Genetically modified canola may be busted in Australia, but GM cotton is booming -- new Bollgard II varieties, doubly protected against bollworm attack, will make up 60 per cent of Australia's total crop in season 2004-05.

The crop that anti-GM activists ignore, and state governments prefer not to mention, continues to be an exemplar of the promise of GM agriculture.

CSIRO Plant Industry cotton breeder Dr Greg Constable said Bollgard II varieties were likely to account for up to 80 per cent of the national crop in season 2005-06, with individual farms planting up to 90 per cent of their crop acreage to GM cotton.

Season 2003-04 marked the demise of the Ingard cultivars that revolutionised Australia's cotton industry after their introduction in 1996.

Ingard cottons -- the first, and so far, the only GM crop planted commercially in Australia -- were protected by a single Bt insecticide transgene. They have delivered sterling service, cutting synthetic pesticide use in GM cotton fields by 50 per cent since their introduction.

Because Ingard cultivars were theoretically vulnerable to emergent, Bt-resistant strains of Helicoverpa caterpillars, Australia's worst cotton pests, the industry voluntarily limited plantings to no more than 30 per cent of the total area of the national cotton crop, and to plant a specified area to refuge crops to attract wild-type moths to genetically swamp any Bt-resistant strains that might emerge from GM fields.

The strategy has been extremely successful - no resistant Helicoverpa bollworms have been detected in the field in the six years since Ingard varieties were introduced.

Constable said seed companies' orders for seed, which will close on July 31, indicated that Bollgard II cultivars would account for 60 per cent of Australia's total cotton acreage in the coming season, up from 16 per cent in 2003-04, and 5 per cent in the introductory season, 2002-03. The acreage might have been higher if more seed had been available after the drought-affected 2003-04 season.

The orders attest to farmers' confidence in the new Bollgard II varieties developed by CSIRO and other Australian seed companies, according to Constable.

But the biggest attraction is that Bollgard II cuts consumption of expensive synthetic pesticides by 80 per cent, relative to non-GM cotton varieties. Constable said farmers preferred GM cotton because it minimised the high costs of aerial spraying with synthetic pesticides. When high winds prevented aerial spraying of non-GM crops, farmers could rapidly lose control over pests, and suffer heavy crop losses.

Constable said trial plantings in the Ord River irrigation region had shown that both Ingard and Bollgard II varieties performed just as well in the tropics, where pest problems are much greater.

In the early 1970s, massive plagues of insecticide-resistant pests forced the cotton industry to abandon the Ord River irrigation area and re-establish in temperate NSW. Without the advent of Bt-protected GM cotton, the industry might also have collapsed in eastern Australia.

The way is now open for cotton to be grown in Australia's tropics, where there is abundant water. Lack of water is now the major constraint on production in eastern Australia.

But the Northern Territory government announced this year that it would not allow the industry to expand into the territory, while the WA government's moratorium on all genetically modified crops would prevent cotton's return to the Ord River irrigation scheme -- which was originally developed, at enormous cost to taxpayers, to grow cotton.