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A CHANGE in the ascochyta blight (AB) pathogen is causing concern for the chickpea industry.
The mutation to the AB pathogen means all chickpea varieties have been downgraded at least one level of resistance in terms of official ratings.
It means there are now no commercially available chickpea varieties with a resistant or moderately resistant rating to AB in Victoria or South Australia, while northern Australian chickpea lines are also under pressure.
South Australian Research and Development Institute (SARDI) pulse pathology principal research scientist Jenny Davidson urged all chickpea producers in Victoria and South Australia to closely monitor crops this season as resistance has broken down.
“All current chickpea varieties in these two states are now rated as either susceptible to moderately susceptible to infection,” Dr Davidson said.
DPI NSW pathologist Kevin Moore, Tamworth, said there was pressure on resistance in the north too.
He said trial work in northern NSW done using the popular Hat Trick variety highlighted the breakdown in resistance to AB.
“Our untreated plots of Hat Trick lost 35pc of yield compared to the control in 2010, a similarly wet year to last year.
“Trial data from last year shows 98pc yield loss on the Hat Trick plots that did not receive a fungicide.”
Agriculture Victoria pulse breeder Jason Brand said the AB pathogen had virulently changed over 2015 and 2016 meaning previously resistant chickpea varieties were now exposed to the potentially damaging fungal disease.
He said the key was for farmers to be informed.
“It is something you can keep on top of with a fungicide program, but the problem would be if you just left the crop thinking you had resistance and it got smashed by the new strain.”
Dr Davidson said AB infection is more severe in high and medium rainfall zones, but added effective disease control strategies are also required in low rainfall regions as severe disease outbreaks can occur in these environments during wet seasons, as was the case in 2016.
She said farmers would have to budget for multiple applications of fungicides.
“Moderately susceptible varieties will generally require three to four strategic fungicide sprays ahead of rain events, offering two to three weeks of protection, starting at six to eight weeks post-sowing,” advised Dr Davidson.
“Susceptible varieties will require regular fungicide sprays every two to three weeks throughout the growing season in front of rainfall events.”
Dr Moore said there were concerns about the continued efficacy of fungicides.
“At present they work and they are relatively cheap, but there is the prospect for fungicide efficacy to crash, and crash hard.
He said the industry was now trying to assess how the AB resistance had occurred.
“We don’t know whether it occurred systematically in response to the use of varieties with improved resistance or whether it was simply a chance mutation.
“A Grains Research and Development Corporation (GRDC) project is looking into the changes in the pathogen and hopefully that will provide us with some answers.”
From the farmer perspective, AgForce grains section president Wayne Newton said while overplanting of chickpeas was a concern for some growers, generally farmers were happy to rely on fungicides for disease control.
“In southern Queensland people are thinking about the rotation and where they need to give chickpeas a spell because of rising disease pressure,” he said.
“However, in places like Central Queensland, where the winter is normally really dry, they are not as worried with the disease risk and you will see more chickpea on chickpea rotations.”
Mr Newton said over the past couple of years farmers had generated good gross margins from chickpeas even with up to eight fungicide applications included in the input costs.
“They feel they have managed the problem with fungicide, which is not that expensive given the prices for chickpeas, so at this stage some people are comfortable with pushing their rotations harder than is strictly recommended.”