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Hexazinone 75% WDG

Herbicide
HRAC C1 WSSA 5; 1,2,4-triazinone

Hexazinone NOMENCLATURE
Common name hexazinone (BSI, E-ISO, (m) F-ISO, ANSI, WSSA)
IUPAC name 3-cyclohexyl-6-dimethylamino-1-methyl-1,3,5-triazine-2,4-(1H,3H)-dione
Chemical Abstracts name 3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4-(1H,3H)-dione
CAS RN [51235-04-2] EEC no. 257-074-4 Development codes DPX A3674 (Du Pont)

Hexazinone APPLICATIONS
Biochemistry Photosynthetic electron transport inhibitor at the photosystem II receptor site. Mode of action Non-selective, primarily contact herbicide, absorbed by the leaves and roots, with translocation acropetally. Uses A post-emergence contact herbicide effective against many annual and biennial weeds and, except for Sorghum halepense, most perennial weeds, at 6-12 kg a.i./ha. Used for selective control in alfalfa, pineapples, sugar cane and in plantations of certain coniferous species; also on non-crop areas, but not on sites adjacent to deciduous trees or other desirable plants. Phytotoxicity Should not be used for weed control in larch (Larix spp.) or in areas planted with deciduous species. Formulation types GR; SL; SP. Selected tradenames: 'Velpar' (Du Pont)

Hexazinone OTHER TRADENAMES
Mixtures: 'Oustar' (+ sulfometuron-methyl) (Du Pont)

Hexazinone ANALYSIS
Product analysis by hplc or by glc with FID (C. L. McIntosh et al., Anal. Methods Pestic. Plant Growth Regul., 1984, 13, 267). Residues determined by glc (idem, ibid.; R. F. Holt, J. Agric. Food Chem., 1981, 29, 165). In drinking water, by gc with FID (AOAC Methods, 1995, 991.07).

MAMMALIAN TOXICOLOGY
Hexazinone
Oral Acute oral LD50 for rats 1690, guinea pigs 860 mg/kg. Skin and eye Acute percutaneous LD50 for rabbits >5278 mg/kg. Reversible irritant to eyes (rabbits); non-irritating to skin (guinea pigs). Inhalation LC50 (1 h) for rats >7.48 mg/l. NOEL (2 y) for rats 200, mice 200 ppm; (1 y) for dogs 200 ppm. Toxicity class WHO (a.i.) III; EPA (formulation) II EC hazard Xn; R22| Xi; R36| N; R50, R53

Hexazinone ECOTOXICOLOGY
Birds Acute oral LD50 for bobwhite quail 2258 mg/kg. Dietary LC50 (8 d) for bobwhite quail and mallard ducklings >10 000 mg/kg diet. Fish LC50 (96 h) for rainbow trout 320-420, fathead minnow 274, bluegill sunfish 370-420 mg/l. Daphnia LC50 (48 h) 442 mg/l. Bees Not toxic to bees; LD50 >60 mg/bee.

Hexazinone ENVIRONMENTAL FATE
Animals Major urinary metabolites in rats are 3-(4-hydroxycyclohexyl)-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4-(1H,3H)-dione, 3-cyclohexyl-6-(methylamino)-1-methyl-1,3,5-triazine-2,4-(1H,3H)-dione, and 3-(4-hydroxycyclohexyl)-6-(methylamino)-1-methyl-1,3,5-triazine-2,4-(1H,3H)-dione. Soil/Environment Microbial degradation occurs in soil and natural waters. The triazine ring is broken, with the liberation of CO2. DT50 in soil c. 1-6 mo, depending on climate and soil type.