02775nas a2200229 4500008004100000245013500041210006900176260001600245300000900261490000700270520202600277100002302303700002202326700002002348700001702368700001602385700001802401700002602419700002502445700002502470856005002495 2020 eng d00aPhytophthora Introductions in Restoration Areas: Responding to Protect California Native Flora from Human-Assisted Pathogen Spread0 aPhytophthora Introductions in Restoration Areas Responding to Pr cNov-30-2020 a12910 v113 a

Over the past several years, plantings of California native plant nursery stock in restoration areas have become recognized as a pathway for invasive species introductions, in particular Phytophthora pathogens, including first in the U.S. detections (Phytophthora tentaculata, Phytophthora quercina), new taxa, new hybrid species, and dozens of other soilborne species. Restoration plantings may be conducted in high-value and limited habitats to sustain or re-establish rare plant populations. Once established, Phytophthora pathogens infest the site and are very difficult to eradicate or manage—they degrade the natural resources the plantings were intended to enhance. To respond to unintended Phytophthora introductions, vegetation ecologists took a variety of measures to prevent pathogen introduction and spread, including treating infested areas by solarization, suspending plantings, switching to direct seeding, applying stringent phytosanitation requirements on contracted nursery stock, and building their own nursery for clean plant production. These individual or collective actions, loosely coordinated by the Phytophthoras in Native Habitats Work Group ensued as demands intensified for protection from the inadvertent purchase of infected plants from commercial native plant nurseries. Regulation and management of the dozens of Phytophthora species and scores of plant hosts present a challenge to the state, county, and federal agriculture officials and to the ornamental and restoration nursery industries. To rebuild confidence in the health of restoration nursery stock and prevent further Phytophthora introductions, a voluntary, statewide accreditation pilot project is underway which, upon completion of validation, is planned for statewide implementation.

1 aFrankel, Susan, J.1 aConforti, Christa1 aHillman, Janell1 aIngolia, Mia1 aShor, Alisa1 aBenner, Diana1 aAlexander, Janice, M.1 aBernhardt, Elizabeth1 aSwiecki, Tedmund, J. uhttps://www.mdpi.com/1999-4907/11/12/1291/htm