease in revenue by 5% or less Moderate damage: 〃 6-15% Major damage: 〃 16-30% Severe damage: 〃 31% or more

[Table] Test example 2 Field test Paddy fields in which common weeds naturally coexist were plowed, fertilized (1 kg/a each as N, P ₂ O ₅ , and K ₂ O), plowed, and leveled using the usual methods. 1 ward
Divide into a 10m ² (2.5m x 4m) plot, each with two paddy rice seedlings of leaf age 2.5, spaced 30cm apart, and spaced horizontally.
It was transplanted at 15 cm. After transplanting, while maintaining the water depth at 3 to 5 cm, test compounds prepared according to the method shown in the above example were applied at the beginning of weed germination (3 days after rice planting) and at the 3.0 to 3.5 leaf stage of Japanese millet (15 days after rice planting). Mixed or single granules were spread by hand. The amount of weeds one month after spraying and the yield of paddy rice four months after spraying were investigated, and the results are shown in Table 2.

[Table] The excellent synergistic effect brought about by the herbicide composition of the present invention can be fully understood from the herbicidal effects shown in the test examples above. The test weeds will be explained in more detail below. The following method is usually used to test for interaction between any combination of three herbicides. (SRColby., “Calculating Synergistic and
Antagonistic Responses of Herbicide
(See Combinations” Weeds 15 , 20-22 (1973)). % damage when using rg/a E = Expected % damage when herbicides A, B, and C are mixed with p, q, and rg/a, respectively. Then, E = X + Y + Z - (XY + XZ + YZ) / 100 + XYZ / 10000 If the measured actual damage exceeds the calculated expected damage, this indicates the presence of synergy in the herbicidal composition. The results of testing the interaction are shown in the following Test Example 3. Test Example 3 Interaction Verification Test 1 kg of paddy soil was filled into a R/10,000 pot, and N, P ₂ O ₅ and K ₂ O were added to the pot. 0.3g each
The entire layer was fertilized with chemical fertilizer. To this, 10 tubers of Cyperus japonica were planted in each pot, and an appropriate amount of water was gently added to create a stagnant state. When the cypress reached the 2-3 leaf stage, a predetermined amount of the test compound was treated under swamping using granules prepared according to the method described in the example above. 20 days after the treatment, the water snails were pulled out and their air-dry weight was measured, and the damage was evaluated as % damage compared to the untreated control plot.The results are shown in Table 3. In this table, the numbers for measured values and calculated values represent the following: 0% = No effect 100% = Complete extermination

[Table] Test Example 4 Paddy soil was placed in a 1/2000 Ahl Wagner pot, and a chemical fertilizer containing 1 g each of N, P ₂ O ₅ , and K ₂ O was applied to the entire layer, and an appropriate amount of water was added. Stir thoroughly to submerge. Two paddy rice seedlings (leaf age 2.5) grown in advance in a greenhouse were used as one seedling, two seedlings per pot were planted at a depth of 3 cm, and seeds of Japanese millet and firefly were sown into these. Also,
Tubers of Urikawa were transplanted to this and grown in a greenhouse while maintaining the water depth at 3 cm. During the weed growth period 20 days after transplantation, a predetermined amount of the test compound was treated using granules prepared according to the method shown in the above example. After treatment, water leakage of 1 cm per day was applied. The herbicidal effect was investigated 30 days after chemical treatment. The results are shown in Table 4. In the table, the herbicidal effect on each grass species was expressed using the same criteria as Test Example 1. Also in this test, the predicted value of the effect was calculated using Colby's formula described above in order to test for interaction. As a result of Test Examples 3 and 4, the mixture of the three types of compounds of the present invention showed a great synergistic effect against various weeds that could not be expected from the mixture of two types of compounds.

[Table] As is clear from the above results, the composition of the present invention is harmless to paddy rice when used at any time from the beginning of weed germination to the peak of weed growth immediately after rice transplantation, and is synergistic with the three types of agents. Due to its action, it is possible to control all weeds in a single application using doses that cannot be controlled by individual chemicals.It is a preferable herbicide from the standpoint of environmental pollution, and is significantly superior to many conventionally used herbicides. There is.

Claims (1)

[Claims] 1 α-(2-naphthoxy)propionanilide,
A herbicidal composition for paddy fields, comprising 2-benzothiazol-2-yloxy-N-methylacetanilide and N-(α,α-dimethylbenzyl)-α-bromotertiarybutylacetamide as active ingredients.