Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Wendy Sutton; Paul Reeser; Everett Hansen
    Date: 2009
    Source: Gen. Tech. Rep. PSW-GTR-221. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 327-330.
    Publication Series: General Technical Report (GTR)
    Station: Pacific Southwest Research Station
    PDF: View PDF  (86.0 KB)


    Long-term storage of cultures of Phytophthora species is a challenge for any lab managing a working collection of isolates. Storage in liquid nitrogen is generally considered to be optimal for archival storage, and successful recovery of most species is regularly achieved after many years. Nitrogen storage has its drawbacks, however, especially for a working collection. It requires species specific freezing conditions, and thawing must be done carefully. Equipment is bulky, and regular addition of liquid nitrogen is necessary. Storage in vials in water at room temperature is an efficient, effective alternative for many collections. Isolates are grown on agar, and plugs are removed from the colony margin and placed in sterile water in 1.5 ml plastic tubes, with or without pieces of sterilized hemp seed. Tubes are kept in coded racks at room temperature, in the dark. Agar plugs can be removed one at a time as needed and plated on selective agar to resume growth. In a recent test, we had nearly 100 percent recovery of several Phytophthora species, including P. ramorum, after 7 years in water storage.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • 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.


    Sutton, Wendy; Reeser, Paul; Hansen, Everett. 2009. Long-term storage of Phytophthora cultures in water. In: Goheen, E.M.; Frankel, S.J., tech. coords. Proceedings of the fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09: Phytophthoras in forests and natural ecosystems. Gen. Tech. Rep. PSW-GTR-221. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 327-330.

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page