ABOVE average levels of mouse activity have built up over the summer, particularly in the Northampton district, with one local reporting more than 1800 rodents trapped since Christmas.
Further south, Ravensthorpe also continues to be a hotspot.
In many paddocks there are significant levels of active mice holes, plus a lot of activity around houses and sheds.
With seeding just around the corner, farmers have been urged to step up monitoring and to take action to protect this year's cropping program.
Department of Primary Industries and Regional Development's (DPIRD) Esperance manager Brendan Nicholas said it was important for landholders to control mouse numbers as best they could now so populations did not threaten this year's crops.
"Mice can cause damage at all stages of crop development, including seeding, tillering, during grain development and mature grain, so it's best to get on top of control measures before seeding starts," Mr Nicholas said.
"Damage tends to be most severe at sowing so it is critical to control mice as the crop is being sown.
"Baiting will help to minimise the potential for damage."
In the north, Elders Geraldton agronomist Peter Eliott-Lockhart said they were about four to six weeks away from seeding, depending on the rain, so growers needed to get a fair idea of activity levels, especially in the paddocks which were going to go into lupins and canola.
"If there are enough mice to cause a problem, then we need to get an effective bait control going," Mr Eliott-Lockhart said.
"The most effective way is to limit their food source and get a maximum amount of bait, especially after we've sown and before the crop comes up.
"The effectiveness of that will depend on the type of sowing - if we're wet sowing, there isn't a lot of time, but if we're dry sowing there's time in between to get that done."
Mice are not a declared pest in WA, so it is up to farmers to implement control measures to protect their crops and those of their neighbours.
DPIRD recommends the use of 50 grams per kilogram of zinc phosphide baits, which have demonstrated increased effectiveness.
However, farmers were advised to adhere to strict label requirements governing the use of zinc phosphide baits and to ensure livestock and pets are restrained to reduce the risk of poisoning.
Good onfarm hygiene is also imperative to reduce the risk of mouse damage, including cleaning up spilt grain around sheds and silos, mouse proofing grain storage and stock feed areas, while grazing stubble could also be useful.
"Monitoring and detection are essential to achieve effective control and can include the use of active burrow counts, census or chew cards and trapping to determine the number of mice present," Mr Nicholas said.
"Indications that mice are present include numerous burrows, mouse droppings and more prey in the vicinity.
"Late afternoon and evening are the best time to monitor, using at least three 100 metre long by one metre wide active burrow searches, lightly covering the mouse holes and revisiting them the next morning to record how many have been re-opened."
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