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Thwarting Invasives in the Pacific Northwest: Success Stories from the Field

With the negative impacts that invasive species have upon the landscapes in the Pacific Northwest and the threats that new invasives pose, it’s easy to forget there are success stories. Native species can reclaim a landscape once invasive plants are removed. Volunteers are willing to spend weekends clearing out knotweed or English ivy. Individual trees have resistance to foreign pathogens. The surveying measures at our ports do prevent invasives from entering the United States and the field surveys identify early infestations that can be eradicated.

Here are two success stories.

Posed for a Comeback: Port-Orford-Cedar

By Richard Sniezko

Pollinations of these Port-Orford-cedar orchard trees will be used to increase resistance
in the next generation. Photo Courtesy of Richard Sniezko 

Port-Orford-cedar (Chamaecyparis lawsoniana, Lawson’s cypress) is a long-lived conifer native to northwestern California and southwestern Oregon. It used to be widely planted in urban landscapes, particularly in North America and Europe until the accidental introduction nearly 100 years ago of a non-native pathogen, Phytophthora lateralis. The pathogen causes Port-Orford-cedar root disease, which can kill large old-growth trees, as well as young seedlings. It led to a decline of the cedar in its native range and in North American urban forests. What was once a multi-million-dollar product for the horticulture industry was no longer profitable. More recently, the disease has also appeared in Europe.

Genetic resistance is an organism’s primary line of defense, but it was initially unknown if Port-Orford-cedar had any. Testing at Oregon State University (OSU) confirmed there was some resistance. Because resistance breeding is a vital tool to save our native tree species affected by non-native pathogens and insects, in 1997, a large-scale inter-agency, inter-regional applied resistance program was led by the US Forest Service (USFS) and Bureau of Land Management (BLM). The program was based at the USFS’s Dorena Genetic Resource Center (DGRC) in Cottage Grove, Oregon; the Dorena Genetic Resource Center is an internationally recognized world leader in developing resistant tree populations.

With the assistance of many USFS and BLM employees and other cooperators, more than 14,000 parent trees have been selected and tested for resistance at OSU. Two types of resistance have been characterized:

(1) qualitative (controlled by a single major gene) and (2) quantitative (putatively polygenic).

Unique, containerized seed orchards for each of the 13 breeding zones in the Pacific Northwest are being established. The goal is to provide resistant seed for deployment while retaining genetic diversity and adaptability. Results from the field trials are encouraging, but ongoing monitoring is needed to confirm the durability and stability of the resistance. While most trees in natural stands are highly susceptible, early data indicates that 50 percent or more of the seedlings produced from orchard seed are resistant, and breeding is underway to increase resistance further.

Resistant orchard seed is now available for several breeding zones and is being used in reforestation and restoration. The discovery of resistance may even provide an avenue to once again use this native tree species in urban plantings. Because of this success, the Port-Orford-cedar Resistance Program may be one of the fastest moving and successful resistance programs for forest trees in the world.  u

Richard Sniezko, an SAF member, is a geneticist at the U.S. Forest Service Dorena Genetic Resource Center in Cottage Grove, Oregon. Sniezko can be reached at 541-767-5716 or Interested in Port-Orford-cedar seed? Contact Don Kaczmarek, Oregon Department of Forestry,


Oregon Forest Pest Detector program

By Wyatt Williams

Since 2013, many Oregon’s natural resource agencies, such as the Oregon Department of Forestry (ODF) and Oregon Department of Agriculture (ODA), and local governments have teamed up on the Oregon Forest Pest Detector (OFPD) program to protect the state’s forests and agriculture from damaging invasive species. The USDA-funded program, coordinated and led by Oregon State University Extension Forestry, aims to train arborists, landscapers, park workers, and other professionals on the early signs and symptoms of priority invasive forest insects.

Using a combination of online presentations, face-to-face seminars and field training courses, over 500 professionals have been trained as “First Detectors” of emerald ash borer, Asian long-horned beetles, and other exotic forest insects, which have yet to be detected in Oregon but whose arrival is imminent. The OFPD uses the online reporting system, Oregon Invasives Online Hotline, which is a product of Oregon Invasive Species Council and Portland State University. While in the field using any smart device. First Detectors can take a picture, record a GPS point, and log a report of possible invasive species. The overall goal is to detect key forest invaders early in their invasion when eradication is still feasible.

In the summer of 2019, two graduates of the OFPD independently submitted reports to the state’s invasive species hotline of suspicious exotic insect damage to native twinberry plants (Lonicera involucrata) in the Portland metro region. ODF Forest Health staff, alongside partners with the ODA, responded to the reports and identified an exotic woodborer, Agrilus cyanescens, previously unknown to the Pacific Northwest. This Eurasian insect has been present in the northeastern US since at least 1921 and feeds on native honeysuckles (Lonicera sp.). ODF is assisting ODA and other partners in monitoring and outreach of this discovery.

The discovery and report of previously undocumented exotic woodborer is proof-of-concept for targeting education of Oregon’s forest professionals through the Pest Detector program and demonstrates the effectiveness of a statewide Invasive Species Hotline. However, given the uncertainty in funding and outlook for government programs, the OFPD is at a tenuous crossroads. Short-term funding will expire in coming months. After that, the state’s forests and agriculture will be more vulnerable to new, establishing invasive species.

Wyatt Williams is an invasive species specialist with the Oregon Department of Forestry. Williams can be reached at 503-945-7472 or For more information on the Oregon Forest Pest Detectors and current class schedule, visit the OFPD website: or

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