Ask the Expert - Rodent preparation

Prepare for the autumn rodent invasion with Bayer Racumin® rodenticides. Article by Dr Gerhard H Verdoorn, Griffon Poison Information Centre +27-82-446-8946

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With autumn we have to consider the response of nature to the events of the past twelve months: 2019 had the country gripped in the claws of a terrible drought that only broke in late November over some parts while the rains only arrived in January 2020 for many of the summer rainfall areas of South Africa. Typically, following such rains after a crippling drought, every single species exploded and produced legions of offspring to capitalize on the rapid improvement of the climatic conditions. Rodents are no different to insects in this regard and it is highly likely that brown rats and house mice also had a steep population increase. One may question why we don’t see an increase in their invasion of residences, shopping malls, restaurants and farmyards and the answer is quite simple: there is still enough food to keep them at bay. As the season progresses towards winter the ambient food supply will decline, forcing rodents to seek fodder in our own living space and the onslaught may be worse than ever just like the country experienced with insect pests.


It is time to be vigilant in order to notice the signs of rodent infestation: droppings in garages, kitchens, storerooms and laundries, that awful smell of rodent urine and possibly fast disappearing pet food in your clients’ homes. Rodents also chew through plastic food containers and gnaw on wood and plastic commodities. Once these signs are there it is time to launch a control campaign that will be effective, safe for pets and children, and not be harmful to owls that are our allies in rodent management.


Bayer Racumin® rodenticides have been on the market since the early 1990s and it is still one of the best on the market with a significant safety margin for owls because neither coumatetralyl (which is the primary active ingredient) nor cholecalciferol pose a real secondary poisoning risk to owls. This does not mean that you can ignore safety precautions with any Racumin® product; you must still adhere to the strict safety principles when using Racumin® rodenticides.


Bait stations are a non-negotiable component of safe use of rodenticides. The use of bait stations prevents dogs, children and uninformed persons from gaining access to rodenticides and ingesting the products. Be reminded that rodenticides are highly effective mammal toxins, so don’t take a chance, use a bait station. The labels of all Racumin® products explicitly state that bait stations must be used, and it is not because Bayer sells bait stations, it is because it is the only safe way to apply any rodenticide.


Racumin® Paste is a rodent killer of note. The highly palatable paste formulation is irresistible to rodents and can be used when there is a real infestation of rodents. Mice may require the use of Racumin® 3D Paste because the addition of cholecalciferol to the coumatetralyl in the formulation causes anorexia and the mice loose appetite within a day and perish very quickly compared to their normal feasting on rodenticides. If the infestation is only brown rats, then the standard Racumin® Paste will eliminate them within seven days. Take special care when using either of the paste baits; they are both highly palatable to dogs also and digest very quickly in a dog’s stomach with severe consequences. It is good practice to put the bait in a bait station totally out of sight and reach of any dogs in your customers’ homes.


As a suppressor for rat infestations one should always have Racumin® Wax Blocks on hand and apply them when the first signs of rats are discovered. Rats are obligate gnawers and the wax blocks are good to offer them the pleasure of gnawing with deadly consequences. Again, as with the paste baits, use a bait station! Do not deviate from this safety principle!


Bayer also offers its highly effective Racumin® Tracking Powder which can be applied to rodent burrows and runways like wooden beams. A bait station is not needed due to the method of application but heed the safety warnings and do not apply it where a client’s dogs may tamper with the blue powder in rodent burrows.


There is no evidence to date that rodents in South Africa have developed resistance to the anti-coagulant rodenticides even for the first-generation coumaryl derivatives like coumatetralyl. Use it according to label instructions, use it wisely, use it safely and the rodents will not stand a chance against the power of the Racumin® range.

Product registration details
Racumin® Wax Blocks L8465 (contains 0.375 g/kg coumatetralyl) CAUTION, Racumin® Paste L6401 (contains 0.375 g/kg coumatetralyl) CAUTION, Racumin® 3D Paste L10218 (contains 0.375 g/kg coumatetralyl and 0.1 g/kg cholecalciferol) CAUTION, Racumin® Tracking Powder L2800 (contains 7.5 g/kg coumatetralyl) CAUTION, registered under Act No. 36 of 1947 to Bayer (Pty) Ltd, P.O. Box 143, Isando 1600, South Africa.