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Chlorsulfuron - Herbicide Profile 3/85


      CHEMICAL name:      2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)
                          aminocarbonyl]-benzenesulfonamide (58)

      TRADE name(S):      Glean Weed Killer (56)

      FORMULATION(S):     75% dry flowable (56)

      TYPE:               Triazine herbicide

      BASIC PRODUCER(S):  E.I. du Pont de Nemours and Co., Inc.
                          1007 Market St.
                          Wilmington, DE 19898

      STATUS:             General use

      PRINCIPAL USES:  Glean Weed Killer is recommended for selective
      control of weeds in wheat (pre- and/or postemergent to crop) and barley
      (postemergent to crop) as well as reduced tillage fallow preceding
      wheat.  Controls most broadleaf and some grass weeds at 1/6 and 1/2
      ounce product/acre.
           Glean is intended for use on land having a soil pH of 7.5 or
      lower, and dedicated primarily to the production of wheat and barley

      APPLICATION METHOD(S):  Preemergence or early postemergence treatments
      show the most activity on annual grass weeds and broadleaf weeds.
      Later postemergence treatments are effective on most broadleaf weeds
      but less effective on grasses.  Treatments may be made with aerial or
      ground equipment (58).

                                    I.  EFFICACY

      Important Weeds Controlled:  Velvetleaf, pigweed, mustards, shepard's
      purse, lambsquarters, Canada thistle, sunflower, henbit, plantain,
      smartweed, curly dock, Russian thistle, chickweed, cocklebur and many
      others (8b).
           It has activity on most broadleaf weeds and some annual grass weeds.
      Certain perennials like Cirsium arvense are sensitive (58).
           Wild oats, cheat and nightshade are tolerant of this material.
      Broadleaves are more susceptible than grasses.  Shallow incorporation
      may improve grass control but may also reduce broadleaf control.  Plant
      death is often slow (8b).

                              II.  PHYSICAL PROPERTIES

      MOLECULAR FORMULA:  C12 H12 Cl N5 O4 S (58)

      MOLECULAR WEIGHT:   357.8 (58)

      PHYSICAL STATE:     White crystalline solid (pure compound) (58); the
                          technical material has a minimum purity of 94%

      ODOR:               Odorless (pure compound) (58)

      MELTING POINT:      174-178 C (pure compound) (58)

      DECOMPOSITION TEMPERATURE:  192 C (pure compound) (58)

      VAPOR PRESSURE:     4.6 x 10-6 mmHg at 25 C (pure compound) (58)

      SOLUBILITY:         At 25 C:  100-125 mg/l water (solution has pH 4.1),
                          300 mg/l (at pH 5), 27.9 g/l (at pH 7) (pure
                          compound) (62).

                          III.  HEALTH HAZARD INFORMATION

      OSHA STANDARD:  None established

      NIOSH RECOMMENDED LIMIT:  None established

      ACGIH RECOMMENDED LIMIT:  None established

      DU PONT ACCEPtable EXPOSURE LIMITS (AEL; 8-hour time weighted average):
           5 mg/m3 for respirable dust, or 10 mg/m3 for total dust (Glean
           Weed Killer) (31y).


           A.  ACUTE TOXICITY

               DERMAL:  LD50 = >3400 mg/kg (rabbit); not a skin irritant
                          (rabbit) or sensitizer (guinea pig) (31x).
                        LD50 = 3400 mg/kg (rabbit, techncal) (21h).
                          Very mild skin irritant (rabbit, formulated product
                          - 75% chlorsulfuron) (21h).
                        LD50 = >2000 mg/kg (rabbit, formulated product -

                          75% chlorsulfuron ) (21h).

               ORAL:    LD50 (technical chlorsulfuron) = 5545 mg/kg (male

                          rat), 6293 mg/kg (female rat), 1363 mg/kg (guinea
                          pig), >2500 mg/kg (dog) (21h).
                        LD50 = 3053 mg/kg (male rat), 2341 mg/kg (female
                          rat) (Glean Weed Killer (31y).
                        LD50 (formulated product - 75% chlorsulfuron) =
                          4147 mg/kg (male rat), 2493 mg/kg (female rat)

               INHALATION:  LC50 = >5.9 mg/l (rat, technical) (21h).

               EYES:    Administration of 10 mg to rabbit eye produced very
                          mild temporary conjunctival irritation (31x).
                        Mild eye irritant (rabbit, formulated product - 75%
                          chlorsulfuron) (21h).


           No observable effect levels of 100 ppm in the diet of rats (3
      months) and 2500 ppm in the diets of mice (3 months) and dog (6 months).

           No observable effect levels of 100 ppm in the diet of rats for 2
      years and 500 ppm in the diet of mice for 2 years.  No oncogenic effects
      at any level; highest level fed was 2500 ppm rats and 5000 ppm mouse.

           The dietary presence of chlorsulfuron at 500 ppm had no adverse
      effect on the reproduction or lactation performance of young adult rats
      (3-generation, 2-litters per generation).

           Not teratogenic in rats at 2500 ppm or up to 75 mg/kg in rabbits.

           Not mutagenic in Ames bacterial assay, Chinese Hamster Ovary
      Mammalian cell assay, rat dominant lethal assay, in vitro cytogenetic
      assay, or DNA repair assay (31x).

                         IV.  ENVIRONMENTAL CONSIDERATIONS

      Behavior In Or On Soils

      1.   Adsorption and leaching characteristics in basic soil types:
             Adsorption to clay is low while organic matter has some
             affinity.  The K value of 0.69 on a Flanagan silt loam is
             similar to metribuzin's 0.68.  Rate of leaching is correlated
             with net movement of soil moisture with less leaching if pH
             is less than 6.0.
      2.   Microbial breakdown:  Initial deactivation of the molecule is
             through hydrolysis followed by complete metabolism to low
             molecular weight compounds through normal soil microbial
      3.   Loss from photodecomposition and/or volatilization:  In the field
             photodecomposition and volatilization play minor roles in its
             disappearance.  Hydrolysis into nonherbicidal compounds is
             the major form of degradation and its rate is influenced by
             soil temperature, pH and levels of oxygen and moisture.
      4.   Resultant average persistence at recommended rates:  Under growing
             season conditions the half-life is 4-6 weeks.  Soil
             temperature influences length of half-life with shorter
             persistence at higher temperature.  Low pH accelerates
             hydrolysis while soil texture does not appear to be a major
             factor in rate of degradation (58).

      General toxicity to wildlife and fish:  Oral LD50 >5000 mg/kg for quail
           and duck, oral dietary LC50 of >5000 ppm for quail and duck, LC50
           (96 hr) >250 ppm for trout and bluegill (58).

      Ninety-six hour LC50 = >300 ppm (fathead minnow), >50 ppm (catfish)
           (technical material) (21h).

      Forty-eight hour LC50 = 370 ppm (Daphnia magna) (technical material)


           The chemical information provided below has been condensed from
      original source documents, primarily from "Recognition and Management
      of Pesticide Poisonings", 3rd ed. by Donald P.  Morgan, which have been
      footnoted.  This information has been provided in this form for your
      convenience and general guidance only.  In specific cases, further
      consultation and reference may be required and is recommended.  This
      information is not intended as a substitute for a more exhaustive
      review of the literature nor for the judgement of a physician or other
      trained professional.

           If poisoning is suspected, do not wait for symptoms to develop.
      Contact a physician, the nearest hospital, or the nearest Poison
      Control Center.

           EYE CONTACT:  Immediately flush with plenty of water.  Get medical
      attention if irritation persists (31x).

                        VI.  FIRE AND EXPLOSION INFORMATION

      GENERAL:  May be ignited by heat or open flame (Glean Weed Killer) (31y).

      EXTINGUISHER TYPE:  On small fire use dry chemical, CO2, foam or water
      spray.  Wear self-contained breathing apparatus.  If area is heavily
      exposed to fire and if conditions permit, let fire burn itself out
      since water may increase the contamination hazard.  If conditions do
      not permit, extinguish with water spray.  If conditions permit, cool
      containers with water if exposed to fire (Glean Weed Killer) (31y).

                                VII.  COMPATIBILITY

           It is adequately stable in tank mixtures with other crop protection
      chemicals including liquid fertilizers.  Stability of other components
      appears good while evaluations continue.  Noncorrosive (58).

                             VIII.  PROTECTIVE MEASURES

      STORAGE AND HANDLING:  Formulation is stable if stored in an airtight
      container and free of moisture and high humidity (58).
      Keep out of reach of children.  Do not contaminate water, food, or feed
      by storage or disposal.  Keep from contact with fertilizers,
      insecticides, fungicides, and seeds during storage.  Avoid breathing
      dust or spray mist.  Avoid contact with skin, eyes, and clothing.  Do
      not apply, drain, or flush equipment on or near desirable trees or
      other plants.

      PROTECTIVE EQUIPMENT:  Where dust levels in operating areas may exceed
      AEL value, respirators approved for pesticide dusts should be worn
      (Glean Weed Killer) (31y).

                        IX.  PROCEDURES FOR SPILLS AND LEAKS

                      IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
                                   (800) 424-9300

           Clean up promptly by scoop or vacuum; do not flush with water.  If
      spill area is on ground near trees or other valuable plants, remove top
      2 inches of soil after initial cleanup (Glean Weed Killer) (31y).

                               X.  LITERATURE CITED

       8b. Thomson, W.T.  1981.  Agricultural chemicals - book 2:
               herbicides.  Revised ed.  Thomson Publications, Fresno, CA.
               274 pp.

      21h. Agriculture Canada, Food Production and Inspection Branch,
               Pesticides Division.  1982.  Report of new registration:
               Glean weed killer.  Ottawa, Ontario, Canada.

      31x. E. I. du Pont de Nemours and Company, Inc., Biochemicals Department.
               1982.  Technical data sheet for chlorsulfuron.  Wilmington, DE.

      31y. E. I. du Pont de Nemours and Company, Inc., Biochemicals Department.
               1981.  Material safety data sheet for Glean Weed Killer.
               Wilmington, DE.

      56.  Farm Chemicals Handbook, 70th ed.  1984.  R. T. Meister, G. L.
               Berg, C. Sine, S. Meister, and J. Poplyk, eds.  Meister
               Publishing Co., Willoughby, OH.

      58.  Weed Science Society of America, Herbicide Handbook Committee.
               1983.  Herbicide handbook of the weed science society of
               America, 5th ed.  Weed Science Society of America, Champaign,
               IL.  515 pp.

      62.  The Pesticide Manual:  A World Compendium, 7th ed.  1983.  C.R.
               Worthing, ed.  The British Crop Protection Council, Croydon,
               England.  695 pp.