Following concerns raised by members; we are reproducing a couple of informational articles on aminopyralid. Some information may be a little out-of-date, but this will hopefully provide some general background. The first item was published by Garden Organic in June 2020, under the title “Worrying damage to plants from herbicide contamination in compost” (Link to Original)

In 2019 gardeners noticed significant damage to some of their plants – particularly annual vegetables which showed weak and stunted growth. It is thought the problem came from weedkiller residues remaining in compost and manure. There were multiple reports circulating on social media, and professional gardener and well-known proponent of ‘No Dig’, Charles Dowding, raised awareness in the Daily Telegraph in July 2019, which resulted in a six-fold increase in gardeners reporting similar damage.

One probable culprit was identified as the chemical ‘aminopyralid’, which is used by farmers and local councils as a weed killer for grasslands. When grass cuttings and weeds which have been treated with this particular chemical are incorporated into manure or compost, or fed to animals whose manure is then used, the residue remains, and can contaminate the mix with devastating effect.

James Campbell, Chief Executive of Garden Organic says:
“This poisoning has been of huge concern to growers and gardeners. Particularly as many may not have connected the distressing plant damage to the organic compost or manure in which they grow.”

Garden Organic, the Soil Association, and the Organic Growers Alliance, have worked collaboratively to investigate the aminopyralid contamination. They met with Corteva, the agricultural chemical manufacturer and distributor, who make the deadly herbicide.

Corteva themselves are investigating the issue. But their knowledge of actual incidents is likely to be incomplete as not many growers know of Corteva’s existence, nor how to contact them. So now organic growers want an independent assessor involved.

We encourage growers who think they may have been affected to contact the government’s Chemical Regulations Division,”

says Peter Richardson, Chair of the Organic Growers Alliance. “As part of the Health and Safety Executive, CRD monitor contamination incidents – which still occur despite their clear warnings to users on how to use aminopyralids,” (see below in Notes for Editors.) We think it is simpler and more effective if growers send an email to both CRD and Corteva.”

“We are asking CRD to work with Corteva to find a lasting solution to this issue and address any future impact on growers using manure, or green waste/municipal compost,” says Gareth Morgan, Head of Farming and Land Use Policy at the Soil Association. “We encourage all growers who think they may have been affected to make use of the impartial process to sort out this issue once and for all.”

If you think your plants have been poisoned, emails should be sent to CRDEnforcement@hse.gov.uk and UKHotline@corteva.com, headed “Aminopyralid contamination”.

The second item is taken from the Organic Growers Alliance website; published in 2019/2020 under the title “Aminopyralid – the herbicide that hasn’t gone away” (Link to Original)

Aminopyralid (AP) and its close ‘cousin’ clopyralid (CP) contamination have been increasingly detected in compost this year – a real headache for market gardeners and domestic growers. It can have devastating effects, wiping out entire crops. Key symptoms are distorted leaves and growing tips on tomatoes, potatoes and other veg affected by the herbicide.

This is a particularly potent herbicide. It does not degrade in  composting, it is found in hay, grass and silage cut from sprayed fields and the chemical passes through feeding animals into their manure.

Almost every day Charles Dowding and myself have been hearing about new cases of contamination, not just in animal manures but also in council waste composts and bagged composts from various companies. For the past decade I have been advising people using horse manures, which seemed to be the most affected, to check for AP contamination. However, I recently discovered that horses are not allowed to graze on land previously sprayed with AP or eat or be bedded using products which have been sprayed. It is only licensed for use with cows and sheep – yet in our experience of talking with growers across the UK and worldwide, horse manure is the key affected manure/compost – yet it is only licensed for use with cows and sheep! Clearly something is not working with the current legislation.

A meeting this summer with a consultant from the company, Corteva Agriscience, part of Dow Chemical, who manufactures both of these chemicals revealed that they have received very few complaints. Therefore, it is hugely important that anyone who thinks they have been affected by AP or CP contamination reports it – details of how to do it at the end of this article. Otherwise it will still be seen as an occasional problem.

AP was approved for use in the UK in 2005 as a herbicide that targets mainly broadleaved weeds including ragwort. It didn’t take long before allotment associations were reporting catastrophic damage caused by people using contaminated composted manures on their plots. Use was suspended in 2008 and new legislation brought in, the theory being to prevent the herbicide from leaving the land where it was sprayed and contaminating other land.

However, the problem did not go away. In 2011 George Monbiot wrote an article explaining some of the serious consequences   of the herbicide and called for a suspension of sales, but that  didn’t happen. It has continued to be a problem for growers and gardeners alike, which has increased significantly this year.

In April, Charles noticed that a small area of broad beans were looking pale, weak and distorted, unlike adjacent beans which were growing well and they displayed the distinctive signs of AP contamination. This area had been mulched with compost containing a small amount of bedding and manure from the neighbouring stables and shows that AP is so strong that even a small amount can contaminate. The remaining compost from that

Aminopyralid damage in potatoes

heap was spread on a different part of the garden and beans, with dahlias and other plants included as an experiment. We were able to show this to the consultant from Corteva who agreed that it clearly showed AP contamination.

Charles has since made two videos explaining what happened here and detailing some of the cases we have encountered.

AP is turning up in some, but not all, horse, cow and chicken manure, small animal poo/bedding, council green waste compost, straw, hay, grass and some branded composts from shops. It is  a potential problem for everyone, even veganic growers. The contaminated compost starts to break down in contact with soil bacteria and in the past, tests at Homeacres suggested that spread as a mulch, it takes around 12-15 months.

What you can do

If you think you have aminopyralid contamination, contact: https://www.corteva.co.uk Corteva’s Technical Hotline: 0800 689 8899 or e-mail them at: ukhotline@corteva.com

The Health and Safety Executive www.hse.gov.uk

How to test for aminopyralid – The Bean Test

Beans, peas, tomatoes and white clover show aminopyralid contamination quickly. Fill some pots with contaminated compost and others with a known ‘safe’ compost, certified organic composts are fine. Sow the seeds and wait for approximately 3 – 4 weeks. If the plants in both composts look healthy then all should be well. Alternatively, sow some clover which detects tiny amounts of AP.