January 2017


Understanding grazing tolerances when using herbicides

When applying herbicides on a utility right-of-way, roadside or other approved use site, it’s important to read and understand product labels. If not, the application can lead to unintended consequences, such as off-target crop damage. Furthermore, if a herbicide without established grazing tolerances is mistakenly applied to land used for grazing, or even land that is potentially susceptible to grazing, it can lead to the contamination of livestock or other animals.

GrazinginsetWhat are grazing tolerances?
Grazing tolerances are established for a pesticide by the U.S. Environmental Protection Agency (EPA). They are only established for products that have undergone stringent testing for use of the pesticide on grass, hay or other feedstock for livestock animals such as cattle, horses, sheep and goats. Only herbicides with grazing tolerances should be used to treat unwanted vegetation in grazed areas.

Products with grazing tolerances may have certain grazing restrictions, which are listed on the product label. The restrictions include any special instructions (such as maximum allowable use rates, how to handle hay or manure, or use for lactating dairy animals) pertaining to applying the herbicide within grazed areas.

Why are grazing tolerances important?
When treating an area such as a right-of-way that crosses a pasture, even though the herbicide may be registered for use on rights-ofway, the EPA still requires a tolerance or exemption from tolerance for any food or feed commodity, including meat, milk, grass or hay.

This means that unless it can be assured that no animals graze the treated area, a herbicide product without a grazing tolerance cannot be used in that area. It also means that responsible vegetation managers should not use products without grazing tolerances if the land they are treating may be grazed, as they could be cited for misapplication of a herbicide.

What is the difference between a herbicide with grazing tolerances and one with grazing restrictions on its label?
In short, a herbicide with grazing tolerances means it has undergone extensive testing and received EPA approval for use to treat vegetation in areas grazed by livestock. If tolerances exist, then the label will have instructions for how to use the herbicide and comply with the established grazing tolerance.

A herbicide that contains grazing restrictions on its label means that the product can be used to treat vegetation in grazed areas, but there are certain restrictions that should be followed. These restrictions could apply to use rates, application methods or how to handle hay, manure or the movement of livestock in and out of the treated areas. If the listed restrictions are not followed, it could be a violation of the label and cause any animal that grazes the treated vegetation to be unacceptable for slaughter and human consumption.

Grazinginset1Does using herbicides without grazing tolerances increase your liability when applying near grazed areas?
When using herbicides with no grazing tolerances on a right-of-way, treatment cannot continue when pastures or other land susceptible to grazing animals is encountered. If treating grazed areas with a herbicide that does not have grazing tolerances, it is a violation of the label and subject to state and federal regulatory action. When a pasture in a right-of-way has been treated, the area is subject to the grazing restrictions, if any, on the product label.

Having grazing tolerances is similar to using herbicides registered for both aquatic and terrestrial use when making an application. When a herbicide has both aquatic and terrestrial labeling, vegetation managers and applicators are able to treat entire rights-of-way, even when encountering creeks, streams and wetlands, instead of having to switch from a terrestrial herbicide to an aquatic herbicide. It is similar for vegetation managers and applicators using a herbicide with grazing tolerances. They are able to treat the entire right-of-way without having to switch herbicides or herbicide mixtures, even when the right-of-way contains both nongrazing and grazing areas.

What happens if cattle eat grass treated with herbicides without established grazing tolerances?
The short answer is that these animals cannot be sold or slaughtered for human consumption. This means cows, horses, goats, sheep or any animal that may graze and ingest treated grass. So, even if an animal escapes from a fenced-in pasture and grazes an area treated with a herbicide without a grazing tolerance, that animal is considered adulterated and cannot be sold for food. This is potentially devastating to ranchers and farmers who make a living selling livestock.

What products does Dow AgroSciences offer with established grazing tolerances?
Dow AgroSciences offers a full portfolio of products with grazing tolerances, all developed with the end user in mind. Dow AgroSciences’ latest commitment to vegetation managers are Milestone®, Vastlan™, Capstone® and Opensight® specialty herbicides. These products provide vegetation managers with the ultimate flexibility and convenience when making treatments. Some other popular Dow AgroSciences herbicides with established grazing tolerances include Rodeo®, Spike® 80DF, Garlon® 3A, Garlon 4 Ultra and Transline®. Even with these established tolerances, some restrictions or precautions exist on certain products. Read each product label carefully for more information.