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Herbicide Flumetsulam
NOMENCLATURE Flumetsulam
Common name flumetsulam (BSI, pa E-ISO, ANSI)
IUPAC name 2',6'-difluoro-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonanilide
Chemical Abstracts name N-(2,6-difluorophenyl)-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide
CAS RN [98967-40-9] Development codes DE-498; XRD-498 (both Dow)
PHYSICAL CHEMISTRY Flumetsulam
Mol. wt. 325.3 M.f. C12H9F2N5O2S Form Off-white, odourless solid. M.p. 251-253 ºC V.p. 3.7 ´ 10-7 mPa (25 ºC) KOW logP = -0.68 (25 ºC, unstated pH) S.g./density 1.77 (21 ºC) Solubility In water 49 mg/l (pH 2.5); solubility increases with pH. Very slightly soluble in acetone and methanol. Insoluble in hexane and xylene. Stability Aqueous photolysis DT50 6-12 mo. Soil photolysis DT50 3 mo. pKa 4.6 F.p. >93 °C
USES Flumetsulam
Uses Used alone and in combination with trifluralin or metolachlor for control of broad-leaved weeds and grasses in soya beans, field peas and maize. Phytotoxicity Crops damaged by soil application of flumetsulam include sugar beet, cotton, oilseed rape, grain sorghum, tomatoes, and sunflowers. Formulation types OF; SC; WG. Selected tradenames: 'Broadstrike' (Dow AgroSciences)
MAMMALIAN TOXICOLOGY Flumetsulam
Oral Acute oral LD50 for rats >5000 mg/kg. Skin and eye Acute percutaneous LD50 for rabbits >2000 mg/kg. Slightly irritating to eyes (rabbits). Non-sensitising to skin (guinea pigs). Inhalation LC50 (4 h) >1.2 mg/l. NOEL for mice >1000, female rats 500, male rats 1000, dogs 1000 mg/kg. Other Non-teratogenic (dietary) in rats. Non-mutagenic in the Ames test. Toxicity class WHO (a.i.) III (Table 5)
ECOTOXICOLOGY Flumetsulam
Birds Acute oral LD50 for bobwhite quail >2250 mg/l. Dietary LC50 (8 d) for bobwhite quail and mallard ducks >5620 mg/l. Fish LC50 (96 h) for silverside minnow >379 mg/l. Non-toxic to fathead minnow and bluegill sunfish. Daphnia Non-toxic. Other aquatic spp. LC50 for shrimp >349. Bees LC50 >100 mg/bee. NOEL 36 mg/bee.
ENVIRONMENTAL FATE Flumetsulam
Animals Rapidly cleared via urine and faeces with no metabolites. 5-Hydroxy metabolite found in the hen. Plants DT50 in maize 2 h, soya beans 18 h, Chenopodium 131 h. Metabolites depend on the species; 5-hydroxy or 5-methoxy derivatives are common. Soil/Environment Availability of flumetsulam in soil is principally dependent upon soil pH and organic matter. Herbicidal activity increases as pH increases and organic matter decreases. DT50 in soil (25 ºC, pH ³7, o.m. content <4%; or pH 6-7, o.m. content c. 1%) £1 mo. DT50 in soil (pH 6-7, o.m. content 2-4%) 1-2 mo. Koc 5 - 182; Kd 0.05 - 2.4.
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