August 2014

Q&A on grazing tolerances with 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.

To address this subject in this issue of Vistas™, we caught up with IVM specialists Travis Rogers and Scott Wright to talk about the importance of understanding grazing restrictions and grazing tolerances, the impact of off-label applications, and much more. Rogers has been with Dow AgroSciences for 17 years, 8 as a VM specialist, and is currently an IVM market development specialist, where he works closely with the company’s field biology group. Wright was with Mississippi State as a research associate with a focus on roadside weed control prior to joining Dow AgroSciences in 2011 as an IVM specialist.

Vistas: What are grazing tolerances?
Rogers: 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, manure, or use for lactating dairy animals) pertaining to applying the herbicide within grazed areas.

Vistas: Why are grazing tolerances important?
Wright: 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-of-way, the U.S. 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.

Vistas: What is the difference between a herbicide with grazing tolerances and one with grazing restrictions on its label?
Rogers: 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 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 which 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.

Vistas: Does using herbicides without grazing tolerances increase your liability when applying near grazed areas?
Wright: 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 rights-of-way without having to switch herbicides or herbicide mixtures, even when the right-of-way contains both non-grazing and grazing areas.

Vistas: What is the definition of grazed areas?
Rogers: The definition of grazed areas is somewhat broad. It mainly refers to pasture or rangeland set aside for grazing cattle or other livestock. Since right-of-ways often cross these areas vegetation managers are charged with managing these sites. When managing vegetation in these areas it is important and more efficient if the products used are labeled for every type of site on the right-of-way.

Vistas: What happens if cattle eat grass treated with herbicides without established grazing tolerances?
Wright: 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.

Vistas: How does Dow AgroSciences develop products that provide broad options for use?
Rogers: When working with herbicides, vegetation managers appreciate working with broad, flexible labeling, which helps minimize potential issues with both regulatory agencies and the discerning public. It’s also fundamental that users understand and follow product labels; for instance, understanding the difference between herbicides with and without grazing tolerances.

Dow AgroSciences invests significantly in developing products with the industry’s most flexible labeling, including grazing tolerances. The company also strives to provide easy-to-understand product labels to help minimize user error. Using these products as per label instructions minimizes applicator liability and provides peace of mind. Furthermore, the nationwide team of vegetation management specialists and field scientists from Dow AgroSciences provides unparalleled customer support to help promote good stewardship when using Dow AgroSciences herbicides.

Vistas: What products does Dow AgroSciences offer with established grazing tolerances ?
Wright: 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®, 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 Accord® XRT II, Garlon® 3A, Garlon® 4 Ultra, Rodeo®, Spike® 80DF, Tordon® K, Tordon 101M, Transline® and Vista® XRT specialty herbicides, as well as DMA® 4 IVM herbicide. Even with these established tolerances, some restrictions or precautions exist on certain products. Read each product label carefully for more information.