WELL-ROTTED farmyard muck has for generations proved a product that gardeners annually hanker for to improve the fertility of their soils and boost yields.
The much sought after material can, however, have the opposite effect as award-winning gardener Bill Davidson has found out twice in the last three years.
His vegetables have shriveled up after being grown in muck that he believes has been tainted with a range of herbicides used to control grassland weeds and which remains in the waste – even after the grass has passed through cattle.
Mr Davidson, a retired teacher of 7 South Street, Aberchirder, Banffshire, is not alone. Hundreds of similar complaints have been made by gardeners and allotment owners across the UK. Even farmers have been caught out.
The chemical at the root of the problem appears to be aminopyralid, one of the main active ingredients in a range of products including Forefront, Halcyon and GF928. Similar problems have also been reported with another chemical called clopyralid.
Mr Davidson first had a problem in 2006. It has emerged again this year. His potatoes, tomatoes and beans, all of which were planted in fresh muck, have been affected.
He said: “The root of the plant hits the muck and the leaves at the top of the plant just curl up. The plant then stops growing. I'm too late to replant this year. The work that I've put into the garden has all been wasted and I'm going to have as much work again digging up and taking out all the muck.
“I don't want to condemn the products nor the farmers, but instead want to raise awareness of this so that both gardeners and farmers are aware."
All the products containing the active ingredients have warnings on the labels.
Dow AgroSciences, which makes Forefront, has reinforced the existing messages this year with an information sheet which warns anyone using the product not to pass any manure on to the public if their grass has been treated with it.
Colin Bowers at Dow said the problem with herbicide-contaminated manures had been ongoing for more than 20 years. He insisted the product was safe and that there was no impact for human health.
“There are pretty clear warnings on the labels of all the products that farmers should not use manures in particular situations. Mr Davidson is not alone. Every year we get phone calls from gardeners and from farmers who have had a similar experience. It is pretty emotive when potato and tomato plants go curly."
Mr Bowers said the best advice for anyone using farmyard muck in their gardens was to ask the farmer supplying it if they had used any herbicides and to get them to check the product label about it causing problems in sensitive garden plants.