Early prediction of soilborne disease could cut losses
Researchers are working to cut yield losses in Western Australian grain crops by improving the detection and analysis of soilborne (root) diseases before they occur.
Supported by the Grains Research and Development Corporation (GRDC), the research is being conducted by the Department of Agriculture and Food (DAFWA) and the South Australian Research and Development Institute (SARDI).
DAFWA project leader Martin Harries said soilborne diseases were a major cost to the cropping industry, estimated to cause losses in WA of about $100 million per year in cereals alone.
“There is scope to reduce these losses through management actions – such as choice of crop type or application of fungicide seed dressings - if these pathogens can be more accurately detected and quantified prior to sowing,” he said.
Mr Harries said researchers were intensively calibrating, for WA conditions, the DNA-based soil testing service PreDictaB, provided by SARDI.
“The risk management service has been operating for more than 10 years,” he said.
“During this time about 16,000 soil samples have been analysed from Australian cereal growers, influencing management practices on up to 100,000 hectares of cropping land each year.
“But while the test is well calibrated for South Australia and Victoria, it has not yet been intensively calibrated across WA cropping zones – as a result it is not used extensively in WA.
“Calibration of the test, by taking into account WA environmental factors and soil types, will improve PreDictaB’s usefulness as a diagnostic tool to predict potential losses from soilborne diseases.
“Currently we can detect if inoculum – of most of the important diseases - is in the soil, but what we are trying to do is use WA environmental information to help predict how bad the expression of the disease could be.”
Mr Harries said the other important part of the research was to include Pratylenchus teres in the suite of pathogens detected by PreDictaB.
“P. Teres is a very damaging species of root lesion nematode and is the second most common species in WA,” he said.
Mr Harries said the research was comparing the level of pathogen DNA in the soil to the root rot symptoms that actually occurred across 184 paddocks from Yuna in the north to Ravensthorpe in the south.
“Initial monitoring of these paddocks detected rhizoctonia DNA in a high number of paddocks – 51 per cent of those tested,” he said.
“The DNA levels detected indicated that, on average, the potential yield loss in these paddocks was up to 12 per cent.”
SARDI researcher Grant Poole has analysed early data and presented preliminary findings at the Australasian Soilborne Diseases Symposium in 2012.
“Across WA there are a range of environments that influence disease expression,” Dr Poole said.
“These need to be taken into account for WA when developing any new calibrations for PreDictaB.”
Collaboration between DAFWA and SARDI will continue, to ensure that reliable and useful results are delivered to WA growers.
Calibration of PreDictaB in WA has included collaboration with the DAFWA-led research project ‘Putting the Focus on Profitable Crop and Pasture Sequencing in WA’.
This project is the WA component of the GRDC’s national Crop Sequencing Initiative, established to improve understanding of the risks and benefits associated with including a broader range of crop types, and end uses, in farming system.
PHOTO CAPTION: DAFWA project leader Martin Harries and technical officer Jo Walker testing paddocks in WA.
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