What Are the Dangers of Grazon Herbicide?

Grazon herbicide is a restricted-use herbicide produced by Dow AgroSciences. This chemical is used to control herbaceous weeds and some woody plants, without killing desirable lawn and turf grasses. It may be applied as a one-pass spray or applied in combination with liquid fertilizer, and it may be mixed with other herbicides to control a wide range of weeds. Like most other chemical herbicides, Grazon must be used according to package instructions and does carry some risks.

Grazon herbicide is designed to kill weeds but leave grass intact.

Personal Safety

According to NuTurf Australia, Grazon is a hazardous chemical that acts as a skin, eye and respiratory irritant. It can cause damage to the lungs if swallowed and may cause pain and irritation on skin contact. Users can minimize the dangers of applying Grazon herbicide by washing their hands immediately after using it and wearing protective clothing, such as goggles and gloves. Respirators may be required in some circumstances, since Grazon spray or vapor is dangerous to the lungs and respiratory tract.


As an herbicide, Grazon is toxic to many plants and may damage native species. Pesticide drift may kill non-target species. Grazon also acts as a water contaminant and should not be applied to bodies of water, in wet areas with visible surface water or in areas below the high tide mark. Spray and runoff must be kept clear of wells, irrigation ditches and irrigation ponds. In some cases, Grazon may leach through soil into ground water. This is particularly likely in areas where the water table is shallow and the soil is permeable.

Animal Transmission

Lactating dairy cows should not graze in areas that have been treated with Grazon for at least a week after application, and meat animals should not graze in these areas for at least three days before slaughter. Areas treated with Grazon must not be harvested for hay within a month of application. If animals have grazed on treated pasture, they should graze on untreated areas for at least one week before being moved to areas with broadleaf crops, as their urine can kill sensitive plants. Manure from animals that have grazed on Grazon-treated areas is not suitable for compost.

Physical Hazards

Grazon is a flammable material and should not be stored near heat or open flame. This pesticide vaporizes and combusts at 180 degrees Fahrenheit. If a fire occurs, this material may produce cyanide compounds, hydrogen chloride and oxides of carbon and sulfur. Burning Grazon herbicide can be extinguished using foam, CO2, dry chemical and water fog fire extinguishers. This herbicide must be stored in a tightly closed container away from direct sunlight and away from fertilizer, animal feed or human food.

G.D. Palmer

G.D. Palmer is a freelance writer and illustrator living in Milwaukee, Wis. She has been producing print and Web content for various organizations since 1998 and has been freelancing full-time since 2007. Palmer holds a Bachelor of Arts degree in writing and studio art from Beloit College in Beloit, Wis.