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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Research Project #443397

Research Project: Understanding Pacific Northwest Turfgrass Plant Parasitic Nematode Communities to Improve Management Efficiency

Location: Forage Seed and Cereal Research Unit

Project Number: 2072-21600-001-003-T
Project Type: Trust Fund Cooperative Agreement

Start Date: Jan 1, 2023
End Date: Dec 31, 2025

Our goal is to better understand the putting green associated plant parasitic nematode (PPN) population life cycles to improve identification methods and develop action thresholds for Pacific Northwest (PNW) golf courses. This work will help West Coast superintendents to better identify and understand the risk of PPN to course quality, and reduce over- or under-management of greens for these pathogens. To meet this goal, we will utilize the following objectives: 1) Determine PPN genus/species presence across multiple PNW locations using both traditional morphological examination and PPN community metabarcoding; 2) Evaluate survey timing (spring, summer, fall) and collection method (soil, thatch, tillers) for the most accurate detection of PPN associated with annual bluegrass and bentgrass putting greens; 3) Develop action thresholds and integrated pest management programs for PNW PPN of putting greens and deploy via publication and extension efforts.

Objective 1 and 2: This survey will begin in spring of 2023 and conclude fall of 2025 (four samples per calendar year, 12 sample times total). Putting green samples will be collected, in person and via superintendent participation, each season from golf courses in north-coastal California, Oregon, and Washington. For courses with superintendents willing to sample subsequent timings for us, specific instructions and pre-paid mailing kits will be provided. We will attend each sampling event either in person or via phone call for superintendents to take samples and overnight cores to us. At each course, 6 greens of varying turf health will be surveyed. Golf greens will be walked in a zig-zag fashion, collecting samples every 10 feet (15-20 samples per green depending on size). Soil and tiller samples will be bulked by green before nematode extraction. Visual turfgrass quality ratings will be recorded of those greens, using the National Turfgrass Evaluation Program (NTEP) scale of 1-9. In conjunction with visual ratings, we will conduct a detailed survey of overall management practices, prior spray records, and other environmental factors that could influence the health of the putting green, to develop more detailed action threshold levels. Nematodes will be extracted from soil using a Baermann funnel for 5 days. Extraction of nematodes from plant material will be conducted under intermittent mist for 5 days. In addition, thatch and tiller layers will be manually evaluated for cyst and gall nematodes under a microscope. Specifically, this research will be looking for Anguina pacificae, Punctodera spp., Heterodera spp., Meloidogyne spp., Paratylenchus spp., Pratylenchus spp., and Heliocotylenchus spp. Extracted nematodes will be morphologically identified and characterized with a microscope. The USDA-Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville, MD will be consulted as needed for assistance. A composite soil sample for each green from at least two time points will be used for metabarcoding. Total nucleic acids will be extracted using a Qiagen PowerSoil Kit. With the assistance of the Center for Quantitative Life Sciences (CQLS) at Oregon State University (OSU), samples will be prepared for metabarcoding of the D2-D3 expansion segments of the 28S rRNA gene and Internal Transcribe Spacer of the rRNA gene, two common PPN barcoding regions. Data will be analyzed using Geneious Prime software and will provide complementary community data on those nematodes that were not captured in the Baermann or mist chamber extractions. Objective 3: To determine action thresholds, we will use the data collected from our management survey of participating courses. Respective action thresholds will be set at nematode populations that cause visible damage. We will then compare these data to management practices using step-wise regression to determine the inputs contributing most to PPN populations and turfgrass health. We will develop and disseminate standardized action thresholds and maintenance protocols for PPN in PNW golf greens.