Golf courses contribute to Oregon’s economy through jobs, tourism, recreation and local spending. On each course, putting greens represent the smallest acreage but the highest-value turf because their quality directly affects play, customer satisfaction and maintenance costs.
The work lays the foundation for Pacific Northwest-specific action thresholds, which can improve return on investment for course maintenance and support more efficient pesticide use.
Along the Oregon Coast, golf course superintendents have reported increasing damage on putting greens from plant-parasitic nematodes, microscopic worms that feed on roots and weaken turf. The damage can resemble drought stress, nutrient problems or disease, making it difficult to diagnose and expensive to manage without clear information.
Despite rising concern, relatively little was known about which nematode species were present on Pacific Northwest putting greens, when their populations peaked or how they differed by turf type and season. That left superintendents with limited regional guidance for deciding when to sample, when to treat and which pests posed the greatest risk.
Researchers with Oregon State University and the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) surveyed 30 putting greens at five independently managed golf courses on the Southern Oregon coast in 2023. They sampled greens in January, May, August and November to track seasonal patterns and compare nematode communities across courses.
The team used both traditional microscopy and molecular methods to identify plant-parasitic nematodes. This allowed researchers to move beyond broad genus-level diagnosis and identify many populations to the species level, providing more precise information for turf managers and diagnosticians.
The study, published in the journal Plant Disease, also compared extraction methods to improve recovery of nematodes from putting green samples and analyzed how course, season and turf composition influenced nematode communities.
Findings identify key pests and timing of risk
Researchers recovered 13 genera of plant-parasitic nematodes and identified 11 to species. Two species, Helicotylenchus pseudorobustus and Meloidogyne naasi, were found at all five courses.
Meloidogyne naasi emerged as a nematode of concern on three annual bluegrass courses, especially in January, when populations were highest just before superintendents reported visible turf damage in late winter. In one sample, Meloidogyne populations reached 59,100 nematodes per 100 cubic centimeters of soil.
The study showed that nematode communities differed significantly by course and season. Annual bluegrass greens had the most severe reported damage, while fine fescue greens showed different nematode patterns and less damage.
Researchers also documented several species new to Oregon records and found evidence of a potentially undescribed Heterodera species.
These findings give turf managers a stronger basis for identifying which nematodes are most likely to threaten putting green performance and when those threats are most likely to emerge.
Study authors included:
- Emily Braithwaite, OSU graduate student, Department of Botany and Plant Pathology
- Hannah M. Rivedal, research plant pathologist in the USDA-ARS Forage Seed and Cereal Research Unit in Corvallis
- Robert J. Starchvick, faculty research assistant, OSU Department of Horticulture
- Alec R. Kowalewski, professor and Grover Family Endowed Sustainable Urban Landscapes Specialist, Department of Horticulture
- Todd N. Temple, USDA-ARS Forage Seed and Cereal Research Unit in Corvallis
- Hannah V. Baker, USDA-ARS Horticultural Crops Disease and Pest Management Research Unit, Corvallis
- Megan Kitner, USDA-ARS Horticultural Crops Disease and Pest Management Research Unit, Corvallis
- Amy B. Peetz, USDA-ARS Horticultural Crops Disease and Pest Management Research Unit, Corvallis
- Inga A. Zasada, USDA-ARS Horticultural Crops Disease and Pest Management Research Unit, Corvallis
Public value
This research gives Oregon’s golf industry better tools to protect a high-value recreational and economic asset.
By identifying the nematode species present on coastal putting greens and showing when damaging populations are most likely to peak, Oregon State helps superintendents improve diagnosis, target management more precisely and reduce unnecessary treatment costs.
The work also lays the foundation for Pacific Northwest-specific action thresholds, which can improve return on investment for course maintenance and support more efficient pesticide use.
The study shows how applied research helps Oregon businesses solve region-specific problems, protect jobs and strengthen the performance of industries tied to tourism, recreation and landscape management.
The study was funded by the Northwest Turfgrass Association; USDA-ARS CRIS 2072-21600-001-000-D; and the United States Golf Association 2023-07-774.