oxadiazon (Ronstar) Herbicide Profile 2/85
CHEMICAL NAME: 2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-
TRADE NAME(S): Ronstar (56)
FORMULATION(S): Emulsifiable concentrates, granules, flowable (56).
Ronstar 0.24 kg/l (2 lb/gal EC), Chipco Ronstar
G (2% granular) (58).
TYPE: Oxadiazolinone herbicide
BASIC PRODUCER(S): Rhone-Poulenc, Inc., Agricultural Div.
P.O. Box 125
Monmouth Junction, NJ 08852
STATUS: General use
PRINCIPAL USES: Provides preemergence and early postemergence
control of annual grasses and broadleaf weeds. Registered in the U.S.
and France as a selective preemergent herbicide for control of annual
grasses and broadleaf weeds in turf and ornamentals (56).
APPLICATION METHOD(S): Aerial or ground applications preemergence and
shows some activity early postemergence (58).
Shows promise in rice, turf, orchards, peanuts, soybeans, and
ornamentals for control of grasses and broadleaf weeds such as:
Annual bluegrass Florida beggarweed Prickly sida
Barnyardgrass Carpetweed Prostrate knotweed
Crabgrass Cudweed Purslane
Fall panicum Dayflower Redmaids
Yellow, green, giant foxtail Ducksalad Smartweed
Goosegrass Filaree Sowthistle
Junglerice Groundsel Velvetleaf
Signalgrass Jimsonweed Morningglory
Sprangletop Lambsquarters Black nightshade
Texas panicum Mustards
Hophornbeam copperleaf Pigweed (58)
II. PHYSICAL PROPERTIES
MOLECULAR FORMULA: C15 H18 Cl2 N2 O3 (62)
MOLECULAR WEIGHT: 345.2 (62)
PHYSICAL STATE: Colorless crystals (pure compound) (62)
ODOR: Odorless (pure chemical) (58)
MELTING POINT: c. 90 C (pure compound) (62)
VAPOR PRESSURE: <133 uPa at 20 C (pure compound) (62)
SOLUBILITY: 0.7 mg/l water at 20 C (pure compound) (62)
III. HEALTH HAZARD INFORMATION
OSHA STANDARD: NA
NIOSH RECOMMENDED LIMIT: NA
ACGIH RECOMMENDED LIMIT: NA
A. ACUTE TOXICITY
DERMAL: LD50 = >8000 mg/kg, mild irritant (rat, technical);
8000 mg/kg, severe skin irritation (rabbit, Ronstar
2 lb/gal EC); >10,000 mg/kg, moderate skin
irritation (rabbit, Chipco Ronstar G) (58).
Oxadiazon has been shown to be nonirritating and
nonsensitizing when applied to normal intact skin
ORAL: LD50 = >8000 mg/kg (rat, mouse, technical); 2.31 ml/kg
(rat, Ronstar 2 lb/gal EC); >30,000 mg/kg (rat,
Chipco Ronstar G) (58).
INHALATION: LC50 = >200 mg/l (rat, technical); LD50 = >34
mg/l (Ronstar 2 lb/gal EC) (58).
EYES: Primary eye irritation: mild transient irritant
(technical); severe (Ronstar 2 lb/gal EC); severe
when not followed by a washout (Chipco Ronstar G)
B. SUBACUTE AND CHRONIC TOXICITY:
In feeding trials rats and dogs receiving 25 mg/kg daily were not
Subacute dermal LD50 (rabbit): >7000 mg/kg (58).
Two-year feeding studies in rats and dogs showed that the level of
no adverse effect is at least 100 ppm of the total dietary intake in
both species (58).
IV. ENVIRONMENTAL CONSIDERATIONS
The acute oral LD50 is: for bobwhite quail 6000 mg/kg; for
mallard duck 1000 mg/kg (62).
The LC50 in fresh water fish is >2 ppm for all species tested
It is strongly adsorbed by soil colloids (and humus) and very
little migration or leaching occurs.
Presents no danger for soil microorganisms at rates likely to be
applied in the field.
There is negligible loss of oxadiazon due to volatilization under
normal field conditions (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
KNOWN OR SUSPECTED ADVERSE EFFECTS: Irritating to skin and eyes (25).
SKIN CONTACT: Wash contaminated skin with soap and water (25).
INGESTION: Ingestions of small amounts (less than 10 mg/kg
body weight) occurring less than an hour before treatment, are probably
best treated by: Syrup of Ipecac, followed by 1-2 glasses of water.
Dose for adults and children over 12 years: 30 ml. Dose for children
under 12 years: 15 ml (25).
EYE CONTACT: Flush contaminated eyes with copious amounts of
fresh water for 15 minutes (25).
NOTES TO PHYSICIAN:
INGESTIONS of LARGE amounts (more than 10 mg/kg) occurring less than an
hour before treatment, should probably be treated by gastric lavage:
A. INTUBATE stomach and ASPIRATE contents.
B. LAVAGE stomach with slurry of ACTIVATED CHARCOAL IN 0.9% saline.
Leave 30-50 gm activated charcoal in the stomach before
C. SODIUM SULFATE, 0.25 gm/kg in tap water, as a cathartic.
CAUTION: Hydrocarbons (kerosene, petroleum distillates) are
included in some formulations of these chemicals.
Ingestion of very LARGE AMOUNTS may cause CNS
depression. In this case, IPECAC IS CONTRAINDICATED.
Also, gastric intubation incurs a risk of HYDROCARBON
PNEUMONITIS. For this reason observe the following
(1) If the victim is unconscious or obtunded and
facilities are at hand, insert an ENDOTRACHEAL TUBE
(cuffed, if available) prior to gastric intubation.
(2) Keep victim's HEAD BELOW LEVEL OF STOMACH during
intubation and lavage (Trendelenburg, or left
lateral decubitus, with head of table tipped
downward). Keep victim's head turned to the left.
(3) ASPIRATE PHARYNX as regularly as possible to remove
gagged or vomited stomach contents.
INGESTIONS occurring MORE THAN an HOUR before treatment are probably
best treated only by ACTIVATED CHARCOAL, 30-50 gm, and SODIUM or
MAGNESIUM SULFATE, 0.25 gm/kg, as described above.
There are no specific antidotes for these chemicals. Because
manifestations of toxicity do occasionally occur in peculiarly
predisposed individuals, MAINTAIN CONTACT with victim for at least 72
hours so that unexpected adverse effects can be treated promptly (25).
VI. FIRE AND EXPLOSION INFORMATION
Technical material is not flammable. For formulated
emulsifiable concentrate, use ordinary precautions for volatile
VIII. PROTECTIVE MEASURES
STORAGE AND HANDLING: Stable in excess of 2 years. Avoid contact with
skin and clothing (58).
IX. PROCEDURES FOR SPILLS AND LEAKS
IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
X. LITERATURE CITED
25. Morgan, D.P. 1982. Recognition and management of pesticide
poisonings, 3rd ed. U.S. Environmental Protection Agency,
Washington, DC. 120 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.