Information for Gardeners

Growing your own vegetables is a satisfying and healthy pursuit.  Your questions or concerns about possible herbicide residues in the manure you use to fertilize your gardens are important to Dow AgroSciences.

Here is some information, in answer to questions by gardeners.  You will also find more questions and answers here.

What is aminopyralid?

Aminopyralid is the active ingredient in several herbicides under the brand names Milestone®, Milestone VM, Milestone VM Plus, ForeFront® R&P, Chaparral, GrazonNext, Opensight and CleanWave. Based on registration and label directions, they are used by farmers, ranchers and vegetation managers for effective control of deep-rooted perennial weeds in grassland, including thistle, ragweed, knapweed, starthistle and some woody species.

When grassland is sprayed with aminopyralid, the target weeds are killed but the grass is not affected. However, when this grass is eaten by animals, either out in the field or as hay or silage, a small amount of aminopyralid may be in the resulting manure.

Aminopyralid poses no health risk to any animal that eats treated grass, but there may be enough active ingredient in the manure to cause growth and leaf damage to sensitive plants, such as potatoes and beans, if the aminopyralid in the manure comes into contact with these sensitive plants.

Is aminopyralid harmful to me?

No. Aminopyralid has an excellent environmental profile, and the U.S. Environmental Protection Agency, along with regulatory agencies in other countries, has determined it does not pose an unreasonable risk to human or animal health when used in accordance with label directions. In fact, aminopyralid was reviewed and registered by the U.S. EPA under the Agency’s Reduced Risk Pesticide Initiative.

Will all my plants be affected?

No. Only certain vegetables and ornamentals are sensitive to aminopyralid residues. They include the following:

  • Potatoes
  • Peas, beans and other legumes
  • Carrots and other umbelliferae
  • Tomatoes
  • Lettuce, spinach and other compositae
  • Dahlias
  • Some species of roses

If you have planted any of these susceptible plants, but only some of them are affected, then it is unlikely that aminopyralid is the reason for the plant damage.

Why is aminopyralid in the manure I use?

The short answer is that it shouldn’t be in the manure. Product labeling contains warnings and instructions about the use of aminopyralid-containing herbicide products. If followed, these instructions should prevent residues from ever reaching your garden. As with all herbicides, applicators should always read and follow the label instructions.

We are aware that there could be some instances of animal manure being supplied to gardeners that was generated by animals that grazed in pastures treated with an aminopyralid herbicide. We are working to promote awareness of the stewardship and proper labeled use of aminopyralid products.

How long does it take for aminopyralid to break down?

Aminopyralid decomposes with the help of microorganisms found in soil over the growing season and in many cases dissipates by the following year. Residues in manure alone break down slowly, but may break down faster if incorporated into soil and rototilled or turned over regularly. A bioassay test can be used to determine if it is OK to plant sensitive plants in your garden.

What Can I Do?

  1. Ask your manure or compost supplier if their manure came from a farm or equine business where aminopyralid-containing products were used.
  2. Return affected manure to your source or supply it to a local farmer for use on rangeland, permanent grass pastures, wheat fields or fields where grass is grown for seed.
  3. Request herbicide-free manure, or certified organic manure or compost.
  4. Test your manure, compost or garden soils before planting using this recommended method.

Contact Dow AgroSciences

If you believe you have manure that has been affected or you have additional questions, please call the Dow AgroSciences Customer Information Group at 1-800-992-5994 and select Option 4; or email info@dow.com.