Trifluralin

Lead Editor

Overview


Trifluralin is a pre-emergent herbicide belonging to the dinitroaniline chemical family. It was registered with the EPA in 1963 (#EPA). It is used to control annual grasses and broadleaf weeds (#EXTOXNET). Trifluralin is registered for use on a very wide range of food crops, and is used very extensively on soybean and cotton crops. It may also be used to protect residential ornamental plants.

Trifluralin may be marketed under names such as Treflan, L-36352, Crisalin, Su Seguro Carpidor, Trefanocide, Treficon, TR-10, Triflurex, Trim, Ipersan, Sinflouran, and Ipifluor (#EPA).

Chemical Description


Trifluralin is a yellow-orange crystal. It is odorless. Trifluralin has a low solubility in water, and forms strong bonds with soil (#EXTOXNET). It has a half-life in soil of 116 to 201 days (#EPA).

Trifluralin is commercially available as an emulsifiable concentrate, liquid, or granular formulation. The technical-grade solid can also be purchased (#EPA).

Uses


Trifluralin is usually used as a spray or a soil treatment in the pre-emergent control of weeds (#EPA).

Trifluralin is registered for use on an immense number of food crops, most notably broccoli, cabbage, onions, a number of leafy green vegetables, beans, tomatoes, potatoes, wheat, soybeans, sugar beet, and sugar cane. Registrations on some other food crops stipulate that the plant must not be bearing fruit at the time of application. Trifluralin may also be used to treat a number of animal feed crops, such as corn and wheat. It is also used to treat cotton crops (#EPA).

Both residentially and commercially, trifluralin is used to protect ornamental plants, such as trees, herbaceous plants, woody shrubs, and vines. It may be used on golf courses and recreational lawns (#EPA).

Approximately 25 millions pounds of trifluralin are used on agricultural crops annually. Of that, 19% is used on cotton, and 64% is used on soybean alone. 150,000 pounds are used annually on ornamental plants, and there is very little reported use on turf (#EPA).

Trifluralin has a wide range of targeted pests: annual bluegrass, bottlegrass, bristlegrass, bromegrass, broncograss, burgrass, carelessweed, carpetweed, cheat, chess, chickweed, Coloradograss, crabgrass,  cupgrass, field morningglory, Florida pusley, German millet, giant foxtail, goathead, goosefoot, guineagrass, hairy crabgrass, henbit, johnsongrass, jointed goatgrass, junglerice, knotweed, lambsquarters, lovegrass, Mexican fireweed, nettle, panicum, pigeongrass, pigweed, pusley, red rice, rough pigweed, Russian thistle, silver crabgrass, small crabgrass, spiny pigweed, sprangletop, spreading pigweed, stinging nettle, watergrass, wild barley, wild oat, wiregrass, and woolly cupgrass (#EPA).

Human Health Effects


In acute exposures, trifluralin is practically nontoxic to mammals. The oral LD50 was over 10,000 mg/kg for rats, over 5,000 mg/kg in mice, and over 2,000 mg/kg in dogs and rabbits (#EXTOXNET). Trifluralin is absorbed very slowly through the skin. Only 1% of a dose applied dermally is absorbed (#EPA).

A study in which dogs were fed trifluralin for one year found reduced body weight, decreased red blood cells, increased liver weight, and increased triglyceride and cholesterol levels. Two-year studies on rats found an increase in urinary bladder tumors in females, and an increase in renal pelvis carcinomas and thyroid gland tumors males (#EPA). The EPA has classified trifluralin as a possible carcinogen, and the Illinois EPA has listed trifluralin as a probable endocrine disruptor (PANNA).

Ingestion of trifluralin may cause nausea and severe discomfort. Inhalation may irritate the lining of the mouth, nose, and throat (#EXTOXNET). Exposing the eyes may cause redness and pain (#PANNA).

Environmental Health Effects


Trifluralin is a meristematic inhibitor. It is absorbed into developing plant roots where it disrupts plant cell growth and division (#EPA). Trifluralin usually does not translocate to other parts of the plant other than the roots (#EXTOXNET). Trifluralin may adversely affect the growth of some plants it is intended to protect. It was found to inhibit onion and cabbage germination in lab tests (#EPA).

Trifluralin is practically nontoxic to birds in acute exposures. The LD50 exceeds 2000 mg/kg in both mallard duck and Northern bobwhite.

Trifluralin has a very high toxicity to fish. The acute LC50 is 41 ppb in rainbow trout, 58 ppb in bluegill sunfish, and 75 ppb in largemouth bass. It is also highly toxic to other aquatic organisms (#EPA).

Trifluralin is environmentally persistent, but has a low mobility due to its high affinity for soils and low solubility (#EXTOXNET).

Regulation


Trifluralin is registered as a General Use Pesticide. Products with trifluralin may be purchased for residential use.

Precautionary Notes


Do not heat or burn trifluralin, as this will release toxic and corrosive gasses (#NIOSH). Exercise caution near sources of water. Although it is insoluble, trifluralin is highly toxic to aquatic organisms, and it is not known whether trifluralin can bioaccumulate in fish.

References



Environmental Protection Agency. Reregistraion Eligibility Decision: Trifluralin. (April 1996). http://www.epa.gov/oppsrrd1/REDs/0179.pdf [Accessed 8-26-10].


Extension Toxicology Network. Trifluralin. (1996). http://extoxnet.orst.edu/pips/triflura.htm [Accessed 8-26-10].


National Institute for Occupational Safety and Health. Trifluralin. http://www.cdc.gov/niosh/ipcsneng/neng0205.html [Accessed 8-26-10].


Pesticide Action Network North America. Trifluralin. http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC35146 [Accessed 8-26-10].
 

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