Pyroxasulfone technical

Product Spec:

Physical and chemical properties：

Pyroxasulfone technical belongs to the new pyrazole class of selective herbicides. The appearance of the pure product is white crystals; Melting point: 130.7 ℃; Vapour pressure (25 ℃): 2.4 ×  10-6 Pa; Distribution coefficient: n-octanol/water Log Pow=2 39 (25 ℃);

Chemical name: 3-[[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)pyrazol-4-yl]methylsulfonyl]-5,5-dimethyl-4H-1,2-oxazole 

The mass fraction of Pyroxasulfone technical is 98%; Appearance is white crystals or white crystal powder; Melting point: 130.7 ℃; Solubility (20 ℃): 3.49 x10^-3g/L (20 ℃± 0.5 ℃) in water; In organic solvents (g/L): n-hexane 0.072, toluene 11.3, dichloromethane 151, methanol 11.4, ethyl acetate 97, acetone>250. 40% Pyroxasulfone suspension, pH 5.5-8 5; Fineness (through 75 μm test sieve) ≥ 98%; Suspension rate ≥ 80%. The product is stable during cold and hot storage, as well as 2-year storage at room temperature.

Toxicity:

Pyroxasulfone technical and 40% suspension have acute oral LD50>5000 mg/kg, acute percutaneous LD50>2000 mg/kg, and acute inhalation LC50>2000 mg/m3 in rats; Rabbit skin and eyes are non irritating; The allergic reaction (allergenicity) test result of guinea pig skin is non allergenic; 24 month chronic toxicity carcinogenicity (combined) test of the original drug in rats. The maximum ineffective dose in the feeding toxicity test is 3.86 ± 0.48mg/kg/day for males and 18.87 ± 1.71mg/kg/day for females; The results of four mutagenic tests: Ames test, micronucleus or bone marrow cell chromosome aberration test, in vitro mammalian cell gene mutation test, and in vitro mammalian cell chromosome aberration test were all negative, and no mutagenic effect was observed. Pyroxasulfone technical and 40% suspension agent are both micro toxic herbicides.

Environmental biosafety assessment: 

The measured LC50 (96h) of 40% Pyroxasulfone  suspension on zebrafish is greater than 4.16mga.i./L; Japanese quail LD50>2000mg a.i./kg bw; Bee oral LD50 (48h)>99.5 μ G a.i./Bee, contact LD50 (48h)>100 μ G a.i./Bee; The LC50 of Jingsong ×  Haoyue silkworms is greater than 2000mg a.i./L. There was no death in the fish test, and toxicity cannot be determined; Low toxicity to birds, bees, and silkworms. When using, it is prohibited to use this product or clean pesticide equipment near water sources such as rivers and ponds in aquaculture areas.

Application: 

Pyroxasulfone is a new type of pyrazole selective herbicide, which is applied before seedlings to control the main grasses and broad-leaved weeds in dryland crop fields. The application time range is wide, from pre planting to post emergence, and it is compatible with most commonly used herbicides.The mechanism of action is that the treatment with Pyroxasulfone can greatly reduce the biosynthesis of ultra long chain fatty acids (VLCFAs) and lead to the construction of fatty acid precursor substances. Pyroxasulfonecan specifically inhibit many elongation steps catalyzed by VLCFA elongation enzyme. Through indoor activity experiments and field efficacy trials, the results showed that 40% Pyroxasulfone suspension had good control effects on annual grass weeds such as bromegrass, Kanmai niang, wild oats, and some annual broad-leaved weeds such as Sophora annua, shepherd's purse, and pig weed in winter wheat fields. During the period from winter wheat sowing to the 1.5-leaved stage of grass weeds, the soil moisture was good or after irrigation and rainfall, water was mixed with 30-40L/667m², Soil spray or early spray of stems and leaves after sprouting of miscellaneous grass, especially soil spray, had the best control effect.

Suitable for use in winter wheat fields without rice wheat rotation. Wheat can be used up to once throughout the entire growing season. Within the dosage range of the medication, it is safe for crops and no pesticide damage has occurred. It has no effect on predatory or parasitic natural enemies. 40% Pyroxasulfone suspension is used to control annual grass weeds and small grain broad-leaved weeds such as bromegrass. The maximum dosage of the formulation is 35g/667m² (210g a.i./ha), with a maximum of one application. Based on the measured data and risk assessment results, it is recommended to have a maximum residue limit (MRL) of 0.1mg/kg, and the safe interval can be recommended as the harvest period.