Milestone Receives a Supplemental Label for Off-Farm Distribution of Hay in Montana

Dr. Cecil Tharp, MSU Pesticide Education Specialist


close-up photo of Canada thistle, showing broad-leafs and flowers

Canada thistle (Cirsium arvense)

Milestone® (aminopyralid) is an effective chemistry that provides effective management of a wide array of broad-leaf weeds. A supplemental label is now available for use in Montana allowing off-farm distribution of grass harvested for hay.

It should be noted that many pesticide products can be introduced via manure, grass-clippings and compost to non-target sites. Most prevalent are the pyridine carboxylic acid (PCA) growth regulator herbicides. Many PCA active ingredients persist for long periods of time under anaerobic conditions (in manure, grass-clippings and compost). Those include pesticide products containing the active ingredients:

  • aminopyralid
  • clopyralid
  • picloram
  • aminocyclopyrachlor

Pesticide applicators should be cautious when using these highly persistent active ingredients by reading and following the entire pesticide product label!

Pesticide applicators desiring off-farm distribution of grass treated with Milestone® can use the supplemental label located at [expired link] in combination with the original pesticide product label.

Pesticide applicators using Milestone® should remember to:

  • not use grasses treated with Milestone® in the preceding 18-months for hay intended for export outside the United States.
  • not use hay or straw from areas treated with Milestone® within the preceding 18-months, or manure from animals feeding on hay treated with Milestone®, in compost.
  • not use grasses treated within the preceding 18-months for seed production.
  • not use manure from animals that have grazed forage or eaten hay harvested from aminopyralid- treated areas within the previous 3 days on pasture grasses, grasses grown for seed, and wheat.

Applicators must give homeowners, land managers or other clients a copy of the DOW Agro-Sciences stewardship instructions regarding uses of forage from areas treated with aminopyralid.  Printable version of the stewardship instructions can be found at [expired link].

With proper use, this supplemental label will economically benefit producers that use Milestone® for weed control while helping to deliver weed free grass hay to clients.

Further Information

Contact your county Extension agent or the MSU Pesticide Education Specialist (Cecil Tharp; 406-994-5067; [email protected]) for more information. Homeowners or applicators can also find directions on conducting their own soil bioassays, links on determining their pesticides environmental characteristics, as well as additional reference materials including the MSU MontGuide titled Minimizing Pesticide Contaminated Soil around the Home and Garden [expired link].

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