Shannon Lynch1,2, Suzanne Rooney-Latham3, Akif Eskalen2

1. Center for Conservation Biology, UC Riverside

2. Department of Plant Pathology and Microbiology, UC Riverside

3. California Department of Food and Agriculture

Foamy Bark Canker A New Insect-Disease Complex on Coast Live Oak in California Caused by Western Oak Bark

Beetle and Geosmithia sp.

Background • A decline of coast live oak in California has been observed

since late 2012 throughout urban landscapes and private lands in Los Angeles, Orange, Riverside, Santa Barbara, Ventura and Monterey counties

Photo: Robert Sartain, Santa Clarita

Foamy Bark Canker on Coast Live Oak

Santa Clarita, Los Angeles County CA Open Space

Foamy Bark Canker on Coast Live Oak

Photo: Robert Sartain, Santa Clarita

Foamy Bark Canker on Coast Live Oak

Santa Clarita, Los Angeles County CA Private Property

Santa Clarita, Los Angeles County CA Private Property

Foamy Bark Canker on Coast Live Oak

Thousands Oaks, Ventura County Private Property

Foamy Bark Canker on Coast Live Oak

San Mateo County

Foamy Bark Canker on Coast Live Oak

Photo Credit: Bruce Schaar

Foamy Bark Canker on Coast Live Oak

Arroyo Grande, San Louis Obispo County Private Property Photo Credit: Dawn Fluharty

Western Oak Bark Beetle

•Molecular ID: •Stouthamer lab UCR •94% Match based on COI gene

•Morphological ID: •Dr. Robert Rabaglia USDA Forest Service

Fungus and Beetle Association

Geosmithia sp.

Geosmithia sp. conidiophore Geosmithia sp. conidia

Area of Detection in California

Q. wislizeni

Q. agrifolia + Q. rubra

Confirmed by CDFA

Confirmed by UCR

Maximum likelihood phylogeny based on ITS sequences

Oak687

Oak1068

Oak1527

Oak1489

Oak1180

Oak520

Oak1131

Oak1132

Oak1179

Oak1151

HF546338 Geosmithia fassatiae

HF546275 Geosmithia fassatiae

HF546272 Geosmithia fassatiae

HF546270 Geosmithia fassatiae

Oak1518

Oak1298

Geosmithia fassatiae

KJ513212 Geosmithia flava

KJ513211 Geosmithia flava

KJ513208 Geosmithia flava

KJ513209 Geosmithia flava

Geosmithia flava

HE604153 Geosmithia sp.

HE604152 Geosmithia sp.

HE604143 Geosmithia sp.

HE604134 Geosmithia sp.

Geosmithia sp.

KF914640 Geosmithia langdonii

KF808298 Geosmithia langdonii

KF808297 Geosmithia langdonii

HF546356 Geosmithia langdonii

Geosmithia langdonii

HF546281 Geosmithia pallida

HF546342 Geosmithia pallida

HF546311 Geosmithia pallida

HF546253 Geosmithia pallida

CDFA1654 Redoak

TOakwobb2075 CL

CDFA1580859-2 CL

HF546351 Geosmithia pallida

HF546349 Geosmithia pallida

Oakwobb2208 CL

Oakwobb2209 CL

Oakwobb2210 CL

Geosmithia pallida

AM4210771 Geosmithia sp.

UCR2897 Geosmithia lavendula

KF808300.1|Geosmithia lavendula

KF808300.1 Geosmithia lavendula

Geosmithia lavendula

99

65

64

100

92

98

94

91

89

77

56 61

94

65

Geosmithia pallida complex Kolarik et. al in press

• G. pallida is a complex of more species, but in the strict sense has previously been detected on oak species in Europe only.

• Identified G. pallida as Geosmithia sp. 41 recovered from Quercus spp. and other hosts associated with P. pubipennis and other beetles in CA in 2009

• ITS sequences of our isolates match with Geosmithia sp. 41

• Did not observe FBC symptoms, presuming the trees were over-run with P. ramorum

• Brief remarks from oaks sampled in non-infested P. ramorum stands

Symptoms of Foamy Bark Canker

Quercus wislizeni

Photo: Jessica Honeycutt from El Dorado Co. Dept of Ag.

Symptoms of Foamy Bark Canker

Symptoms of Foamy Bark Canker

Symptoms of Foamy Bark Canker

Phloem necrosis and xylem streaking caused by the fungus

Santa Barbara, CA Thousand Oaks, CA

WOBB Galleries Branch Trunk

The beetle burrows in the phloem to the level of the cambium where she constructs ~2 cm galleries against the grain

At one end of these primary galleries, the female lays eggs, then builds a secondary gallery half way up and dies

1-2 cm

Larval Galleries Parent Gallery

Fungal grows within the secondary gallery walls.

Photo: Suzanne Latham

Pathogenicity Test

0

1

2

3

4

5

6

7

8

9

Geosmithia pallida Control

A

B

Average extent of vascular necrosis (cm) produced in Q. agrifolia shoots artificially inoculated with G. pallida.

vasc

ula

r n

ecro

sis

(cm

)

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Conclusions • Geosmithia sp. 41 (Kolarik et al. in press) was consistently

recovered from cankered tissues of Q. agrifolia associated with western oak bark beetle from different locations in CA

• The fungus was directly isolated from P. pubipennis and its gallery walls

• Earliest detection of the fungus is 2009 • Pathogenicity of Geosmithia sp. 41 was confirmed by

conducting Koch’s postulates. • Preliminary data suggest that the beetle collected from FBC

infested trees is a cryptic species, but a larger sample size (populations and loci) is needed to determine the precise taxonomic status of P. pubipennis.

• Drought stressed trees may be prone to attack by WOBB • Fungal growth appears to girdle the plant, causing branch

dieback and tree death

Future Work

• Determine taxonomic status of the beetle with more loci • Further identify the life cycle of the beetle (number of

generations per year, etc.) • Diet tests to determine function of the fungus in the life cycle

of the beetle • Inoculation trials to characterize disease progress in the

greenhouse • Identify olfactory cues that attract the beetle to trees • Compare water potential between infested and non-infested

trees • Monitor distribution and impact of pest/disease

Acknowledgements

Miroslav Kolarik: Academy of Sciences of the Czech Republic Kim Corella, CalFire Robert Sartain: Oak Specialist, Santa Clarita Melody Lardner, USDA, Forest Service Brian Carrera: Arborist, Santa Barbara and San Louis Obispo Phil Cannon, USDA, Forest Service Robert Rabaglia: USDA Forest Service Entomologist Tom Roberts: Pest Control Advisor, Ventura and Santa Barbara County Rebecca Latta: Arborist, Los Angeles County