Sunday, November 1, 2020

Status of Emerald Ash Borer in Minnesota

 

Range of confirmed emerald ash borer in Minnesota. Source: Minnesota Department of Agriculture.

Emerald ash borer, or EAB, has been confirmed in 25 counties in Minnesota. The latest discoveries were in late summer 2020 in Carver and Sibley Counties, southwest of the Twin Cities. All affected counties are shown in the map above, which is a snapshot of an interactive map maintained by the Minnesota Department of Agriculture. It shows quarantined counties in pink, the quarantine boundary in red, and the boundaries of generally infested areas in green. Click on the map or the link in this paragraph to view the interactive version.

Movement of some types of wood out of the quarantine area is regulated. Ash logs and lumber, ash tree waste, ash chips and mulch, and any hardwood (deciduous) firewood should not be moved outside the quarantine area without a Compliance Agreement with the MDA. The agreement requires that the wood be treated in any of several ways to minimize the risk of EAB spread. To get an agreement, call Arrest the Pest at 888-545-6684 or email arrest.the.pest@state.mn.us.

How to Detect EAB

EAB is a serious pest of all native ash trees. The insect, Agrilus planipennis, overwinters as larveae or pupae in the bark or wood. Metallic, green adults, just shorter than the width of a penny, emerge from the trees in spring or early summer and later lay their eggs on ash trees. The larvae burrow into the bark and feed on the inner bark and outer sapwood, tissues that conduct water, nutrients and sugars throughout the tree. Infested trees die 1-3 years later.

During the growing season, one symptom of EAB infestation is die-back of the canopy, starting at the crown and moving down. Some trees also develop epicormic sprouts, branches that grow from the lower part of the trunk. In fall and winter, look for woodpecker holes (the birds eat EAB larvae), cracks in the bark and, under the bark, S-shaped galleries of EAB larvae.

From left: 1) Canopy dieback; Source: Steven Katovich, Bugwood.org. 2) Epicormic sprouts; Source: Pennsylvania Department of Conservation and Natural Resources - Forestry, Bugwood.org. 3) Woodpecker damage; Source: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org. 4) EAB galleries: Source: Kelly Oten, North Carolina Forest Service, Bugwood.org. Full photo credits are below.


To determine if an ash tree might be infested with EAB, use the MDA’s “Does My Tree Have Emerald Ash Borer (EAB)?”  If you then suspect an EAB infestation, call Arrest the Pest at 1-888-545-6684 or email arrest.the.pest@state.mn.us.

Help Find EAB

Emerald ashborer. Source:Leah Bauer, 
USDA Forest Service Northern Research 
Station, Bugwood.org.

Emerald ash borer beetles are inconspicuous, but a University of Minnesota citizen science project used a unique tool to find them: Wasps. Volunteers for the project, called Wasp Watchers, monitored nests of the smoky winged beetle bandit wasp, Cerceris fumipennis, for their beetle prey. Finding EAB alerted scientists to locations of affected ash trees, sometimes before the trees began showing symptoms.

The Wasp Watchers program ended in July 2020, but volunteers can still monitor wasp colonies for beetle prey and report their findings through iNaturalist. Wasps or nesting sites with EAB should also be reported to Arrest the Pest. These web pages offer more information:

What About Other States?

For information about EAB in neighboring states, visit these websites:

References and More Information

Haack, R. A., et al. Emerald Ash Borer Biology and Invasion History. Chapter 1 in Biology and Control of Emerald Ash Borer. USDA, March 2015. https://www.fs.fed.us/foresthealth/technology/pdfs/FHTET-2014-09_Biology_Control_EAB.pdf

Emerald Ash Borer Program. Minnesota Department of Agriculture. Website accessed October 29, 2020.

Questions & Answers About the EAB Quarantine & Compliance Agreements. Minnesota Department of Agriculture. Website accessed October 29, 2020.

Photo Credits

Canopy dieback by Steven Katovich, Bugwood.org, licensed under a Creative Commons Attribution 3.0 license.

Epicormic sprouts by Pennsylvania Department of Conservation and Natural Resources – Forestry, Bugwood.org, licensed under a Creative Commons Attribution 3.0 License.

Woodpecker damage by Kenneth R. Law, USDA APHIS PPQ, Bugwood.org, licensed under a Creative Commons Attribution 3.0 License.

EAB galleries by Kelly Oten, North Carolina Forest Service, Bugwood.org, licensed under a Creative Commons Attribution-Noncommercial 3.0 License.

Emerald ash borer by Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org, licensed under a Creative Commons Attribution-Noncommercial 3.0 License.


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