The label is the law. Rates and restrictions below are taken from the product labels listed under Sources. Your product's own label governs; read it before you mix or apply. Mixing calculator · Disclaimer
- Active ingredient
- Aminopyralid (CAS 150114-71-9)
- Chemical class
- Pyridine carboxylic acid; WSSA Group 4 synthetic auxin. Milestone contains it as the triisopropanolammonium salt.[2][1]
- Mode of action
- WSSA Group 4: Synthetic auxins (pyridine carboxylic acids)[2][1]
- Signal word
- Milestone Specialty Herbicide (alternate brand name Ironside): Caution[1]
Hay, straw, manure and compost
Don't use grass, hay, straw, wood or other plant residues from areas treated within the preceding 18 months in compost, mulch, wood chips or mushroom spawn. Hay from those areas can't leave the farm or ranch where it was cut unless supplemental labeling allows.[1]
Manure from animals that ate treated forage or hay within the previous 3 days can't go into compost, mulch or mushroom spawn. It may be spread only on pasture, grass grown for seed, wheat or corn, never on land for susceptible broadleaf crops.[1]
Don't plant a broadleaf crop such as vegetables, beans, potatoes or sunflowers where aminopyralid or that manure was used until a sensitive field bioassay shows the soil is safe. Residues break down faster in warm, moist soil.[1]
Not a lawn or garden product
The label bars use on lawns, turf, ornamental plantings, walkways, driveways, golf courses, athletic fields and other fine turfgrass areas. Rotating to any crop takes at least a year, and canola, flax or alfalfa can need 2 to 3 years.[1]
Where it is used
Avoid mowing, haying, shredding, burning or disturbing the soil for at least 14 days after spraying so the herbicide can move through the weeds. Wait 14 days to cut grass hay.[1]
Keep spray drift off any broadleaf crop, flowers, vegetables, fruit trees and ornamentals; very small amounts can seriously injure them. Use special caution near roses and legume trees such as locust, redbud and mimosa.[1]
Don't spray within the root zone of desirable trees, since roots can take it up. Don't treat frozen soil where runoff could reach sensitive plants.[1]
Livestock need 3 days on untreated pasture or hay before moving to areas with sensitive broadleaf crops, or their urine and manure may carry enough aminopyralid to injure those plants.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Milestone Specialty Herbicide (alternate brand name Ironside)[1] | Corteva Agriscience, LLC | 62719-519 | 40.6% | liquid concentrate (2 lb aminopyralid acid equivalent per gallon) | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Milestone Specialty Herbicide (alternate brand name Ironside) | Rangeland, permanent grass pastures, CRP acres, non-crop areas and natural areas | Canada, bull, musk and plumeless thistles, spotted and diffuse knapweed, yellow starthistle and other listed broadleaf weeds and woody plants | 3–7 fl oz product per acre[1] Rates vary by weed, for example 3 to 5 fl oz for musk and bull thistle and 5 to 7 fl oz for Canada thistle and knapweeds. Broadcast, spot and repeat applications together may not exceed 7 fl oz per acre per year. |
Safety and environmental hazards
People
Signal word CAUTION: causes moderate eye irritation. Applicators wear long sleeves, long pants, shoes and socks.[1]
Pets
The hazard statement for humans and domestic animals is moderate eye irritation. On pastures, rangeland and non-cropland, the label says not to enter treated areas until sprays have dried.[1]
Bees and pollinators
The label has no bee or pollinator statement; its non-target warnings center on broadleaf crops, flowers, ornamentals and trees.[1]
Fish and water
Don't apply directly to water. Aminopyralid shares traits with chemicals found in groundwater, and spraying around a cistern or well may contaminate drinking water.[1]
Common questions
- Can I compost hay or manure from a field sprayed with Milestone?
- No. The label forbids using plant residues from areas treated in the preceding 18 months, or manure from animals that ate treated forage within 3 days, in compost, mulch or mushroom spawn.[1]
- Is aminopyralid safe to use on my lawn?
- Milestone's label says not to apply it to lawns, turf, ornamental plantings or other high-maintenance fine turfgrass areas.[1]
- Can livestock graze after Milestone is sprayed?
- The label sets no grazing or grass hay restrictions at labeled rates, but animals need 3 days on untreated feed before moving near sensitive broadleaf crops.[1]
Sources
- U.S. EPA Pesticide Product Label System, “Milestone Specialty Herbicide label, EPA Reg. No. 62719-519 (EPA-stamped, Feb. 4, 2021).” www3.epa.gov/pesticides/chem_search/ppls/062719-00519-20210204.pdf (accessed 2026-10-06)
- Weed Science Society of America, “Summary of Herbicide Mechanism of Action According to the Weed Science Society of America.” wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf (accessed 2026-10-06)