Progress report for WLED25-002
Project Information
Symphylans (Scutigerella immaculata Newport) are a persistent soil pest that affects many fresh vegetable and seed crops in Oregon’s Willamette Valley, resulting in poor stand establishment and economic damage. They are consistently identified as a major pest in the maritime Pacific Northwest, particularly in fields with fine-textured soils, high organic matter, and irrigation, which are common here. This project will demonstrate innovative monitoring and management strategies at OSU and on organic fresh vegetable and specialty seed farms. Our objectives are to: 1) Increase the adoption of symphylan monitoring; 2) Strengthen confidence in suppressive and tolerant crops; 3) Demonstrate judicious and effective use of biopesticides for symphylan management; and 4) Expand symphylan management knowledge among a broader audience.
We developed this project in close consultation with growers at a workshop in February 2024 and individual interviews. We will demonstrate symphylan bait sampling, the effectiveness of suppressive crops, and promising biopesticides identified in previous WSARE-funded projects and in Kaur’s ongoing research.
We propose a combination of OSU and on-farm demonstrations and field days that include interactive symphylan monitoring and management activities and peer-to-peer conversations around symphylan management. OSU demonstrations will include all components (monitoring, suppressive and tolerant crops, and biopesticides). Farmers will choose management methods based on monitoring results from their farm. This work will be shared more widely at an intensive symphylan management workshop and at grower conferences. Written information will also be distributed through newsletter articles and a new symphylan management Extension publication.
We will measure project outcomes with surveys at field days and workshops that evaluate knowledge gain and intention to adopt the research-based practices we promote. Collaborator interviews, notes from peer-to-peer conversations and the level of engagement with workshop and field day activities will provide qualitative evaluation information to complement survey results.
- Increase adoption of symphylan monitoring. Bait sampling is effective but nuanced. When used correctly it can identify hot spots and guide management decisions. We will monitor an OSU demonstration site and collaborator’s fields for symphylans and associated predators and interpret results to guide crop rotations (e.g., susceptible, tolerant or suppressive crop) and biopesticide choices.
- Strengthen confidence in the use of suppressive and tolerant crops. We will recommend areas to plant suppressive or tolerant crops based on monitoring results. Choices will vary between farms and may include potato cash crops, potatoes terminated early as a pest management cover crop, grass or cereal cover crops, or other suppressive plants identified in Kaur’s research. We will develop a list of suppressive and tolerant crops based on a review of scientific literature and the experiences of collaborators.
- Demonstrate judicious and effective use of biopesticides for symphylan management. Drawing on Kaur’s ongoing insecticide efficacy trials, we will demonstrate promising biopesticides at OSU. We will present biopesticide options to collaborators monitor results on their farms. All our collaborators are certified organic or use organic methods, so this work will focus on NOP-compliant biopesticides. Some collaborators are reluctant to use any pesticides.
- Increase symphylan management knowledge among a wider audience using the PAMS approach: Prevention, Avoidance, Monitoring, and Suppression (Coble 2003). We will host a wide range of events to share knowledge from this and related projects and publish at least one newsletter article and one peer-reviewed Extension publication.
Garden symphylans (Scutigerella immaculata Newport) damage the roots of many specialty crops in western Oregon, Washington and California (Umble and Fisher 2003a and b, Josef 2015). They reduce water and nutrient uptake and can stunt or kill plants especially during establishment. Infestations are mostly reported in fine textured soils with high organic matter content and are often severe under irrigation. Symphylans aggregate in high densities within fields creating hotspots with severe damage and little to no damage elsewhere, the area damaged varies but can be as large as 0.1 ha.
In a survey of 106 organic farmers in the PNW to identify “what is needed to enhance organic agriculture in Oregon?”, Stephenson et al. (2012) reported that “pest and disease issues – symphylans in particular” where a top priority for farmers. More recently, the Oregon Chlorpyrifos Critical Use Survey of 189 respondents found that symphylan is a priority pest in multiple crops in Oregon, and symphylan control relies heavily on the use of broad-spectrum insecticides (Lightle et al. 2022). Our collaborators want to improve ecologically sound symphylan management methods on their farms.
On February 16 2024, 30 vegetable and specialty seed farmers and related professionals joined our “Symphylans – In a Class of Their Own” workshop to discuss the latest research, share experiences, and prioritize future work using a dot survey of strategies identified during the event. Reducing symphylans with potatoes or other suppressive crops garnered the most interest, followed by crop timing, tillage and biopesticides (Andrews et al. 2024). Surprisingly, monitoring was not highly rated, but in follow-up conversations collaborators recognized its importance for mapping infestations and measuring success. Many don’t grow potatoes and lack planting or digging equipment; for those that do, potatoes are a low margin crop. This stands in the way of wider adoption. One collaborator explained that they grow nearly double the area of potatoes they normally would because of their suppressive effect on symphylans. One workshop participant gave up farming due to symphylan pressure and chided soil health advocates for their “ignorance about symphylans”. Others have removed acreage from production due to symphylan damage.
Symphylans are challenging to study because populations fluctuate in response to field management and other unknown factors. OSU has two sites with high pressure and all six farm collaborators report infestations. We expect to increase adoption of bait monitoring, suppressive and tolerant crops in rotation, and judicious use of biopesticides.
Spring/summer 2025: We will monitor symphylans with bait traps at OSU and collaborating farms and collect soil samples for natural enemy sampling. We will provide results to farmers and note their normal practices in 2025. In an OSU symphylan hot spot we will grow potatoes for early termination and to maturity, demonstrate spinosad bait (Seduce) and azadirachtin (e.g. AzaGuard) as a potting soil drench with a susceptible indicator (e.g. broccoli) and untreated comparison. We will also grow potentially suppressive crops that are unfamiliar to collaborators (e.g. litchi tomatoes, ashwagandha). Our first field day will demonstrate bait sampling techniques and these suppressive methods for collaborating farmers.
Winter 2025-26: We will host a focus group or interview collaborating farmers to discuss current knowledge and plan 2026 activities.
Spring/summer 2026: We will continue on-farm bait sampling and adapt the 2025 demonstrations at OSU. We will conduct on-farm demonstrations with the farmer’s choice of suppression methods and host a public field day.
Winter 2026-27: We will host a symphylan management workshop and share findings from this and related projects. We will invite collaborating farmers to describe their strategies and host a farmer-to-farmer conversation about symphylan management. We will make note of any participants interested in adopting symphylan monitoring and management practices. We will publish a newsletter article on the project and start drafting the peer-reviewed Extension publication.
Spring/summer 2027: We will adapt on-farm demonstrations from 2026 and host another public field day. We will provide technical information to farmers from the winter workshop who decide to adopt monitoring and management strategies.
Winter 2027-28: We will present project findings at grower conferences such as the OSU Small Farms Conference, Hermiston Farm Fair, etc., and prepare the new Extension publication for peer review.
Cooperators
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Education & Outreach Initiatives
Grow novel crops with the potential to suppress symphylan in rotation, demonstrate promising biopesticides, grow potatoes as a suppression crop with different termination dates to assess subsequent weed management potential, and demonstrate symphylan sampling. Host field days for collaborating farmers.
We transplanted organically grown demonstration plots of nine novel crops being tested in lab bioassays (separate grant) for symphylan suppression. We transplanted ‘Green Magic’ broccoli as a susceptible crop in a symphylan hotspot confirmed by spring monitoring, and treated them with biopesticides (e.g. Entrust, Seduce and AzaGuard) and an untreated control. We grew organic Russet Burbank potatoes and tilled them under about 8, 11, 14 and 17 weeks after planted to observe subsequent weed pressure. On August 5, 2025 this project was featured with other projects during the Organic Agriculture field day. Nick described the project and demonstration plots, Navneet described related research findings and Alison demonstrated bait sampling for symphylans. Navneet and Alison also hosted a display table with symphylans and educational bait stations. All participants received handouts with sampling instructions, on-farm monitoring results and a resource list. The project was also featured during an Extension faculty and staff field tour for the OSU Center for Resilient Agriculture and Food Systems, Nick described the project and Sai demonstrated bait sampling for symphylans.
Approximately 75 farmers and 10 agricultural service providers attended the Organic Agriculture field day. Of the 24 who completed evaluations, 23 (95.8%) reported learning a lot (19) or moderate amount (4) about symphylan management. Results were extrapolated to include participants who did not complete evaluations.
Present project results so far and related research, host a farmer-to-farmer discussion and discussed options for the 2026 on-farm demonstrations.
We hosted our first project collaborator meeting on Jan 23, 2026 at the Linn County Extension office. We provided handouts with project findings, related research findings and a resource list. We created and distributed a draft survey of symphylan management practiced to be modified for larger audiences, and a sign-up sheet for 2026 demonstrations.
Six farmers attended the meeting representing four of the participating farms. We will follow up with the other two farms individually. One farm reported high damage from symphylans in hot spots recently, two reported moderate damage and one reported mild damage. Spring 2025 was unusually dry, these conditions lower the risk of symphylan damage. On average, the farms reported significant crop loss due to symphylans in 6.6 of 10 years. All four farms use potatoes in rotation to suppress symphylans. Three of the four reported problems using potatoes to suppress symphylans and one more verbally, challenges were similar such being unable to grow enough potatoes to suppress symphylans, potatoes being too low value and, no market for potatoes and expensive labor during harvest. Four of the respondents (including verbal respondent) are organic fresh market vegetable growers supplying direct markets, one is an organic specialty seed grower. So far, three of the six farms have signed up for on-farm demonstrations. Two were interested in monitoring, one in the natural enemy survey, two in tolerant crops, one in potatoes for harvest, one in potatoes as a pest management crop (not for harvest), one in other suppressive crops and two in biopesticides.
Educational & Outreach Activities
Participation summary:
We conducted one demonstration of four management practices at OSU and five on-farm monitoring demonstrations. We participated in two field days as described above. We created handouts with project findings, related research updates and resource lists for the Organic Agriculture field day and the 2026 collaborator meeting. We provided an estimated 12 consultations related to symphylan management and project findings so far.
Learning Outcomes
Project Outcomes
Most collaborating farmers know that potatoes suppress symphylans. None used effective monitoring methods, five have now seen bait traps used multiple times (one new farmer joined the project in January, 2026). Collaborating farmers are using potatoes as much as they can in rotation. Research findings from the two related grants are opening up opportunities for managing symphylans with other suppressive crops. Collaborators are also interested in supporting symphylan predators.