Enhancing Risk Management for Oregon Grass Seed
Growers through Integrated Pest Management
Oregon’s grass seed producers face environmental and production risks from pests, unpredictable weather, and rising costs, threatening their economic viability. Integrated Pest Management (IPM) offers a sustainable solution by reducing reliance on chemical inputs while maintaining crop yield. Through IPM-focused education, the Oregon IPM Center helps producers manage risks and strengthen the resilience of their production systems.
Project Overview
Oregon’s grass seed industry spans about 400,000 acres and produces roughly 650 million pounds annually (ODA, 2024). This project delivers Integrated Pest Management (IPM) education to improve pest control, reduce pesticide use, and support sustainable production. Growers in the Willamette Valley will participate in hands-on workshops and a filed day, and will have access to educational and outreach resources available in both print and online. It targets Willamette Valley producers and includes two four-hour workshops and one field day with hands-on training, demonstrations, and accessible resources.
Expected outcomes include increased IPM adoption, improved pest control, and reduced input costs. About 100 producers are expected to participate, with 75% achieving measurable improvements, enhancing sustainability and economic viability in the region.
Program Goals
Grass seed producers in the Willamette Valley face significant environmental and production risks including pest damages, erratic weather conditions, and the rising cost of input. This project provides tailored IPM Extension education that assists in effectively managing key pests, preventing and delaying pesticide resistance, and demonstrating precision technologies for pest monitoring and application of pesticides, such as spot spraying.
Program Milestones
Execution Phase:
- Assess current needs and stakeholder engagement
- Deliver hands-on IPM workshops
- Conduct field demonstration on implemented IPM trials in collaboration with IPM researchers.
- Offer follow-up support and disseminate IPM educational resources
- Final project evaluation and reporting
Importance of IPM Education for Grass Seed Production
Often known as the “grass seed capital of the world,” the Willamette Valley produces nearly two-thirds of U.S. cool-season grass seed. Oregon’s industry includes about 1,500 farms and generated an estimated $455 million in farm gate sales (ODA, 2024). Favorable climate conditions support production, but growers face increasing risks from pests, diseases, erratic weather, and rising input costs.
Integrated Pest Management (IPM) offers a practical, sustainable approach to address these challenges by reducing pesticide use while maintaining yields. However, few programs specifically support grass seed producers. This project addresses that gap through targeted workshops and field demonstrations developed in collaboration with researchers and Extension experts.
Key Pests in Grass Seed Production Systems
Major pest challenges in Oregon's grass seed crops include rodents, slugs and snails, insect and pest, herbicide resistant weeds and fungal pathogens such as:
Gray-tailed Voles, Microtus canicaudus
This rodent pest causes substantial damage to grass seed fields in the Willamette Valley (Verhoeven and Anderson, 2021). The gray-tailed vole is the most common rodent found in these crops. Voles feed on the leafy plant growth and developing grass seed, resulting in stunted growth and substantial yield losses (Verhoeven and Anderson, 2021).Their colonies also construct extensive tunnel networks beneath fields, leaving multiple entrance holes, and concentrating patchy grazing damage around colony sites during the vegetative growth stage of grass seed crops.
For more information: OSU Extension
Slugs and Snails
Slugs and snails are key pests in grass seed crops such as ryegrass, tall fescue, orchardgrass, and bentgrass, where they can cause significant yield loss. In orchardgrass, slugs also contribute indirectly to crop decline by facilitating fertilization of fungal pathogens that cause choke disease (Hoffman and Rao, 2013). Slugs and snails feed by rasping between leaf veins and leaving a shredding, stripping, or scraping damage. Affected plants often dry out or exhibit stunted growth. Damage can be especially severe on young seedlings, sometimes leading to partial or complete row loss soon after establishment.
For more information: OSU Slug portal ; OSU Crop & Soil Sciences ; PNW Insect Management Handbook
Billbugs, Sphenophorus Spp.
Billbugs are key insect pest in bluegrass, tall fescue and orchard grass production systems in grass seed production systems in Willamette Valley (Kaur et al., 2024). The larval or grub stage of billbugs causes most damage by feeding on stems, roots and crowns. Infested plants exhibit severe discoloration and can gradually die (Kaur et al., 2020). Multiple billbug species with different life cycles often coexist in Oregon’s grass seed production systems, making the management efforts more challenging (Kaur et al., 2024).
For more information: OSU Extension ; PNW Insect Management Handbook
Sod Webworm, Chrysoteuchia topiaria Zeller
is a common insect pest impacting cool-season forage and turfgrass seed production in Willamette Valley. Sod webworm is a serious pest of fine fescue, perennial ryegrass, tall fescue, orchardgrass, and bentgrass fields. The intensity and frequency of damage is severe in older fine fescue fields (Kaur, 2021). Larvae are the damaging life stage and are subterranean, feeding specifically on crowns and roots of grasses, which results in thin, weakened stands in localized areas. In contrast, other sod worms typically clip leaf blades just above the crown, leaving visibly thin patches. Severe infestations cause injuries to established stands, resulting in failure to regrow in the fall (Hodgson and Roe, 2007).
For more information: PNW Insect Management Handbook
Armyworm, Pseudaletia unipuncta
This insect is a major pest of grasses grown for seed, particularly in western Oregon. Armyworm usually targets tall fescue and orchardgrass during the late summer and fall. The larval stage is responsible for crop damage, feeding on leaf blades above the crown. Fall regrowth is especially vulnerable, with larger larvae that can chew through leaf veins and seed stalks. Severe infestations may damage young grass seed stands and lead to regrowth failure (Dreves et al., 2021).
For more information: OSU extension service ; PNW Insect Management Handbook ; OSU extension service
Garden Symphylans, Scutigerella immaculata
Symphylans are soil dwelling arthropods that feed on roots of various plant hosts, including grass seed crops in western Oregon. Severe infestations, particularly during crop establishment, can result in substantial yield losses due to reduced seed germination, seedling mortality, and stunted growth (Willette et al., 2022).
For More Information: PNW Insect Management Handbook ; OSU
Pythium Root Rot (Pythium graminicola), and Fusarium Wilt (Fusarium acuminatum)
These fungal pathogens cause crown and root rot in grass seed production and are favored by the wet, flooded conditions common in western Oregon. The Fusarium Spp. complex has been reported in orchardgrass, tall fescue, bentgrass, Kentucky bluegrass, and ryegrass seed production fields in Oregon (Ocamb, 2002). Under conducive environmental conditions, spores are produced and dispersed by wind or water, allowing them to infect root and crowns of host plants. Spores can survive harsh conditions in soil and infected plant residues. Symptoms on diseased plants include dry, dark-brown rot in roots or crown tissues; affected plants turn light green, then tan, before eventually drying up and dying (Pscheidt and Ocamb, 2025).
For more information: PNW Insect Management Handbook ; PNW Insect Management Handbook
Italian Ryegrass (Lolium multiflorum), Roughstalk Bluegrass (Poa trivialis), and Annual Bluegrass (Poa annua)
Major grassy weeds that compete with crops and increase seed-cleaning losses in grass seed production systems include Italian Ryegrass (Lolium multiflorum), roughstalk bluegrass (Poa trivialis) and annual bluegrass (Poa annua) (Mueller-Warrant, 2018).
Italian Ryegrass, Lolium multiflorum
It is a problematic, cool season, annual or biennial bunchgrass originated from southern Europe (Lyon et al., 2024). Late-season Italian ryegrass has become a major concern in Oregon’s grass seed fields, particularly in tall fescue grown for seed (Bobadilla et al., 2020). A single Italian ryegrass can produce 2,000 to 6000 seeds per plant, many of which enter the seed bank and contribute to long-term weed population persistence. Herbicide resistant Italian ryegrass populations are also reported in established in grass seed production systems, further complicating management (Bobadilla et al., 2020).
For more information: PNW Insect Management Handbook ; OSU Extension
Funding Acknowledgment
This material is based upon work supported by USDA/NIFA
