With grain stores full, combines back in the shed and temperatures declining, rats are making a comeback – and could be in heightened numbers after a bumper summer season.
Ken Black, Bayer’s rural hygiene manager, finds out how to mitigate against damage...
As temperatures decline, rodents start to migrate to shelter, so it’s essential to ensure buildings and machinery are protected from the risk of infestation to minimise the risk of damage and the spread of disease.
More than 20 per cent of farm fires are caused by rodents gnawing through electrical wiring and therefore integrated management is key to include monitoring activity, removing food sources, keeping areas clean and tidy and baiting correctly.
Here are some common questions asked by farmers who want to manage the risk.
How do you defend buildings against rodents?
Proofing buildings is the first and foremost practice to minimise the risk of infestation before it starts.
Rodents can get through very small gaps and gnaw through materials such as wood or plastic, so fill in any holes with bricks, concrete or mesh and make sure materials are secured down.
How do I decide where to lay bait?
Firstly, it’s important to monitor for rodent activity. Historical knowledge is always beneficial to identify problem areas. High activity is typically found in areas near livestock, feed and grain stores.
Placing baiting points down with feed or grain inside prior to baiting can help identify areas of higher activity, or a non-toxic monitoring bait can be used to highlight droppings.
What else can be done to reduce rodent activity?
Ensure all buildings are kept clean and tidy and reduce access to feed sources such as stored grain.
Remove any shelter to reduce nesting within buildings as pests tend to avoid open spaces.
What are the latest constraints around baiting with rodenticides on farm?
Since April 2016 farmers have been required to show a certificate demonstrating competence in the use of professional rodenticides. However, those enrolled in certain farm assurance schemes are currently exempt from this ruling.
Accredited training courses are run by several organisations recognised by Campaign for Responsible Rodenticide Use (CRRU). Without certification or exemption only 1.5kg of rodenticide may be purchased and applied, meaning only very small rodent infestations could be controlled.
How and where should the bait be put down?
Baiting points should be placed in the hotspots, near to walls and surfaces where rodent activity is expected and in areas that have historically been problematic. Infestations expand quickly so repeat treatment as soon as bait has been consumed.
Don’t forget baiting points should be checked daily and topped up until activity has stopped.
What is permanent baiting?
Permanent baiting is when a rodenticide is left out in protected, usually tamper-resistant, bait stations in areas where there is no current sign of rodent infestations, but the risk is high.
How can farmers adhere to new permanent baiting regulations?
Carefully read the labels when considering this as an option. Only products containing bromadiolene and difenacoum have been approved for permanent baiting, however not all products with these actives are authorised.
Products not authorised for permanent baiting should not be put down for longer than 35 days.
What type of rodenticide should be used?
When deciding what product to use, the first thing to identify is the rodent’s feed source. If they’re eating stored grain then the best option is to use loose grain product such as a high quality whole wheat bait which increases consumption.
If the rodents are around livestock feed, there is a wide range of soft block products that are highly palatable and most suitable in a dry environment.
Alternatively, foams can often be successful and can be applied where there is known activity or in areas such as holes, narrow gaps or rodent runs.
This works by taking advantage of a pest’s natural grooming habits. When it brushes past the foam, it gets transferred on to its coat and is ingested when self-grooming.
Is pesticide resistance an issue with rodents?
Yes, resistance can occur when rodenticides with the same active ingredient have been used for many years without rotation. Actives such as difenacoum and bromadiolone are known to be becoming resistant on some farms.
If resistance is a concern, then consider products with alternative active ingredients such as difethialone.
How can you ensure non-target species are not affected?
When applying a rodenticide, ensure baiting points are secure so that bait cannot be removed or spread. Attaching blocks on stainless steel threads can help this for example. Once rodent activity can no longer be seen, remove the bait but continue to monitor for activity.
Dead rodents should be disposed of safely in line with the product label. This is particularly important to reduce the risk of secondary poisoning to birds and other mammals. For further advice on the disposal of rodents contact the Environment Agency.
How can you minimise damage to farm machinery?
To reduce the risk of damage, clean down machinery at the end of harvest and remove any residual grain.
There are numerous access points in most machines, including the tyres or header. Place monitoring points near these areas and be vigilant, looking out for signs of activity. If activity is confirmed, then bait these identified areas and regularly replenish.
Starting machines regularly is another great tip for disturbing and flushing out any nesting rodents.