A WATER firm has appealed to farmers near two North Yorkshire rivers to carefully manage the use of a slug control pesticide which can be toxic to animals that ingest it.

Yorkshire Water has labelled the area north of Northallerton as "a problem area" after finding metaldehyde concentration levels in the rivers Ure and Swale to be higher than other river catchment areas in the region.

The firm said the appeal aimed to reduce the impact the pesticide had on tap water quality.

Use of metaldehyde, which is most extensively used on potatoes and oilseed rape, has also sparked concerns over poisoning incidents involving domestic pets, wild animals and birds.

Yorkshire Water said slug pellets, commonly used by farmers during this time of the year, had been found to leak from farmland or flow through field drains into the rivers Ure and Swale, that feed the River Ouse.

A spokesman for the firm said: "Although this poses no danger to health or the environment, metaldehyde levels in the River Ouse have occasionally breached EU drinking water standards."

Farmers are being urged to avoid applying slug pellets within six metres of a watercourse, to apply the minimum amount needed to avoid drainage and run-off losses and not to use the pellets when heavy rain is forecast.

The spokesman added: "We are positively working with farmers on this issue as we recognise the demands they have to meet food production targets. So we are not saying to farmers to stop using slug pellets, but instead to ensure they are applied correctly and to consider alternative measures that have a lower water impact."