FARMERS should be ready to implement an effective rodent control strategy as the weather starts to turn cooler.

David Reece, technical adviser at Lodi UK the pest control specialist, says they need to protect grain stores, livestock housing, farm workshops and other agricultural buildings from damage.

He said: "Last winter was relatively mild in most areas of the country and followed by warm, wet weather throughout the spring and summer. This provided ideal conditions for rats and mice to breed and survive, giving rise to a significant increase in numbers on farms this autumn and winter.

"With plenty of food still available from fields and hedgerows, most rodents will currently be living outside and farmers may not realise that they have a problem until temperatures start to fall when, they will quickly migrate to farm buildings in search of food and shelter, but by then concentrations could be high, placing businesses and infrastructures at risk."

Grain stores, livestock buildings and feed stores are particularly vulnerable to contamination of grain and feed, damage to the fabric of buildings and equipment, and potential fire hazards due to damaged electrical wiring.

Mr Reece said the key is to deal with rodent problems at an early stage as rodents multiply at an alarming rate and also spread disease.

"A single breeding pair of brown rats can multiply to 200 in just a year, while house mice breed year-round and a pair can become 60 in three months," he said.

The key signs to watch out for include droppings, urine, rub marks, gnawing, damage to insulation within buildings and unusual smells.

In April, rodenticide products with new "stewardship condition" labels for use by professionals – including farmers – were introduced. The rodenticides in question, edible baits containing first- or second-generation anticoagulant active ingredients, but not fumigant gases, have legally binding label instructions pertaining to their use.

Stocks of old label products have begun to run down and farmers, professional pest controllers and gamekeepers purchasing stewardship label products will require proof of competence at the point-of-sale.

Farmers have four options to use these rodenticides on their premises:

1 possess a certificate from an approved training programme and awarding organisation confirming professional competence. Lodi UK offer a free on-line course – see lodi-farmsolutions.com;

2 employ a professional pest control contractor, which employs technicians with such approved certificates;

3 membership of a UK farm assurance scheme which has a structured, documented and audited programme of rodenticide pest management. However, this will cease after December 2017, unless the farm assurance schemes in question bring their standards in line with the CRRU Code of Best Practice;

4 the purchase and use of amateur rodenticide products – limited to pack sizes of up to 1.5kg (bait point packs).