Research and grower experience have confirmed the role of varieties and good agronomic practices in helping manage fusarium wilt in cotton.

Queensland Department of Primary Industries and Fisheries principal plant pathologist Joe Kochman said southern Queensland cotton growers felt fusarium wilt had less impact on the 2003-2004 cotton crop than in previous years.

Dr Kochman said that while dead stunted and wilted plants were less obvious in many crops, stem cuts showed brown discolouration and indicated up to 55 per cent of plants had been infected by the fungus.

He said the season had been somewhat unusual, with cold days in October and November, followed by good growing conditions.

There were and plantings as late as mid November, rather than the traditional time of mid October and many timely rainfalls.

The rain and good growing conditions for most of the season meant that many crops were less stressed this year with less disease being expressed.

"The message seems to be that if you plant the right variety at a time to avoid seedling stress, fusarium will have less impact on the crop."

Dr Kochman said his team was analysing results from almost 8000 trial plots at Graham Clapham's property Cowan, in the Cecil Plans district, to assess performance of varieties and lines in an area where fusarium wilt was severe.

The trials were done in conjunction with the Cotton Research and Development Corporation, the Australian Cotton Cooperative Research Centre and the Cooperative Research Centre for Tropical Plant Protection.

The trials included new and near release varieties and lines from Deltapine and CSIRO including the latest transgenic types.

As in commercial crops, plants in the trials showed signs of cold shock in October and November, resulting in poor seedling establishment.

He said the encouraging news was that there were better fusarium resistant varieties becoming available that would have an important role in high-risk areas where the disease was known to occur.

"The trials confirm that it's possible to keep fighting fusarium with resistant varieties," he said.

Dr Kochman said there were no reports of fusarium wilt from new areas during the season but there were new outbreaks of the disease in most of the previously affected areas.

The fusarium fungus could survive in the soil for more than a decade and cause major plant and yield losses in susceptible cotton varieties.