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    Author(s): Natasha Vizcarra; Rick Kelsey; Joe Karchesy
    Date: 2017
    Source: Science Findings 194. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 5 p.
    Publication Series: Science Findings
    Station: Pacific Northwest Research Station
    PDF: Download Publication  (4.0 MB)


    Societies use biologically active chemicals as medicines and pesticides to protect human and agricultural health. But widespread use of synthetic compounds raises concerns about their safety, and resistance development in targeted pests.

    To find safer alternatives, scientists turned to native plants and trees in Pacific Northwest forests using multiyear exploratory surveys. Researchers collected samples from different plant and tree parts for extraction and toxicity testing with a simple brine shrimp bioassay. These bioassays detected strong biological activity in heartwood extracts from four cedar and one juniper species.

    In followup experiments, researchers discovered that heartwood extracts from yellow-cedar (Callitropsis nootkatensis), incense cedar (Calocedrus decurrens), Port Orford cedar Chamaecyparis lawsoniana), and western juniper (Juniperus occidentalis) had strong toxicity or repellent activity toward mosquitoes, ticks, or fleas. A patent was issued for compounds with activity toward these pests. It has been licensed to a company interested in developing them into commercial products.

    In other experiments, researchers found extracts and compounds from cedar heartwood possess strong antimicrobial activity against Phytophthora ramorum, the pathogen causing sudden oak death. To mitigate movement of P. ramorum spores by hikers and cyclists, forest health specialists have used western redcedar (Thuja plicata) heartwood chips on a popular hiking trail on the Rogue River-Siskiyou National Forest, where retreatment continues to show promising results.

    Publication Notes

    • Visit PNW's Publication Request Page to request a hard copy of this publication.
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Vizcarra, Natasha; Kelsey, Rick; Karchesy, Joe. 2017. Northwest forest plants defeat pests and diseases! Science Findings 194. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 5 p.


    Heartwood extracts, sudden oak death, phytophthora ramorum, nootkatone.

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