Aminopyralid Contamination Of Manures And Compost Is A Potential Problem We Should All Be Aware Of.
Aminopyralid and Clopyralid are weedkillers used by farmers AND gardeners to kill broad-leafed weeds in grass. The problem is that Aminopyralid In Manures And Compost are persistent and can contaminate manures if the grass (hay or silage) then gets into the manure. This can affect vegetable crops where the manure has been used. Therefore we need Aminopyralid Testing In Manures And Compost. Here’s how.
Beware, Grass Clippings Can Be Contaminated!
Before going further, here’s a fact that most posts about aminopyralids forget to mention. If the grass you use in your compost heap has been sprayed with herbicide then the clippings could contain aminopyralids.
Aminopyralid Symptoms In Vegetables And Fruit
Distorted growth is typical as the hormone weedkiller affects the crop. Leaves are often fernlike or “cupped”. The growing tips of the plant go narrow, distorted and pale with prominent veining. This usually means the crop dies or is unusable.
How Long Does Aminopyralid Persist?
In heaped manure or composts the aminopyralid can persist for several years. It will eventually break down but it isn’t quick. Bacterial activity will speed breakdown but it takes time. So aminopyralids can b present in fresh and well rotted manures AND home made composts
Aminopyralid Testing In Manures And Compost. How to Test For Aminopyralids
NB there are variations on this methods but al fundamentally test in the same way.

- Take two clean pots. Fill one with the suspect compost. Fill the second with compost that is known to be OK.
- Label them
- Into each pot put 4-5 broad beans or tomato seedlings.
- Grow these on in normal growing conditions for three weeks.
- Check for distorted or fernlike leaves, compare with the control pot.
- If after three weeks no signs of contamination are seen then you cn assume the compost trusted was clear of contamination. If contamination is very bad it will show up before three weeks.
This video from my colleague, Charles Dowding, is very useful.
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Thank you for this article. I brought this to the attention of a horse owning friend a couple of years ago and she thinks that the presence of aminopyralids has contributed to the digestive problems of her horse.