Notice to County Road Ditch Hay Users:


Lyon County applied the Dow AgroSciences herbicide Milestone to all county right-of-way in the fall of 2017 as a weed control measure.  There are certain label restrictions for use of Milestone-treated grass hay, specifically concerning manure spread on alfalfa or land to be planted with soybeans.  Please contact the Lyon County Highway Department or an agronomy professional for questions regarding label restrictions of this application. 


Dean Berg

Maintenance Superintendent



Aaron VanMoer

County Engineer




Additional Information


The soil residual activity of Milestone herbicide is what provides more than a few days’ worth of weed control. By contrast, 2,4-D controls some weeds that have emerged, but 2,4-D does little to control weed seedlings that emerge days later.


In the soil

The active ingredient aminopyralid in Milestone both broadens the spectrum of control and provides soil residual activity to control susceptible weeds that germinate for several weeks after spraying.

Over the season, the active ingredient breaks down and its soil residual activity dissipates. But enough may remain for the next two to three years to damage extremely sensitive crops if Milestone ends up in cropland.  Don’t plant a broadleaf crop until an adequately sensitive field bioassay shows the crop won’t be affected, Dow AgroSciences recommends.


In the plant

While the herbicide is still active in the soil, grasses may absorb and store the active ingredient, so it may be present in hay harvested from treated grass for up to 18 months after treatment. Treated grass hay should never be used, sold or given away for mulch or compost. Enough aminopyralid could leach from the hay to damage sensitive broadleaf plants. Likewise, don’t feed treated hay on land to be planted to sensitive crops.


Through the animal

When a grazing animal ingests treated grass or grass hay carrying aminopyralid residue, the residue passes through without harm to the animal. But the active ingredient may be present in the manure or urine for three days after consuming the treated forage. For that reason, manure from animals that have consumed grass or hay treated with aminopyralid should be used only on permanent grass

pasture. Don’t spread it on cropland or provide it to others for gardening purposes. Spread the manure on permanent pastures only.

Hours and Locations

Lyon County Government Center

8:00-4:30 M-F   Map

Public Works Building

8:00-4:30 M-F   Map

Law Enforcement Center

8:00-4:00 M-F   Map

Lyon County Zoning/SWCD

8:00-4:30 M-F   Map

Lyon County Landfill

6:00-4:00 M-F   Map


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Highway Engineer

Aaron VanMoer
Highway Engineer
504 Fairgrounds Rd
Marshall, MN 56258
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