O25 Scott

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2008 Phytophthora Workshop in Italy

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O25 Scott

  1. 1. Pythiaceous root pathogens associated with Eucalyptus gomphocephala decline in Western Australia
  2. 2. Tuart distribution in main affected area Tuart forest + Extent of decline:- 1990 2007 (Distribution map )
  3. 3. Expression of typical Phytophthora symptoms
  4. 4. Overview of research Investigations into potential role of Phytophthora species in Tuart decline Stem, lateral and fine feeder root surveys for necrosis Phosphite was applied - to explore if a role of a Phytophthora was likely Phytophthora sp. was Isolated
  5. 5. Roots (magnified sections) illustrating: fine root loss and root tip dieback
  6. 6. • Aim: Assess whether Phosphite, Nutrient and Insecticide injections can improve tree health – Phosphite: 25, 50 & 75 g L-1 – Nutrients: Combined (Zn, Fe & Mn), Zn & Fe MEDICAP® – Insecticide: Orthene®.
  7. 7. Results after 12 and 24 months 60 Phosphite 25g/L a.i 50 and ZINC year after treatment 1 years after treatment 2 40 Phosphite 25g/L a.i & complete nutrients Percentage canopy change (Grimes Index) 30 20 10 0 -10 -20 Source: Peter Scott. PhD student. Murdoch University -30 Control P25 P50 P75 Com Zn Fe P25 P50, P75, P25, Zn P50, Zn P75, Zn P25, P50, P75, Com Com Com Fe Fe Fe Treatments
  8. 8. Aim: assess the influence of different phosphite concentrations tree health Phosphite at 75, 150, 225, 300 & 375 g L-1 Confirm Phosphite uptake (foliar) Monitor Phytotoxicity
  9. 9. 20 15 Percentage Change in Canopy Condition Percentage change in Canopy condition 10 5 0 -5 -10 -15 Control Control 75 p75 150 p150 225 p225 300 p300 375 p375 Phosphite g/Litre Treatments
  10. 10. Phytophthora isolated from 5 of 32 sites sampled From 4 declining sites and 1 healthy site
  11. 11. AY879291 P. inflata AF266789 P. inflata Phylogeny and morphology g2 Phytophthora inflata 92 DQ486661 P. citricola DQ396420 P. citricola EF423556 P.citricola EF418946 P. citricola EF193216 P. citricola DQ648135 P. citricola 1 g2 Phytophthora citricola AB217677 P. citricola 93 VHS 16158 - P.sp. 4 VHS 16168 - P.sp. 4 VHS 16298 - P.sp. 4 VHS 16439 - P.sp. 4 Phytophthora species tuart 98 Phytophthora species tuart 81 Phytophthora species tuart Phytophthora species tuart Phytophthora species tuart VHS 16803 - P.sp. 4 VHS 16870 - P.sp. 4 93 AY946257 P. tropicalis 100 AY207010 P. tropicalis 100 g2 Phytophthora capsici AF266787 P. capsici 91 g2 Phytophthora citrophthora 100 g2 Phytophthora botryosa g2 Phytophthora colocasiae
  12. 12. Current Work • Pathogenicity trial (soil inoculation) • Describe the new species
  13. 13. 140 120 Lesion (mm) 100 80 60 40 20 0 Inoculated Tuart Control Tuart Inoculated Jarrah Control Jarrah Treatment
  14. 14. Phytophthora species and role in tree declines • Many new Phytophthora species being linked to tree declines worldwide • Strict Quarantine critical
  15. 15. Conclusion Loss of fine roots were identified Phosphite was applied - improved crown condition A new Phytophthora species isolated

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