Sydney  - As if the worst drought in a generation wasn't bad enough, wheat farmers in Australia's south-east corner were Friday warned that locusts could decimate this year's winter harvest.

"We expect to see locusts swarming in the next week or so and members of the community especially those in northern Victoria, who have not previously seen locusts, need to be prepared for their arrival," Victorian Agriculture Minister Joe Helper said.

"It's still vital that landholders report locust sightings as swarming locusts are capable of laying eggs that can hatch as early as within two weeks, if ideal conditions prevail."

The long dry spell has cut the forecast for the winter grain crop by almost 9 per cent to 23 million tons. Earlier in the year, estimates for a crop that will be harvested from October were as high as 26 million tons but low rainfall forced the projection to be scaled back.

Wheat sowing has risen by 13 per cent to a record 14 million hectares and the wheat harvest should trump last year's by 10 million tons. Last year's harvest came in at 13 million tons. (dpa)