Gardeners and Allotment Holders

Growing your own vegetables is a satisfying and healthy pursuit. Your concerns about herbicide residues in the manure you use to fertilize your gardens also concern us. 

In addition to our own testing, the Pesticides Safety Directorate (PSD) has conducted safety testing on aminopyralid.

Here are some facts, in answer to questions by gardeners and allotment holders.

What is aminopyralid?

Aminopyralid is the active ingredient in herbicides such as Forefront, Pharaoh, and Banish. They are used by farmers for effective control of deep-rooted perennial weeds in grassland, including docks, thistles, nettles, and ragwort.

Ragwort control is especially important to equine, sheep, and cattle farmers, as it can be deadly if eaten by their livestock.

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 conserved feed such as hay or silage, a small amount passes out with the resulting manure.

Aminopyralid poses no health risk to any animal that eats treated grass, but there is enough active ingredient in the manure to cause a problem for plants that are sensitive to it, such as potatoes and legumes.

You can test manure (see instructions on right) for aminopyralid residue. If you believe you have manure containing aminopyralid, please contact us.

Is aminopyralid harmful to me?

No. Studies conducted by the PSD concluded that the levels of aminopyralid found in crops will not have any implications for human health, including the health of pregnant women and their babies.

However, the fruits of sensitive plants that have been affected by aminopyralid residues might not have the quality you'll want for serving at your table.

It is best to dispose of affected plants by incorporating them into the soil or via approved waste disposal methods.

Will all my plants be affected?

No. Vegetables and ornamentals such as the following are susceptible to aminopyralid residues:

  • 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 crops, but only some of them are affected, it is unlikely that aminopyralid is to blame for the damaged crops.

Why is aminopyralid in the manure I use?

The short answer is that they shouldn't be. Product labeling contains warnings and instructions about the use of aminopyralid. If carefully followed, these instructions should prevent residues from ever reaching your garden.

We are aware that there have been some instances of animal manure generated from pasture or forage previously treated with aminopyralid-containing herbicides being supplied to gardeners or allotment growers. We are working as a company and in collaboration with other organisations to promote awareness of the stewardship and use of this product.

When is affected manure ok to use?

Aminopyralid decomposes with the help of microorganisms found in soil. Manure that has been well-rotovated into the soil and turned over regularly is safe to use on all but the most sensitive plants after 6 months. Properly incorporated manure is considered aminopyralid free after one year.

Composting after you harvest in the fall should allow enough time for any aminopyralid present in the manure to break down, as long as you keep the soil well-rotovated or turned over frequently. However, you might wish to use suspect manure only in those areas of the garden or plot that will not be used for growing susceptible plants.

Where can I get more information?

Link to the following sites for more information about the effects of aminopyralid:

Royal Horticultural Society:

http://www.rhs.org.uk/advice/profiles0708/Weedkiller-manure.asp

Local Council Directory (for manure disposal):

http://www.direct.gov.uk/en/Dl1/Directories/Localcouncils/index.htm

Pesticides Safety Directorate:

http://www.pesticides.gov.uk/garden.asp?id=2480

Department for Environment, Food, and Rural Affairs:

http://www.defra.gov.uk/farm/wildlife/weeds/index.htm

What Can I Do?

Ask your manure supplier

Ask your manure or compost supplier if their material came from a farm or equine business where Forefront, Pharaoh, or Banish were used. Request herbicide-free manure, where available.

Test manure before using it at home

  1. Thoroughly mix 1 part manure with 1 part multi-purpose compost in a clean bucket. Prepare enough to fill four 5-inch pots.
  2. Fill another four clean pots solely with multi-purpose compost. These will be the untreated comparisons.
  3. Place each of the pots in a separate saucer to prevent water from on pot reaching another.
  4. Water the pots and leave to stand for 24 hours.
  5. Plant each pot with four broad bean seeds.
  6. Observe subsequent growth for four-week period and note any ill effects in the pots containing the manure mix, such as cupped leaves and fernlike growth on new shoots.

These symptoms may indicate aminopyralid residue in the manure. Signs of other kinds of damage will most likely indicate other issues such as damping off or bacteria-infected soil, etc.

Or send a sample to a laboratory...

You can have manure samples analysed for the presence of aminopyralid. The Central Science Laboratory (CSL) will provide this service at approximately 200 per sample. Contact them at era@csl.gov.uk

Use affected manure wisely

  • Incorporate suspect manure into areas of your garden where sensitive plants will not be grown.
  • Mix affected manure into the soil in the autumn to give any aminopyralid time to break down before sowing and planting.
  • Rotovate the ground well (and frequently) to aerate the soil, which will speed aminopyralid breakdown.
Or
  • Return affected manure to the manufacturer or dispose of it with your household refuse, NOT your green refuse. (Ask your local council if they allow this in your area.)

Contact us

If you have further questions, email us at UKHotline@dow.com.