IDENTIFICATION
Common name: Cymoxanil
Chemical abstracts name: 2-cyano-N-[(ethylamino)carbonyl]-2-(methoxyimino) acetamide
Type: Fungicide
CAS RN: [57966-95-7]
M.F.: C7H10N4O3
Mol Wt: 198.2
PHYSICAL CHEMISTRY
Form (appearance): Colourless, odourless crystals; (tech. is peach colour)
Composition: Tech. is >95%;
M.P.: 160-161℃; (tech., 159-160℃)
V.P.: 0.15 mPa (20℃)
S.G.: 1.31 (25℃)
Solubility.: In water 890 mg/kg (pH 5, 20℃). In hexane 1.85, toluene 5.29, acetonitrile 57, ethyl acetate 28, n-octanol 1.43, methanol 22.9, acetone 62.4, methylene chloride 133.0 (all in g/l, 20℃).
Stability: Hydrolysis DT50 148 d (pH 5), 34 h (pH 7), 31 rain (pH 9). Aqueous photolysis DT50 1.8 d (pH 5)
Henry: 3.8 × 10-5 (pH 7), 3.3 × 10-5 (pH 5) (both Pa m3 mol-1, calc.)
KowlogP: 0.59 (pH 5), 0.67 (pH 7)
Pka: 9.7 (decomp.)
APPLICATION
Formulation types: WR
Mode of action: Foliar fungicide with protective and curative action. Has contact and local systemic activity, and also inhibits sporulation
Uses: Control of Peronosporales, especially Peronospora, Phytophthora, and Plasmopara spp. Normally used in combination with protectant fungicides (to improve residual activity) on a range of crops, including vines, hops, potatoes, and tomatoes
Compatibility: Incompatible with alkaline materials
MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for male and female rats 960 mg/kg.
Skin and eye: Acute percutaneous LD50 for rabbits >2000 mg/kg. Not an eye irritant; slight skin irritant (rabbits). Not a skin sensitiser (guinea pigs).
Inhalation: LC50 (4 h) for male and female rats >5.06 mg/l.
Noel: (2 y) for male rats 4.1, female rats 5.4, male mice 4.2, female mice 5.8, male dogs 3.0, female dogs 1.6 mg/kg b.w. daily.
ADI: 0.016 mg/kg.
Toxicity: WHO (a.i.) III; EPA (formulation) III
EC hazard: Xn; R22| R43| N; R50, R53
ECOTOXICOLOGY
Birds: Acute oral LD50 for bobwhite quail and mallard ducks >2250 mg/kg. Dietary LC50 (8 d) for bobwhite quail and mallard ducks >5620 mg/kg diet.
Fish: LC50 (96 h) for rainbow trout 61, bluegill sunfish 29, common carp 91, sheepshead minnow >47.5 mg/l.
Daphnia: LC50 (48 h) 27 mg/l.
Algae: 23% inhibition of Selenastrum capricornutum at 1.05 mg/l after 5 d; EC50 for Anabaena rios-aquae 231 ppb.
Other aquatic spp. LC50 (96 h) for Eastern oyster >46.9, mysid shrimp >44.4 ppm.
Worms:LC50 (14 d) >2208 mg/kg soil.
Bees: Not toxic to bees; LD50 (48 h, contact) >25 μg/bee; LC50 (48 h, oral) >1000 ppm.
ENVIRONMENTAL FATE
Plant: Degraded to glycine with subsequent incorporation into natural products (proteins and starch).
Animals: In rats, cymoxanil was readily absorbed through the intestines; the majority of the dose was excreted in the urine. The proposed metabolic pathway involves hydrolysis of cymoxanil and then degradation to glycine.
Soil/Environment: In lab. soils, DT50 0.75-1.5 d (5 soils, pH range 5.7-7.8, o.m. 0.8-3.5%). In the field, DT50 (bare soil) 0.9-9 d. In aquatic studies, DT50 <1 d. Koc 39-250. Cymoxanil is mobile, adsorption Freundlich K 0.29 to 2.86 in four soil types.
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