Chickpea webinar scopes threat of ascochyta

Liz Wells July 11, 2024

Speakers gathered on-screen to field questions at the end of Tuesday’s webinar about ascochyta in chickpeas.

AUSTRALIA’S desi chickpea crop now in the ground is expected to be the biggest since the record year of 2016-17.

That year produced 2 million tonnes (Mt) from 1 million hectares, while this one is officially forecast by ABARES to yield 1.15Mt from 730,000ha, and unofficially forecast by industry at 1.5Mt from 800,000ha.

Due to a combination of unfavourable prices and seasonal conditions, crops in the intervening years have been small, and this showery season to date will see varieties with a quantified susceptibility to ascochyta blight put to the test.

With subsoil moisture across southern and Central Queensland and northern New South Wales generally ample to get the crop through to harvest, disease remains the biggest threat to yield and quality.

How to head that threat off was the subject of the Practical management of ascochyta in chickpeas webinar organised by the Grains Research and Development Corporation and held on Tuesday.

Tuning in were 105 people from the major growing areas, plus some from other mainland states and three from overseas.

“This webinar was actually initiated by some farmers out at Mungindi who thought it would be appropriate that we looked at some of the diseases associated with chickpeas with such a large chickpea crop being grown at the moment,” GRDC grower manager relations north Bob Ford said in introducing the session.

Facilitated by ICAN’s John Cameron, it included presentations from pulse specialist Paul McIntosh, Griffith University researcher Ido Bar, agronomists Ross Pomroy of Nutrien Ag Solutions, Dalby, and Rob Holmes of HMAg, Moree, and Agriculture Victoria plant pathologist Josh Fanning.

Test for seed

Area sown to chickpeas is estimated to be close to double the 400,000ha planted last year, and a surge in chickpea values brought about by India’s removal in early May of its longstanding tariffs is believed to have further shortened supplies of good-quality seed for planting.

With many chickpea crops now germinating, the health and vigour of the seedlings will soon become apparent.

“Healthy crops start with quality seed,” Mr McIntosh said.

While a shortage of planting seed was expected, it has not appeared to limit planted area, and Mr McIntosh said that may indicate some seed with less-than-ideal specifications has made its way to seeders.

“It’s not (like) the Australian Mungbean Association, where we screen all the seed before it gets into a bag; stocks have come out of nowhere.”

He said the traits of newer varieties, as outlined on the National Variety Trial disease ratings, also do not bode well for the possibility of a high disease-pressure growing season.

“Genetics have helped us in the past, but with these susceptibility ranges, we’re going to have to be on the ball.”

Even the newest varieties, the 2020-released PBA Captain, and the 2018-released PBA Drummond, are respectively rated as susceptible and very susceptible to ascochyta, putting them in line on that front with other commercially available desi varieties.

“None of them are really resistant, are they?

“As soon as these crops come out of the ground, we need to be spot on with looking for our disease.”

Mr McIntosh advised growers and consultants to watch for “ghosting” on parts of the leaf edge as an early indicator of ascochyta, which can spread to affect large parts of the leaf, stem, and pods.

Ghosting can also be caused by other factors including frost, excessive salt, and simazine sprays, so Mr McIntosh advised close inspection of leaves with a hand lens to see if concentric circles of pycnidia spores are present to indicate ascochyta.

The take-home message was that chickpea seedlings with 3-5 leaves should be sprayed with fungicide prior to rain coming their way to head off any possible breakouts of the fungal disease.

“These patches will spread with rainfall events,” Mr McIntosh said, adding that even 1-2mm can see spores spread from a hotspot.

“You’ll see it spread along rows, and alongside rows.”

“Spraying of registered fungicides should be done at the right time ahead of any rainfall event.”

As outlined by Dr Fanning, fungicides used to combat ascochyta can have a plant-back period of up to 56 days, which limits options for those wishing to follow chickpeas with a summer crop, and growers are advised to choose their fungicides with that in mind.

Light years lower risk

Mr Pomroy said a “very low incidence” of ascochyta currently existed on the Downs because of the small crops of the past two seasons, but vigilance was nonetheless required.

“We have got crops still emerging at the moment,” Mr Pomroy said.

“I can’t stress enough that you check multiple places in paddocks; it does start in hotspots.”

As outlined by Dr Bar, several new strains of ascochyta have been detected in growing regions, and Mr Pomroy said spraying with fungicide should ideally be done early if rain is coming.

“Pre canopy closure are the most important sprays.”

“Get on there earlier.

“It really is about prevention rather than cure when it comes to ascochyta as well as botrytis.”

Mr Holmes gave the perspective from northern NSW, where he said chickpea crops were still coming out of the ground amid showery conditions that were “highly conducive to disease”.

As with the Downs, he said northern NSW was looking at a relatively low-risk season due to the small crops of recent years.

Check the dashboard

A five-year project funded by GRDC into ascochyta blight in chickpeas is winding up this year, and has delivered considerable insights into the pathogens, hosts and environments associated with the Ascochyta rabiei fungus.

Dr Bar presented on the findings, and recommended use of the AscoDashboard, a database which also offers a scenario-based risk-prediction tool.

He said the pathogenicity of A. rabiei has increased significantly over the past five years, leading to reduced resistance of current chickpea varieties, and wet weather further increases susceptibility.

“Rainfall frequency and total amounts together with numbers of days at specific temperatures during the cropping season are important predictions for the emergence of highly aggressive isolates,” Dr Bar said.

Growers, consultants and researchers are also invited to submit images and details of ascochyta infections to Dr Bar and his team to help build the database.

GPA ready to answer call for permits

As Pulse Australia’s northern agronomist, Mr McIntosh was kept busy in the wet growing season of 2016-17 applying for permits to spray chickpeas with fungicides that include the northern region’s major pulse crop for regular approved use.

While Pulse Australia’s market-access functions have rolled into Grains Australia, its authority to apply for permits on behalf of industry has transferred to Grain Producers Australia.

Speaking with Grain Central this morning, Victorian grower and GPA board member and RD&E spokesperson Andrew Weidemann said he remained the contact point to lodge applications for fungicide permits with the Australian Pesticides and Veterinary Medicines Association.

“At GPA, my role covers R&D, which includes looking after permits for chemicals on behalf of industry,” Mr Weidemann.

“We’re very conscious that there are wet conditions in northern NSW and southern Qld, which has been inundated by rain, and we want to make sure there are appropriate fungicides available for growers to use.”

GPA and its members have this week been rocked by the news that GPA chief executive officer Colin Bettles has been seriously injured following an assault while visiting the United States.

After some days in an induced coma in a San Francisco hospital, Mr Bettles is now conscious, and all of us at the Centrals join with GPA and the wider industry in wishing him a full and speedy recovery.


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