O16 Geoffrey

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O16 Geoffrey

  1. 1. Phytophthora diversity in UK gardens Geoff Denton Plant Pathologist The Royal Horticultural Society
  2. 2. Detection Methods Apple Baiting Nested PCR Immunoassay
  3. 3. Comparison of positive results from 2006 and 2007 from apple baiting, nested PCR and immunoassay n 90 n = = 380 144 80 Stem 70 n Root = n Soil 60 320 = Positive results (%) 92 50 40 30 n n = 20 = n 401 145 = 413 10 0 Apple baiting Nested PCR Immunoassay
  4. 4. Positive results for the last 10 years from apple baiting, nested PCR and immunoassay Total tested 350 Positive apple baiting results Positive nested PCR results 300 Positive immunoassay results 250 Number of Enquiries 200 150 100 50 0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
  5. 5. Phytophthora species identified through sequencing ITS P. alni P. cactorum P. cambivora P. cinnamomi P. cinnamomi P. citricola P. citricola P. citrophthora P. cryptogea P. cryptogea P. drechsleri P. fragariae P. gonapodyides P. hibernalis P. ideai P. ilicis P. inundata P. megasperma P. nicotianae P. niederhauserii P. niederhauserii P. pgchlamydo P. porri P. primulae P. quercina P. ramorum P. ramorum P. sp.510 P. syringae P. tropicalis/capsici P. tropicalis/capsici 0 20 40 60 80 100 120 140 160 Occurrence of species (n=489)
  6. 6. Phytophthora diversity • In total 25 Phytophthora species have been recorded in UK gardens • During 2006 and 2007 alone we recorded 87 different host genera • Top hosts are; Taxus (19%), Rhododendron (5.6%), Rubus (4.2%) and Viburnum (4.2%)
  7. 7. Taxus Rubus Rhododendron Viburnum P. cactorum - 1 - - P. cinnamomi 32 - 2 2 P. citricola 20 9 4 2 P. citrophthora 6 - - - P. cryptogea 7 2 2 - P. fragariae - 3 - - P. gonapodydies 3 - - 2 P. megasperma 1 - - - P. nicotianae - - - 1 P. syringae 2 - - - Phytophthora sp. - - - 1
  8. 8. Following the identification of the Phytophthora species, potential new hosts for the following species have been found: • P. cactorum: Phylliopsis • P. cambivora: Prunus laurocerasus • P. citricola: Abutilon, Aesculus, Buddleja, Ceanothus, Convolvulus, Cornus, Enkianthus, Fothergilla, Fremontodendron, Helleborus, Lavendula, Pieris, Sorbus, Santolina, Symphoricarpus, Taxus, Trachelospermum, Wisteria • P. citrophthora: Ceanothus, Daphne, Heuchera • P. cryptogea: Anemone, Araucaria, Calluna, Caryopteris, Choisya, Cistus, Delphinum, Heliopsis, Heuchera, Prunus laurocerasus, Tilia, Polemonium, Ribes, Rosmarinus, Ruta, Taxus, Thuja • P. gonapodyides: Rubus, Sorbus, Taxus • P. hibernalis: Hebe • P. megasperma: Hedera
  9. 9. Proportion of Pythium and Phytophthora identified by sequencing of ITS region, through all detection methods 300 Pythium 250 Phytophthora & Pythium 38% Phytophthora Number of Enquiries 200 5% 150 100 57% 50 30% 9% 61% 0 2006 2007 Year
  10. 10. Comparison of total Phytophthora and Pythium identified, by method and sample 250 Pythium Phytophthora 200 Number of Enquiries 150 100 50 0 Stem (PCR) Roots (PCR) Soil (PCR) Stem (Bait) Roots (Bait) Soil (Bait)
  11. 11. Pythium species identified through sequencing ITS Py attrantheridium Py attrantheridium Py chamaehyphon Py heterothallicum Py helicoides Py intermedium Py intermedium Py irregulare Py macrosporum Py minus Py monospermum Py montanum Py oligandrum Py parvum Pythium sp. Py sylvaticum Py sylvaticum Py ultimum Py vanterpoolii Py vexans Py violae 0 5 10 15 20 25 30 35 40 45 Occurrence of species (n=160)
  12. 12. Pythium diversity • In total 17 Pythium species have been recorded in UK gardens • During 2006 and 2007 alone we recorded 72 different host genera • Top hosts are; Taxus (12.6%), Prunus (4.9%), Rubus (4.2%) and Cornus (3.5%)
  13. 13. Taxus Prunus Rubus Cornus Py attrantheridium 3 1 2 2 Py heterothallicum 2 1 2 - Py intermedium 2 3 1 - Py irregulare 1 - - - Py macrosporum 1 - - - Py monospernum 1 - - - Py montanum 1 - - - Py oligandrum - - 1 - Py sylvaticum 3 1 - 2 Py vexans - - - 1 Pythium sp. 7 4 - -

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