OSU Extension Service

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Flowers, shrubs and trees

Photo Credit: Alyson Yates (Cropped from original)

Meet Our Flowers, shrubs and trees Experts

Signe Danler

Home Horticulture Online Program Instructor

Contact for questions about Home Horticulture online. Submit other questions to Ask Extension, link below.

[email protected]

Amy Jo Detweiler

Horticulture

541-548-6088 x79510
[email protected]

Brooke Edmunds

she/her/hers

Community Horticulture, Master Gardeners

Contact me about the Master Gardener Program or gardening questions from Marion or Polk counties

[email protected]

Dan Leavell

541-883-7131
[email protected]

Jay W. Pscheidt

Plant Pathologist

541-737-3472
[email protected]
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Ask Extension is a way for you to get answers from the Oregon State University Extension Service. We have experts in family and health, community development, food and agriculture, coastal issues, forestry, programs for young people, and gardening.

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Which herbicides should I use on poison oak?

Q: I am dealing with poison oak growing in a stand of trees: Douglas firs, big-leaf maple saplings, and others. I have tried manual control and was unsuccessful. What would be the safest topical herbicide to apply to the leaves and stems while minimizing damage to the surrounding trees?

A: View answer | View all featured questions

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