October is peak breeding month for Australian country mice. Australian farmers are partly blaming shortages of zinc phosphide mouse bait in Australia on environmental opposition to the use of mouse bait, resulting in a run-down of stocks. Some pressure was alleviated earlier this week when a shipment of 50 tonnes of prepared mouse bait, enough totreat around 50,000 ha of crops, arrived in NSW.

"NSW Agriculture has been searching out alternative sources of this zinc phosphide mouse bait after supplies in Australia ran out," NSW Agriculture Minister Richard Amery announced. Australian farm officials are now scouring the world for more, with incoming quantities sourced from the United States, India and Egypt. Singapore and Japan are possible sources. With timing vital, the bait is being air-freighted in instead of normal shipping by sea.

"There's an urgency to get the product in," Glenn Dalton, director of grains of New South Wales Farmers Federation said. Bait is still arriving only in dribs and drabs and is not enough to satisfy demand, he said. About 100,000 ha of NSW crops will have been treated by next week, ahead of the peak breed.The race is on to get in enough to treat the remaining 200,000 ha in the next couple of weeks. The past week or two had produced growing evidence of mice damage in central-western NSW crops, "very significant" insome areas, Dalton told Reuters on Friday. "This is an unusual year. Mice damage was happening but people were not aware there were that many mice around and were probably slow to react for that reason." Dalton estimates that 250,000-300,000 ha in NSW now has a severe mouse problem, with the plague extending much more widely on a lesser scale . "With a generational build-up of mice numbers, it's quite likely that that will get more severe from October," he said. Dalton finds the bottom line question of how much of the crop will be lost an "imponderable".