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

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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

Oregon. Tanoak, Notholithocarpus densiflorus

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

Marin County, CA

Photos: Darren Strenge, The Bloedel Reserve

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!

Southern US

- 9 stream

positives

- Adj. to positive

nurseries

Forest Service national wildland survey

David Hockney, DeYoung Museum

Phytophthoras on native nursery plants

Diplacus aurantiacus (=Mimulus aurantiacus)

Diplacus aurantiacus

(=Mimulus)

sticky monkey flower

P. tentaculata

detected in 2012

in 1 nursery,

Monterey Co., CA

(in 2012)

San Francisco’s water comes from near Yosemite National Park

1910

Credits:

SFPUC

Distance: 167 miles (269 km)

$86 million

Construction 2011 – 2017

19 sites.

SFPUC

SFPUC

Phytosphere Research

SFPUC

Credit: Latham, CDFA

Toyon, Heteromeles arbutifolia

P. tentaculata on outplanted toyon

Phytophthora tentaculata on native plant nursery stock

Photos: Latham, CDFA

Photos: Hillman, SCVWD & SFPUC

Intensive plantings

Photos: Phytosphere Research, CALFLORA

P. cinnamomi,

unknown

origin

Rare &

endangered

plant

- Santa Clara Valley Water District

Flood control

Guadalupe River

near San Jose

Credit: Santa Clara Valley

Water District

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

Phytosphere Research

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

Phytophthora quercina

on Quercus lobata

(planted in 2002)

San Jose, CA

Credits: Q-bank & Bourret, UC-Davis

First detection in the USA

P. taxon mugwort on Artemisia douglasiana

Santa Clara Valley Water District lands, near San Jose, CA

Courtesy of Bourret, UC-Davis; Phytosphere Research

P. taxon juncus on Juncus species (rush)

Santa Clara Valley Water District lands, near San Jose, CA

More surveys

David Hockney, DeYoung Museum

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

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

David Hockney, DeYoung Museum

Prevention

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)

http://sanc.nationalplantboard.org

CA avocado nursery stock certification for P. cinnamomi

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

Restoration plant sanitation signage

Ted Swiecki, Phytosphere Research setting up

effluent baiting

Accreditation - CA native plant stock for restoration

KPIX TV; A. Shor, GGNPS; The Watershed Nursery

Courtesy of Phytosphere Research

Accreditation checklist

Inspiration

D. Hockney, DeYoung Museum

Photos: A. Shor; Golden Gate NPS

A.Shor, GGNPS

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.

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.

Phytophthora tentaculata

CDFA;

NPS;

Q bank Mimulus, Sticky monkey flower