Determining the cause of onion stunting in South Australia: Phase 3 of VN08004

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Determining the cause of onion stunting in South
Australia Phase 3 of VN08004
Trevor Wicks, Sue Pederick, Greg Walker and Simon
Anstis SARDI
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Project overview

• Field symptoms
• Root symptoms
• DNA studies
• Nematode/Rhizoctonia interactions
• Management
• New areas
• Aerial mapping
• Future work

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Waikerie
Murray Bridge
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Field symptoms
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Field symptoms
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Roots symptoms
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2008/9 StudiesRhizoctonia solani DNA in soil
pg DNA/g soil
Normal 1710
Stunted 5011
Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Nematode/Rhizoctonia interactions
Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Management studies

• Soil fumigation
• Seed treatments
• Fungicide drenches
• Organic matter
• Biologicals

Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Management studies

• Seedling transplants
• With and without fungicide and biological
  treatments

Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Areas sampled in (lower Mallee and SE)
Rhizoctonia detected in 11 of the 13 sites with
stunting
Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Aerial mapping

• New Technology (software)
• Yield reductions
• Crop rotations
• New areas

Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Project summary

• Rhizoctonia solani AG 8 the main cause of
  stunting
• Other AGs (2.1, 2.2, 3, 4, 11), fungi and
  nematodes also detected but their role is
  uncertain
• Praytlenchus nematodes were rarely detected, but
  indications that interaction with R. solani
  increase stunting
• Management- fumigation and organic matter
• Stunting detected in the South East
• Aerial photography used to identify and map
  stunting

Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Next stepsGreenhouse Evaluation

• Studying new areas
• Seed treatments
• Biological seed/ soil treatments
• Fumigants
• Alternative nurse crops
• Interaction of Rhizoctonia with other fungi

No organic matter
Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Field trials

• Predictive tests
• soil sampling procedures
• time, depth and distribution, samples
• threshold levels
• Aerial mapping
• extent of problems new and old areas
• correlation with previous crops
• estimation of yield losses
• efficacy of treatments
• Seed treatments
• Soil treatments
• organic matter
• fumigation
• soil disturbance

Australian Vegetable Industry Conference
Melbourne 4-6th May 2009
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Acknowledgements

• The South Australian onion growers
• John Heap for the aerial photography

This project was facilitated by HAL in
partnership with AUSVEG and was funded by the
National Vegetable Levy. The Australian
Government provides matched funding for all HAL
RD activities
Australian Vegetable Industry Conference
Melbourne 4-6th May 2009