Tree care

OSU Extension offers science-based guidance to help Oregonians care for trees in urban, suburban and rural landscapes. We provide resources on planting, pruning, disease prevention and long-term maintenance to support healthy trees and resilient communities.

Trees to Know in Oregon and Washington

By Ed Jensen

For 70 years, people have turned to one book to learn about Northwest trees. This edition expands its scope, covering even more species of trees — including several rare species native to southwest Oregon. It also updates scientific names and adds a new section on how Northwest forests are likely to be affected by changing climates.

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Photo Credit: Stephen - Adobe Stock (Cropped from original)

Latest Resources

What’s wrong with my droopy dogwood?

We planted a ‘Snowy Peak’ dogwood last fall in loamy soil in a spot that gets full sun. It didn’t bloom this year. The leaves have black tips and some are turning brown. Is this leaf scorch or something else? A ...

Erica Chernoh | Jul 2025 | Featured question

Take care dealing with storm-damaged trees (in English)

The Colorado State Forest Service advises, "don't try to do it all yourself," when dealing with storm-damaged trees.

Jun 2025 | Online resource

First aid for storm-damaged trees (in English)

Storm-damaged trees can add up to big problems, but this guide from University of Missouri Extension advises people not to make any hasty decisions.

Jun 2025 | Online resource

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Pruning videos

Pruning with the Pros - Thinning a canopy (in English)

Getting sunlight into the canopy of a tree can help provide good light penetration and air circulation, assist ripening in fruit trees, and is pleasing to look at. Join our pruning pros for a demonstration on thinning the canopy of a mature crabapple tree.

Feb 2022 | Video

Pruning with the Pros - Collars and Ridges (in English)

Identifying collars and ridge tissue in woody plants can help us determine the best places to make pruning cuts.

Feb 2022 | Video

Pruning with the Pros - Removing a Double Trunk (in English)

The best practice for removing a “double trunk” from a young landscape tree.

Feb 2022 | Video

Pruning with the Pros - Removing a Wayward Branch (in English)

How to remove a wayward branch that doesn't contribute to the structure and aesthetic of a tree. With Oregon State University Extension’s Nicole Sanchez and certified arborists John Bellon and Tom Ford.

Feb 2022 | Video

Featured Questions

Will wildlife damage my old growth juniper?

We have an old growth juniper on our property, and it has been taken over by squirrels. They have made their homes underneath the tree. I am afraid they will weaken the root structure, and the tree could fall over in ...

Dana Sanchez | Jul 2021 | Featured question

Latest News

Extension forester distributes seedlings to help restore Port-Orford-cedar

The efforts enhanced reforestation with disease-resistant trees and also built a foundation for landscape-scale genetic resilience through local partnerships and grassroots action.

Norma Kline | May 2025 | Impact story

Tree School Online expands access to forest education for Oregon’s landowners

Tree School events were provided online in a series of 35 webinars hosted by OSU Extension in Clackamas County in collaboration with the Oregon Forest Resources Institute and the Oregon Partnership for Forestry Education.

Sarah Cameron, Glenn Ahrens | Mar 2025 | Impact story

OSU Extension works with partners to fight emerald ash borer

Efforts to manage the emerald ash borer in Oregon help protect the state's ash trees and maintain the health of its forests and urban landscapes.

Dan Stark, Lorelle Sherman, Lauren Grand | Feb 2025 | Impact story

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Explore more resources

Christmas trees

Cutting and selling trees

Forest health and management

Flowers, shrubs and trees

Urban forestry

Integrated pest management

Upcoming Events

Jul 12

Thinning Your Forest (Mark Havel Memorial Field Day)

9:00 am - 12:00 pm Oregon City, OR - Registration closed.

Sep 27

Tree School Field Day

8:00 am - 4:15 pm Oregon City, OR

Meet Our Experts

Alicia Christiansen

Forestry & Natural Resources, Associate Professor of Practice

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“Pregúntale a Extensión” es una forma de obtener respuestas del Servicio de Extensión de Oregon State University. Contamos con expertos en familia y salud, desarrollo comunitario, alimentación y agricultura, temas costeros, silvicultura, programas para jóvenes y jardinería.

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What’s wrong with my droopy dogwood?

P: We planted a ‘Snowy Peak’ dogwood last fall in loamy soil in a spot that gets full sun. It didn’t bloom this year. The leaves have black tips and some are turning brown. Is this leaf scorch or something else? A ...

R: View answer | View all featured questions

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