Cymoxanil

Description

Cymoxanil is a cyanoacetamide fungicide. It inhibits the mycelial growth of 12 isolates of P. infestans with EC₅₀ values of 0.27-0.57 μg/ml. Cymoxanil (5-100 mg/l) inhibits the growth of several strains of S. cerevisiae (IC₅₀s = 8-25 mg/l) but not S. pombe, K. marxianus, P. anomala, or C. utilis. A spray application of cymoxanil (1 mg/mL) one day after inoculation of potato leaves with P. infestans and cucumber leaves with P. cubensis reduces blighted leaves by 79 and 60%, respectively. It is toxic to rats with an acute LD₅₀ value of 3.8 mmol/kg. Formulations containing cymoxanil have been used to prevent fungal growth on crops and treat late potato blight in agriculture.

Chemical properties

A white to peach (pale pink) crystalline solid.

The Uses of Cymoxanil

Cymoxanil is a fungicide applied as a seed treatment or as a foliar application to the plants to control late blight.

The Uses of Cymoxanil

Agricultural fungicide.

The Uses of Cymoxanil

Cymoxanil is a foliar applied fungicide which provides preventive and curative control of pathogen species of the order Peronosporales (eg. Phytophthora, Plasmopara and Peronospora) in grapes, potatoes, tomatoes, hops, tobacco and cucurbits.

Definition

ChEBI: A member of the class of ureas that is urea in which the two nitrogen atoms are substituted by an ethyl group and a 2-cyano-2-(methoxyimino)acetyl group respectively. A fungicide used to control Peronosporales on a range of crops including vin s, hops and potatoes.

Agricultural Uses

Fungicide: Cymoxanil is applied as a seed treatment to cut potato seed pieces or as a foliar to control late blight.

Trade name

CURZATE®; DPX 3217®; DPX 3217 M®; DPX-T3217®; EVOLVE®; MZ-CURZATE®; TANOS® Cymoxanil

Contact allergens

Cymoxanil, an urea derivative, is included (10%) with dithianone (25%) in Aktuan?. It is a fungicide agent, possibly sensitizing agricultural workers

Potential Exposure

Cymoxanil is a cyanoacetamide oxime fungicide applied as a seed treatment to cut potato seed pieces or as a foliar to control late blight.

Metabolic pathway

Cymoxanil is rapidly degraded in neutral to alkaline aqueous solutions and is metabolised extensively in soil, plants and animals. Cymoxanil degradation follows a series of cyclisation and /or hydrolysis reactions to form 5- and 6-membered ring compounds and shorter chain keto acids and amides. In plants and animals, cymoxanil is metabolised to form natural products, especially glycine.

Metabolism

Animals
Radiolabeled cymoxanil is metabolized in the goat to natural products, including fatty acids, glycerol, glycerin, and other amino acids, lactose, and acid-hydrolysable formyl and acetyl groups.
Plants
Rapid degradation to naturally occurring amino acids, particularly to glycine, with subsequent incorporation into constituent sugars, starch, fatty acids, and lignin (6).
Soil
In laboratory 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.

Shipping

UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous haz- ardous material, Technical Name Required.

Degradation

The hydrolysis of cymoxanil is pH dependent. It degraded rapidly in alkaline solution at 25 °C with calculated DT₅₀ values at pH 5,7 and 9, of 148 days, 34 hours and 31 minutes, respectively (PM). The principal hydrolysis products at pH 9 were 1-ethyldihydro-dimino-2,4,5(³H)- pyrimidinetrione 5-(O-methyloxime) (2), cyano(methoxyimino)acetic acid (3) and [[(ethylamino)carbonyl]amino]oxoacetic acid (4). Oxalic(5) and aminooxoacetic acid (6) were recovered as minor products. The principal degradation products at pH 7 were compounds 2 and 4. No hydrolytic products at pH 5 exceeded 10% of the applied radioactivity throughout the 30-day incubation (Lawler, 1996).
Photolysis of cymoxanil occurred rapidly at pH 5 when irradiated under a xenon arc light source. The DT₅₀ values of cymoxanil at 25 °C were 1.8 and 148 days, light exposed vs. dark control, respectively. 3-Ethyl-4- (methoxyamino)-2,5-dioxo-4-imidazolidinecarbonitrile(7) and 1-ethyl-imidazolidinetrione 5-(O-methyloxime) (8) were the major degradation products. Compounds 2, 4, 6 and ethylimidazolidinetrione (9) were also present as minor products (Anderson et al., 1993). The hydrolytic degradation and photolytic degradation pathways of cymoxanil are presented in Scheme 1.

Environmental considerations

Oral LD₅₀ for bobwhite quail and mallard ducks >2,250 mg/kg. Eight-day dietary LC50 for bobwhite quail and mallard ducks >5,620 mg/kg diet. Fish LC50 (in mg/L at 96 h): rainbow trout 61, bluegill sunfish 29, common carp 91, Zebra fish >47.5 mg/L. Earthworm LC50 (14 d) >2,208 mg/kg soil. Daphnia magna LC50 (48 h) 27 mg/L. Algal growth inhibition LC50 (72 h) 5.2 mg/L. Honeybee contact LD₅₀ >25 μg/bee.

Toxicity evaluation

Rat oral LD₅₀: 960 mg/kg, mouse oral LD₅₀: 860 mg/kg. Rabbit dermal LD₅₀: >2,000 mg/kg. Mild eye irritant to rabbit (clears at 48 h). Mild, transient dermal irritation to rabbit (clears at 48 h). Inhalation LC50 (4 h) for male and female rats >5.06 mg/L. Nononcogenic and nonteratogenic.

Incompatibilities

Slowly hydrolyzes in water, releasing ammonia and forming acetate salts. Light sensitive.

Waste Disposal

Do not discharge into drains or sewers. Burn in incinerator specifically designed for pes- ticide disposal or dispose as a Hazardous waste in a landfill approved and licensed for the disposal of pesticides. Consult with environmental regulatory agencies for guid- ance on acceptable disposal practices. Ultimate disposal of the chemical must consider: the material’s impact on air quality; potential migration in soil or water; effects on ani- mal, aquatic, and plant life; and conformance with environ- mental and public health regulations.