Susan Frankel, USDA Forest Service

1. A Common Foe: Phytophthoras in Nurseries and
Landscapes in the USA
Susan Frankel,
USDA Forest Service,
Pacific Southwest Research Station
Albany, CA, USA
sfrankel@fs.fed.us
Robert O’Brien artwork
Pacific.Hort.org

2. A Common Foe: Phytophthoras in Nurseries and Landscapes in the USA
1) Review Phytophthora detections & status - nurseries, wildlands
- P. ramorum
- California native plants
2) CA, OR, WA survey; Golden Gate National Park – The Presidio
3) www.calphytos.org
4) US & CA accreditation
programs
Photo: The Herald, Western Morning News

4. Oregon. Tanoak, Notholithocarpus densiflorus

5. Phytophthora ramorum U.S. statistics
Credit: Kanaskie, ODF

6. Marin County, CA

7. Photos: Darren Strenge, The Bloedel Reserve

8. Phytophthora ramorum U.S. statistics – 580 positive nurseries
2015, P. ramorum
in 18 nurseries;
1 commercial
landscape (LA);
2 residences (OH,
OR), and a botanic
garden (WA)
Regulation reformed
in 2014 & 2015!

9. Southern US
- 9 stream
positives
- Adj. to positive
nurseries
Forest Service national wildland survey

10. David Hockney, DeYoung Museum

11. Phytophthoras on native nursery plants

12. Diplacus aurantiacus (=Mimulus aurantiacus)
Diplacus aurantiacus
(=Mimulus)
sticky monkey flower
P. tentaculata
detected in 2012
in 1 nursery,
Monterey Co., CA

13. (in 2012)

14. San Francisco’s water comes from near Yosemite National Park
1910
Credits:
SFPUC
Distance: 167 miles (269 km)

15. $86 million
Construction 2011 – 2017
19 sites.
SFPUC
SFPUC
Phytosphere Research
SFPUC

16. Credit: Latham, CDFA
Toyon, Heteromeles arbutifolia
P. tentaculata on outplanted toyon

17. Phytophthora tentaculata on native plant nursery stock
Photos: Latham, CDFA

18. Photos: Hillman, SCVWD & SFPUC
Intensive plantings

19. Photos: Phytosphere Research, CALFLORA
P. cinnamomi,
unknown
origin
Rare &
endangered
plant

20. - Santa Clara Valley Water District
Flood control
Guadalupe River
near San Jose
Credit: Santa Clara Valley
Water District

21. Phytophthora cactorum
Plant is endemic to Santa Clara County, CA.
6000 individuals remaining in 5 occurrences.
Endangered species – Ceanothus ferrisiae, Rhamnaceae
- Coyote ceanothus, California lilac
Photos: J. Hillman, SCVWD; Phytosphere Research

22. Phytosphere Research

23. California Department of Food and Agriculture
- 1,500 samples 2014 – June 2016
25+ species from nursery and field - CA native plants
25% of
samples
positive for 1
or more
Phytophthora
species
Latham and Blomquist, CDFA

24. Phytophthora quercina
on Quercus lobata
(planted in 2002)
San Jose, CA
Credits: Q-bank & Bourret, UC-Davis
First detection in the USA

25. P. taxon mugwort on Artemisia douglasiana
Santa Clara Valley Water District lands, near San Jose, CA
Courtesy of Bourret, UC-Davis; Phytosphere Researc
P. taxon juncus on Juncus species (rush)
Santa Clara Valley Water District lands, near San Jose, CA

26. More surveys
David Hockney, DeYoung Museum

27. Geographic area CA, WA, OR
Chastagner, WSU
Parke, OSU
Latham & Blomquist,
CDFA
Swiecki, Phytosphere
Research
Are native plant nurseries serving as pathogen gateways?
25% of the nursery plants tested
positive for Phytophthora.
P. uniformis on red alder
(aka P. alni ssp. uniformis)
detected in WA, a first detection
in a U.S. nursery
Lupine, (Kew.org)Red alder; Plant OR.com
Ceanothus; PFAF.org

28. Tested all purchased landscape plants - June 2015 - Aug 2016.
- 80 plant species; +800 plants from 6 nurseries.
New to the USA Phytophthora species (pending)
26.4% (145 of 549) immunoassays were positive
35.5% (16 of 45) lots pear-baited, positive for Phytophthora
~10 Phytophthora species
The Presidio - National Park in San Francisco
Courtesy of C. Conforti and others, GGNPS

29. David Hockney, DeYoung Museum
Prevention

30. U.S. pilot for nursery certification - SANC
Voluntary, audit-based – 8 nurseries in pilot
IPPC Standard, ISPM 36, “Integrated Measures for Plants for Planting” (2012)
NAPPO Standard, RSPM24, “Integrated Pest Risk Management Measures for the Importation of
Plants for Planting into NAPPO Member Countries” (2005)

31. http://sanc.nationalplantboard.org

33. CA avocado nursery stock certification for P. cinnamomi

34. 1) No oomycete
fungicides
2) Raised
benches
3) Heat-treated
media/soil
Best management practices
- CA native plant nursery stock for restoration
www.calphytos.org

35. Restoration plant sanitation signage

36. Ted Swiecki, Phytosphere Research setting up
effluent baiting

37. Accreditation - CA native plant stock for restoration
KPIX TV; A. Shor, GGNPS; The Watershed Nursery

38. Courtesy of Phytosphere Research
Accreditation checklist

39. Inspiration
D. Hockney, DeYoung Museum

41. Photos: A. Shor; Golden Gate NPS

42. A.Shor, GGNPS

43. Acknowledgements
USDA Forest Service, Pacific Southwest Research Station
Phytophthoras in Native Habitats Work Group - Janice Alexander, UC
Cooperative Extension, Marin Co.; Diana Benner, The Watershed
Nursery; Alisa Shor, Golden Gate Parks Conservancy. Also at Univ. of
CA: David Rizzo, Tyler Bourret, Heather Mehl, Matteo Garbelotto, Laura
Sims; and at CDFA: Suzanne Latham and Cheryl Blomquist; Ted Swiecki
and Elizabeth Bernhardt, Phytosphere Research and many others.

44. Photos: Phytosphere Research
Uncommon or new to
California
-P. tentaculata,
-P. quercetorum,
-P. inundata,
-P. plurivora.
Common in CA
-P. cactorum,
-P. cambivora,
-P. cryptogea,
-P. megasperma,
-P. gonapodyides.

45. Phytophthora tentaculata
CDFA;
NPS;
Q bankMimulus, Sticky monkey flower