POISON baits will be deployed again in Victoria's grain belt to combat a mice plague now in its third year.
While mouse numbers are far less than last season, some growers of canola and legumes have made an early decision to bait where pockets of the plague remain.
Cereal growers will make their own decisions in the next few weeks when sowing begins.
Experienced Mallee scientist Ivan Mock believes it is the widespread use of paddock-wide baiting that may have prolonged the plague.
"It hasn't been been allowed to peak and die out as past plagues have done," Mr Mock, a former research agronomist at the Walpeup Agricultural Research Institute, said.
Mr Mock said large-scale poison baiting had really only been utilised for the current plague. "It just seems the numbers haven't dropped away to nothing as you would expect they would in a normal plague.
"Because the baiting has kept the number low they've not been allowed to reach a peak."
Mr Mock said numbers had fallen away this season but were still causing problems and would "need to be baited again in some stubborn pockets".
He said the end of the long drought could also be a reason for the longevity of the plague.
"We came out of 10 poor seasons and now we've had two good seasons ... (there's) plenty of feed around for them."
Department of Primary Industries program manager, natural disasters and emergencies, Banjo Patterson, said field surveys conducted by the department this year had found "significantly lower numbers of mice compared to last year".
"DPI undertakes surveys at more than 150 sites in the Wimmera and Mallee," Mr Patterson said. "This time last year we found high numbers of mice at 37 per cent of those sites compared to only 3 per cent this year."
Mr Patterson said there was no evidence to suggest that baiting had prolonged the presence of mice.
"Other factors are more likely to contribute to their on-going presence, such as sufficient food supply and the availability of shelter."