Yellow spot monitoring vital

The West Australian

Results from the first year of the Stop the Spot campaign have shown increased national monitoring of yellow spot is essential.

Preliminary analysis suggests there may be an increase in the severity of the disease.

Yellow spot, known overseas as tan spot, causes national wheat crop losses of $212 million, plus control costs of $463 million a year. In hard hits areas, losses can exceed $30 a hectare.

The Curtin University and Grains Research and Development Corporation Stop the Spot initiative will continue this year, with the aim of significantly reducing the economic impact of yellow spot.

Growers have been urged to send in leaf samples of yellow spot, which will enable researchers at the Centre for Crop and Disease Management to develop genetic tools for breeders, monitor biosecurity risks and have an understanding of how the pathogen may be changing in the paddock.

CCDM's yellow spot progra leader Caroline Moffat said from the 189 samples received last year, it was clear yellow spot was a national problem.

She hoped for increased involvement from growers, especially from the Eastern States, because there was increased evidence of a change in virulence between Australia's western and eastern cropping areas.

Dr Moffat said one of the more interesting findings was that yellow spot isolates were recovered even from moderately resistant varieties.

"This just shows how vital it is that we continually monitor yellow spot," she said.

"Our ultimate goal is to develop tools and markers for wheat breeders which are tailored to current yellow spot strains, to help them release more resistant varieties for growers."

Dr Moffat said the 2014 findings showed evidence of undiscovered effectors - toxins secreted by the fungal pathogen that kill wheat cells and cause disease symptoms.

She said of the three effectors identified for yellow spot, ToxA, ToxB and ToxC, molecular analysis revealed ToxB was not found in any of the Australian yellow spot samples. However, ToxB remained a profound biosecurity threat.

"If ToxB-containing strains invaded Australia, yellow spot disease virulence would increase," Dr Moffat said.

"On the other hand, ToxA was found in all yellow spot samples received, reiterating the importance of using ToxA insensitive varieties, such as Mace and Magenta, in areas under high disease pressure."

Dr Moffat said most infected samples submitted to the Stop the Spot campaign in 2014 came from wheat-on-wheat paddocks, followed by wheat-on-canola then wheat-on-lupin.

Most samples were collected at the stem elongation growth stage.

For a full copy of the report on 2014 results or for information on how to submit samples for this year's campaign, visit stopthe spot.com.au.

The CCDM was set up at Curtin University last year to conduct cutting-edge crop disease research into genetics, breeding and fungicides, and to improve agronomy and farm management.

The GRDC has committed $30 million over five years to the $100 million CCDM as part of its long-term bilateral agreement with Curtin University.

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