JPS606326B2 - herbicide - Google Patents

Description

Detailed Description of the Invention The present invention uses 2,3-dicyanopyrazine as an active ingredient, and has remarkable selectivity for rice, wheat, etc., and has the property of contact-selectively controlling almost all grass species that coexist in fields. A novel and non-toxic selective herbicide having the following properties.

The cultivated area of rice has reached 102,000 hectares worldwide, providing food for nearly half of the world's population, and wheat also feeds nearly 50% of the world's population.

In recent years, a number of herbicides have been invented for important cultivated crops, but weed killers that can be sprayed over the entire surface (overhead spraying) during the early and middle stages of crop growth have no effect on the target crop, and can directly control various weeds that coexist with the crop. There are very few drugs. 3,4-dichloropropionanilide (P) in rice cultivation
ropanil), 2-chloro-4-ethylamide/1-6-isopropylamino-S- in corn cultivation
Only triazine (Atrazzne) and the like are known. Of course, there is still no known contact-type herbicide that is completely harmless to rice crops (rice and wheat), two extremely important food resource crops for humankind. The present inventors have repeatedly researched the herbicidal effects of numerous compounds,
We finally discovered that among pyrazine compounds, 2,3-dicyanopyrazine has an excellent contact-selective herbicidal effect,
In particular, it was discovered that the compound is harmless to rice and wheat, which are the most important crops in the world, and can effectively control almost all noxious weeds, leading to the present invention. That is, the 2,3-dicyanopyrazine of the present invention exhibits the greatest characteristic in catalytic selective activity, is generally less harmful to rice crops, and has a greater ability to control broad-leaved weeds.

Furthermore, among rice plants, there is excellent intergeneric selectivity, and the genera Rice, Triticum, Sugarcane, Rye, and Oat have extremely high resistance, and it is surprising that they are harmless even at a dose of more than 1 pep, which is the amount required for broad-leaved weeds. Possesses selectivity. The genus Barley, Maize, Bentgrass, Helicoptera, Prunus genus, Prunus genus, and Prunus genus show severe damage even at the highest concentration of Ki to Point 6 used for rice, wheat, etc. As described above, the 213-dicyanopyrazine of the present invention is a highly selective contact herbicide that is extremely safe for rice, wheat, etc. Of course, the compound also shows soil treatment efficacy in upland fields, causing serious damage to broad-leaved plants and less harm to grass crops, but compared to whole-foliage treatment, more chemicals are required and the residual effect is less. It can also be used in woodcutter paddy fields, starting to control grass family weeds and broad-leaved weeds at 250 yen per melon, nearly completely controlling them at 1000 yen per melon, and is harmless to rice seedlings. When the agent of the present invention is used as a contact selective herbicide, which is its most distinctive feature, on rice, wheat, etc., the following are the main plants that can be controlled.

Chenopodiaceae (e.g. Coaxiae), Brassicaceae (e.g. shepherd's purse, radish, mustard), Hypnosis (e.g. Aobu spp.), Polygonum (e.g. Kishigigi, Hurtade), Rubiaceae (e.g. Cyanophyllaceae), Caryophyllaceae (e.g. Chrysanthemum spp. b),
Asteraceae (e.g., Asteraceae), Asteraceae (e.g., Harujon, Hymemucashomogi, Dandelion, Artemisia)
Convolvulaceae (e.g. Oxalis), Poaceae (e.g. Oxalis, Poaceae), Poaceae (e.g. Oxalis), Roses (e.g. Oxalis), Solanaceae (e.g. Physalis), Primulaceae The 2,3-dicyanopyrazine of the present invention can be used to treat soil microorganisms, heat, and It also has the property of being decomposed by light.

Moreover, since the decomposition products have a structure consisting of carbon, hydrogen, nitrogen, and oxygen, they do not contain metal elements or halogen elements, so there is no concern about environmental pollution such as soil or water quality. It also has low toxicity to fish and belongs to class B. An example of the method for synthesizing 2,3-dicia/pyrazine, which is the active ingredient of the drug of the present invention, will be specifically explained below (
(parts represent parts by weight).

Example 1 (Method for synthesizing active ingredients) A solution prepared by dissolving 27 parts of diaminomaleonitrile in 50 parts of hot water and a solution prepared by dissolving 45 parts of a 40% glyoxal aqueous solution in 300 parts of hot water were mixed and mixed for 18 minutes. After heating, 6 parts of oxalic acid was added and the mixture was refluxed for 30 minutes.

After cooling the reaction solution, the precipitated solid was separated in a furnace and recrystallized from ethanol to obtain 28 parts of 213-dicyanopyrazine having a melting point of 127-13,100. The crystals were purified again using ethanol and activated carbon until the melting point was 132 to 132.5 qo.
A white 213-dicyanopyrazine was obtained. Elemental analysis value measured value C: 55.07%, H: 1.62% "N: 4
Calculated value as 2.98%C 6 days 2N4 C: 55.1
3% H: 1.55%, N: 43.07% When using the herbicide of the present invention, the above-mentioned 2'3-dicyanopyrazine, which is the active ingredient, may be used in an appropriate dosage form depending on the purpose. Can be done.

The preparation can be made by conventional means,
Generally, 2Q3-dicyanopyrazine is diluted with an inert liquid or solid carrier, and if necessary, a surfactant and other substances are added thereto, and used in the form of a powder, wettable powder, emulsion, granule, or the like. Furthermore, if necessary, other active ingredients such as fertilizers, fungicides, insecticides, nematicides, herbicides, plant growth regulators, etc. can be mixed and used. Next, the formulation method will be specifically explained with reference to Examples. Example 2 (hydrating powder) 213-dicyanopyrazine 4 foundations 2 of ziecrite and kunilite (trade name: manufactured by Kunimine Magnetic Industry ■) as bulking agents
55 parts of the :1 mixture and 5 parts of Solpol 800 (trade name: Toho Chemical Industry ■) as a surfactant were mixed and ground to obtain a 40% hydrating powder.

Example 3 (Emulsion) 15 parts of 2,3-dicyanopyrazine, 8 parts of tetrahydrofuran, and 8005 parts of Solpol as a surfactant were mixed and dissolved to obtain a 15% emulsion.

Example 4 (Granules) 2,3-dicyanopyrazine Isobe, bentonite 5 Ikaribe,
35 parts of Kunilite, Solpol 800 as a surfactant
After mixing and pulverizing 5 parts, 1 part of water is added and the mixture is uniformly poured, extruded through a hole on the 0.7 diameter side, dried and cut into appropriate lengths to obtain 10% granules.

Next, the results of plant tests of the herbicide according to the present invention will be shown, and the usage and effects of the herbicide will be clarified. Test example 1 Stem-leaf contact selection ability '11 Materials and methods A large vat with an inner diameter (both vertical and horizontal) of 5 mm is filled with volcanic ash soil to a depth of 15 mm and leveled, and rice, wheat, and barley are placed on top of it. , pumpkin, beet, soybean, mustard greens, blueberry, mehishino, koakaza, bentgrass, corn, tomato, shepherd's purse, radish, daikon radish, husk, hartade, japonica, japonica,
Seeds of small chickweed, dogfish, harjiyon, Japanese dandelion, European dandelion, mugwort, Japanese commonweed, Japanese staghorn, Japanese sparrow, Japanese staghorn, Japanese cypress, Hebistrawberry, Japanese Physalis, Physalis japonica, and Japanese cypress were sown and the seeds were covered with soil once and kept at an appropriate temperature. Weeds were grown in a greenhouse, observed 15 days after germination, and replenished by transplanting seedlings at the 1st to 3rd hollyhock stage in the greenhouse or in an outdoor field. Dandelion, Mugwort, Common Bindweed, Kata/
These are ゞmi, konishikisou, and lindenflower).

Therefore, the developmental stages of both crops and weeds, including those germinated from seeds and those transplanted, were in the 1-3 leaf (true leaf) stage, and most were in the 2-hollyhock stage. After waiting for the transplanted weeds to take root and 24 days after sowing, apply the 40% hydrating powder of the present invention at 0.25, 0.5,
1, 2 and 4% (active ingredient amount), 100 per shipboard
The amount was evenly spread over the entire surface using a small rumor sprayer. Thereafter, they were placed in a greenhouse for 10 days, and their herbicidal power and phytotoxicity were examined for each crop and weed, and the potency was determined. The evaluation criteria are as follows.

0: Same as no treatment, no herbicidal power (also known as phytotoxicity).

1: Slight harm 2:4・Harm 3: Intermediate damage 4: Big book 5: Death (2) The test results are shown in Table 1.

Table 1. Test Example 2 Stalk-leaf contact selection ability {1} Materials and Methods Using the same materials and methods as in Test Example 1, 0.2f 0.5 of a 15% emulsion of the present invention was applied to crops and weeds 24 days after sowing.
1, 2, and 4% (active ingredient), and 100 ml of each melon was uniformly spread over the entire surface using a small spraying machine, and then the same machine as in Test Example 1 was left in a greenhouse for 10 days to determine the titer. Ta.

[2} The test results are shown in Table 2.

Table 2. Test Example 3 Flooded Soil Treatment Ability ○' Materials and Methods Paddy soil (shield loam) made of volcanic ash soil was filled to a depth of 10 arcs into a porcelain pot with an inner diameter of 16 mm and used to grow nopye, broad-leaved weeds (kikashigusa, japonica spp. , Azena) and fireflies are uniformly mixed in one arc of the surface layer, and the water is flooded to a depth of 2 to 3 feet.
Seedlings of 3rd season of pine were transplanted to a depth of 3 arcs, and 2 plants of the perennial weed Mabbai were also transplanted.

The pots were placed in a greenhouse and treated with the 10% granules of the present invention when weeds germinated 5 days later, and the herbicidal effect and paddy rice damage were investigated 20 days after the treatment. The evaluation criteria are as follows. ■ Paddy rice chemical damage... carried out exactly as in Test Example 1 ■ Herbicidal effect 5: Remaining amount of weeds 0% 4: 〃 20 3: 〃 40 2: 〃 60 1: 〃 80 0; 〃 100 '2) The test results are shown in Table 3.

Table 3. Test Example 4 Upland Soil Treatment Capacity {1} Materials and Methods A porcelain pot with an inner diameter of 20 mm was filled with volcanic ash field soil and leveled. Wheat, rice, radish, and mustard were sown on top of it and covered with soil. After conducting one arc, mix the seeds of crabgrass, aobu, and koakaza on the surface layer 5 sails, and after lightly crushing them, immediately apply a diluted solution of 40% hydrating powder of the present invention to the surface of the rock with a small sprayer at a rate of 200 per melon. Spread evenly.

After that, the crops were kept at an appropriate temperature in a greenhouse and grown for 20 days, after which the phytotoxicity and herbicidal effects of the crops were investigated. The evaluation criteria are exactly the same as in Test Example 3.

{21 The test results are shown in Table 4.

Table 4.

Claims (1)

[Claims] 1. A selective herbicide harmless to rice, wheat, etc., characterized by containing 2,3-dicyanopyrazine as an active ingredient.