Testing and Implementing Methods to Manage

Phytophthora Root Diseases in California Native Habitats

and Restoration Sites

Ted Swiecki and Elizabeth Bernhardt Phytosphere Research

MMWD Mt. Tamalpias Watershed 9.12.2012

madrone - P. cinnamomi

Pacific Ocean

Sampled parks and natural areas with Phytophthora root rots in non-planted vegetation - P. cinnamomi, P. cambivora most common

What do you have?

What do you want?

How do you get what you want?

Are you getting what you want?

● Identify needs

● Set goals and objectives

● Biological resources ● Physical / environmental factors ● Existing management ● Regulatory constraints ● Trends

● Select management strategies ● Develop time/action schedule ● Implement plan

● Monitor ● Analyze ● Revise as needed

Developing an adaptive disease management plan

Not possible or feasible

“You can’t always get what you want” -Mick Jagger & Keith Richards

What do you have?

Arctostaphylos myrtifolia – Ione manzanita

Federal status: Threatened

Arctostaphylos myrtifolia —Phytophthora cinnamomi

Multiple introductions: 3 lineages of P. cinnamomi

+ 1 site P. cambivora

Arctostaphylos myrtifolia, A. viscida —P. cinnamomi

Giant chinquapin— P. cinnamomi

2014 1991 1953 P. cambivora

SFPUC Peninsula Watershed, San Mateo Co.

P. cinnamomi

chlamydospora

D8- P. cinnamomi

1993: 30-50+ nursery-grown Ceanothus ferrisiae planted

P. cactorum

P. syringae

P. cactorum, P. cambivora

P. cactorum

P. cactorum

P. cactorum P. cactorum

P. cactorum

P. "kelmania"

P. cactorum, P. cambivora, P. "kelmania"

22 years after planting - Apparent infested area covers at least 2 ha (5 acres)

Phytophthora quercina

Planted 14 yr ago

P. tentaculata

Planted 2-3 yr ago

Ceanothus ferrisiae assisted migration planting — P. cactorum

Planted <1 yr ago

Sampling – how much is needed to inform management decisions?

SFPUC SAC samples

Surface water samples in plastic bags, pear baits added at time of collection

Clade Phytophthora species Transplant Assoc_veg Water

6 aff. clade 6 0 0 1

6 amnicola 0 0 3

6 amnicola X canalensis 0 0 1

6 bilorbang 0 0 1

6 ripara 0 0 1

6 riparia X lacustris/cambivora 0 0 3

6 thermophila 0 0 1

8 erythroseptica 0 0 1

9 polonica 0 0 1

6 gregata X megasperma/canalensis 1 0 1

6 sp. nov.? aff. lacustris 1 0 1

6 chlamydospora 1 0 4

6 ripara X lacustris 1 0 11

6 gonapodyides 1 0 17

6 chlamydospora X "erwinii" 2 0 1

8 ramorum 1 0 1

6 inundata 3 1 5

1 cactorum 29 1 2

6 lacustris 8 5 28

6 megasperma 12 5 7

7 cambivora 10 8 8

8 cryptogea complex 21 9 13

8 syringae 0 1 1

6 chlamydospora X drechsleri 0 1 8

6 lacustris X riparia 0 2 6

1 tentaculata 15 0 0

2 plurivora 1 0 0

4 quercetorum 1 0 0

6 chlamydospora X gonapodyides 1 0 0

7 cinnamomi 1 0 0

7 niederhauserii 1 0 0

8 taxon agrifolia 1 0 0

2 citricola complex 6 1 0

6 borealis X "erwinii" 0 1 0

9 hydropathica X parsiana 0 1 0

Phytophthora species detected in water, soil/roots, or both

44

43

37

38

40 41

42

G22

G21

No detection No detection

Samples collected around Artemisia douglasiana G21 and G22

T

C C

C

C

L

h

L

T C

L

L

C

C

P. lacustris

P. chlamydosporaXdrechsleri

P. lacustrisXriparia

P. hydropathicaXparsiana

T P. tentaculata

C

C P. chlamydospora

C

C P. citricola/pini

L

h

L

P. cryptogea/kelmania/drechsleri

Pond: P. chlamydospora

Pond: P. megasperma P. gonapodyides P. chlamydospora x drechsleri

MA5-megasperma

Rain runoff: P. cambivora P, cryptogea complex

Rain runoff: P. cambivora

No detection Phytophthora 1 m from plant

1.5-2 m from plant

Phytophthora spp. recovered from sites with removed plants

P. cactorum

lacustris/riparia

lacustris

citricola/pini

cryptogea

lacustris cryptogea

tentaculata citricola kelmania

cryptogea/allies lacustris

cryptogea/allies

Phytophthora detection efficiency varies by methods used

Phytophthora=Red Artemisia douglasiana

Baccharis douglasii Euthamia occidentalis

water

by pear baiting

kelmania/drechsleri

by direct isolation, immunoassay, PCR

P. tentaculata on pear

Valley and interior live oaks – direct seeded, nonirrigated 21 years post planting

No Phytophthora:

Prevention Avoidance

Cheaper, easier, more effective than

Phytophthora: Eradication Perpetual management

How do you get what you want?

Systems approach needed to prevent contamination

What about nursery stock?

- Not a new problem - No lack of information - Lack of awareness, lack of motivation (market forces)

1957 Nursery BMPs 2012

http://phytosphere.com/BMPsnursery/index.htm

2016

Start clean, keep it clean

Water Containers Potting media Plant propagules

Nursery layout Production practices Biosecurity

Testing methods for quality control in clean nursery, not trying to pick out uninfected plants in an infested nursery

Bench-level baiting of irrigation leachate

Water drains from ~ 7 cm above bottom of collection vessel water column to maximize zoospore density

Phytophthora colocasiae detected

Phytophthora cambivora - Field-collected salvaged plants

Phytophthora spp. in planted nursery stock

Can sites be treated to eradicate introductions?

Small-area, long-duration solarization

CE

LS

US

PINE

PINE

LS 10 cm

20 cm

CELS US PINEPlot:

0

500

1000

1500

2000

2500

3000

3500

10 20 10 20 10 20 10 20

Ho

url

y r

ead

ings

Depth, cm:

≥45 C

≥40 C

≥35 C

Photo courtesy Dr. Brad Hanson, UC Davis

Steam auger

Photovoltaic electric heating

51 C

China Camp State Park, Marin County

Jack London State Park

madrone, bay - P. cinnamomi + P. cambivora

Bay removal for P. ramorum management – BMPs for working in infested areas

15 m

Arctostaphylos myrtifolia —Phytophthora cinnamomi

Percent positive samples: 0% 0% 80% 50%

2004 2014

5 m

2.5 m

0 m

-2.5 m

2016

0 m

Typical rate of spread about 1m/year on level or uphill

5 m

Use of phosphite (phosphonate) to manage Phytophthora diseases

• simple mineral salt (KH2PO3) with low non-target toxicity and a high level of environmental safety

• used in Australia against P. cinnamomi in native vegetation

Phytotoxicity tests

Phytotoxicity at 18.6 kg ai/ha, 300 L/ha with 0.05% surfactant (Breakthru)

Safe rate: 12.4 kg ai/ha, 300 L/ha with 0.03% surfactant

7 m length, 2 m swath width Metronome used to pace speed of spray boom to deliver 300 L/ha

June 2011 April 2015

Plot 3B—Control

Plot 3A—Phosphite treated

Control plot

Phosphite-treated

Nontreated control

-100

0

100

200

300

400

500

Ave

rage

dis

tan

ce o

f dis

eas

e fr

on

t in

to p

lot

(cm

)

Date evaluated

Control,1

Control,2

Control,3

Control,4

Phosphite,1

Phosphite,2

Phosphite,3

Phosphite,4

June 2011

Phosphite-treated (12.4 kg/ha, 300 L/ha spray volume)

Mar 2016

June 2011 Mar 2016

Phosphite-treated

Nontreated control

Ultra-low volume application – 10X reduction spray volume (30 L/ha)

How low can you go?

Sprayer head

Power switches

Battery /pump / spray reservoir unit

Extendable pole

12 V battery 12V peristaltic pump (in enclosure)

DC/DC voltage converter

Hacked Herbi sprayer

Flysight Doppler GPS

Powered speaker

Spray head target velocity 0.5 m/s, 2 passes a 1 m/s to apply 30 L/ha

Split application: 8 and 10 kg ai/ha ULV (30 L/ha) applied 6-12 weeks apart (16-20 kg ai/ha)

Band treatment of edges 2.4 – 3.6 m wide

Low elevation aerial images

2015

2016

Thanks for support and cooperation: USDA Forest Service, Pacific Southwest Experiment Station

USDA Forest Service, Forest Health Protection

San Francisco Public Utilities Commission Bureau of Land Management

California Dept. of Fish and Wildlife Santa Clara Valley Water District

California Dept. of Parks and Recreation California Dept. of Food and Agriculture, Plant Diagnostic Lab

Rizzo Lab-UC Davis Garbelotto Lab-UC Berkeley