FAQ

manure

Frequently Asked Questions

In response to concerns about the use of aminopyralid, we have compiled some questions to help you find the answers you are looking for. 

If these products cause problems, why are they used by farmers?

For grassland farmers, these products offer the most effective weed control on the market today. Aminopyralid sprays work especially well on difficult to control weeds, such as thistles and docks as well as weeds that are potentially dangerous to livestock, such as ragwort.

These sprays deliver a level of control that frequently removes the need for follow-up treatment, so less herbicide is used overall. Forefront T, which contains aminopyralid, can only be used on grassland that is grazed by sheep and cattle only, and the manure produced by these animals must stay on the field. It is not to be used where horses graze. It is not to be used on grass intended for hay or silage. 

If herbicide users follow the clearly stated recommendations on the label printed on each pack, there is very little chance that they will be found in manure in your garden.

Is food from affected crops safe to eat?

Yes. In their review, CRD (previously PSD) indicate that the levels of residues found in affected crops do not have any implications for human health.

“Although aminopyralid is an effective weedkiller it is of low toxicity to mammals. Additionally the Chemicals Regulation Directorate (CRD) has assessed further information from the manufacturer that confirmed that using manure which may contain residues of aminopyralid in the ground used to grow vegetables does not have implications for human or animal health.

Even if the manure was derived from animals fed only grass, or silage made from grass treated with aminopyralid, and the plants took up all the aminopyralid present in that manure, the highest residues would not give rise to consumer health concerns and the vegetables should be safe to eat."

Which plants are affected by the presence of aminopyralid residues?

Sensitive plants include peas, beans and other legumes, carrots,  potatoes, tomatoes, lettuces and spinach. Dahlia corms and a few species of rose are also affected.

What are the symptoms of aminopyralid damage on sensitive plants?

Symptoms are expressed as cupping of leaves, stunting of plants, and curling of the growing point, giving it a fern-like appearance. See examples.

Can other factors cause these or similar symptoms?

Yes, there are a number of other factors that may cause plant injury such as damping off, or insect or disease damage, trace elements and nutrient deficiency caused by weather conditions, soil and / or compost interactions, and you should check for these. You should also check the compost is appropriate for the intended use (i.e. mulch, potting compost, soil enrichment), follow compost recommendations regarding digging in and use rate.

Similar symptoms may also be observed if the compost or soil enricher contains an amount of green waste based upon grass clippings which have previously been treated with lawn care products.

Some vegetables have been affected, others have not?

If peas, beans, or potatoes (the most sensitive crops) are not affected, it is unlikely that aminopyralid is to blame.

Will my plants be OK next year if I plant them in an affected allotment?

Assuming that any affected manure or compost is worked in to the soil, and the ground is turned over, well cultivated and moist to ensure the breakdown of plant material in the manure/compost, then the ground will be safe to grow dahlia corms or vegetables the following year. If practicing a no-dig garden approach, then rake off and remove any residual manure or compost in the year prior to planting.

How can I test for aminopyralid residue in my manure?

The simplest and quickest option is to ask your manure supplier the following questions:

  • Did their animal manure come from a farm or equine business where the herbicide product Forefront T was used? If the answer is no, then the animal manure should be free of aminopyralid .
  • Were the animals that produced the manure fed on forage e.g. Hay, haylage or silage that could have been inadvertently been produced from grass treated with Forefront T? If the answer is no, then the animal manure should be free of aminopyralid.

Another option is to test the manure / compost  using a sensitive crop:

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

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.

How is aminopyralid broken down?

Aminopyralid is broken down by soil micro-organisms, which live in damp, well-aerated soil. These conditions are best achieved by maintaining good soil conditions, and thoroughly incorporating the manure or compost into the soil. In dry soil conditions, breakdown may take longer, and you may need to consider watering.

I believe I used manure containing aminopyralid in my allotment this year.

Contact our technical hotline UKHotline@corteva.com for further advice.

Where it is possible to dig the soil, the best way to reduce the likelihood of a problem next season is to keep the land turned over to aerate the soil which encourages breakdown of the cellulose material in manure. As it breaks down aminopyralid is released into the soil and then broken down rapidly by naturally occurring micro-organisms.

Alternatively, around perennial plants such as roses and dhalias, rake away any visible signs of manure or mulch, then keep the soil around the plant in good condition to encourage microbial activity.

I used manure containing aminopyralid this year – what can I grow?

Dig in the compost or manure as much as possible, and maintain good soil conditions and you can then grow the following plants as appropriate to the season:

Grasses

Sweetcorn

Brassicae e.g. broccoli, cabbage, cauliflower

Cucubits (e.g. courgettes, squash etc.)

Sensitivity or tolerance to any herbicide is dose‐dependent, so the list above is drawn up in the context of the likely amounts of aminopyralid found in manure that might be used in gardens or allotment.

Can manure containing aminopyralid be used in the garden?

We would advise that affected manure is not used where sensitive crops like potatoes, beans, lettuce and tomatoes are likely to be grown.

Does aminopyralid break down in a rotting manure heap?

No. Until the aminopyralid is released from the cellulose and comes into contact with soil dwelling micro-organisms it will be stable. Breakdown will occur only after manure is incorporated into aerobic soil.

What can I do with affected manure?

The following options are available to you:

  • DO NOT dispose of affected manure / compost in your green waste. 
  • Return to your source of supply
  • Supply it to a local farmer for use on grassland or land intended for grass, cereals or maize, as these plants are not sensitive to aminopyralid.