September 13, 2002

TThe Grains Research & Development Corporation will join its cotton counterpart, the Cotton Research and Development Corporation, in backing studies of silverleaf whitefly populations in Central Queensland.

The new research, part of a coordinated control effort between the cotton, grains and horticultural industries, comes as a study by CSIRO entomologist and whitefly specialist Paul De Barro suggests the pest will be a problem in summer crops again this year.

Believed to have entered Australia from the United States, the whitefly totally destroyed soybean crops in Central Queensland last summer, and caused up to 50 per cent loss in irrigated peanuts.

It was found in soybeans on the New South Wales north coast and is believed to have the potential to damage crops as far south as Dubbo.

Dr De Barro¹s sampling of whitefly numbers in the Emerald Irrigation Area showed numbers 33 times higher than in August 2001, the beginning of Australia¹s first major outbreak of the pest in broadacre crops.

Dr De Barro found the whitefly distribution pattern in August 2002 to be similar to 2001, with numbers highest in horticultural areas and where weed densities, particularly of sow thistle, were also high.

With predictions of an ongoing El Nino weather pattern, he said the coming summer season was likely to follow the hot and dry conditions that so suited whitefly in 2001/2002.

Based on current understanding of the pest on Queensland¹s Central Highlands, the much larger numbers currently present suggested an outbreak with above threshold numbers being experienced over a much greater portion of the district earlier than last year.

GRDC Northern Panel chairman Ian Buss said the corporation would invest $117,000 and the Cotton Research and Development Corporation $35,000 in the spatial study by a Queensland Department of Primary Industries team led by entomologist Richard Sequeira.

Dr De Barro would act as a consultant to the study team.

Dr Sequeira said that, while the Australian whitefly control effort could draw on United States experience with the pest, scientists knew very little about whitefly habits and genetics in the Central Queensland situation.

"In the first 12 months our objective will be to find out where the whitefly populations are, how those populations develop, how they move around throughout the year and what crops they affect," he said.

"We need to know whether whitefly populations explode as what we call a point outbreak ­ as a result of a combination of environmental factors like the hot, dry weather last summer ­ or whether whitefly is likely to be a recurring pest into the foreseeable future.

"Biological control might be able to keep populations down in point outbreaks but, if whitefly is going to be a problem year in year out, we will be looking at different control strategies in addition to biological control, possibly requiring a crop free period under an area wide management program"

Dr Sequeira said the research team knew that cotton was potentially the biggest nursery of whitefly in the February/March period and he hoped the study would have progressed by then to the stage of being able to predict possible problems for peanut and pulse crops.

Mr Buss said the GRDC was supporting moves to have whitefly control chemistry available for the coming peanut season in Central Queensland.