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).
Sooty Bark Disease
Introduction
Cryptostroma corticale
Sooty bark disease is caused by the fungus Cryptostroma [Biscogniauxia] corticale.
More Information
Please check our other webpage for more information and resources:
Sooty Bark Diseaese, Ornamental Plant Pathology Program, Washington State University
Is this Sooty Bark Disease?
You’re welcome to send samples to our lab for confirmation. Instructions for collecting samples are available here.
Contact us if you’re interested in submitting a sample.
The Pacific Northwest Story
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.
"The impacts of this disease on our forests and communities are likely to get worse as summer droughts become longer and hotter in the Pacific Northwest"
Joey Hulbert
Program Director
Learn More
Preparing and Responding to Mediterranean Oak Borer in Washington State – Online Workshop
Visit https://treehealth.wsu.edu/mob to register for this online event.
Additional Resources
Public Health
Tree Disease
Local Reports
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
Public Health Concerns
Please note, inhaling spores from Cryptostroma corticale can cause hypersensitivity pneumonitis or temporary respiratory issues in some people. If you’re vulnerable, we recommend wearing a N95 mask or respirator for protection against inhaling the fungal spores while handling possibly infected plant samples. If you’re concerned, please read more at this Maple Bark Disease resource provided by the Washington State Department of Health.
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What are your research needs?
What questions do you have?
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.
Upcoming Research
Is the prevalence of Sooty Bark Disease worse in hotter areas of Tacoma?
Together we can answer this question.
Air temperature data collected in July 2018 and shared by the City of Tacoma. Learn more in the Tacoma Community Forestry Story Map.
Visit our webpage here to accelerate research in Tacoma
