CARBENDAZIM

IDENTIFICATION

Common name: Carbendazim

Iupac name: methyl benzimidazol-2-ylcarbamate

Chemical abstracts name: methyl 1H-benzimidazol-2-ylcarbamate

CAS RN: [10605 21 7]

M.F.: C₉H₉N₃O₂

Mol Wt: 191.2

]

Type: Fungicide

Form (appearance): Crystalline powder.

M.P.: 302-307℃ (decomp.)

V.P.: 0.09 mPa (20℃); 0.15 mPa (25℃); 1.3 mPa (50℃); separate study gives <0.0001 mpa (20℃)

S.G.: 1.45 (20℃)

Solubility.: In water 29 mg/l (pH 4), 8 mg/l (pH 7), 7 mg/l (pH 8) (24℃). In dimethylformamide 5, acetone 0.3, ethanol 0.3, chloroform 0.1, ethyl acetate 0.135, dichloromethane 0.068, benzene 0.036, cyclohexane <0.01, diethyl ether <0.01, hexane 0.0005 (all in g/l, 24℃).

Stability: Decomposes at m.p.; stable for at least 2 y below 50℃. Stable after 7 d at 20000 lux. Slowly decomposed in alkaline solution (22℃); DT₅₀ >350 d (pH 5 and pH 7), 124 d (pH 9). Stable in acids, forming water soluble salts.

Henry: 3.6 × 10^-3 Pa m³ mol^-1 (calc.)

K_owlogP: 1.38 (pH 5), 1.51 (pH 7), 1.49 (pH 9)

Pka: 4.2, weak base

 

Formulation types: OP; SC; SL; WG; WP; Seed treatment;WDG

Biochemistry: Reported to inhibit beta-tubulin synthesis

Mode of action: Systemic fungicide with protective and curative action. Absorbed through the roots and green tissues, with translocation acropetally. Acts by inhibiting development of the germ tubes, the formation of appressoria, and the growth of mycelia.

Uses: Control of Septorio, Fusarium, Erysiphe and Pseudocercosporella in cereals; Sclerotinia, Alternaria and Cylindrosporiurn in oilseed rape; Cercospora and Erysiphe in sugar beet; Uncinula and Botrytis in grapes; Cladosporium and Botrytis in tomatoes; Venturia and Podosphaera in pome fruit; and Monilia and Sclerotinia in stone fruit. Application rates vary from 120-600 g/ha, depending on crop. A seed treatment (0.6-0.8 g/kg) will control Tilletia, Ustilago, Fusarium and Septoria in cereals, and Rhizoctonia in cotton. Also shows activity against storage diseases of fruit as a dip (0.3-0.5 g/l).

Compatibility: Incompatible with alkaline materials.

Oral: Acute oral LD₅₀ for rats >15000, dogs >2500 mg/kg

Skin and eye: Acute percutaneous LD₅₀ for rabbits >10000, rats >2000 mg/kg. Non-irritating to skin and eyes (rabbits). Not a skin sensitiser (guinea pigs). Inhalation LC₅₀ (4 h) for rats, rabbits, guinea pigs or cats, no effect with suspension (10 g/l water)

Noel: (2 y) for dogs 300 mg/kg diet, corresponding to 6-7 mg/kg b.w.

ADI: (JMPR) 0.03 mg/kg b.w. [_1995].
Other Acute i.p. LD₅₀ for male rats 7320, female rats 15000 mg/kg.

Toxicity: WHO (a.i.) III (Table 5)

EC hazard: R40

 

Birds: Acute oral LD₅₀ for quail 5826-15 595 mg/kg.

Fish: LC₅₀ (96 h) for carp 0.61, rainbow trout 0.83, bluegill sunfish >17.25, guppy >8 mg/l.

Daphnia: ECs0 (48 h) 0.13-0.22 mg/l.

Algae: EC₅₀ (72 h) for Scenedesmus subspicatus 419, Selenastrum capricornutum 1.3 mg/l.

Worms: LC₅₀ (4 w) for Eisenia foetida 6 mg/kg soil.
Bees: LD₅₀ (contact) >50 μg/bee

 

Plant: EHC 149 (WHO, 1993). EHC 149 concludes that, although highly toxic to aquatic organisms, law bJoavailability in surface waters mai< field. the in occur will toxicity this unlikely it>

Animals: In male rats, following a single oral administration of 3 mg/kg, 66% was eliminated in the urine within 6 hours. Plants Readily absorbed by plants. One degradation product is 2-aminobenzimidazole.

Soil/Environment: 2-Aminobenzimidazole has been found as a minor metabolite. DT₅₀ in soil 8-32 d under outdoor conditions. Carbendazim decomposes in the environment, DT₅₀ 6-12 mo on bare soil, 3-6 mo on turf, and 2-25 mo in water under aerobic and anaerobic conditions, respectively. It is mainly decomposed by micro-organisms. K_oc 200-250.