No crowning achievement

Jo FulwoodThe West Australian

The stubble-borne pathogen that causes crown rot is silently but ferociously eating away at millions of dollars of WA wheat crops, and many farmers are unaware of its devastating impact.

A senior research scientist from the NSW Department of Primary Industries has urged WA farmers to focus greater resources on preventing crown rot, claiming much of the disease goes undiagnosed throughout the grain growing areas.

Steven Simpfendorfer, who leads a GRDC-funded project on crown rot, last week visited a series of trials run by the Department of Agriculture and Food. He said 2009 estimates of up to $7 million of grain losses attributable to the disease were grossly understating the problem in WA.

Nationally, it is estimated crown rot costs the grain industry up to $97 million each year.

Dr Simpfendorfer said growers were often unaware that poor plant establishment and low yields were the result of crown rot.

"Crown rot can have a particularly devastating effect in drier springs, with our national research showing up to 50 per cent yield loss can occur in wheat and barley crops as a result of this disease," he said.

"If growers don't control crown rot through stubble management strategies and crop rotation tactics, they are effectively rolling the dice with the seasonal finish."

Dr Simpfendorfer said in a wet year, the disease would wipe 5 per cent off cereal yields with the effects likely going unnoticed.

"But it's effectively taking the cream off the crop," he said.

Dr Simpfendorfer said since there was no post emergent fungicide control options for crown rot, growers should soil test any paddocks using PreDicta B if they suspected they might have the disease in summer, and make crop management decisions based on test results before sowing in 2016.

"We know that only 360 paddocks were soil-tested in WA for crown rot and other soil-borne diseases this autumn," he said.

He said many growers only looked for white heads on wheat plants, but the evidence of crown rot was often only visible as browning at the base of the plant stem, where the fungus clogs up the vascular system, prematurely "droughting" the plant.

The GRDC-funded trials, based at the DAFWA Merredin and Wongan Hills research facilities and co-ordinated by plant pathologist Daniel Hüberli, are investigating which wheat varieties are more susceptible to crown rot, and what strategies growers can employ to minimise the impact.

Dr Hüberli said 12 varieties, artificially inoculated with the disease, were showing visual differences in responses to the disease before harvest.

"We know Emu Rock is moderately susceptible to the disease, and Mace is highly susceptible to the disease in our yield results from last year, and our trials this year are showing stark contrasts between the infected plots infected, and the uninfected control plots," he said.

Varietal resistance ratings against crown rot have now been added to the current WA wheat variety guide.

Dr Hüberli said growers with paddocks that tested positive for crown rot should look at an integrated strategy, including using break crops the following year to reduce the impact of the disease.

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