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.
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.
First aid
f this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek Medical attention immediately. If
this chemical has been inhaled, remove from exposure, begin
rescue breathing (using universal precautions) if breathing has stopped, and CPR if heart action has stopped. Transfer
promptly to a medical facility. When this chemical has been
swallowed, get medical attention. Give large quantities of
water and induce vomiting. Do not make an unconscious
person vomit. Evaluation by a qualified allergist, including
exposure history and testing, may help diagnose allergy.
Shipping
UN3077 Environmentally hazardous substances,
solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous haz-
ardous material, Technical Name Required.
Incompatibilities
Slowly hydrolyzes in water, releasing
ammonia and forming acetate salts. Light sensitive.
Chemical Properties
A white to peach (pale pink) crystalline solid.
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.
Production Methods
Cymoxanil is commercially produced through a specialised chemical synthesis involving cyanoacetamide-oxime derivatives. The process typically begins with the formation of a cyanoacetyl intermediate, which is then reacted with ethylurea to yield cymoxanil—formally known as 1-(2-cyano-2-methoxyiminoacetyl)-3-ethylurea.
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
Mechanism of action
Foliar with protective and curative activity. Disrupts RNA synthesis by inhibiting dihydrofolate reductase, preventing the formation of essential cell components and halting fungal growth.
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.
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.
