| Chemical Abstract Number (CAS #) |
2303164
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| Synonyms | Diallate |
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S-(2,3-Dichloroallyl) diisopropyl-thiocarbamate | Carbamothioic acid, bis(1-methylethyl)-S-(2,3-dichloro-2-propenyl) ester | Avadex | 2,3-DCDT |
| Analytical Method |
EPA Method 8081 |
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| Molecular Formula | C10H17Cl2NOS |
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| Use | AN EXTREMELY ACTIVE PRE-EMERGENCE HERBICIDE AGAINST CERTAIN
ANNUAL MONOCOTS, PARTICULARLY AVENA FATUA, WITH SAFETY FOR CEREAL
GRAINS AT RATES NECESSARY TO CONTROL THE WEEDS. IT HAS ALSO SHOWN
PROMISE AS A SPROUT INHIBITOR IN POTATOES.
USED AS A BEFORE OR AFTER PLANTING TREATMENT DEPENDING ON CROP
FOR CONTROL OF WILD OATS. FOR USE ON ALFALFA, ALSIKE CLOVER, BARLEY,
CORN, FLAX, SOYBEANS, LENTILS, PEAS, POTATOES, RED CLOVER, SUGAR
BEETS, AND SWEET CLOVER. WORKS WELL UNDER MANY SOIL AND CLIMATIC
CONDITIONS.
HERBICIDE FOR FIELD CROPS-EG, SUGAR BEETS & LENTILS
HERBICIDE FOR FLAX & PEAS
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| Consumption Patterns | HERBICIDE FOR SUGAR BEETS, 88%; OTHER FIELD CROPS, 12% (1982)
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| Apparent Color | BROWN LIQUID; Oily liquid
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| Boiling Point | 150 DEG C @ 9 MM HG
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| Melting Point | 25-30 deg C
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| Molecular Weight | 270.24
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| Density | 1.188 @ 25 DEG C/15.6 DEG C
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| Sensitivity Data | SLIGHTLY IRRITATING TO SKIN AND EYES.
THE CONCENTRATE MAY CAUSE IRRITATION TO SKIN, EYES, & MUCOUS
MEMBRANES.
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| Environmental Impact | Diallate is a mixture of the Z- and E-isomers. Diallate will be released to the environment
during its application as a pre-emergence herbicide for field crops such as sugar beets, flax,
lentels, and peas. Releases may also occur during formulation, transport, and storage. Diallate is
generally incorporated into the soil and it will be lost (half-life 2-6 wk) principally by
biodegradation although adsorption to soil and to a lesser extent volatilization and
photodegradation are also important. Diallate released to the atmosphere as aerosols or by
volatilization from soil will be subject to gravitational settling and photodegradation. If released to
water, a combination of adsorption to sediment, photodegradation and microbial degradation will
occur but no experimental data applicable to natural systems are available. Only moderate
bioconcentration in fish would be expected. Human exposure is principally occupational.
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| Environmental Fate | TERRESTRIAL FATE: Diallate disappears from a variety of agricultural soils with a
half-life of 2-6 weeks. The major routes of loss in decending order of importance are
biodegradation, adsorption to soil, and volatilization . There is some evidence that microbial
degradation is more dominant when adsorptive forces are weaker . The kinetics of diallate loss
from soil is complex and appear to lie between first and second order . The only volatile
degradation product is carbon dioxide . When applied to field plots in May, all the diallate was
degraded within the growing season .
AQUATIC FATE: Diallate released into water would adsorb to sediment and particulate matter
in the water column. It will also photodegrade in surface layers and possibly biodegrade,
however, no experimental data for these degradative processes in natural water systems could be
found.
ATMOSPHERIC FATE: Diallate released to the atmosphere during its application or volatilized
from soil will photodegrade. Vapor phase diallate will react with photochemically produced
hydroxyl radicals and have an estimated half-life of 5.1 hours . The half-life of diallate in
aerosols is approximately 8 days . Aerosols and diallate adsorbed to particulate matter will also
be subject to gravitational settling.
ENVIRONMENTAL PERSISTENCE: AT 42 DEG C 52, 53, & 56% DIALLATE
REMAINED ON REGINA CLAY @ 7, 14, & 28 DAYS, RESPECTIVELY. FOR WEYBURN
LOAM CORRESPONDING FIGURES WERE 81, 82, & 83% & FOR ASQUITE SANDY
LOAM 98, 98, & 93%. AMT REMAINING @ 50 DEG C WAS 45-60% FOR ALL SOIL
TYPES. LOSSES WERE NEGLIGIBLE @ 22 OR - 2 DEG C.
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