SOUTHEAST Australia is experiencing its worst attack of mice in 50 years.

About 1.5 million hectares of land has already been baited in a massive control program, yet the makers of the main registered product used for control predict the worst may be yet to come.

Favourable seasonal conditions have led a boom in mice numbers in recent months, causing big headaches for farmers, particularly those sowing their winter crops.

The Victorian Farmers Federation will meet the Victorian Government this week to discuss control measures.

Animal Control Technologies, the makers of Mouseoff, is seeking permission from state authorities to make bait with non-sterilised grain.

ACT managing director Linton Staples said orders were currently taking three to four weeks to fill.

The hold-up has been the amount of sterilised grain the company can get processed, despite using all three sterilising plants in Australia to maximum capacity.

To get around this hurdle, South Australia is this week expected to give permission for non-sterilised grain to be treated to produce Mouseoff.

The new product will be known as Mouseoff Econobait, and 200 tonnes will be produced for South Australia over the next fortnight.

The company has also asked authorities in Victoria, NSW and Queensland to allow the same. It will be about 15 per cent cheaper to merchants and the company expects this price saving to be passed on.

Dr Staples said using non-sterilised grain would boost bait production "substantially" and help overcome the four-week backlog in supplies. "I understand farmers are frustrated and concerned about their crops and the lack of supply of bait but using chemicals off label is illegal," he said.

The Department of Primary Industries has taken a more cautious approach and said its monitoring showed mice numbers were declining. However it admitted crops were still at risk.