The state's peak body for farmers is concerned mice could significantly impact this year's winter cereal crop, and gobble up seed as soon as it goes in the soil.
During a visit to the Dubbo region this week, NSW Farmers president James Jackson also said numbers of the rodents were "still huge".
"We've already had case studies where people have planted fodder crops and various crops and the mice have eaten it out of the ground," he said.
Advice from experts to farmers was to bait six weeks out from sowing and then again at sowing, he said.
"But we've seen for some people that has proved not to be effective, so they've still lost seed, valuable seed, $70 to $80 a hectare, if it's something like canola," he said.
The association president also reported of concerns about the cost of baits, and in some areas, supply.
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The cost of key chemical zinc phosphide was looking like it was about $17 per hectare, Mr Jackson said.
"I know we priced Mouseoff at Moree, and I think it was about $8.50/ kg," he said.
"It has gone up significantly in the last little while, there is a supply shortage especially with... sterilised grain, which they tend to like to use, so that price has gone up.
"We've seen down in Griffith, there's actually supply shortages down there, but my understanding is there is still bait being produced in South Australia.
"So it is still available, but the price is going north."
NSW Farmers started calling for a special purpose permit for using baits on bare or fallow ground in February.
"...the government finally did that and came good last week, so that's in time for the winter cereal crop, so that will improve the functionality of baiting," Mr Jackson said.
He said it was a valuable move, because it gave people "legal coverage" for using the bait in those circumstances.
But Mr Jackson repeated his call for $25,000 from the government for grants or rebates to help people pay for mouse control.
He said the government should stump up for health reasons, because mice could cause diseases, and for environmental reasons, because when mice were "hungry, they [would] kill anything".
"There is a reason that the government should intervene, because it is an extraordinary set of circumstances, the size of the plague," he said.
Concerns about the winter crop come after mice showed their form over summer.
"That's the other piece of the equation, I mean the sorghum crop, there's been a lot of sorghum crops or summer crops damaged," Mr Jackson.
"The hay, I've heard huge numbers of people say their whole hay supply, they've gone and done the right thing and filled the hay shed up with hay, and now it's just collapsed, all the strings are gone and they've just eaten the whole hay shed out.
"So people have absolutely been torched with their fodder reserves, building up for the next drought."
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