How best to protect stores from rodents

A sharp rise in autumn rodent numbers is prompting reminders to protect grain stores as falling temperatures see rats seek solace on farms. 

“Farmers should take an integrated pest management approach and use a variety of baits to combat resistant rats and prevent infestations that can result in grain losses and contamination,” says David Reece, from pest control specialist Lodi.

Rats can thrive in a grain store and multiply quickly. But protecting stores does not have to involve the use of rodenticides, says Mr Reece. Farmers should select bait carefully to avoid wasting money baiting resistant rats, he adds.

“Farmers can take many non-chemical measures such as proofing buildings, identifying areas that rodents may be using for harbourage and making regular checks by walking the farm,” Mr Reece explains.

Resistant rats

Rodenticides should contain actives such as cholecalciferol or brodifacoum because some rats are now resistant to previously popular actives such as bromadiolone and difenacoum,” he says.

The advice comes ahead of next year’s changes to rodenticide authorisation. The changes will effectively rule out using any second-generation anticoagulant (SGAR) in open areas away from buildings.

Alan Buckle, chairman of the Campaign for Responsible Rodenticide Use (CCRU) says many farmers will face a challenge when modifying control measures in a way that remains effective, affordable and environmentally responsible.

“Doing so may not be particularly straightforward and will certainly demand sound knowledge of what next year’s changes to SGAR authorisations involve and why they are being made,” says Dr Buckle.

Uncomfortable truth

“An uncomfortable truth is that, seven years since inception, the regime’s environmental targets have not been met. Responsible farmers will be all too aware that many wildlife species are widely exposed to and contaminated by SGARs.

“The widespread nature of this exposure is a grave concern and what the stewardship regime is required to reduce. The panel’s specified sentinel species, of course, whose exposure to SGARs is indicative of several others with similar ecology, is the barn owl.”

The HSE has said that, unless the stewardship regime’s environmental targets are met, there will be a review of who can use SGARs, how they are used and where they can be applied. Dr Buckle said: “Clearly, we have been warned.”

A summary of the changes can be found at bit.ly/ratchange. Farmers are invited to submit questions about the changes to the CRRU by the end of October at thinkwildlife.org/survey. Answers will be published next month.

5 Tips For Successful Control

1 Look for signs of rodents such as droppings and gnaw marks. Regularly walk the farm and record where rodent activity is apparent. Just because there are signs of rodents it doesn’t mean baiting that area will always be totally effective.

2 Rats do not like open spaces, so reduce activity by keeping the farm clear of rubbish, weeds, and objects – especially around grain stores. Preventing access to food and water will reduce the likelihood of rats breeding.

3 Reduce the risk of infestation by ensuring there are no access points for rodents to enter buildings. Small measures like using mesh smaller than 10mm to cover gaps in grain stores will help to prevent both mice and rats gaining access.

4 Rats have a fear of new objects (neophobia) so establish bait boxes at least four weeks ahead of baiting to improve bait take. Adding non-toxic bait can encourage rats to ‘trust’ the boxes.

5 When non-chemical methods have been exhausted, the use of rodenticides to control rats and mice should be carried out methodically and carefully. Using a highly palatable bait is particularly important in grain stores where food is plentiful.