Myclobutanil

Pesticides

Pesticide -> EPA IRIS

Fungicides

Active substance -> EU Pesticides database: Not approved

Pesticides -> Fungicides

Environmental transformation -> Pesticides (parent, predecessor)

log Kow = 2.94

3.16

Pale yellow solid.

Light yellow crystals

Soluble in common organic solvents, e.g. ketones, esters, alcohols and aromatic hydrocarbons, all 50 to 100 g/L. Insoluble in aliphatic hydrocarbons.

Soluble in ethanol, benzene, ethyl acetate, and acetone.

In water, 142 mg/L at 25 °C

0.0000016 [mmHg]

1.6X10-6 mm Hg at 25 °C

Myclobutanil is a light yellow solid used as a fungicide.

Light yellow solid; [Merck Index]

Stable under normal storage conditions.

Aqueous solutions decompose on exposure to light ...

Positive

2.99

2.7

Agilent XCT

Electrospray ionization

formic acid (5.3nM)

174.5 Ų [M+H]+ [CCS Type: DT; Buffer gas: N2; Ionization: ESI+; Dataset: Pesticides]

173.77 Ų [M+H]+

Warning

H302: Harmful if swallowed [Warning Acute toxicity, oral]

P203, P264, P264+P265, P270, P273, P280, P301+P317, P305+P351+P338, P318, P330, P337+P317, P391, P405, and P501 (click each P-code to see the statement)

Warning

H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]

P203, P260, P264, P264+P265, P270, P273, P280, P301+P317, P305+P351+P338, P318, P319, P330, P337+P317, P391, P405, and P501 (click each P-code to see the statement)

Hazard Traits - Developmental Toxicity; Reproductive Toxicity

Commission Regulation (EC) No 1490/2002

Myclobutanil is listed in the dataset of EPA Human Health Benchmarks for Pesticides under the Safe Drinking Water Act (40 eCFR 141)

2011/2/EU, Reg. (EU) 2018/155, Reg. (EU) 2022/801, Reg. (EU) No 540/2011

Status: Active Update: 07-10-2021 https://echa.europa.eu/registration-dossier/-/registered-dossier/33152

Myclobutanil: HSNO Approval: HSR002866 Approved with controls

Tolerances are established for combined residues of the fungicide myclobutanil alpha-butyl-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile and its alcohol metabolite (alpha-(3-hydroxybutyl)-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile (free and bound), in or on the following food commodities: [Table#6209]

Time-limited tolerances are established for residues of the fungicide myclobutanil in connection with use of the pesticide under section 18 emergency exemptions granted by EPA. These tolerances will expire and are revoked on the dates specified in the following table. [Table#6210]

Tolerances are established for residues of the fungicide myclobutanil alpha-butyl-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile in or on the following food commodities: [Table#6211]

New Active Ingredients ... includes pesticide active ingredients initially registered after November 1, 1984, that currently have active product registrations. By law, these newer pesticides are not subject to the reregistration program. They must, however, meet the new safety standard of the FQPA, and will be reviewed on a 15-year cycle under the registration review program. ... Active Ingredient Number: 128857 /(myclobutanil)/; Type of Pesticide: Conventional - Fungicide; Use Site: Food use, ornamentals; Year: 1989.

Acute Tox. 4 (100%)

Acute Tox. 4 (100%)

Reproductive toxicity - category 2

Acute toxicity (Oral) - Category 4

Repr. 2

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

Do not discharge effluent containing this product into lakes, streams, ponds, estuaries, occans or other waters unless in accordance with the requirements of a National Pollutant Discharge Elimination System (NPDES) permit and the permitting authority has been notified in writing prior to dischape. Do not discharge effluent containing this product to sewer systems without previously notifying the local sewage treatment plant authority. For guidance contact your State Water Board or Regional Office of the EPA. /RH-3866 Technical/

Do not apply directly to water. Do not contaminate water when disposing of equipment washwaters. /Chemsico Fungicide Concentrate M6/

Do not contaminate water, food, or feed by ... disposal. ... Pesticide Disposal: Securely wrap original container in several layers of newspaper and discard in trash. Container DIsposal: Do not reuse container. Rinse thoroughly before discarding in trash. /Chemsico Fungicide Concentrate M6/

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place. /Technical concentrates/

WARNING: Causes substantial but temporary eye injury. Do not get in eyes or on clothing. Wear protective eyewear (goggles, face shield, or safety glasses). Remove contaminated clothing and wash clothing before reuse. Harmful if swallowed. Wash thoroughly with soap and water after handling. /Chemsico Fungicide Concentrate M6/

Avoid contact with skin, eyes or clothing. Wear protective eyewear (goggles, face shield, or safety glasses). Remove contaminated clothing and wash clothing before reuse. Prolonged or frequently repeated skin contact may cause allergic reactions In some individuals. /RH-3866 Technical/

First Aid. If In Eyes: Hold eye open and rinse slowly and gently with water for 15 - 20 minutes. Remove contact lenses, If present, after the first 5 minutes, then continue rinsing eye. Call a Poison Control Center or doctor for treatment advice. If Swallowed: Call a Poison Control Center or doctor immediately for treatment advice. Have person sip a glass of water if able to swallow. Do not induce vomiting unless told to by a Poison Control Center or doctor. Do not give anything by mouth to an unconscious person. Have the product container or label with you when calling the Poison Control Center or doctor, or going for treatment. /Chemsico Fungicide Concentrate M6/

First Aid. If in eyes: Hold eye open and rinse slowly and gently with water for 15-20 minutes. Remove contact lenses, if present, after the first 5 minutes, then continue rinsing eye. Call a poison control center or doctor for treatment advice. If on skin or clothing: Take off contaminated clothing. Rinse skin immediately with plenty of water for 15-20 minutes. Call a poison control center or doctor for treatment advice. If swallowed: Call a poison control center or doctor immediately for treatment advice. Have a person sip a glass of water if able to swallow. Do not induce vomiting unless told to do so by a poison control center or doctor. Do not give anything by mouth to an unconscious person. If inhaled: Move person to fresh air. If person is not breathing, call 911 or an ambulance, then give artificial respiration ... Call a poison control center or doctor for further treatment advice. /RH-3866 Technical/

Tolerances are established for combined residues of the fungicide myclobutanil alpha-butyl-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile and its alcohol metabolite (alpha-(3-hydroxybutyl)-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile (free and bound), in or on the following food commodities: [Table#6206]

Time-limited tolerances are established for residues of the fungicide myclobutanil in connection with use of the pesticide under section 18 emergency exemptions granted by EPA. These tolerances will expire and are revoked on the dates specified in the following table. [Table#6207]

Tolerances are established for residues of the fungicide myclobutanil alpha-butyl-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile in or on the following food commodities: [Table#6208]

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

/SRP/ When working with strong solutions of acids or bases or other caustic or corrosive materials, always wear a full face mask. When working with caustic or corrosive gases or vapors, a full face mask with not protect the eyes or prevent inhaling the material. A full face respirator is required. /Technical concentrates/

LC50; Species: Lepomis macrochirus (Bluegill); Conditions: freshwater, static; Concentration: 2400 ug/L for 96 hr (95% confidence interval: 1500-4700 ug/L) /84.5% purity/

LC50; Species: Oncorhynchus mykiss (Rainbow trout); Conditions: freshwater, static; Concentration: 4200 ug/L for 96 hr (95% confidence interval: 3500-5600 ug/L) /84.5% purity/

LD50 /Colinus virginianus/ (Bobwhite quail) oral 510 mg/kg

LD50 Grey partridge oral 1635 mg/kg

For more Ecotoxicity Values (Complete) data for MYCLOBUTANIL (11 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 950(SRC), determined from a log Kow of 2.94(2) and a regression-derived equation(3), indicates that myclobutanil is expected to have low mobility in soil(SRC). An Rf of 0.13 was determined for (14)C-myclobutanil on Versailles silt loam (1.94% organic matter, 20.5% clay, pH 6.4); based upon this Rf, myclobutanil was classified as slightly mobile(4). Volatilization of myclobutanil from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 4.3X10-9 atm-cu m/mole(SRC), derived from its vapor pressure, 1.6X10-6 mm Hg(5), and water solubility, 1.4X10+2 mg/L(6). Myclobutanil is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1.6X10-6 mm Hg(5). The biodegradation half-life of myclobutanil in silt loam soil is about 66 days(6).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 950(SRC), determined from a log Kow of 2.94(2) and a regression-derived equation(3), indicates that myclobutanil is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 4.3X10-9 atm-cu m/mole(SRC), derived from its vapor pressure, 1.6X10-6 mm Hg(4), and water solubility, 1.42X10+2 mg/L(5). According to a classification scheme(6), an estimated BCF of 37(SRC), from an estimated log Kow(2) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is moderate(SRC). Aqueous solutions of myclobutanil are decomposed by light with half-lives ranging from 25-222 days(5), therefore, myclobutanil may be susceptible to direct photolysis in the atmosphere(SRC).The biodegradation half-life of myclobutanil in silt loam soil is about 66 days(5).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), myclobutanil, which has a vapor pressure of 1.6X10-6 mm Hg at 25 °C(2), is expected to exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase myclobutanil is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 2.3 days(SRC), calculated from its rate constant of 7.0X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase myclobutanil may be removed from the air by wet or dry deposition(SRC). Aqueous solutions of myclobutanil are decomposed by light with half-lives ranging from 25-222 days(4), therefore, myclobutanil may be susceptible to direct photolysis in the atmosphere(SRC).

Myclobutanil was detected in the U.S. food supply during the 1990 and 1994 Fiscal Years(1,2). Myclobutanil was detected a total of 7 times on imported cherries in the Hyogo Prefecture, Japan at residues ranging from <0.01 to <0.5 ug/g during a monitoring study conducted from April 1995 to March 2000(3). Myclobutanil was detected a total of 24 times during a monitoring study conducted from 1991 to 1995 on fruits and vegetables grown in Ontario, Canada with residues ranging from <0.01 to <0.5 ug/g(4).

Organic nitriles decompose into cyanide ions both in vivo and in vitro. Consequently the primary mechanism of toxicity for organic nitriles is their production of toxic cyanide ions or hydrogen cyanide. Cyanide is an inhibitor of cytochrome c oxidase in the fourth complex of the electron transport chain (found in the membrane of the mitochondria of eukaryotic cells). It complexes with the ferric iron atom in this enzyme. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted and the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Cyanide is also known produce some of its toxic effects by binding to catalase, glutathione peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, succinic dehydrogenase, and Cu/Zn superoxide dismutase. Cyanide binds to the ferric ion of methemoglobin to form inactive cyanmethemoglobin. (L97)

Systhane

Reproductive

2.5 x 10 ^-2 mg/kg-day

The Koc of myclobutanil is estimated as 950(SRC), using a log Kow of 2.94(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that myclobutanil is expected to have low mobility in soil. An Rf of 0.13 was determined for (14)C-myclobutanil on Versailles silt loam (1.94% organic matter, 20.5% clay, pH 6.4); based upon this Rf, myclobutanil was classified as slightly mobile(4).

Myclobutanil's production may result in its release to the environment through various waste streams; its use as a systemic fungicide to control Ascomycetes, Fungi Imperfecti, and Basidiomycetes on a wide variety of crops(1) will result in its direct release to the environment(SRC).

Tolerances are established for combined residues of the fungicide myclobutanil alpha-butyl-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile and its alcohol metabolite (alpha-(3-hydroxybutyl)-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile (free and bound), in or on the following food commodities: [Table#6209]

Time-limited tolerances are established for residues of the fungicide myclobutanil in connection with use of the pesticide under section 18 emergency exemptions granted by EPA. These tolerances will expire and are revoked on the dates specified in the following table. [Table#6210]

Tolerances are established for residues of the fungicide myclobutanil alpha-butyl-alpha-(4-chlorophenyl)-1 H -1,2,4-triazole-1-propanenitrile in or on the following food commodities: [Table#6211]

New Active Ingredients ... includes pesticide active ingredients initially registered after November 1, 1984, that currently have active product registrations. By law, these newer pesticides are not subject to the reregistration program. They must, however, meet the new safety standard of the FQPA, and will be reviewed on a 15-year cycle under the registration review program. ... Active Ingredient Number: 128857 /(myclobutanil)/; Type of Pesticide: Conventional - Fungicide; Use Site: Food use, ornamentals; Year: 1989.

1,2,4-Triazole (1,2,4-T); triazole alanine (TA); and triazole acetic acid (TAA) are common metabolites to the class of compounds known as triazoles. In plants, 1,2,4-T is rapidly conjugated with serine to form TA. The TA can then be oxidized to form TAA. The extent to which 1,2,4-T, TA, and/or TAA forms in a given plant or animal is primarily dependent on the parent triazole-derivative fungicide. Across the various parent compounds, maximum formation of 1,2 4-T in plants ranges from 0% of the total radioactive residue (TRR) to 17% TRR, with the majority of compounds yielding 1,2,4-T at around 5-10% TRR. In rats, goats, and hens, maximum 1,2,4-T formation ranges from 0 to 77% TRR. Formation of 1,2,4-T in the rat is less than 20% TRR for the majority (approximately 80%) of the triazole-derivative fungicides for which data are available. Formation of TA ranges from 0 to 89% TRR in plants. Triazole acetic acid formation in plants ranges from 0 to 76% TRR. Triazole alanine and triazole acetic acid have generally not been found to be significant metabolites in rats, lactating goats, or laying hens. The exception to this appears to be fenbuconazole. In studies with radio-labeled fenbuconazole fed to goats and hens, TA formation ranges from 0 to 35% TRR; formation of TA from fenbuconazole was not noted in the rat metabolism studies. There is evidence from toxicological studies that there can be limited reduction of TA to 1,2,4-T following oral exposure to TA. /Triazole-derivative fungicide compounds/

Metabolism of two triazole-containing antifungal azoles was studied using expressed human and rat cytochrome P450s (CYP) and liver microsomes. Substrate depletion methods were used due to the complex array of metabolites produced from myclobutanil and triadimefon. Myclobutanil was metabolized more rapidly than triadimefon, which is consistent with metabolism of the n-butyl side-chain in the former and the t-butyl group in the latter compound. Human and rat CYP2C and CYP3A enzymes were the most active. Metabolism was similar in microsomes prepared from livers of control and low-dose rats. High-dose (115 mg/kg/day of triadimefon or 150 mg/kg/day of myclobutanil) rats showed increased liver weight, induction of total CYP, and increased metabolism of the two triazoles, though the apparent Km appeared unchanged relative to the control.

Myclobutanil metabolizes into 1,2,4-triazole, which has a lower acute toxicity than the parent compound (L2093). Organic nitriles are converted into cyanide ions through the action of cytochrome P450 enzymes in the liver. Cyanide is rapidly absorbed and distributed throughout the body. Cyanide is mainly metabolized into thiocyanate by either rhodanese or 3-mercaptopyruvate sulfur transferase. Cyanide metabolites are excreted in the urine. (L96)

Rapidly absorbed and excreted. Completely eliminated by 96 hrs. Extensively metabolized prior to excretion. Metabolic patterns similar for both sexes. Disposition & metabolism after pulse administration is linear over dose range. ... Elimination of label from plasma biphasic and evenly distribution between urine and feces. No tissue accumulation after 96 hours. At least 7 major metabolites recovered and identified. Highest amounts of radioactivity found in liver, kidneys, large and small intestines. No tissue accumulation.

Used as broad spectrum triazole fungicide; [Merck Index] Used as a food additive; [Hawley]

Farming (Pesticides) [Category: Industry]

Myclobutanil (USEPA/OPP Pesticide Code: 128857) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./

Myclobutanil is a systematic fungicide used on grapes and tree fruits.

Systemic fungicide ... control of Ascomycetes, Fungi imperfecti, and Basidiomycetes on a wide variety of crops.

Myclobutanil is a man-made compound that is used as a pesticide. Myclobutanil is registered for use on a wide range of food and feed crops. It may also be used in greenhouses, public rights of way, turf, and in landscaping applications. Cotton seeds may be treated with myclobutanil. California accounts for roughly 50% of all myclobutanil use in the US, using 70,000 to 90,000 lbs. annually. Grapes are the most heavily treated crop, using 60% of all myclobutanil in California. Almonds and strawberries are also account for a notable percentage of myclobutanil use in California. (L2093)

... Produced by the alkylation of 4-chlorophenylacetonitrile with butyl chloride, followed by treatment with dibromomethane and sodium hydroxide in dimethyl sulfoxide. The resulting intermediate is then reacted with the potassium salt of 1,2,4-triazole in dimethyl formamide.

alpha,4-Dichloroacetophenone + n-butyl chloride + 1,2,4-triazole + hydrogen cyanide (amine formation/Grignard reagent formation/Grignard reaction/alcohol bromination/cyanidation).

ANDERSONS GOLF PRODUCTS GOLDEN EAGLE FUNGICIDE Active Ingredient 1.00% myclobutanil; FERTILIZER PLUS FUNGICIDE XI Active Ingredient 1.00% myclobutanil

CHEMSICO CONCENTRATE Active Ingredients 1.250% Permethrin, mixed cis,trans and 0.78% Myclobutanil; CHEMSICO RTU MP Active Ingredients 0.020% Permethrin, mixed cis,trans and 0.012% Myclobutanil; CHEMSICO AEROSOL MP Active Ingredients 0.020% Permethrin, mixed cis,trans and 0.0120% Myclobutanil; CHEMSICO FUNGICIDE M Active Ingredient 1.550% Myclobutanil; CHEMSICO AEROSOL M Active Ingredient 0.012% Myclobutanil; CHEMSICO RTU M Active Ingredient 0.012% Myclobutanil; CHEMSICO FUNGICIDE CONCENTRATE M6 Active Ingredient 6.00% Myclobutanil; CHEMSICO FUNGICIDE CONCENTRATE 3000 Active Ingredient 2.000% Myclobutanil

MYCLOBUTANIL 40 WP AG Active Ingredient 40.0% Myclobutanil; MYCLOBUTANIL TGAI Active Ingredient 98.0% Myclobutanil; MYCOBUTANIL 40W T&O Active Ingredient 40.0% Myclobutanil; MYCLOBUTANL 20EW AG Active Ingredient 19.7% Myclobutanil; MYCLOBUTANIL 20EW T&O Active Ingredient 19.7% Myclobutanil

RH-3866 TECHNICAL Active Ingredient 95.5% Myclobutanil; RALLY 60 DF FUNGICIDE Active Ingredient 60.0% Myclobutanil; SYSTHANE 40 WP AGRICULTURAL FUNGICIDE Active Ingredient 40.0% Myclobutanil; RALLY 40W AGRICULTURAL FUNGICIDE IN-WATER-SOLUBLE POUCHES Active Ingredient 40.0% Myclobutanil; NOVA 40W AGRICULTURAL FUNGICIDE IN WATER SOLUBLE POUCHES Active Ingredient 40.0% Myclobutanil; NU-FLOW M SEED TREATMENT FUNGICIDE Active Ingredient 25% Myclobutanil; EAGLE WSP FUNGICIDE Active Ingredient 40.0% Myclobutanil; RH-0611 Active Ingredients 60.0% Mancozeb and 2.25% Myclobutanil; SYSTHANE WSP ORNAMENTAL FUNGICIDE Active Ingredient 40.0% Myclobutanil; RH-144228 FUNGICIDE Active Ingredients 96.75% Sulfur and 0.50% Myclobutanil; EAGLE 0.39G SPECIALTY FUNGICIDE Active Ingredient 0.39% Myclobutanil; EAGLE 0.62G Active Ingredient 0.620% Myclobutanil; EAGLE 20EW Active Ingredient 19.7% Myclobutanil; NU-FLOW M-40 Active Ingredient 40.0% Myclobutanil; LAREDO EW Active Ingredient 19.7% Myclobutanil

Emulsifiable concentrate and wettable powder.

Environmental transformation -> Pesticides (parent, predecessor)

Fungicides

Broad spectrum systemic triazole fungicide; ergosterol - biosynthesis inhibitor

Used as a foliar treatment for control of scab and powdery mildew in apples and pears; powdery mildew, shot-hole, blossom blight, and rust in stone fruit; powdery mildew in vines and cucurbits; powdery mildew and rusts on ornamentals; rusts on perennial grasses grown for seed, and various diseases of wheat; as a seed treatment for control of seed- and soil-borne diseases in barley, maize, cotton, rice, and wheat; and as a post-harvest drench or dip.

The following crops were treated with myclobutanil in the United States during the 1989 to 1991 crop years (from federal and state pesticide surveys of fungicide use patterns), percentage of acres (planted with crop) treated: apples, 37%; grapes, 68%; and strawberries, 2%.