Tree care

Trees to Know in Oregon and Washington

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

Take care dealing with storm-damaged trees

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

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

Storm-related tree damage: steps to take before and after severe storms that may damage trees

Learn what precautions you should take, how to assess damage and when to call an arborist with this PDF from the International Society of Arboriculture.

Jun 2025 | Online resource

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Pruning videos

Pruning with the Pros - Thinning a canopy

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

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

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

Feb 2022 | Video

Pruning with the Pros - Removing a Wayward Branch

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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Upcoming Events

Jun 27

Tree School East 2025

8:00 am - 5:00 pm Baker City, OR

Jul 12

Thinning Your Forest (Mark Havel Memorial Field Day)

9:00 am - 12:00 pm Oregon City, OR

Meet Our Experts

Alicia Christiansen

Forestry & Natural Resources, Associate Professor of Practice

Have a question? Ask Extension!

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Can pine needles be used as mulch for fruit and maple trees?

Q: Is it OK to mulch fruit trees and maple trees with pine needles or are they too acidic?

A: View answer | View all featured questions

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