Predicta B an identity kit for soil borne pathogens

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A multi-state project provides diagnostic tools for soil-borne diseases to guide crop planning

The South Australian Research and Development Institute’s (SARDI) DNA-based soil testing service PreDicta® B has recently been improved by projects to better understand which soil-borne pathogens pose a significant risk to broadacre crops before seeding.

Photo of man in greenhouse

Dr Alan McKay

PHOTO: Emma Leonard

The GRDC-supported projects studied paddocks in Western Australia and New South Wales to identify which pathogens pose the greatest risk to a crop about to be planted. The project also modelled interactions between different pathogens and the surrounding environment to improve predictions of disease risk.

The WA component of the field research (GRDC project DAW00213) was led by Martin Harries, from the Department of Agriculture and Food, WA (DAFWA), and assessed by the DAFWA pathology group, led by Bill MacLeod. The central and northern NSW components (DAN00143) were led by Dr Steven Simpfendorfer, from the NSW Department of Primary Industries. Dr Grant Poole, SARDI, and Dr Roger Lawes, CSIRO, modelled the disease interactions (DAS00115).

In WA, Rhizoctonia was the main pathogen contributing to variation in root health. The impact was greatest in years, and districts, with below-average annual temperatures and rainfall (this work is continuing). Other widespread fungal pathogens included Pratylenchus neglectus and P. thornei, and the Fusarium species associated with crown rot.

It raised questions about how other pathogens affect variation in root health and this is now being analysed based on additional years of data.

The work in northern and central NSW showed that P. thornei was present in 70 per cent of paddocks and at medium-high risk levels in 33 per cent. P. neglectus was present in 38 per cent of paddocks and at medium-high risk levels in five per cent. The Fusarium species that cause crown rot were detected in 63 per cent of paddocks, and medium-high risk levels were detected in 23 per cent.

Even though P. thornei was known to be present in central and northern NSW, the extent and proportion of paddocks with high levels was a surprise given that this was a random survey of grower paddocks.

Grass-free pulses and canola can reduce Rhizoctonia, take-all and cereal cyst nematode levels.

The key messages from the research for crop planning are:

  • grass-free pulses and canola can reduce Rhizoctonia, take-all and cereal cyst nematode levels;
  • fungicides are also available to help reduce yield losses from Rhizoctonia and take-all;
  • take care when selecting crop and cultivar for paddocks with medium to high root lesion nematode levels as each species of nematode has a different host range;
  • if planting cereals, check current crop disease variety guides to avoid susceptible cultivars;
  • if choosing grain legumes or pulses, lupins are resistant to P. neglectus and P. thornei, while lentils are moderately resistant to moderately susceptible to both;
  • field peas, faba beans, soybeans and mungbeans are resistant to P. neglectus;
  • some newer field pea cultivars are rated moderately susceptible to P. thornei, while faba beans, soybeans and mungbeans are rated susceptible to very susceptible;
  • chickpeas are susceptible to
  • P. neglectus and P. thornei; and
  • canola is susceptible to P. neglectus and moderately resistant to P. thornei.

As part of the project, the PreDicta® B training course for consultants was updated and is now available in an electronic format. PreDicta® B is now available (see www.sardi.sa.gov.au/diagnostic_services/predicta_b) to growers in each of the three cropping regions and can provide valuable information for planning cropping programs.

The project also modelled interactions between different pathogens and the surrounding environment to improve predictions of disease risk.

Further improvements to PreDicta® B, including developing more tests and improving risk assessments of crown rot and root lesion nematode, are being pursued by GRDC projects (DAS00137, DAN00175 and DAV00128).


More information:

Alan McKay,
PIRSA-SARDI,

alan.mckay@sa.gov.au;

PreDicta® B,
www.sardi.sa.gov.au/diagnostic_services/predicta_b

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GRDC Project Code DAW00213, DAN00143, DAS00115

Region South, West, North