| Chemical Abstract Number (CAS #) |
330541
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| Synonyms | Diuron |
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3-(3,4-Dichlorophenyl)-1,1-dimethylurea | DCMU |
| Analytical Methods |
EPA Method 553 |
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EPA Method 632 |
| Molecular Formula | C9H10Cl2N2O |
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| Use | PRE-EMERGENCE HERBICIDE
USED FOR GENERAL WEED CONTROL ON NON-CROP AREAS @ 10-30 KG ACTIVE
INGREDIENT/HA; FOR SUBSEQUENT ANNUAL MAINTENANCE 5-10 KG/HA WILL
PREVENT RE-INFESTATION BY SEEDLINGS.
IT IS ALSO USED SELECTIVELY BEFORE EMERGENCE ON CROPS SUCH AS
ASPARAGUS, CITRUS,COTTON, PINEAPPLE, SUGARCANE, TEMPERATE TREE, &
BUSH FRUITS @ 0.6-4.8 KG/HA.
DIURON IS NOW WIDELY EMPLOYED FOR INDUSTRIAL AREA WEED CONTROL,
PARTICULARLY IN HIGHER RAINFALL CLIMATES. LOW WATER SOL & GREATER
ABSORBANCY ON SOIL PARTICLES PERMITS LOW RATES TO HAVE WIDE
APPLICATION.
FOR GENERAL WEED CONTROL, DIURON IS SPRAYED OR SPREAD DRY (AS
GRANULES) DENSE GROWTH SHOULD BE REMOVED BEFORE APPLICATION.
INCR CONTACT ACTIVITY ON ESTABLISHED WEEDS OBTAINED WHEN APPLIED
WITH A SUITABLE SURFACTANT ADDED TO SPRAY SUSPENSION.
HERBICIDE FOR INDUST USES-EG, RAILROAD RIGHTS-OF-WAY
HERBICIDE FOR AGRICULTURAL USES-EG, COTTON & CITRUS
Pre-emergence herbicide, sugar cane flowering suppressant
Effective against emerging and young broadleaf and grass weeds as well as mosses; suitable for
both selective and total weed control. For use on alfalfa, asparagus, cotton, citrus, fruit orchards,
sugarcane, wheat and vineyards.
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| Consumption Patterns | INDUSTRIAL COMMERCIAL USES-EG, ON RAILROAD RIGHTS-OF-WAY, 57%;
COTTON, 19%; CITRUS CROPS, 12%; DECIDUOUS FRUITS & NUTS, 3%; WHEAT, 3%;
VEGETABLES, 2%; OTHER FIELD CROPS, EG, ALFALFA & SUGARCANE, 4% (1978
HERBICIDE USE)
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| Apparent Color | WHITE, CRYSTALLINE SOLID
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| Odor | ODORLESS
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| Boiling Point | Decomposes at 180-190 deg C
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| Melting Point | 158-159 DEG C
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| Molecular Weight | 233.10
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| Sensitivity Data | MAY IRRITATE EYES, NOSE, THROAT, & SKIN.
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| Environmental Impact | Diuron is released to the environment during its use as a preemergence herbicide.
Therefore it is primarily released on soil although releases into water occur from runoff and
possibly in wastewater. It is a strongly adsorbed, highly persistent chemical and if released in soil
will remain in the upper 5-10 cm of soil and have a half-life of about 330 days. If released into
water diuron will adsorb to the sediment where it will slowly biodegrade after acclimation. The
major product of the 6-7 degradation compounds that were isolated was 3,4-dichloroaniline and
this metabolite may be further metabolized to an azobenzene derivative. In clear surface layers of
water, sunlight irradiation will degrade diuron in a matter of days. Slow biodegradation may also
occur. Bioconcentration in fish is not appreciable. Diuron will degrade in air probably within a
half-life in the vapor phase of 5.8 days due to reaction with hydroxyl radical. Human exposure will
primarily be in the workplace and fields where diuron is used.
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| Environmental Fate | TERRESTRIAL FATE: Diuron is a highly persistent and fairly immobile herbicide. When
applied to soil it has a mean half-life of approximately 330 days and will not leach below 5 to 10
cm from the surface . Metabolites of microbial degradation include the major metabolite,
3,4-dichloroaniline, and also 3-(3,4-dichlorophenyl)urea and 3-(3,4,dichlorophenyl)-1-methylurea.
Some diuron is lost with evaporating water when the diuron is applied to the surface of the soil
without being worked in deeply. The levels of diuron found in citrus groves in Florida in which it
was used for 7-8 years ranged from 3.7 to 13.1% of the total diuron applied . The interval
between the last application and the time of sampling was 1-12 months.
AQUATIC FATE: If released into water, diuron will primarily be adsorbed to the sediment
(where it may slowly dehalogenate after acclimation). Degradation occurs in acclimated
organic-rich sediments at moderate temperatures (90%) degradation in 8 mo. Apparently
biodegradation is surface catalyzed and would therefore be more apt to occur in waters where
particulate matter was abundant. In surface waters diuron should photolyze within a few days.
ATMOSPHERIC FATE: It is unlikely that appreciable quantities of diuron are released to the
atmosphere although photolysis (half-life in hours) would be expected to degrade the herbicide
fairly quickly.
UNDER FIELD CONDITIONS @ LOWER SELECTIVE RATES, PHYTOTOXIC CONCN
DISAPPEAR WITHIN 1 SEASON HIGHER SELECTIVE RATES MORE THAN 1
SEASON MAY BE REQUIRED. ACCUMULATION FROM ANNUAL APPLICATIONS @
SELECTIVE RATES TO SAME SOIL NOT A PROBLEM. STERILANT RATE
ACTIVITY MAY BE NOTED MORE THAN 1 SEASON.
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| Drinking Water Impact | DRINKING WATER: Not detected in British drinking water derived from lowland river
water and ground water .
GROUNDWATER: According to the EPA's Pesticides in Ground Water Data Base, Diuron has
been found in water in 2 states as a result of field use . In one state the data was high quality
and the contamination was a result of normal field use. Diuron was detected in 1 of 94 farm wells
survyed in Ontario in 1984 .
SURFACE WATER: Detected, not quantified in river water from lowland rivers in England and
West Germany . Cape Fear River, NC (10 stations)-most samples did not contain diuron in
detectable quantities although 4 samples approached 1.6 ppb, the limit set to protect aquatic
life . The largest amount in the river was in the spring after application to fields as well as in
summer when large amounts were in the soil . The total mass of diuron in the river was
approximately constant in all reaches of the river . Between 1971 and 1985, 211 rural ponds in
Ontario were analyzed for pesticides. Runoff and spray drift were responsible for diuron in two of
these ponds at 4 and 25 ppb .
EFFL: Runoff from field 21 days after application as an emulsion on foliage at 206 kg/ha - 74
ppb .
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