Yana Valachovic, Brendan Twieg and Dan Stark Humboldt and Del Norte Counties UC Cooperative Extension

Funding provided by: USDA Forest Service, State and Private Forestry and SOD Research, American Recovery and Reinvestment Act, CAL FIRE

Since 2004 we have been conducting ground-based and stream monitoring for the pathogen

Installed many management trials to both control the spread of the pathogen and to learn how to protect high-value trees and forests

Developing a set of science-based tools to provide managers and landowners with resources to address the pathogen

Coordinating an inter-agency response team

• Ground Surveys: people on foot look for symptomatic vegetation and take samples

• Aerial Detection: people detect

mortality consistent with disease from an aircraft

• Stream Monitoring: detects when

pathogen is input—often from terrestrial infection—upstream of leaf baits

SOD Detection

Aerial Surveys

USDA Forest Service Aerial Pest Detection Unit (those boys & girls are good!) Maps all types of abnormalities

of all tree species Sometimes more focused SOD

surveys are conducted

‐ Can’t see trees under canopy ‐ Symptoms are not unique to P.

ramorum; ground sampling & lab testing still necessary

Aerial Surveys

Risk models

Meentemeyer et al., 2004

2001 Disease

Distribution

2014 Disease

Distribution

Most moderate-risk area here does not contain bay laurel; risk model here is driven by veg. types that include shrub-form tanoak or have tanoak associated commonly elsewhere.

Notholithocarpus densiflorus varieties densiflorus & echinoides

• Ten individuals of each var. from Trinity County (uninfected locations) – 6 branches per tree, each with

multiple sub-branches • 1 control • 5 inoculated

– Two strains each branch » Santa Cruz nursery-

origin » Trinity County wildland

origin

• Inoculate twigs and measure lesion growth

• Experimental design and bulk of lab work by the Rizzo Lab: Dave Rizzo, Heather Mehl, Kamyar Aram, et al.

Inoculations

Both varieties highly susceptible…

var. densiflorus (tree form) var. echinoides (shrub form)

Both varieties formed lesions that girdled the stems and killed all distal leaves • Do varieties differ in the frequency of such girdling lesions? • Do the two inoculant strains differ in virulence?

Notholithocarpus densiflorus var. echinoides

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Acres of SOD-consistent tanoak mortality identified by USFS Aerial Surveys

Unresolved issues How to clean heavy equipment?

California bay laurel stumps Equipment is working where trees have been fallen

Logging Equipment: Lots of Infested Soil

LOG LOADER: CAN HARBOR OVER 500

LITERS OF SOIL/DEBRIS