Managing Phytophthora cinnamomi



                 Liz Dann, Ken Pegg, Luke Smith
                 QPIF, Indooroopilly, Q...
Queensland Primary Industries and Fisheries




Topics covered

  • Experimental results
     • Rootstock trials
     • Op...
Queensland Primary Industries and Fisheries




Phytophthora root rot (PRR)




                          © The State of Q...
Queensland Primary Industries and Fisheries




PRR linked to seasonal physiology of the tree

- temperature & soil satura...
Queensland Primary Industries and Fisheries




Effect of rootstock on PRR




                             © The State of...
Queensland Primary Industries and Fisheries




Velvick clone (7.7)                                  SHSR-04 (2.7)
Reed (8...
Queensland Primary Industries and Fisheries




Clonal Hass (4.8)




            © The State of Queensland, Department of...
Queensland Primary Industries and Fisheries




Duranbah rootstock trial, tree health

                 10
               ...
Queensland Primary Industries and Fisheries




This work is continuing…
                                        SHSR-02

...
Queensland Primary Industries and Fisheries




Optimising phosphonates




                          © The State of Queen...
Queensland Primary Industries and Fisheries




How do phosphonates work?



                  Dual action:
• High root le...
Queensland Primary Industries and Fisheries




Methods of phosphonate application

•   Trunk injections
•   Foliar sprays...
Queensland Primary Industries and Fisheries




Trunk injection

• Most effective treatment – 20% PO3 injected at even
  s...
Queensland Primary Industries and Fisheries




Foliar Sprays

• Achieve same root concentrations as injections
• Need to ...
Queensland Primary Industries and Fisheries




Bark Sprays

• Highly effective in young trees where stem has some
  photo...
Queensland Primary Industries and Fisheries




Soil Drenching

• Initial increase in root concentration but quickly decli...
Queensland Primary Industries and Fisheries




© The State of Queensland, Department of Employment, Economic Development ...
Queensland Primary Industries and Fisheries




Later maturing varieties eg. Reed
                                80
  pho...
Queensland Primary Industries and Fisheries




Think about using metalaxyl

• Upward movement in transpiration
  stream –...
Queensland Primary Industries and Fisheries




Integrated control

•   Drainage
•   Nursery practices
•   Cultural contro...
Queensland Primary Industries and Fisheries




Acknowledgements

Thank you to the many growers
and collaborators for supp...
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Elizabeth Dann

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Elizabeth Dann

  1. 1. Managing Phytophthora cinnamomi Liz Dann, Ken Pegg, Luke Smith QPIF, Indooroopilly, QLD Tony Whiley Sunshine Horticultural Services
  2. 2. Queensland Primary Industries and Fisheries Topics covered • Experimental results • Rootstock trials • Optimisation of phosphonate applications • Integrated control © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  3. 3. Queensland Primary Industries and Fisheries Phytophthora root rot (PRR) © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  4. 4. Queensland Primary Industries and Fisheries PRR linked to seasonal physiology of the tree - temperature & soil saturation play a major role in PRR severity • Optimum temperature for • PRR development 19 – 25° C • Avocado growth 21 – 33°C • < 22 °C root growth slows = PRR severe • > 27 °C avocado grows better than Pc = PRR less severe • Pc stress on trees greatest in spring © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  5. 5. Queensland Primary Industries and Fisheries Effect of rootstock on PRR © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  6. 6. Queensland Primary Industries and Fisheries Velvick clone (7.7) SHSR-04 (2.7) Reed (8.3) © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  7. 7. Queensland Primary Industries and Fisheries Clonal Hass (4.8) © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  8. 8. Queensland Primary Industries and Fisheries Duranbah rootstock trial, tree health 10 a a a a a a a 8 ab Tree health 6 bc cd 4 d 2 0 04 7 ss 0 d as as ke sa g l na A1 e in ke Ha t om Du Du R- Re La dl clo Du S ee Th SH rr ck Ba ks lvi c Ve lvi Ve © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  9. 9. Queensland Primary Industries and Fisheries This work is continuing… SHSR-02 © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  10. 10. Queensland Primary Industries and Fisheries Optimising phosphonates © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  11. 11. Queensland Primary Industries and Fisheries How do phosphonates work? Dual action: • High root levels – direct antimicrobial action • Low root levels – plant defence responses activated • Moves with photosynthates, accumulates and persists in plant tissue with greatest metabolic activity at time of application © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  12. 12. Queensland Primary Industries and Fisheries Methods of phosphonate application • Trunk injections • Foliar sprays • Bark application • Soil application Phosphonate applications must be continued for the life of the tree © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  13. 13. Queensland Primary Industries and Fisheries Trunk injection • Most effective treatment – 20% PO3 injected at even spacing around the trunk (15mL per metre canopy diam.) • Central wood retains its transport function (unique in avocados) • Injury to xylem near injection site – Becomes non-conductive – Replaced by tree in 1 – 2 years • Healthy trees – 1 annual injection at maturation of summer flush • Sick trees – 2 injections - at maturation of both summer and spring flushes © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  14. 14. Queensland Primary Industries and Fisheries Foliar Sprays • Achieve same root concentrations as injections • Need to monitor root levels to determine number of applications necessary • 0.5% (8.3mL/L of the 600 product) • More sprays required to achieve 0-50ppm, than >50ppm • No applications within 6 weeks of flowering © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  15. 15. Queensland Primary Industries and Fisheries Bark Sprays • Highly effective in young trees where stem has some photosynthetic (green) activity • Very effective against trunk cankers • Unable to achieve and maintain adequate root levels in older trees, unless applied frequently • 20% product with 2% bark penetrant – Higher than 20% causes chemical cincturing © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  16. 16. Queensland Primary Industries and Fisheries Soil Drenching • Initial increase in root concentration but quickly declines • Need to apply monthly to maintain root levels • Moves in xylem with water transport, thus not effectively distributed to target tissues © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  17. 17. Queensland Primary Industries and Fisheries © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  18. 18. Queensland Primary Industries and Fisheries Later maturing varieties eg. Reed 80 phosphorus acid level mg/kg 60 inject foliar 40 bark untreated 20 0 ay l ov ug n ct p ec Ju Ju Se O M N D A Inject, bark, foliar Foliar © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  19. 19. Queensland Primary Industries and Fisheries Think about using metalaxyl • Upward movement in transpiration stream – taken up only by roots • Prevents colonisation of roots by zoospores (major) • Toxic to germinating chlamydospores (minor) • If feeder roots healthy, will be absorbed before degradation by soil micro- organisms • Off patent (cheaper) © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  20. 20. Queensland Primary Industries and Fisheries Integrated control • Drainage • Nursery practices • Cultural control • Resistance • Chemicals – Phosphonates – Metalaxyl © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009
  21. 21. Queensland Primary Industries and Fisheries Acknowledgements Thank you to the many growers and collaborators for supporting our research! © The State of Queensland, Department of Employment, Economic Development and Innovation, 2009

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