Australia
November 20, 2014
Southern region grain growers are advised to have their soils tested ahead of next year’s barley plantings in the wake of this year’s yield losses caused by disease.
CCN on Scope barley roots. Photo: Brad Bennett, AGRIvision
Soil-borne diseases cereal cyst nematode (CCN) and crown rot have had a significant impact on barley yields, particularly on the lighter, sandy soils of Victoria, South Australia and southern New South Wales.
Grains Research and Development Corporation (GRDC) Southern Regional Panel member, Rob Sonogan (pictured), says to avoid further yield losses next season, it will be critical to test disease levels in paddocks earmarked for sowing.
“If disease levels don’t break down over the summer, crops will be at risk next year, especially if growers select new varieties that aren’t disease-tolerant,” said Mr Sonogan, who is also an agronomic consultant based at Swan Hill (Victoria).
“Back in the 1970s and ’80s, CCN was rampant but the breeding of tolerant and resistant varieties and the uptake of these had reduced the problem. You may only need to grow one non-resistant crop in one season to have CCN raise its head again.”
Growing susceptible varieties can result in an escalation of disease levels, as was seen this season in some crops where yields were cut to a quarter of their potential due to CCN. Scope barley is especially susceptible to CCN.
Mr Sonogan encouraged agronomic advisers to have their clients’ properties soil tested, preferably in February next year, to determine disease and risk levels.
“Testing will help inform growers to choose the most appropriate crop variety and hopefully reduce the likelihood of yield losses in 2015.”
Mr Sonogan recommended that PreDicta B® DNA-based soil testing be undertaken to assist in identification of soil-borne diseases prior to seeding. Grain producers can access PreDicta B® via agronomists accredited by the SA Research and Development Institute (SARDI) to interpret the results and provide advice on management options to reduce the risk of yield loss.
PreDicta B® samples are processed weekly from February to mid May (less frequently at other times of the year) and tests are for most of the soil-borne diseases of cereals and some pulse crops, including CCN, crown rot, rhizoctonia root rot, take-all, Pratylenchus thornei, Pratylenchus neglectus, stem nematode and blackspot.
About 1500 agronomists and consultants across Australia have been PreDicta B® accredited through SARDI’s annual Agronomist Root Disease Risk Management training courses, which are supported by the GRDC.
The latest round of training courses began in Adelaide (SA) on November 20. Another course in the southern cropping region will be held in Bendigo (Victoria) on December 11.
SARDI senior research officer Shawn Rowe says the one day courses are an opportunity for new and experienced agronomists to refresh their skills and knowledge to better manage soil-borne diseases. The courses in Adelaide and Bendigo will focus on rhizoctonia root rot, root lesion nematodes and crown rot, and discuss the importance of sampling on the row of the previous crop.
Accredited agronomists have, in addition to a hard copy, access to an electronic version of the Root Disease Risk Management Resource Manual that has now been reformatted for easier use on mobile devices. To register for the courses, visit www.orm.com.au, or for further information contact Shawn Rowe, phone 0477 744305 or email shawn.rowe@sa.gov.au.
Meanwhile, Mr Sonogan said rotation of crops to create a disease break also needed to be factored into next year’s sowing program considerations.
And he said while it was now too late in the season to be physically assessing crops for CCN and other root diseases, this activity should be undertaken during next year’s growing season if crops appear disease-affected.
“I urge consultants to go out into crops with a shovel and a bucket of water. Dig up some plants, wash off the soil and inspect the roots.”
In the case of CCN, roots are thickened, shortened and distinctly ‘knotted’ with lots of small laterals. In spring, white pinhead-sized nematode cysts are visible on roots when the soil is carefully washed off.
Having examined the roots of crops during the 2014 growing season, Mr Sonogan said he observed non-typical expression of CCN disease this year.
“The root system of affected plants in some cases went deep into the soil profile – up to 25 centimetres – and there was clumping of the roots and cysts at different intervals. I’ve not seen this before; it appeared the roots were attacked by nematodes but would persist and continue to grow, only to be attacked several times further down in the soil profile.
“When I first dug up these plants and inspected them it didn’t look like CCN so it’s really important that we undertake thorough inspections and get a second opinion if we’re not sure. It’s critical to know what diseases are in the soil so we can put in place measures to reduce the risk in following seasons.”
In the meantime, a suite of new national GRDC programs has been launched in a fresh attack on root and crown diseases, which collectively cost Australian growers hundreds of millions of dollars in lost production and control costs each year.
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