Threat of two-year NSW mouse plague

NSW Farmers say the out-of-control mouse plague will cut the value of the state's winter crop by one billion dollars as the eight-month long scourge continues to worsen.

The government-funded Mouse Alert website indicates sightings have doubled since March, with a growing number of mice being sighted in and around Sydney.

NSW Farmers Vice President Xavier Martin says farmers were abandoning some paddocks and couldn't defer sowing winter crops any longer, while researchers warn that "without a concerted baiting effort in the next few weeks this could easily turn into a two year plague event".

The $50 million NSW government assistance package announced last week isn't helping.

"The state government's assistance package is impractical, dysfunctional and weeks away, which is not helping farmers who need support right now to drive mouse numbers down and break this horrible unrelenting cycle," he said on Wednesday.

"After more than eight months of battling growing mouse numbers farmers are still waiting for state government assistance to hit the ground and offer some practical support to our farming community," Mr Martin said.

The NSW government said on Thursday it had secured 5000 litres of the super deadly rodent poison bromadiolone - enough to treat about 95 tonnes of grain - offering to provide it for free once federal authorities approve its use.

But farmers are concerned about the poison's possible effect on farm dogs, piggeries and other animals.

NSW Farmers say the simplest, safest and most timely way for the government to help farmers is to provide rebates of up to $25,000 per farm business to cover 50 per cent of the cost of zinc phosphide bait.

While NSW Farmers initially welcomed the state government's assistance package, Mr Martin says it's now apparent that the provision of "free baits for farmers" are still dependent on federal approval which could be weeks away.

"Each day we delay in taking effective action to control these mice will increase economic losses and the likelihood we will still be battling mice come Christmas time," Mr Martin said.