IDENTIFICATION
Common name: Tebuconazole
Other name: tebuconazole (BSI, draft E-ISO) / fenetrazole*; terbuconazole*; terbutrazole*; ethyltrianol*
Iupac name: (RS)-1-p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1ylmethyl)pentan-3-ol
Chemical abstracts name: (±) –α- [2-(4-chlorophenyl)ethyl]- α-(1,1 dimethylethyl)- 1H 1,2,4-triazole-1-ethanol
Type: Fungicide
CAS RN: [107534-96-3]
M.F.: C16H22ClN3O
Mol Wt: 307.8
PHYSICAL CHEMISTRY
Form (appearance): Colourless crystals; (tech., colourless to light brown powder).
Composition:: Racemate.
M.P.: 105 ℃
V.P.: 1.7 × 10-3 mPa (20℃) (OECD 104)
S.G.: 1.25 (26℃)
Solubility.: In water 36 mg/l (pH 5-9, 20℃). In dichloromethane >200, isopropanol, toluene 50-100, hexane <0.1 (all in g/l, 20℃).
Stability: Stable to elevated temperatures, and to photolysis and hydrolysis in pure water, under sterile conditions; hydrolysis DT50 >1 y (pH 4 9, 22℃). See also Environmental Fate
Henry: 1 × 10-5 Pa m3 mol-1 (20℃)
KowlogP: 3.7 (20℃)
APPLICATION
Formulation types: DS; EC: ES; EW; FS; GF; SC; SE: WG; WP: WS
Biochemistry: Steroid demethylation (ergosterol biosynthesis) inhibitor.
Mode of action: Systemic fungicide with protective, curative, and eradicant action. Rapidly absorbed into the vegetative parts of the plant, with translocation principally acropetally.
Uses: As a seed dressing, tebuconazole is effective against various smut and bunt diseases of cereals such as Tilletia spp., Ustilago spp., and Urocystis spp., also against Septoria nodorum (seed-borne), at 1-3 g/dt seed; and Sphacelotheca reiliana in maize, at 7.5 g/dt seed. As a spray, tebuconazole controls numerous pathogens in various crops including: rust species (Puccinia spp.) at 125-250 g/ha, powdery mildew (Erysiphe grominis) at 200-250 g/ha, scald (Rhynchosporium secalis) at 200-312 g/ha, Septoria spp. at 200-250 g/ha, Pyrenophora spp. at 200-312 g/ha, Cochliobolus sativus at 150-200 g/ha, and head scab (Fusarium spp.) at 188-250 g/ha, in cereals; leaf spots (Mycosphaerella spp.) at 125-250 g/ha, leaf rust (Puccinia arachidis) at 125 g/ha, and Sclerotium rolfsii at 200-250 g/ha, in peanuts; black leaf streak (Mycosphaerella fijiensis) at 100 g/ha, in bananas; stem rot (Sclerotinia sclerotiorum) at 250-375 g/ha, Alternaria spp. at 150-250 g/ha, stem canker (Leptosphaeria maculans) at 250 g/ha, and Pyrenopeziza brassicae at 125-250 g/ha, in oilseed rape; blister blight (Exobasidium vexans) at 25 g/ha, in tea; Phakopsora pachyrhizi at 100-150 g/ha, in soya beans; Monilinia spp. at 12.5-18.8 g/100 l, powdery mildew (Podosphaera leucotricho) at 10.0-12.5 g/100 l, Sphaerotheca pannosa at 12.5-18.8 g/100 l, scab (Venturia spp.) at 7.5-10.0 g/100 l, white rot in apples (Botryosphaeria dothidea) at 25 g/100 l, in pome and stone fruit; powdery mildew (Uncinula necator) at 100 g/ha, in grapevines; rust (Hemileia vastatrix) at 125-250 g/ha, berry spot disease (Cercospora coffeicola) at 188-250 g/ha, and American leaf disease (Mycena citricolor) at 125-188 g/ha, in coffee; white rot (Sclerotium cepivorum) at 250-375 g/ha, and purple blotch (Alternaria porri) at 125-250 g/ha, in bulb vegetables; leaf spot (Phaeoisariopsis griseola) at 250 g/ha, in beans; early blight (Alternaria solani) at 150-200 g/ha, in tomatoes and potatoes.
Phytotoxicity: Good plant compatibility in most crops with any formulatio and achieved in more sensitive crops by appropriate formulations, e.g. WP, WG or SC.
MAMMALIAN TOXICOLOGY
Reviews: FAO/WHO 71, 73 (see part 2 of the Bibliography).
Oral: Acute oral LD50 for male rats 4000, female rats 1700, mice c. 3000 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats >5000 mg/kg. Non-irritating to skin; mild irritant t, eyes (rabbits).
Inhalation: LC50 (4 h) for rats 0.37 mg/l air (aerosol), >5.1 mg/l (dust).
Noel: (2 y) for rats 300, dogs 100, mice 20 mg/kg diet.
ADI: (JMPR) 0.03 mg/kg b.w. [1994].
Toxicity: WHO (a.i.) III; EPA (formulation) Il (`Elite` 45DF); III (`Folicur` 3.6F)
EC hazard: (Xn; R22)
ECOTOXICOLOGY
Birds: Acute oral LDs0 for male Japanese quail 4438, female Japanese quail 2912, bobwhite quail 1988 mg/kg b.w. Dietary LC50 (5 d) for mallard ducks >4816, bobwhite quai >5000 mg/kg feed. Fish LC50 (96 h) for rainbow trout 4.4, bluegill sunfish 5.7 mg/l (flowthrough).
Daphnia: LC50 (48 h) 4.2 mg/l (flow through).
Algae: ErC50 (96 h) for Scenedesmus subspicatus 4.01 mg/l (static).
Other aquatic spp. No effect on Cbironomus riparius at 0.1 mg/l (28 d).
Worms: Acute LC50 (14 d) for Eisenia foetida 1381 mg/kg dry soil.
Bees: LD50 (48 h) (oral) 175.8 pg/bee: (contact) 0.6 lag/bee.
Other beneficial spp. No adverse effects on ground dwellers e.g. ground beetles (Poecilus cupreus) (adults and larvae) or on foliage dwellers e.g. ladybirds (Coccinella septempunctata), up to 375 g/ha (EW 250 formulation).
ENVIRONMENTAL FATE
Plant: Metabolism studies on wheat, grapes and peanuts show that tebuconazole is the major terminal residue. The metabolites detecto were mainly triazole containing compounds of no toxicological relevance. In plant tissue, a mean halFlife of 12 days could be derived (cereals)
Animals: After three days, elimination was almost complete (>99%). Tebuconazole was excreted with the urine and the faeces.
Soil/Environment: The degradation of tebuconazol, in soil was slow in laboratory studies. Under field conditions, the compound degraded much more rapidly, and did not accumulate in long term studies (3 5 y). Since no residues could be detected in deeper soil layers of these and other studies, and adsorption/desorption studies indicated a low mobility in the soil, groundwater contamination through leaching can be excluded, in natural water hydrolysis and indirect photolysis occur; in a pond study, the compound dissipated from the water body with DT50 1 4 w. Low vapour pressure and strong adsorption result in low volatilisation into the air.
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