Update June 2008

Vegetable damage in British gardens and allotments appears to be more prevalent this year due to weed killer contamination of manure, following dressing with
farmyard manure.

The Royal Horticultural Society (RHS) advisory department has received an
increasing number of calls from its members concerned about abnormal growth
of vegetable crops, in particular, tomatoes, potatoes and legumes. On average the
advisory department at RHS Garden Wisley receives 20 calls a week relating to weed killer damage; early reports also indicate that delphiniums and roses may
also be affected.

It is believed that the manure available for domestic gardeners has been
inadvertently contaminated with aminopyralid. This selective, hormone-type
herbicide is used to control broad-leaved weeds found in pastures; potatoes and
tomatoes are especially sensitive to them. The agricultural community has also
reported damage to potato crops following the use of manure and slurry from
grasslands treated with aminopyralid.

Symptoms of damage include distorted foliage, with cupping of leaves and fern-like growth. There are no remedies once damage has occurred and there is no assurance that affected produce will be safe to consume. However, as this weed killer can be grazed by livestock soon after application there is no reason to believe that children, pets, gardeners or wildlife are at risk.

Guy Barter, RHS Head of Horticultural Advisory Services said: "Until recently weed killer damage was fairly unusual and usually due to inadvertent mistakes in applying lawn weed killers and using contaminated watering cans and sprayers. This year not only are there far more instances reported to us than usual, but farmyard manure is frequently implicated as the source of the weed killer. Clearly gardeners should seek assurances from their suppliers that the bedding or forage used in the manure has not been treated with hormone-type weed killers. For gardeners in the unfortunate situation of having damaged crops and plants the good news is that the weed killers should be gone by 2009, but this year's plants and produce are probably ruined. Unfortunately the weed killer breaks down slowly in stacked manure and could take much longer to be eliminated, so left-over contaminated manure should ideally be returned to the supplier to be spread on grassland. Gardeners with affected plants should contact their suppliers to find out if manure could be the source of damage; seek recompense if manure can be proved to have been involved and also to return any left-over manure".

For more information on aminopyralid and clopyralid visit the Pesticide Safety
Directorate website: www.pesticides.gov.uk