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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #429375
Research Project: Development of Plant and Molecular Resources to Improve Performance, Utility, and Tolerance of Cool Season Grasses and Legumes

Location: Forage Seed and Cereal Research Unit

Title: Comparing grass seed cleaning methods to reduce Anguina funesta seed gall infestation in Lolium multiflorum seed lots

Author
item Herb, Dustin
item Rivedal, Hannah
item Temple, Todd
item JOHNSON, CAELIN - Dlf North America
item Gallagher, Joseph
item BRAITHWAITE, EMILY - Oregon State University
item STARCHVICK, ROBERT - Oregon State University
item BISGAARD, EMMA - Oregon State University
item WOODWARD, MAKENNA - Oregon State University
item Peetz, Amy
item Zasada, Inga

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Oregon’s grass seed industry specializes in production of forage grasses, with annual ryegrass (Lolium multiflorum) representing a large proportion of total seed produced with ~230 million lbs annually and ~146 million sold to export markets. Annual ryegrass is a host species to the seed gall nematodes (SGN) Anguina funesta which has strict phytosanitary regulations leading to rejection of seed lots infested with SGN. Currently, there is no broadly effective treatment for infected annual ryegrass fields and best practices for SGN detection focus on post-harvest seed evaluation, thus elevating the importance of being able to separate and remove SGN galls from clean, marketable seed. In this study, we evaluated two cleaning methods, air screen and gravity table separations, ability to separate and remove seed galls from field-run samples of annual ryegrass. Both methods were highly effective in reducing the number of seed galls present in the “clean cuts” made during each cleaning run, with some runs having complete removal of all seed galls. This provides the Oregon seed industry with a potential roadmap to remediating the annual ryegrass seed lots with SGN infection and making more seed available for export markets.

Technical Abstract: Annual ryegrass (Lolium multiflorum) is a forage and cover crop that is grown for seed primarily in the Willamette Valley of Oregon, United States before being exported globally. The seed gall nematode, Anguina funesta, is a common pathogen affecting annual ryegrass in this seed production region. Seed gall nematode-infected seed lots are frequently rejected by international trade partners. Seed galls of annual ryegrass are similar in size to healthy seed and are difficult to separate in the cleaning and conditioning process. In this study, two types of seed cleaners, an air screen and a gravity table cleaner, were evaluated for their ability to remove seed galls from infected annual ryegrass in commercial seed lots. For both cleaners, four air speeds were evaluated on two replicate samples from two commercial grass seed lots. The air screen cleaner removed galls from clean cuts of seed at a range of airspeeds, but mid-range air speeds led to the highest reduction in galls with the lowest loss of clean seed. The gravity table was highly effective at separating galls from clean seed, leading to significant gall reductions across clean cuts for three of four tested air speeds. However, gravity tables are expensive and infrequently available to annual ryegrass seed producers in Oregon. This study highlights the utility that seed cleaning can provide in an effective integrated pest management program for seed gall nematodes, to reduce the likelihood of seed lot rejections and initial inoculum in saved seed lots, which would help protect the Oregon grass seed industry from this nematode.