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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Research Project #446034

Research Project: Rapid-response Detection and Management of Emerging Outbreaks of Lettuce Fusarium wilt in Coastal California

Location: Crop Improvement and Protection Research

Project Number: 2038-21530-003-019-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Nov 1, 2023
End Date: Jun 30, 2026

Fusarium wilt of lettuce has recently become one of the top lettuce pests on California’s Central Coast. Data on the susceptibility of commercial cultivars to the pathogen is lacking, and rapid diagnostic tools are not available. Additionally, preliminary data suggests a novel race is present on the Central Coast as of August 2021. The goals of this project are to: 1) evaluate commercial cultivars and breeding material against pathogen races; 2) investigate the source of resistance to the potential new race; 3) determine the geographic distribution of races in California; and 4) complete and validate molecular assays to rapidly detect the potential new race in plant material and soil. Anticipated outcomes are that growers will be able to rapidly identify the race present in their soil and make informed cultivar selections. Success of the project will be assessed based on extension of data to growers, shifts in cultivar use patterns, and commercial use of diagnostic assays.

Goal 1 Field trials (Apr-Jul 2024, 2025): UC Riverside Project director (UCR PD) will direct the cultivar field trials. UCR PD and the UCR Lab Assistant (LA) will collect disease data from the trials and perform diagnostic confirmation. UCR Co-PD will assist with all aspects of the Santa Maria trials. USDA ARS Co-PD will provide seed of breeding material or germplasm for the field trials. Goals 1, 2 Greenhouse (Nov 2023-Oct 2025): USDA ARS Co-PD will perform greenhouse experiments to evaluate additional germplasm, and will direct genetic mapping experiments to be performed by the USDA ARS Biological Science Aide. Specific tasks include maintenance of greenhouse experiments, performing crosses, and genetic mapping and analysis. Goal 3 Population Survey (Nov 2023-Jun 2026): UCR PD will direct the population survey and race typing greenhouse experiments, to be performed by the UCR Graduate Student Researcher (GSR), LA, and undergraduate Student Assistant (SA). UCR PD and USDA ARS Co-PD will identify a robust differential set (Nov 2023-Oct 2024). UCR PD and USDA ARS Co-PD will direct the morphological and genetic characterization of the isolates (entire period) as well as development of genomic resources (Nov 2023-Oct 2024), to be performed by the GSR, LA, SA, and the Core Facility. Goal 4 Diagnostic Assays (May 2024-Apr 2025): USDA ARS Co-PD will direct development of the molecular assays, to be performed by the USDA-ARS Postdoctoral Researcher (PR). Specific tasks include use of genomic resources to identify candidate diagnostic markers; design of quantitative PCR and isothermal (recombinase polymerase amplification, RPA) assays; and validation of assays against isolates in our collection, unknown plant samples, and in soil. Extension (Nov 2023-Jun 2026): UCR PD will direct and perform outreach activities, including oral presentations at annual events from UC Cooperative Extension (UCCE) Monterey in November, UCCE Imperial in December, and CA Association of Pest Control Advisors continuing education events throughout the year. Written reports will be distributed via blogs (e.g., UCCE Monterey’s Salinas Valley Agriculture blog), email listservs, and in-person. Extension events are on-going, but specific outputs from this project may not be available until approximately Apr 2024. USDA ARS Co-PD and the PR will extend the assays to diagnostic labs in the form of an in-person workshop or a comprehensive protocol document (Jul 2025-Jun 2026).