Sunday, 22 June 2014

Contaminated compost

The other day I was singing the praises of some composted stable manure that I bought earlier in the year, but I have changed my tune now. I am fairly sure that it is contaminated with aminopyralid weedkiller. This type of weedkiller is used by farmers to control weeds on pastureland. Animals grazing this land ingest the weedkiller (which does them no harm), but it is passed through into their manure - some of which evidently makes its way into commercial compost!

I won't attempt to explain the whole saga in detail, because that has been done before - most notably by Sue Garrett on her blog Our Plot At Green Lane Allotments - but I just want to provide some evidence that although this issue is supposedly a thing of the past, it isn't. In theory, according to regulations introduced in 2010 manure which potentially includes this type of weedkiller should be retained on the farm of origin, but it appears that this does not happen in every case. I bought 12 bags of  composted stable manure in March of this year, and used most of it in the big pots I am using for growing tomatoes and potatoes. I also dug some into my raised beds as a soil-improver.

The main symptom of contamination is distortion and malformation of plants stems and leaves, particularly at their growing points:

The leaves are thin and spindly, often described as "fern-like", and are curled inwards.

In potatoes the leaves adopt a distinctive "cupped" configuration.

The plants most susceptible to this type of damage are tomatoes, potatoes, peas, beans, phlox, delphiniums and roses. Fortunately, everyone seems to agree that food crops affected by this type of weedkiller are not harmful to either humans or animals, though it is accepted that yields are likely to be poor and some fruits (e.g. the tomatoes) will be malformed.

As it happens, my potatoes this year have been very good so far (I have only harvested First Earlies, not Second Earlies or Maincrops yet), so I am not too worried if the leaves are a bit distorted, as long as the crop is OK. Tomatoes are another matter. Evidently the weedkiller took a while to be absorbed by the plants, because their lower leaves are normal. However, the upper parts of the plants are thin and straggly, and I don't see them producing much of a crop.

It's not all bad though, because the first truss on each plant seems to be forming OK. Many of my plants this year are Beefsteak varieities, well known for thier irregular shape, so I was fully expecting some ugly specimens! This, for instance is "Noire Charbonneuse".

This is "Dinnye":

And this is "Banana Legs", which has elongated yellow fruits:

My Runner Beans are planted in a raised bed that was treated with the suspect manure, but so far have shown no signs of being adversely affected. I hope they will be OK.

At this present minute I am awaiting a response from the supplier of my compost, so I don't want to say much about them, but I won't be shy of naming and shaming if it appears they are involved in any malpractice. I have also been in touch with Dow AgroSciences (the manufaturer of the weedkiller), who have promised to take this up directly with the supplier.

If you are similarly affected, or just want further information, here are some additional resources:

Dow AgroSciences have an email address for reporting issues of this nature. It is
They also have a website giving further information. It is called Manure Matters

The Royal Horticultural Society have some useful advice on the issue. You can find it HERE

And of course Sue has compiled lots of evidence and advice which she has published here: If you are affected by this issue, please let her know so that she can add your details to her database.

In the meantime, I shall be doing everything I can think of to mollycoddle my sick plants and help them through their troubles. This begins with adminstering a dose of Comfrey Tea!


  1. Oh how sad. I've certainly read about that happening before in the UK. I hope you still get a decent crop.

  2. Oh my. The first time I heard about something like this was on the PBS program, A Greener World.

  3. The damage looks very familiar Mark!
    I used to help myself to the free horse manure offered at the village gate in our next village. Not any more. I think this problem is very common.
    Such a shame as FYM used to very best bulky material that you could add to your soil.
    PS The other problem for me is that fresh manure is also full of weed seed.

  4. What a shame - Thankfully, you will still be able to eat the produce that you do end up getting. You just never know what you may get, especially when it comes to a new supplier. I purchased this great triple mix when I built my original beds. When I prepared my new beds this year, I went with a different supplier because they were a bit less expensive...definitely a mistake as the triple mix I got was much heavier with lots of clay content, and it was also FULL of weeds - I had half of it covered for a few weeks while I prepared the beds and when I removed the tarp it was a veritable forest....

  5. Wow! I find that scary. If beef cattle ingest weed killers and then are butchered for our use, or if milk cattle ingest it, does that mean that humans might be getting even minute amounts of that stuff in their bodies?So, you see on milk containers that there are no added hormones or pesticides, etc. and the milk is "natural" but then what did those cows eat? I would make my own compost, Mark, and forget the manure.

  6. Oh Mark that is such a shame, I do hope you are able to get a decent crop at the end of it.

  7. It's hard to know what's best for our plants these days. Manure is supposed to be one of the best things to put in our veg beds, but you have to be sure that you know what the animals have eaten and how many of us can say that we do? I used to have a good reliable source of manure but not any more so I'm sticking with chicken pellets at the moment.

  8. Such a shame about the plants and potentially the manure. Chemicals play such havoc on everything. You would think that manure would be a good thing and not damaging. Hope the supplier can give more info & honesty. I'll have to double think purchasing manure.

  9. You are not the only ones affected this year Mark, I was contacted by someone from the Inverness area that has been badly affected, He went back to his manure supplier who admitted using Forefront but was unaware of any issues about its use in spite of supposedly strict regulations being applied.

    There is another hormonal herbicide called clopyralid that is used in some lawn weedkillers available to the public. Instructions for its use state that you shouldn't compost grass clippings from lawns treated so chances are that you will put the clippings in a green council waste bin. Some composts state that green waste is used as an ingredient, it doesn't take much imagination to see a potential problem here.

  10. I'm sorry for your plants, Mark. I've never imagined that something like this could happen. I buy bovine manure in pellets, and so far everything was good with the plants.

  11. I have to agree with Egretta. I don't care how safe they say it is, I would not be wanting to eat anything that eats a weed killer and the weed killer goes all the way through their system like that and is still effective enough to cause problems to plants. But then I never know what I am eating when I get meats from the store either.

  12. Oh Mark. It's every gardeners nightmare. So sorry to hear this.

  13. Bad news but the chemistry and symptoms are interesting. I'm with Egretta and Becky - While this is from horses, one can only imagine meat animals having access to the same food sources. Gives pne pause to think about doesn't it.

  14. I had no idea this was happening. I bought a bag of manure from a garden centre, thinking that I'm good giving my vegetables some decent manure. I have planted a variety of things in it, but I've noticed that in those pots the plants are not behaving right at all. In particular the Swiss chard has had the weirdest looking leaves, and I had to pull them out in the end and get rid of them. I now suspect it's the manure problem you have mentioned! It angers me. We spend a lot of money on compost/manure etc., a lot of our time and effort into sowing seeds, nurturing plants, for them all to be inedible because of where the manure has come from and someone who obviously doesn't give a toss about their customers.

  15. it seems a disaster, I'm very sad for your problem Mark!

  16. I am a newcomer to this blog, and feel that I have to add that here, in northern British Columbia, Canada, we also have become unsuspecting victims to herbicide. My beautiful grapes are no longer beautiful, the leaves are tiny cups, dahlias are twisted stems with tiny leaves, the broad beans are twisted and thin stems, it was painful to look at them. My tomatoes also furled up, and the tops even turned blackish. The potatoes look much the same. I usually sell a lot of bedding plants, but this year, I said that no soil is leaving this property, so have lost quite a bit of money as well. So far, I see that the asparagus doesn't seem to be bothered, so we will make a larger asparagus bed and that way our compost will not have been wasted. When we bought this place five years ago, there was no topsoil, all our garden is in beds with soil that we paid for. Now it is all contaminated. Even the squash and cucumbers, which are supposed to tolerate a higher level of herbicide, is not looking well at all. So we took a plot at the local community garden, it is about 300 square feet, and put some root vegetables in there. We're pensioners and therefore a little old to start over, but what choice do we have? The more that I hear about this herbicide, the more that I suspect it is a deliberate effort to hamstring home gardeners.

    1. That really is a sad tale, which I'm depressed to read, but it expresses thoughts very similar to my own. Who can you trust these days??

  17. I thought I had mosaic virus in my tomatoes until I found this site,and the penny dropped.The symptoms are something I've never seen before..exactly as your pic shows.My new beds have a lot of horse manure we got free from a relative's hobby farm.They don't use weedicides,but maybe neighbours do,or the chaff they buy to feed the horses might be affected.I'm so relieved...I can leave the plants in and hope for the best.Thank you!!

  18. I've been looking for pictures of the exact symptoms I've been experiencing with my tomatoes. I've used different (commercial) bags of compost and only certain plants are affected. Looks like one bag was contaminated. Thanks for posting. NB I'm in the UK.

  19. Hi Mark, thanks for documenting all this. I've been trying to find out what is wrong with my tomatoes this year, now I'm certain it is herbicide residue. I have used commercial grow bags of peat based compost originating in Northern Ireland which I believe are contaminated. I am currently doing a controlled test using broad bean seeds to confirm for myself at least the source of the problem. The first tomatoes which set before they were potted into the growbags are ripening, but although it breaks my heart they will be going into the bin. We may be told it's safe but I don't want to spend the next 20 years wondering if I have poisoned my family. To say I am upset is an understatement. I am in Shropshire in the UK. Best wishes, Sue.

  20. This is a message for "Stormy". I have seen your several comments on this post, but have decided not to publish them because I think they are too controversial.

  21. I wrote the same in the other post maybe it will help someone else. It's a mosaic virus.


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