Public Works and Environmental Services

CONTACT INFORMATION: Our offices are open 8 a.m. – 4 p.m. Mon - Fri - In-person meetings by appointment only.
703-324-1770 TTY 711
12055 Government Center Parkway
Suite 518, Fairfax, Va 22035
Brian Keightley
Division Director, Urban and Community Forestry

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Forest Pest Annual Report Highlights

The Fairfax County Board of Supervisors instruct the Forest Health Branch of the Urban and Community Forestry (UCFD) to monitor for, provide necessary and effective control of, and offer outreach and education about several forest insect pests and diseases. This report describes work completed by staff in 2023 including monitoring, inventories, treatment, and education/outreach. Of the 11 insects, diseases and animals monitored by UCFD, seven of them are found in Fairfax County.

Below are highlights of the full 2023 Forest Pest Annual Report. For questions about any of the topics below, please email treemail@fairfaxcounty.gov or call 703-324-1770, TTY 711.

Team photo of the forest pests team taken in 2023.
Team photo, 2023

Beech Leaf Disease (BLD)

Staff mapped six infestations totaling 60 acres at regional and County parks.

Photo showing leaf stripe patterns indicative of BLD
Striped patterns on leaves indicating BLD
Photo of staff setting up a BLD monitoring plot
Team setting up a BLD monitoring plot
Map showing BLD Surveys and Positive Sites for 2023
Map of BLD Surveys and Confirmed Sites in 2023 (Click to Enlarge)

Thousand Cankers Disease

Photo of thousand cankers disease.
Thousand Cankers Disease

Staff confirmed 199 positive Walnut Twig Beetle (WTB) specimens in 2023. 186 of them were collected at a single trap site in Lorton.

Emerald Ash Borer (EAB)

There are 186 trees currently included in the EAB (Agrilus planipennis) treatment program.

Photo showing adult Emerald Ash Borer, photo credit Davis Cappaert, Michigan State University
Adult EAB, Davis Cappaert, Michigan State University
Photo showing staff administering treatment for EAB. 186 ash trees that were evaluated in the County-wide ash treatment remain in the program. Six ash trees were added for a new total of 192 trees. Fifteen trees were treated for EAB.
186 ash trees that were evaluated in the County-wide ash treatment remain in the program. Six ash trees were added for a new total of 192 trees. 15 trees were treated for EAB.
Staff continued to monitor locations where EAB parasitoids were released within the last two years using yellow-pan traps to determine if the parasitoids have become established.
Staff continued to monitor locations where EAB parasitoids were released within the last two years using yellow-pan traps to determine if the parasitoids have become established.
Since 2016, staff has conducted a release program for EAB parasitoid wasps: Oobius agrili, Spathius agrili, and Tetrasticus planipennisi.
Since 2016, staff has conducted a release program for EAB parasitoid wasps: Oobius agrili, Spathius agrili, and Tetrasticus planipennisi.
Oobius agrili, the parasitic wasp that is a predator of EAB larva.
Oobius agrili, the parasitic wasp that is a predator of EAB larva.

Hemlock Woody Adelgid (HWA)

Staff treated the 1000th tree to protect it from HWA (Adelges tsugae).

Photo of HWA hidden underneath their woolly ovisacs on a heavily infested twig.
HWA hidden underneath their woolly ovisacs on a heavily infested twig.
Staff beat-sheeting for predatory beetles, a biocontrol released at Scotts Run Nature Preserve.
Staff beat-sheeting for predatory beetles, a biocontrol released at Scotts Run Nature Preserve.
Soil drench application on a hemlock tree.
Soil drench application on a hemlock tree.
Urban Foresters measuring pesticide for soil drench application.
Urban Foresters measuring pesticide for soil drench application.

Spongy Moth (SM)

Staff found zero SM caterpillar (Lymantria dispar), formerly called gypsy moth, egg masses in the County, therefore zero control treatments were needed in 2023.
Photo showing oak trees refoliating after a defoliation, photo credit Steven Katovich, Bugwood.org
Photo showing oak trees refoliating after a defoliation, photo credit Steven Katovich, Bugwood.org
Photo showing SM caterpillars chewing oak leaves, photo credit Tim Tigner, Virginia Department of Forestry, Bugwood.org
SM caterpillars chewing oak leaves, Tim Tigner, Virginia Department of Forestry, Bugwood.org

Spotted Lanternfly (SLF)

A total of 111 circle traps (without lure or pesticide strips) were deployed across the County July through October.
SLF nymph photo credit Eric Day, Virginia Tech Insect ID Lab, Virginia Tech Department of Entomology
SLF nymph photo credit Eric Day, Virginia Tech Insect ID Lab, Virginia Tech Department of Entomology
SLF adult and nymph photo credit Stephen Ausmus USDA
SLF adult and nymph photo credit Stephen Ausmus USDA
SLF egg mass
SLF egg mass
Staff using vacuum to control spotted lanternfly
Staff using vacuum to control spotted lanternfly
SLF Trap Locations
SLF Trap Locations (Click to Enlarge)

Outreach

Staff participated in outreach and education efforts to foster an appreciation for trees and the benefits of the urban forest and to inspire others to protect, plant, and manage greenspaces.

Staff at Bluebell at the Riverbend park talking to event participants.
Staff at Bluebell at the Riverbend park talking to event participants.
UFMD Staff at Burke Lake Park pointing out BLD to Architect of the Capital staff.
UCFD Staff at Burke Lake Park pointing out BLD to Architect of the Capital staff.

Forest Pest Annual Report

For more information about the activities the Forest Health team works on, please click on the link for the full 2023 Forest Pest Annual Report

2023 Forest Pest Annual Report
More About Urban Forest Management

Resources

Trees Home
Who To Call- Hazardous Trees
Urban Forestry FAQs
How to Hire an Arborist
Know the Rules
Publications and Forms
About Urban Forest Management
Invasive Species

Tree Planting and Care

Tree Removal
Tree Planting and Care
Insects and Diseases
Tree Identification
Tree Selection
Forest Health – Prevention and Treatment
Tree Preservation and Planting Fund

Outreach and Education

News, Videos and Podcasts
Education Programs
Trees Are The Answer - Benefits of Trees
Be Tree Friendly
Volunteer
Partners and Friends
Close
Fairfax Virtual Assistant

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