Horse Owners and Equestrian Businesses

In the past year, we have received a number of enquiries from gardeners and allotment holders in the UK who may have used manure containing aminopyralid residues as a fertiliser and have requested further information about the potential for such herbicide residues to damage certain sensitive crops.

The manure possibly came from farm animals or horses that had eaten pasture or conserved forage from grassland treated with a herbicide containing aminopyralid as the active ingredient.

Here are some facts about aminopyralid for horse owners and those in charge of equestrian enterprises, such as livery yards, racing stables and riding schools.

What is aminopyralid?

Aminopyralid is the active ingredient in herbicides such as Forefront*, Pharaoh*, and Banish*. These herbicides are among the most effective for controlling and eliminating many deep-rooted perennial weeds found in grassland, including docks, thistles, nettles, and ragwort.

Ragwort control is especially important, as it can be deadly if eaten by horses.

When grassland is sprayed with aminopyralid, it kills the target weeds but does not affect the grass. However, when this grass is eaten by horses, either out in the field or as conserved feed such as hay or haylage, a small amount of aminopyralid may pass out with the resulting manure.

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

Is aminopyralid harmful to my horse?

No, but you must follow all labelling and safety literature, including:

  • Keep livestock out of treated areas for at least seven days after spraying.
  • Where you have been spraying for ragwort, keep animals off the pasture until the weeds have died and become unpalatable or have been removed.

How long does it take for aminopyralid to break down?

Aminopyralid decomposes with the help of micro-organisms found in soil.  Residues in manure break down if rotovated into the soil and turned over regularly.

For people with concerns, we recommend the testing method (see Testing Manure in adjacent column).

What should I do with affected stable waste?

Do not sell on.  Affected manure must not be given or sold on to gardeners or allotment holders as it may affect any sensitive crops that they subsequently grow in the soil it has been incorporated into.  Best practice is to ensure that it gets spread on grassland or land destined for grass, cereals or maize.

If in any doubt please contact us by e-mail on

Where can I get more information?

Link to the following sites for more information about aminopyralid:

Dow AgroSciences Forefront leaflet:

Grassland Management, Dow AgroSciences:

Department for Environment, Food, and Rural Affairs:

* Trademark of Dow AgroSciences LLC


Be informed

Ask your hay or forage supplier if their product came from a farm or grassland where herbicide products Forefront, Pharaoh, or Banish were used. If you are aware, you can take the necessary precautions to prevent affected manure from reaching gardens and allotments.

Testing manure

  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 one 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 a 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.

Follow all safety instructions when spraying grassland

Keep horses and pets safe

  • Keep pets off sprayed areas until dry.
  • Do not allow horses to graze on sprayed pasture for at least seven days or until the weeds (especially ragwort) have died and are unpalatable or have been removed.

Avoid the impact of aminopyralid

If you have bought in hay or haylage or have sprayed your paddocks with aminopyralid, the resulting manure should be:

  • Spread onto pastures or grassland only
  • Supplied to farmers for use on grassland or other land intended for grass, cereal crops, or maize
  • Fully rotovated into soil where sensitive plants such as potatoes, peas, and beans will NOT be grown

Contact us

If you have further questions, email us at