I want to offer someone the reasons that herbicides aren't a good idea.
What exactly does it kill?
What good creatures (worms, etc) can it hurt?
What does it do to ornamental grasses?
Would ground covers or invasive plants be treated as weeds?
This person is just outside the watershed area, so I can't seem to win with that argument.
Your thoughts are appreciated!
Christine

Thanks for the link. :)
Christine

# Soil Microorganisms: No information available.
# Plants: Trifluralin did not accumulate in crops grown in silt loam soil treated with 1 pound active ingredient per acre. Contact with susceptible non-target plants may injure these plants.
# Aquatic Animals:Trifluralin is highly toxic to cold- and warm-water fish and to aquatic invertebrate animals. It is very highly toxic to amphibians (tadpoles). It has not been tested for effects on estuarine and marine animals. It may build up (bioaccumulate) in fish exposed to trifluralin in water at low levels; but in one test it was eliminated from edible fish tissues 7 days after exposure ended. Trifluralin affected the survival of minnows at chronic exposures as low as 5.1 ppb; and affected the survival of water fleas at chronic exposures as low as 7.2 ppb.

Reported effects: Most incidents of trifluralin exposure reported in humans have involved dermal and eye irritation and nausea. Dizziness and headache, fever or chills, and muscle aches or weakness have also been reported.

Potential for adverse health effects from inert ingredients contained in the formulated product: Inert ingredients found in the emulsifiable concentrate (E.C.) of trifluralin include xylene, ethylbenzene and naphthalene. The effects of these compounds include: corneal (eye) damage, liver changes, fetotoxicity, and teratogenicity (xylene); blistering of skin, and liver, kidney and testicular changes (ethylbenzene); and cataracts and liver changes (naphthalene).

Health effects of exposure to formulated products: The Trifluralin E.C. formulation may cause skin and eye irritation. No specific effects of exposure to the granular formulation have been noted.

Health effects associated with contaminants: Trifluralin contains the contaminant N-nitroso-di-n-propylamine (NDPA). This contaminant is an N-nitrosamine class chemical; these chemicals have a known potential for causing cancer. However, the Environmental Protection Agency (EPA) requires that manufacturers of trifluralin certify that technical trifluralin products contain a total N-nitrosamine concentration of no greater than 0.5 ppm. The EPA concluded that the benefits of trifluralin outweighed the identified risks. They also conclude that exposure to NDPA in trifluralin is not of toxicological significance in evaluating the risk of exposure to trifluralin.

Here's a whole lot of information on Preen. I would have linked to it yesterday, but the site was down.

Alfie