There is some serious news to pass on this week, about contaminated manure.

Apparently, allotment holders around the country have been noticing vegetable crops with very stunted growth, and strange and uncharacteristic leaves and stems.

You might argue that these symptoms may have been caused by the weather this summer, but, no, they have been linked to a pesticide type called an aminopyralid, that has been used to spray pasture land.

According to both the Federation of City Farms and Community Gardens (and the Royal Horticultural Society, there has been a surge in complaints from allotmenters and gardeners who have manured beds and then found that plants raised on the manured ground have begun to grow wrong.

So, should allotmenters in Bristol be worried? Well, if you have used bought-in manure, then you will probably have noticed the effects on your crops already. Cupped leaves, with prominent veining, fern-like growth, and shoots which are pale and narrow are some of the more obvious symptoms, although the clearest indicator will be the plants' failure to thrive.

Susceptible crops include potatoes, tomatoes, beans, peas, carrots and salad vegetables. Ornamental plants such as delphinium, phlox and roses may also be at risk.

If you do notice plants with these symptoms, growing in soil that has had bought-in manure incorporated, then it would be worthwhile contacting your manure supplier to let them know and to find out whether an aminopyralid product was used on any grass, hay or silage fed to the animals which produced the manure. Just as importantly, contact Dow Agrosciences, the company that markets the aminopyralid, at ukhotline@dow.com, for further advice.

It is not yet known whether plants that have been affected by this aminopyralid are safe to eat, although, as yet, there has been no suggestion that humans or wildlife are at risk. Unfortunately, there is no means to test manure for contamination.

To this end, the RHS has issued further advice to gardeners regarding what to do with stacked manure and buying manure in the future.

It advises that any potential residues in stacked manure can remain for extended periods, even up to two years.

When buying manure in the future, growers should seek assurances from the supplier that the manure has not come from animals fed on grass or straw bedding treated with aminopyralid products.

For more information, try the RHS and FCFCG websites, or the Green Lane allotments website at www.glallotments.btik.com