Sooty Bark Disease

Introduction

Cryptostroma corticale spores - M. Elliott, WSU
Photo Credit: Marianne Elliott, Washington State University

Cryptostroma corticale

Sooty bark disease is caused by the fungus Cryptostroma [Biscogniauxia] corticale.

The  ‘sooty’ fungal structures may be observed growing on the stem or branches where the bark has flaked off.

These fungal structures release tiny spores that can spread via the wind during certain times of the year (When? See research needs).

The Pacific Northwest Story

2020
2020

C. corticale found in Seattle, WA

Bartlett Tree Experts confirms the presence of C. corticale on 10 trees in Seattle in cooperation with Seattle Parks and Recreation.

2021
2021

C. corticale found in more Puget Sound cities

The Ornamental Plant Pathology program at Washington State University confirms the presence of C. corticale on a number of trees from cities of Tacoma, Bellingham, Anacortes, and Olympia.

2022
2022

iNaturalist project launched

The Sooty Bark Disease Watch project on iNaturalist is launched for a community effort to advance knowledge about the disease distribution and susceptible hosts.

Summary

In general, it is our understanding that C. corticale has been present and spreading in Washington (and greater Pacific Northwest) since at least the late 1960s, but it did not emerge as an noticeable issue until recently.

Why is this disease emerging now?

Longer and Hotter Summer Droughts

Sooty bark disease is likely emerging as an issue now because of the recent increase in the length and intensity of the summer droughts in the Pacific Northwest. 

These changes in climate are likely driving the emergence of sooty bark disease for two reasons:

Increased Tree Stress

Trees are more stressed because of the increased length between rain events

Favorable Fungal Growing Conditions

The fungus is favored by warmer temperatures, growing faster and 'behaving' more aggressively.

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Learn More

Sooty Bark Disease Information Session – September

Have questions about Sooty Bark Disease? Join us for a presentation and discussion about Sooty Bark Disease in the Pacific Northwest.  The event will be held virtually using Microsoft Teams …

Find out more »
Online – Microsoft Teams Meeting,

Sooty Bark Disease Information Session – November

Have questions about Sooty Bark Disease? Join us for a presentation and discussion about Sooty Bark Disease in the Pacific Northwest.  The event will be held virtually using Microsoft Teams …

Find out more »
Online – Microsoft Teams Meeting,

Research Needs (Brainstorm)

Fungal Life History
  • General seasonality and conditions necessary for spore production and release (i.e. to inform decisions about when to prune nearby trees).
Epidemiology
  • Conditions necessary for infection
  • Tree susceptibility after wounding or injury
  • Seasonal and climatic conditions when spore loads are highest
  • Investigating whether sporulation occurs on wood chips or mulch
  • Susceptibility of various tree tissues
Management & Control
  • Importance and efficacy of sanitizing tools, gear and equipment in between jobs
  • Efficacy of phosphonates tree injections or chemical controls
  • Biocontrol options
Public Health
  • Evaluation of risk in day to day activities of professionals
  • Precautions to reduce risk of inhaling spores

What are your research needs?

What questions do you have?

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Upcoming Research

Get Involved

Share observations on iNaturalist

You can accelerate research about the breadth and impact of sooty bark disease. Join the iNaturalist project and share observations of trees infected with sooty bark disease. This information will help us understand where the disease is affecting trees and which species are susceptible.

Be a Tacoma Community Scientist

Visit our webpage here to accelerate research in Tacoma

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