Recognising Aminopyralid Weedkiller Contamination in Manure

Recognising Aminopyralid Weedkiller Contamination in Manure

Mackerel sky Before we get going, here's a photo I took on Monday morning while out walking the dog showing a pretty 'mackerel sky' which, as you know, signals a change in the weather. The old sailors rhyme is 'mackerel scales and mare’s tails make tall ships carry low sails'.

As it turned out the mackerel sky didn't lie with strong winds and heavy rain following on Monday night. I had a couple of large branches down on my lane (another golden opportunity to justify having a tractor to my wife as I dragged them out of the way) but otherwise all OK, I hope things weren't too bad where you are either.

Heavy duty fruit crop protection cage

Heavy Duty Galvanized Fruit Cage Kits It won't be long now (October) until the bare root fruit season starts and we can start planting some fruit bushes like currants, gooseberries, raspberries, tayberries and blueberries. If you are interested in growing some delicious fruit (and why wouldn't you be?) I would strongly advise netting them (to keep birds out) as the fruit ripens or, better again, planning your fruit garden in a purpose built fruit cage.

Naturally, if you need a fruit cage, we would be delighted to supply you one. We can supply pre packed kits but also have a handy parts picker so you can order any of the components you need to build a structure of any size. All the parts are galvanized steel to stand the test of time and easy to put together. We never got our video of cage assembly finished last year but will be doing it in the next couple of weeks if you are interested in how to build one.

Corner braces for steel fruit cages

Pre Packed Kits The pre packed kits we have built include the following sizes: 1.8m x 5.4m, 3.6m x 3.6m, 3.6m x 5.4m and 5.4m x 5.4m. The kits include all the parts you need to build the frame and the door; the net and netting ties are available separately but are linked to each product so are simple to order. I have included links to the kits at the bottom of the page.

Instructions The fruit cages are easy to build with galvanized connectors tightened in place using a hex/ allen key. You can take them to bits again easily too if you make a mistake or want to move the structure so it's pretty versatile. We have written an assembly instruction sheet which you can view below to see how it's done.

Parts Picker As I said, I have also added the components to a parts picker page so you can order them without having to open separate product pages. The total is added up in the box at the foot of the page as you add the parts. If you ned any help designing a cage or need more info on what you might need please reply to this mail and we'll get you sorted.

Horse manure garden mulch

A note on non organic horse manure Last week among other things I mentioned that I have just taken delivery of a couple of tons of well rotted horse manure from my local riding stables. This information resulted in a number of emails concerning the dangers of weedkiller contaminated manure which, it seems, is becoming an increasing problem. Some concerned readers suggested I highlight the issue in case other gardeners were having mysterious growth problems in their gardens and have been at as loss to identify the source.

The problem stems from products that contain aminopyralid, a hormone based weedkiller used to control broad leaf weeds in grassland. A similar concoction, clopyralid, is used in some lawn weedkillers and causes the same issue. The use of Aminopyralids was suspended some years ago so I figured locally sourced manure was safe to use again but I now realise it's back and, sadly, in more regular use.

Courgette plants amino pyralids

As it happens, I had noticed my fruit garden (which I added local manure to last season) was struggling a little this year but as the damage was light I put it down to late frosts and the May/June drought we had this year. I am still not sure but I now realise that the damage may be a result of weedkiller in the manure and will do a couple of tests to find out. If you have a local riding stables and are looking for manure it is worth asking where the hay to feed the horses comes from, if it is not organic it would be worth testing a batch (see how later in the article) before you apply it.

The photo above is from a very detailed (and much appreciated) mail sent by Bec, one of our readers. The images show her courgette plants exhibiting chlorosis (yellowing leaves) as a result of contaminated manure from her own horses. Bec finally discovered the problem originated from hay bought in to feed her horses in winter which was grown (unknown to her) using aminopyralid weedkiller. Unfortunately most commercially available hay, if not organic, is produced in this way as it is important that horse feed does not contain certain weeds.

Aminopyralid damage tomato plant

Test for aminopyralids Crops that are particularly susceptible to aminopyralids are potatoes, tomatoes, peas and beans, others like brassicas or corn seem unaffected. The symptoms can vary depending on the concentration in the manure and include stunted growth, chlorosis, brown leaf margins or curled leaves (as shown on Bec's tomato plants above).

Aminopyralid damage broad bean leaves

If you are concerned about a batch of manure you can do a test by mixing with some compost (which you know to be good) and sowing some broad beans or peas in pots. Do a couple of pots with and without the manure added to compare the results. If you have a problem you should notice it in 2-3 weeks and see distorted growth as shown in the photo above, there will be a marked difference to those grown in the clean compost.

What to do next? The Weed killer is broken down by soil bacteria and,depending on the level of contamination, this could take from four months up to a couple of years to clear. It seems that the soil bacteria can only do this work if the manure is mixed with the soil, it won't break down if left in a pile to compost.

Bec reports that she has seen plants initially struggle but has noticed a growth spurt four months after applying the manure which suggests the contamination has been dealt with. If I have a problem in my fruit garden, it seems very likely that everything will recover next year as symptoms have been mild, in fact I am seeing some healthy new growth on my raspberries already.

Spreading compost on lawn

If you need to remove manure from problem beds or if you need to dispose of effected manure or compost you should not add it to your compost heap as the problem will persist. The same goes for any foliage or prunings from effected plants. The advice for manure seems to be to spread it thinly on grassland or your lawn where it will feed without having a negative impact on the grass.

What are the alternatives for mulching and soil feeding? Well, the best thing you can do is to produce your own compost as you know where the material going into it has come from. It also makes sense to compost everything you can which is where insulated composters like the Hotbin or Joraform come in as they can handle all food waste including meat and fish.

Well rotted compost

The remaining issue is that vegetable gardens can't produce the amount of compost required to sustain themselves (because we eat the produce and don't compost our waste so the nutrients don't go back into the garden). You will therefore need compost or plant feed from another source to add to the material produced in your compost bin.

Like most garden centres we stock a range of compost products including our favourite 'envirogrind' which we can supply in 60L as well as cubic metre bags. I use a cubic metre bag of envirogrind every year on my garden and have never seen any signs of weedkiller contamination (potatoes are very susceptible and I had a fantastic crop grown in envirogrind this year). Similarly, we haven't had any issues with our Gee Up Organic horse manure or any of our composts but I will be doing spot checks every now and then to be sure. As regards a natural, slow release, plant feed, our organic Seaweed and poultry manure pellets are about perfect as poultry manure will never be a problem (unless you feed your chickens hay!).

Homegrown potatoes in compost

Pressure on government It is frustrating that thousands of tonnes of manure are produced around the country which could be used to grow crops yet is rendered useless by persistent weedkillers. In a time where recycling and composting are actively encouraged by government and are important components of a greener, more sustainable lifestyle, surely it is unacceptable to allow weedkiller of this type to enter the compost chain?

Persistent herbicides have the potential to destroy public confidence in composting at a time when there is increased interest in gardening using organic methods. It might be no harm to remind your local politician the next time you see them.

That's all for now, I'll see you next week!