Soil disease database a profit-protection tool

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The DNA-based tool PreDicta® B is providing an unprecedented level of data on the impact of soil-borne diseases, helping to set evidence-based priorities for future research

Key points

  • PreDicta® B allows growers and advisers to prioritise the most important disease risks in their paddocks and select the most effective management options to mitigate those risks
  • The data gathered through PreDicta® B testing has the power to clearly show the cost of soil-borne diseases to Australian growers and guide the GRDC towards the most economically effective solutions

Once symptoms of a soil-borne disease such as crown rot, root lesion or cereal cyst nematode appear in the paddock it is too late for growers to prevent crop losses. Fortunately, today, the world-leading molecular technology of PreDicta® B means growers can identify paddocks at risk of diseases before sowing and implement strategies to prevent losses.

PreDicta® B is also a powerful research tool that is enabling researchers to accelerate the development of control strategies for industry. The vast database of test results provides researchers with the ability to calculate the economic impacts of these diseases and identify priorities for research.

But what exactly is PreDicta® B?

Offered to growers nationally through a network of accredited agronomists, PreDicta® B is a DNA-based soil-testing service to help grain producers identify which soil-borne pathogens pose a significant risk to their crops. Most samples are processed in the few months leading up to sowing at the Molecular Diagnostics Centre (MDC) at the South Australian Research and Development Institute in Adelaide.

Grower value

The world-leading technology developed by the MDC in Australia is a proven, fast and cost-effective way for growers to find out what threats lurk in their soil. Using this information to make informed planting decisions has allowed growers to reduce the impact of soil-borne diseases in Australia.

Many growers and their advisers are using the disease risk information to make major economic decisions about crop rotation, including whether crops such as durum wheat can be safely grown. Others are studying disease trends over time to see how their rotational choices affect disease risk (see The tool that puts a handle on soil pathogens).

On a national scale, the potential cost of soil-borne diseases could be much higher if growers did not have access to the information from PreDicta® B. In 2009 a GRDC study estimated the potential cost of crown rot in wheat to be as high as $434 million per annum, but with appropriate management and favourable seasons the actual cost is just $79 million. Similar figures for other soil-borne diseases show that by understanding the risks and choosing the best available management options growers can reduce the impact of these diseases (Table 1).


Cost in 2009 (A$ million)

Root lesion nematode
Pratylenchus neglectus$226$73
P. thornei$167$50
P. quasitereoides$34$9
P. penetrans$10$2
Crown rot$434$79
Rhizoctonia root rot$165$59
Cereal cyst nematode$547$57
Common root rot$108$30

Source: Murray & Brennan (2009) The current and potential costs from diseases of wheat in Australia, GRDC

Research trials are also contributing to the national database. The MDC’s national molecular diagnostics project has partnered with the national crown rot and nematology projects to validate the PreDicta® B test in field trials and establish risk categories for growers. In turn, researchers are using the technology to measure the effectiveness of different management options.

Economic impact

When mapped, the data provides an insight into the distribution and incidence of soil-borne diseases across Australia. For instance, the maps show that the most widely distributed species of root lesion nematode (RLN) is P. neglectus (Figure 1), with higher incidence in the west and south of Australia, while P. thornei is more common in the eastern states (Figure 2) and P. quasitereoides is almost exclusively found in the west (Figure 3). Similar maps are available for other diseases on the PreDicta® B website, including crown rot (see Reliability proven).

More importantly, information is power and this dataset is providing a clear picture of the distribution and numbers of organisms and is revealing the effects of changes to farming systems. Researchers are now able to identify the diseases with the biggest impact on Australian production and set priorities for future research into breeding resistant varieties and identifying management techniques to reduce their impact on-farm.

The potential of the PreDicta® B test to provide economic impact data is seemingly unlimited, with new tests being added every year (see Soil tests reveal the big picture).

GRDC Research Codes DAS00137, DAV00128, DAN00175, DAW00245

More information:

Dr Alan McKay, 08 8303 9375,

PreDicta® B Website