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pyrazon (Pyramin) Herbicide Profile 2/85

                                      pyrazon
      CHEMICAL NAME:      5-amino-4-chloro-2-phenyl-3-(2H)-pyridazinone (56)
      TRADE NAME(S):      Pyramin (56)
      FORMULATION(S):     Wettable powder (56)
      TYPE:               Herbicide
      BASIC PRODUCER(S):  BASF Wyandotte Corp.
                          Agricultural Chemicals Div.
                          100 Cherry Hill Rd.
                          Parsippany, NJ 07054
      STATUS:             General use
      PRINCIPAL USES:  For preemergence and early postemergence weed
      control.  Applied at planting time or shortly after planting time of
      sugar beets, red beets and fodder beets (56).
      APPLICATION METHOD(S): Generally preemergence, broadcast or early
      postemergence, banded.  In irrigated western regions banded preemergence
      application with sprinkler irrigation or banded, shallow, preplant soil
      incorporation with furrow irrigation is recommended.  Pyrazon can be
      mixed with other herbicides including phenmedipham and desmedipham for
      control of additional weeds in sugarbeets (58).
                                   I.  EFFICACY
           Controls annual broadleaf weeds in sugarbeets and red beets.
      Control of annual grasses is not consistently obtained (58).
      Important Weeds Controlled: Lambsquarters, mustards, ragweed, purslane,
      smartweed, pigweed, henbit, shepherd's purse, nightshade, groundsel,
      dock, spurge, chickweed, wild radish and others (8b).
           Weeds lose much of their susceptibility by the time they have
      four true leaves.  Perennial weeds are not controlled.  Preemergence
      applications are not effective under furrow irrigation unless
      incorporated.  Moisture is required to activate this material.  Weed
      control can be expected for 4-8 weeks.  Somewhat ineffective on grasses.
      A light incorporation (1-2 inches) gives better results than a deep
      one (4-5 inches).  Use on soils where the organic matter is higher than
      5%, will result in erratic weed control under dry weather conditions
      (8b).
                             II.  PHYSICAL PROPERTIES
      MOLECULAR FORMULA:  C10 H8 C1 N3 O (62)
      MOLECULAR WEIGHT:   221.6 (62)
      PHYSICAL STATE:     Tan to brown powder (pure compound) (58);
                          solid, dark brown (technical a.i.) (56).
      ODOR:               Approx. odorless (technical a.i.) (56); odorless
                          when pure (58).
      MELTING POINT:      207 C (with decomp.) (pure compound) (58)
      VAPOR PRESSURE:     0.074 mmHg at 40 C (pure compound) (58)
      SOLUBILITY:         0.04 g/100 g water at 20 C (pure compound) (58)
                          III.  HEALTH HAZARD INFORMATION
      OSHA STANDARD:  NA
      NIOSH RECOMMENDED LIMIT:  NA
      ACGIH RECOMMENDED LIMIT:  NA
      TOXICOLOGY
           A.  ACUTE TOXICITY
               DERMAL:  No toxicity to skin observed (58).
               ORAL:    LD50 = 3030 mg/kg (rat) (form. prod.) (56)
                        LD50 = 3600 mg/kg (rat), 3000 mg/kg (mouse), 1250
                               mg/kg (rabbit) (58).
                        LD50 = 2424 mg a.i. (as w.p.)/kg (rat) (62).
           B.  SUBACUTE AND CHRONIC TOXICITY:
           In 2-year feeding trials rats receiving 300 mg/kg diet suffered no
      detectable toxic effect (62).
           Rats - 15 weeks:  5000 ppm of total diet showed no histological or
      pathological changes over control.
           In 2-year studies, rats and dogs were fed diets containing 300 and
      1500 ppm, respectively, of Pyramin without any noticeable effects (58).
           Application to backs and ears of white rabbits (20-hr) caused slight
      temporary erythema (62).
                        IV.  ENVIRONMENTAL  CONSIDERATIONS
           Not significantly hazardous to fish (bluegill and fathead minnows,
      LC50 approximately 40 ppm) (58).
      Behavior In or On Soils
      1.   Adsorption and leaching characteristics in basic soil types:
             Preemergence use is not recommended on soils classified as sands
             or loamy sands because of leaching and possible crop injury.
             Adsorption on soils containing greater than 5% organic matter
             precludes adequate weed control.
      2.   Microbial breakdown:  Depending upon soil temperature and moisture
             in the treated zone, the microbial breakdown can be moderately
             rapid.  The principal degradation product is dephenylated pyrazon
             which is not significantly herbicidal.
      3.   Loss from photodecomposition and/or volatilization:  Negligible.
      4.   Resultant average persistence at recommended rates:  4 to 8 weeks,
             depending upon soil moisture and temperature (58).
                      V.  EMERGENCY AND FIRST AID PROCEDURES
           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 sub-
      stitute 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.
      SYMPTOMS OF POISONING:  None noted to date for humans (58).
           SKIN CONTACT:  Remove contaminated clothing and wash skin with
      soap and water.  Consult a physician if irritation persists (56).
           INGESTION:  Induce vomiting and consult a physician (56).
           EYE CONTACT:  Flush eyes immediately with water for at least 15
      minutes (56).
                        VI.  FIRE AND EXPLOSION INFORMATION
           Dry powder, nonflammable (58).
                                VII.  COMPATIBILITY
           Generally compatible with other sugarbeet herbicides with which it
      is likely to be used.  As a general precaution when tank-mixing with
      liquid formulations a good suspension of pyrazon should be obtained
      before adding the liquid herbicides.  Noncorrosive (58).
                            VIII.  PROTECTIVE MEASURES
      STORAGE AND HANDLING:  Avoid contact with skin, eyes and clothing.
      Harmful if swallowed (58).
                       IX.  PROCEDURES FOR SPILLS AND LEAKS
                     IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
                                  (800) 424-9300
                      PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
                               X.  LITERATURE CITED
       8b. Thomson, W.T.  1981.  Agricultural chemicals - book 2:
               herbicides.  Revised ed.  Thomson Publications, Fresno, CA.
               274 pp.
      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.
      2/21/85