Testing soil for diseases before potatoes are planted

Australian scientists at SARDI are making major strides in diagnosing potato diseases before the potato crop is planted.

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Australia’s $500 million-plus potato industry will benefit from new DNA tests that can quickly and accurately measure major disease-causing agents.  The tests developed by scientists from South Australian Research and Development Institute (SARDI) identify pathogens that can threaten the supply and quality of potatoes.

Damage and losses caused by potato diseases represent one of the most significant production challenges facing the potato processing industry in Australia costing processes and growers more than $80 million a year in yield losses and rejections.

International collaboration is underway to explore how diagnostic tests can be used as a decision-making tool for growers to assess the risk of disease before crops are planted.

The research success is part of a multi-pronged research drive through Phase 1 of the Australian Potato Research Program, funded by Horticulture Australia Limited using the processing potato levy and voluntary contributions from the New Zealand Institute of Plant and Food and Agriculture and Agrifood Canada, with matched funds from the Federal Government.  SARDI, the Department of Primary Industries Victoria and the University of Tasmania/Tasmania Institute of Agricultural Research have provided in-kind support.

Five years in the making, the DNA tests measure on seed and in soil, the pathogens for powdery scab, common scab, Rhizoctonia and a damaging strain of root knot nematode.

SARDI Sustainable Systems Chief, Dr Kathy Ophel Keller says the relatively straight-forward tests identify what and how much of a pathogen is present on seed and soil.

“The information provided will become a very powerful management tool for farmers and researchers,” she said.

“Research teams around the country are now working to link how the DNA values for each pathogen translate to disease risk under different growing conditions with grower groups.  Once we know this, it will be a major step forward for growers to be able to assess the disease risk before sowing potato crops to consider their options to prevent or reduce crop losses.” 

SARDI pathologist Robin Harding said a big advantage with DNA testing is that one sample can be used to test for a range of diseases, so it significantly reduces the required time to test for diseases, and information is available within weeks. 

Potatoes diseases are a worldwide problem.  A second phase of research has begun linking researchers from the United Kingdom, New Zealand and South Africa to explore how to use diagnostic tests to assess disease risk and practical application in the field.  International partners in Phase 2 include Horticulture New Zealand and New Zealand Plant and Food Research and the Potato Council UK program - involving researchers from the Scottish Crops Research Institute, Scottish Agricultural College and the Food and Environment Research Agency UK.

So far the diagnostic approach has been tested on grower field sites in South Australia, Victoria and Tasmania, giving researchers across the country new insights into the relative effectiveness of different control methods.