A NEW fungicide may give grain growers better control of cereal rust.

Nufarm Australia is in the final stages of the registration process for the fungicide Opera, a co-mixture of pyraclostrobin and epoxiconazole.

Epoxiconazole is the main ingredient of the Opus fungicide.

Nufarm is marketing Opera on behalf of its manufacturer, BASF.

Nufarm Western District manager Philip Jobling said the company hoped registration would be approved in time for use on next year's crops.

He said Opera was being registered in Australia for the main cereals.

He said pyraclostrobin was already widely used overseas and approved for horticultural crops in Australia.

"But this is the first entry into the grain market in Australia," he said.

Opera was used in fungicide trials at the Southern Farming Systems site at Inverleigh.

Speaking at last week's SFS field day, Mr Jobling said pyraclostrobin was a second-generation fungicide from the strobilurin class of chemicals.

He said pyraclostrobin worked well as a preventative treatment against fungal diseases, particularly cereal rust.

"It's the Rolls Royce preventative," he said.

Epoxiconazole is a fungicide from the triazole class of chemicals.

Mr Jobling said it was best suited to attack recent disease infections.

Combining both classes of fungicide gave a better ability to attack diseases.

"Pyraclostrobin and epoxiconazole is the most widely used fungicide package in the world," he said.

Mr Jobling said Opera suited long-season varieties, especially in higher rainfall zones.

The best time to spray it on wheat was at flag leaf emergence, or Growth Stage 39.

"In a longer-season variety, that may extend to head emergence," he said.

"In barley, the best time to apply it is at GS37, or before the flag leaf emerges."

Mr Jobling said that in some Western District crops, it was still worth considering spraying in both cereal crops at GS32, or early tillering.

"That is often when the first disease challenge comes to the crop," he said.

"If you have a strong, healthy crop and you get a disease challenge at the start of the warm weather around tillering, Opera will keep the crop clean and ensure it doesn't turn it into a big orange paddock."

Mr Jobling said spraying wheat at GS39 would give four to six weeks of strong preventative action against fungal diseases, possibly longer.

He said spraying at GS32 gave only four weeks of preventative effect because new leaves emerged after that stage.