PreDicta B

Cereal root diseases cost grain growers in excess of $200 million a year in lost production. Much of this can be prevented.

PreDicta B (B = broadacre) is a DNA-based soil testing service that identifies which soil-borne pathogens pose a significant risk to broadacre crops prior to seeding.

The test has been developed for cropping regions in southern Australia.

PreDicta B includes tests for:

  • Cereal cyst nematode (Heterodera avenae).
  • Take-all (Gaeumannomyces graminis var tritici (Ggt) and G. graminis var avenae (Gga)).
  • Rhizoctonia barepatch (Rhizoctonia solani AG8).
  • Crown rot (Fusarium pseudograminearum and F. culmorum).
  • Root lesion nematode (Pratylenchus neglectus and P. thornei).
  • Stem nematode (Ditylenchus dipsaci).
  • Blackspot of peas (Mycosphaerella pinodes, Phoma medicaginis var pinodella and Phoma koolunga).

Know before you sow Northern (PDF 706.1 KB)

Know before you sow Southern (PDF 675.0 KB)

Access PreDicta B testing service

You can access PreDicta B diagnostic testing services through a SARDI accredited agronomist. They will interpret the results and give you advice on management options to reduce your risk of yield loss.

We process PreDicta B samples weekly between February to mid-May (prior to crops being sown) every year.

These timeframes help us assist you with your cropping program.

PreDicta B is not intended for in-crop diagnosis. See our crop diagnostic webpage for other services.

2016 PreDicta B certification courses

We run 1-day courses to:

  • certify agronomists in use of the PreDicta B testing service run by SARDI
  • educate new and experienced agronomists about how to better manage soilborne diseases.

Completing the course will give agronomists:

  • access to the PreDicta B service
  • access to the e-version of the Root Disease Risk Management Resource Manual
  • a PreDicta B soil corer valued at over $100.

Courses focus on the 3 main diseases in each region selecting from:

  • rhizoctonia
  • root lesion nematodes
  • crown rot.
  • take-all

Courses will begin at 8.30am and finish around 4.00pm.

Contact Dr Alan McKay for more information.

Download the course flyer (PDF 220.5 KB)


Dr Alan McKay
Phone: (08) 8303 9375
Mobile: 0419 842 952

Send your sample to
Postal Address:
Locked Bag 100
Glen Osmond SA 5064

Courier address:
SARDI Molecular Diagnostics Group
Plant Research Centre
Gate 2B
Hartley Grove
Urrbrae SA 5064

Change to pre-sowing soil sampling protocols for PreDicta B

In 2013, some PreDicta B samples did not adequately detect crown rot risks. Consequently, significant crown rot occurred in some cases where PreDicta B indicated a low risk.

Preliminary research shows addition of small pieces of stubble significantly increases reliability of detection. Research to refine this strategy is continuing.

The interim recommendations for collecting PreDicta B soil samples in the Southern and Western regions are:

  • Collect 3 cores (1 cm diameter X 10 cm deep) from each of 15 different locations within the target paddock or sampling zone.
  • Take cores from along the rows of previous cereal crop if visible and retain any stubble collected by the core.
  • Add one piece of cereal stubble (if present) to the sample bag at each of the 15 sampling locations. Each piece should include the segment from the crown to the first node (discard material from above the first node).
  • Maximum sample weight should not exceed 500g.

Sampling protocol - Northern regions (PDF 511.5 KB)

Sampling protocol - Southern & Western regions (PDF 512.3 KB)

Distribution maps for soil-borne pathogens

We are monitoring new-season distribution and risk levels of many soil-borne diseases.

Our distribution maps include information gathered from grower PreDicta B soil samples during autumn 2015.

  • A circle with 28 next to it represents the number of samples taken at that particular location/area.
  • A larger circle represents a larger number of samples.
  • The pie within each circle represents the proportion of samples falling into each risk category.


More information

Dr Alan McKay
Research Leader, Soil Biology and Diagnostics
Phone: (08) 8303 9375

Russell Burns
Phone: 0401 122 115

Nigel Percy
Phone: (08) 8303 9665    

Page Last Reviewed: 27 Sep 2016
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