Widespread and ‘rapid’ mouse plague threatens $1 billion in damage to WA’s crops

WA’s grain growers are facing another whammy to the industry — a $1 billion damaging mouse plague — after thousands of burrows were found in key farming regions.

About 4000 burrows per hectare have been found in crops in the Mid West, Wheatbelt, and Goldfields Esperance regions.

Tenindewa cropper Brendan Weir said he has seen “plenty of mice”, holes, and activity in the paddocks — and in his home.

He said once he begins seeding — planned for next week — he would be aerial baiting behind the seeder to combat the mouse levels and protect his crops.

“It’s not uncommon to come across a patch where you’ll see four or five burrows within a space of a few metres,” Mr Weir said.

“I think it might be worse than the last time we had mice . . . it’s hard to know until you actually get into and see the paddocks and just see how many of the holes are active.”

The population of mice — in combination with soaring fuel and fertiliser costs and supply concerns — has forced Mr Weir to reconsider cutting back on his planned 5000ha seeding operations.

“It’s just the cost of everything, and then when you add the cost of baiting mice — which is not something that you do every year — on top of it, it definitely makes the margins a lot tighter,” he said.

CSIRO researcher Steve Henry said conditions for mouse breeding were ripe for this time of year — a combination of rain left over after ex-tropical cyclone Narelle and a bumper 27Mt harvest last year has provided optimal conditions for a rodent plague.

“While mouse numbers vary across cropping zones, if present in high numbers they could have devastating impacts on crops being sown in the coming months,” he said.

“It is imperative growers get out of their vehicles, walk into their paddocks and get a good feel for what is going on in respect to current mouse numbers and activity.

“High stubble loads can hide the signs of mouse activity.”

Kulin cropper Barry West said he had thankfully seen no signs of mice activity but was ready with a bulk of bait traps sitting in the shed.

“We’ve been seeding canola, and even in the evening and in the dark I didn’t see — I’m sort of hopping across the paddocks — but no mouse holes, I haven’t seen one,” he said.

Emergency permits for ZP-50 have lapsed and growers are limited to ZP-25 baits.

Mingenew crop farmer Fiona Cosgrove explained how the cost of mouse baiting is set to be in the thousands of dollars, with 44-gallon drums used for spreading MOUSEOFF.

They plan to bait between 6000ha and 10,000ha of land, and it does get expensive.

“I’m not sure what the kilo rate is, but obviously it’s an extra run of diesel as well,” Ms Cosgrove said.

“So, it’ll be thousands of dollars.”

Ms Cosgrove said it’s “not as bad” at the moment but would likely see an uptick in dramas with wheat and barley once she starts spreading and sowing wheat crops.

She wants to assure others dealing with the mouse plague that “you’re not alone.”

Ms Cosgrove also deals with them in her own home — having 15 dead mice come out of a hole in her wall once exposed to baits in just one day.

“There are so many other things happening in the world. I mean, you put mice, with diesel shortages, with your urea shortages and all these other things like high cost of living, it just becomes a bit much,” she said.

“They don’t care how clean you are, they’re going to keep coming . . . just keep persevering and do what you have to do to get on top of them.”

Agronomist and Yuna grower Belinda Eastough believed mice numbers were building to levels not seen since the aftermath of 2021 ex-tropical cyclone Seroja.

Record canola planting and yields were also believed to create favourable conditions for the building mice population, with pod shatter harvested last leaving seed on the ground.

“We’re seeing up to 40 burrows per 100msq regularly across sandplain and loamy sand soil types, particularly on canola and wheat stubble,” Ms Eastough said.

“The rapid increase is in part due to record yields leading to higher than usual grain loss per hectare, the removal of sheep from the rotation resulting in minimal competition for food sources, and the weather conditions, as mice are now feeding on germinated radish and volunteer canola cotyledons and grain from harvest.”