Skip to main content
U.S. flag

An official website of the United States government

An accreditation program to produce native plant nursery stock free of Phytophthora for use in habitat restoration


Tedmund J. Swiecki
Elizabeth A. Bernhardt
Diana Benner
Janell Hillman



Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Pacific Southwest Research Station


Plant Health Progress. 22(3): 348-354


Widespread Phytophthora infections have been discovered in nursery stock used in California restoration plantings. In response, Nursery Phytophthora Best Management Practices (NPBMPs) designed to exclude Phytophthora from nursery plants were developed to address the need for clean planting stock in restoration projects. A pilot program to implement the systematic use of the NPBMPs, Accreditation to Improve Restoration (AIR), was developed and started in 2018. As of 2020, 13 northern California restoration nurseries have been evaluated, and five have met all the program requirements. In 564 tests conducted over 4 years with a sensitive leachate baiting protocol, no Phytophthora was detected from over 20,000 nursery plants produced in compliance with the NPBMPs. In comparison, Phytophthora was detected in 25% of tests conducted on partially compliant stock and in 71% of tests from nurseries following few or no NPBMPs. The AIR pilot program has demonstrated that container stock free of detectable Phytophthora can be reliably produced by adhering to an integrated program of clean nursery production practices. To obtain Phytophthora-free plants for habitat restoration, informed clients were willing to pay increased costs required to produce NPBMP-compliant nursery stock.


Swiecki, Tedmund J.; Bernhardt, Elizabeth A.; Frankel, Susan J.; Benner, Diana; Hillman, Janell. 2021. An accreditation program to produce native plant nursery stock free of Phytophthora for use in habitat restoration. Plant Health Progress. 22(3): 348-354.


Publication Notes

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.