The Forest Health Highlights in Washington report is published annually by DNR’s Forest Health and Resiliency Division and the USDA Forest Service each spring. It summarizes the major forest insect and disease conditions from the previous year across all ownerships throughout Washington. Much of what is reported are results of aerial surveys and ground based surveys, but it also includes information on special monitoring projects, suppression projects, and other forest-health related projects and initiatives. It also includes information on recent forest damaging weather events, droughts, and wildfires. Printed copies are available on request by contacting 360-902-1300 or forest_health@dnr.wa.gov.

Past reports

• Forest Health Highlights in Washington - 2019
• Forest Health Highlights in Washington - 2018
• Forest Health Highlights in Washington - 2017
• Forest Health Highlights in Washington - 2016
• Forest Health Highlights in Washington - 2015
• Forest Health Highlights in Washington - 2014
• Forest Health Highlights in Washington - 2013
• Forest Health Highlights in Washington - 2012

(Joseph OBrien/USDA Forest Service photo)

Our trees and forests are subject to a wide variety of pests and diseases, which are usually caused by bacteria, viruses, and most commonly, fungi. Tree diseases can decay wood, decrease tree growth and cause tree mortality in both forested and urban environments. Overall, forest diseases can impact carbon sequestration, purification of water, reduction of flood risk and cultural and recreational values. Many of our diseases in Washington are native and have been here a long time, often directly influencing the biodiversity and nutrient cycling in forests. All parts of a tree, including roots, stems, branches, and foliage, can be infected by the different organisms that cause diseases, resulting in different impacts on a tree’s health. They often have specific host preferences and environmental conditions in which they live, reproduce and spread. Non-native and invasive diseases are a constant threat to our forests since our trees have no natural defenses against the pathogens. Information about specific diseases and projects we are working on can be found below.

If you have questions about tree diseases or other forest health questions, including management and treatment options, please contact our State Forest Pathologist, Dan Omdal, at 360-902-1692 or email dan.omdal@dnr.wa.gov.

Forest Management Guides

• Ecology and Management of Eastern Oregon Forests (OSU Extension)
• Managing Insects and Diseases of Oregon Conifers (OSU Extension)

Forest Insect and Disease Leaflets

Foliar Diseases

• Dothistroma Needle Blight
• Swiss Needle Cast
• Western Larch Foliar Disease

Root Diseases

• Annosus Root Disease
• Armillaria Root Disease
• Black Stain Root Disease
• Laminated Root Rot
• Schweinitzii Root and Butt Rot

Dwarf Mistletoes

• Douglas-fir Dwarf Mistletoe
• True Fir Dwarf Mistletoe
• Hemlock Dwarf Mistletoe
• Larch Dwarf Mistletoe

Other Diseases

• Elytroderma Disease of Ponderosa Pine
• Western Gall Rust

Additional Resources

(Donald Owen/California Department of Forestry and Fire Protection photo)

DNR’s forest entomologists provide technical assistance to private landowners and state land managers with identification and management of forest insect pests. The primary focus is on insects that cause mortality such as bark beetles, those that cause growth loss and stress such as defoliators, and those that affect wood quality. We emphasize integrated forest pest management methods that focus on increasing stand resistance to insect attack and resilience following any damage that may occur. Management strategies that can increase resistance and resilience include increasing vigor of leave trees through selective thinning, reducing the proportion susceptible hosts, altering stand structure and/or age classes, planting species appropriate for the site, and reducing available breeding material (slash management or salvage following storms and fires). We annually monitor populations of Douglas-fir tussock moth and western spruce budworm in eastern Washington. We assist with the annual aerial survey. When unexpected levels of damage occur, we may conduct special monitoring projects to determine levels of mortality and potential causes. We also provide assistance to state and private land managers with specific insect monitoring, stand evaluations, and suppression projects. In some stands where forest health treatments have been applied, we install long-term plots to monitor changes in insect activity.

If you have questions about forest insects in Washington, please contact our State Forest Entomologist, Glenn Kohler, at 360-902-1342 or email glenn.kohler@dnr.wa.gov.

Forest Management Guides

• Ecology and Management of Eastern Oregon Forests (OSU Extension)
• Managing Insects and Diseases of Oregon Conifers (OSU Extension)

Forest Insect and Disease Leaflets

Bark Beetles

• California five-spined Ips
• Douglas-fir beetle
• Fir engraver
• Mountain pine beetle
• Pine engraver
• Red turpentine beetle
• Spruce beetle
• Silver fir beetle
• Western pine beetle

Defoliators

• Douglas fir tussock moth
• Larch Casebearer
• Pine Sawflies
• Western spruce budworm
• Western Tent Caterpillar

Sucking Insects

• Balsam Woolly Adelgid
• Black Pineleaf Scale

Additional Resources

• Douglas-fir tussock moth (DFTM)
• Bark beetle activity following blowdown in Western Washington
• Monitoring Distribution and Flight Periods of California Firespined Ips in Washington State
• WSU Extension California firespined Ipsfactsheet
• U.S. Forest Service DFTM webpage
• Green Alder Sawfly, Monasome pulveratum-Pacific Northwest Surverys in 2011
• US Forest Service green alder sawfly webpage
• Distribution of oak pit scale and associated crown dieback of oregon white oak in Washington
• University of California oak pit scale managment guide
• Refining aerial detection survey (ADS) high-intensity tree mortality estimates in the Pacific Northwest
• Western spruce budworm phenemone results in eastern Washington 2016
• Western Spruce budworm risk factors
• Quaking aspen health
• Land Manager's Guide to Aspen Management in Oregon (OSU Extension)
• Field guide to diseases and insects of quaking aspen in the West (US Forest Service)
• U.S. Forest Service, Pacific Northwest Region, Forest and Grassland Health
• Using MCH to Protect Trees and Stands from Douglas-fir Beetle Infestation (USDA Forest Service)
• Cone and seed insects of North American conifers (Canadian Forest Service)
• Defoliator Information
• Eastern Washington Forests, Conifer Mortality Prediction Criteria
• Gypsy Moth Program, Washington State Department of Agriculture
• Pine Shoot Insects Common in British Columbia (Canadian Forest Service)
• Washington Invasive Species Council
• Management of White Pine Weevil in Spruce (University of Idaho Extension)

Systematic aerial surveys are conducted to collect and report on forest insects, diseases, and other disturbances across federal, state, tribal and private lands. These surveys have been conducted annually since 1947 in the Pacific Northwest by USDA Forest Service (USFS) with the cooperation of State and private partners since 1948. Aerial surveys have proven to be an efficient and economical way to detect and monitor forest change events over large forested areas. Statewide aerial surveys are conducted each year to assess forest health in Washington State. They capture mortality and discoloration caused by insects, diseases and abiotic disturbances. This relatively low cost remote sensing method gives a coarse, landscape-level overview of forest conditions. The data collected are then used with other remote sensing and ground sampling techniques to further enhance the data accuracy of significant forest health events and changes.

Aerial Survey Data Collection Methods

The primary data collection method is known as aerial sketchmapping. Data are collected by specially trained aerial observers from the USFS and Washington Department of Natural Resources (DNR). The necessary components to make this survey happen are a high-winged aircraft that provides good visibility and can fly at relatively slow speeds between 1,000 to 2,000 feet above ground level, a safety conscious pilot, and an experienced sketchmapper who can identify forest damage observed on the ground and plot it on a map while moving in the air. Areas of forest damage are recorded as polygons using a Digital Aerial Sketchmapping System (DASM). The DASM uses a moving map display, GPS, and a touch screen to create a digital version of the data while in the aircraft. The polygons are coded with attributes such as tree species affected, number of trees (or trees per acre) affected, likely cause of damage, and severity of damage. This advanced digital sketchmapping system allows rapid summarization and near real time reporting of tree mortality and damage. This is an extremely valuable tool for forest managers and other clients who can use the data to make timely decisions and assessments.

For more information on the aerial survey program, please contact Glenn Kohler at 360-902-1342 or glenn.kohler@dnr.wa.gov.

Additional Resources