Phytophthora Diseases

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Phytophthora Diseases

  1. 1. Phytophthora Diseases Gary W. Moorman Penn State Plant Pathology & Environmental Microbiology
  2. 2. Late blight of tomato (Phytophthora infestans)
  3. 3. Phytophthora, Oomycete not a true fungus Hyphae Chlamydospores Sporangia Antheridia/oogonia Zoospores Cell walls contain cellulose Usually has 2n chromosomes
  4. 4. Oogonium Antheridium APS Digital Image Collection
  5. 5. Phytophthora, sexual reproduction A1 + A2 mating types required
  6. 6. Sporangium 20-50 Zoospores per sporangium APS Digital Image Collection
  7. 7. Phytophthora plant pathogens soil-borne??? …usually plant-borne APS Digital Image Collection
  8. 8. Sporangium Asexual reproduction Zoospore Release Sporangium Germinating oospore by sporangium Oospore Formation Oospore germinating by germ tube Sporangiophore and sporangia Zoospore Release Sporangium Oogonium & Antheridium Sexual reproduction A1 & A2 mycelium Zoospores Life history and disease cycle of Phytophthora
  9. 9. Phytophthora activity Wet conditions, 65F - 70F sporangia within 4 hours Each sporangium > 20 to 50 zoospores released within 1 hour
  10. 10. Phytophthora dispersal  Short distances Splash Wind  Long distances Movement of plants or soil
  11. 11. Phytophthora cactorum P. citrophthora P. citricola P. cryptogea P. drechsleri P. lateralis P. megasperma P. parasitica P. syringae P. nicotianae P. ramorum …many more top diebacks, leaf spots, stem cankers
  12. 12. Many Phytophthora species have a wide host range: Phytophthora cinnamomi infects 900 different species
  13. 13. Phytophthora root rot APS Digital Image Collection
  14. 14. Douglas-fir infected with Phytophthora spp. APS image collection
  15. 15. Photo: Jennifer Parke, Oregon State University
  16. 16. Phytophthora root rot APS Digital Image Collection
  17. 17. Severe root rot
  18. 18. Phytophthora cinnamomi on Ilex glabra ‘Shamrock’
  19. 19. Top dieback APS Digital Image Collection
  20. 20. Top dieback V-shaped dead areas APS Digital Image Collection
  21. 21. Symptoms on camellia Photos: Oregon Dept. of Agriculture & Cheryl Blomquist, CDFA
  22. 22. Symptoms on camellia Photo: Cheryl Blomquist, CDFA
  23. 23. P. ramorum symptoms on Kalmia Photo: DEFRA
  24. 24. Similar symptoms – not Phytophthora Sun scorch Gray spot on sun scorched leaves Photo: Rich Regan, Oregon State University
  25. 25. Not Phytophthora Cercospora on Kalmia Photo: Peter Angwin, USDA-Forest Service
  26. 26. Bleeding cankers beech
  27. 27. beech
  28. 28. Reddish-brown discoloration cambium area infected with Phytophthora spp. Photo by Joseph O'Brien Bugwood.org image collection
  29. 29. Phytophthora on European beech (Fagus sylvatica) Phytophthora cactorum Phytophthora citricola Phytophthora plurivora Weiland, Nelson and Hudler. 2010 Plant Disease 94: 1009-1014
  30. 30. Taxus
  31. 31. APS image collection Coastal live oak infected with Phytophthora ramorum
  32. 32. Phytophthora ramorum “bleeding” Photos: Mike McWilliams, ODF & Bruce Moltzen, Missouri Dept. of Conservation
  33. 33. Phytophthora ramorum Sudden …usually slow Oak …many other suscepts Death …often not lethal
  34. 34. APS image collection Penn State image collection African violet infected with Phytophthora spp.
  35. 35. Hosta infected with Phytophthora spp. APS image collection
  36. 36. Lavender infected with Phytophthora spp. APS image collection
  37. 37. Polemonium infected with Phytophthora spp. APS image collection
  38. 38. Catharanthus = annual vinca infected with Phytophthora spp. APS image collection
  39. 39. Phytophthora nicotianae on petunia
  40. 40. Phytophthora detection Phytophthora species in general: Antibody test (ELISA) Semi-selective media ELISA Plating Specific Phytophthora (P. ramorum) Nested PCR DNA test Photo: Natalie Goldberg, New Mexico State University PCR
  41. 41. Phytophthora detection Baiting:
  42. 42. If you collect a sample  Collect various stages of symptoms.  Photo symptoms and environment.
  43. 43. Packaging a sample     DRY paper towel Double bag and seal Crush proof box Sample submission form outside of bags  Overnight express Monday-Thursday
  44. 44. Phytophthora ramorum Sporangia releasing zoospores Phytophthora ramorum in culture Photo: UC Davis & UC Berkeley Chlamydospores
  45. 45. QUESTIONS???

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