WARM winters and growing resistance to rodenticides has resulted in a national rat population that is rapidly getting out of hand.
According to Ken Wildey, head of the infestation risk evaluation group at the Central Science Laboratory, York, alternatives to anti-coagulant control products, to which resistance is building, must be found.
Work at York to tackle the problem, however, is obviously not a priority, with Dr Wildeys departmental budget slashed by 66% since 1992.
As well as being carriers of disease, increased numbers of rats could mean that farmers face higher demands from grain assurance schemes such as the Assured Combinable Crops Scheme and Scottish Quality Cereals, according to Sorexs rodenticide specialist Ian Anderson.
But Dr Wildey said that, so far, farmers have been asked only if a rodent control policy is in place. "What we dont know is what these schemes deem as an acceptable level of rats on farm. Many will say a control programme is in place, but no doubt as it gets more specific in terms of numbers, farmers could be in trouble on how to control them."
Mr Anderson said: "The key to control is to adopt a systematic approach and stick to it. The vast number of rats this summer means that farmers are having to be exceptionally vigilant."
And with cereal prices as low as they are, every last grain needs to be protected."
Resistance to poisons has resulted in a rat population explosion.