FARMERS have been warned that there could be much higher numbers of rodents this autumn and winter.

However, many will be unable to tackle them with products they have used in the past because of European legislation governing the sale and use of rodenticides, which came in on March 1, 2018.

Roger Simpson of Lodi UK, a leading manufacturer of pest control products, said the unusually hot, dry summer has encouraged rodents to breed over an extended period and allowed a higher proportion of their offspring to survive.

“So numbers are likely to be well above average this autumn,” he said.

“Sources of food and shelter in fields are declining quickly and average temperatures are beginning to fall, particularly at night, so rodents will quickly begin to migrate indoors.

“Therefore, it is critical to implement effective control measures to prevent them causing loss and damage in crop and feed stores, livestock housing, silage clamps, farm workshops and other rural buildings such as stables.”

The new European rodenticide regulations are designed to ensure that such products are used correctly, in ways which minimise their exposure to wildlife and other non-target species.

The sale and use of professional-strength products are now strictly limited to named individuals who hold a certificate, which is approved by the Campaign for Responsible Rodenticide Use (CRRU) or who work for a farming business which is a member of a CRRU-approved Farm Assured Scheme. Evidence of this will be required at the point of purchase.

Anyone who does not possess the correct paperwork will be unable to purchase any professional-strength product, even those they might have used for years.

Instead, they will be limited to purchasing products that contain less than 30ppm of anticoagulant rodenticide active substances, in maximum pack sizes of 150g for grain and paste bait formulations or 300g packs for block baits. All baits must be used in tamperproof and secure rodent bait stations.

Lodi UK suggest that for many who have previously purchased significant quantities of professional-strength rodenticides the relatively small amount of time it takes to become CRRU-certified will be the best option but said effective alternatives are available.

Mr Simpson said: “Times have changed, but by using the right products for the target species and situation rodents can still be controlled effectively in rural situations.”

To help non-professionals to select the right type and quantity of product Lodi has produced new packs containing pouches of specially-formulated bait, which use the same active ingredients as its Gems professional range, but at a reduced rate of 25ppm.”

David Reece, who owns farm pest control specialists Oakwood Farm Services and is technical adviser to Lodi UK, said: “Whatever type of product you use the key to keeping rodents in check is to deal with them early and effectively.

“Even if you only see the odd one or two rodents, almost certainly you will have many times that number and they multiply at an alarming rate. For every 1kg of food they eat, rodents contaminate a further 3kg, as well as carrying microbial infections and spreading diseases such as salmonellosis and Weil’s disease (leptospirosis), so it is essential to keep them in check.”