Elders senior agronomist Dave Richards, who works in the Bundaberg region, was the first to report the rust problem.

"Soybeans are showing great promise in our cane rotations and with prices of $700 per tonne and above, the area planted could well double this season,” Mr Richards said.

"I am very concerned about what may happen to our summer soybean planting if we don't break the disease cycle and control the volunteer soybean plants now."

Mr Richards said an on-going shortage of fungicides throughout Australia could well compound the problem .

Mancozeb is the only fungicide registered in Australia for the control of soybean rust, and growers are urged to consider planning their summer season requirements.

DPI&F soybean industry development officer, Julie Ferguson, said soybean rust favours cool moist conditions, temperatures between 15ºC and 28ºC, and needs free moisture on the leaf surfaces for at least six hours for infection to take place.

Ms Ferguson said rust is caused by Phakopsora pachyrhizi, a fungal disease that is identified by small brown spots with yellow haloes.

Ms Ferguson recommends that growers planting soybeans in 2008-09 do not plant seed retained from previous seasons.

“Please purchase industry approved seed, which has undergone independent audits during the growing season,” she said.

“Rust can occur on all leaves on soybean plants.

“Spots develop on the upper surfaces of the leaves, and light-brown raised pustules, containing the spores, develop on the underside of leaves below the spots.

“Rust can develop rapidly during showery weather, causing leaf drop and significant yield losses,” Ms Ferguson said.

Ms Ferguson urges growers to check old soybean ground and control volunteers to break the disease cycle.

“Rust will survive in a range of native legumes, however the high incidence of rust in the coastal regions last season means volunteer soybeans are now likely to be an important host,” she said.

“Many growers are currently preparing country for cane planting, which should eliminate any remaining soybeans, however fallow country and area double cropped into cereals are a major concern.”