Governor Schwarzenegger

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Plant Pest Diagnostics Center

Fred Hrusa

Dr. Fred Hrusa

Senior Plant Taxonomist

Plant Pest Diagnostics Branch, California Department of Food & Agriculture
3294 Meadowview Road, Sacramento, CA 95832-1448, U.S.A.
916-262-1143 office, 916-262-1190 fax,


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Curriculum vitae


  • Doctor of Philosophy (Plant Biology) - University of California, Davis. 1995. Dissertation: "The systematics and evolution of Rhododendron occidentale (Torrey & A. Gray) A. Gray (section Pentanthera; subf. Rhododendroideae; Ericaceae)"
  • Master of Science (Botany) - University of California, Davis. 1991. Thesis: "A morphometric analysis of variation in Rhododendron occidentale (T. & G.) Gray, among populations native to ultrabasic and non-ultrabasic substrata (Ericaceae: Rhododendroideae)"
  • Bachelor of Science (Ornamental Horticulture) - California Polytechnic State University, San Luis Obispo. 1983.

Current Employment

  • 1997-present, Senior Plant Taxonomist, California Department of Food and Agriculture


  1. Stebbins, G. L., & G.F. Hrusa. 1995. The North Coast Biodiversity Arena in Central California: A New Scenario for Research and Teaching Processes of Evolution. Madrono 42 (2): 269-294.
  2. Hrusa, G.F., & J.C. Hunter,1996. Black Butte Research Natural Area, Los Padres National Forest, San Luis Obispo County, California. Description, Vegetation and Flora. USDA Forest Service, Pacific SW Research Station, Albany CA. 94 pp.
  3. Brennan, E.B., R.J. Gill, G.F. Hrusa, & S.A. Weinbaum. 1999. First record of Glycaspis brimblecombei (Moore) (Homoptera: Psyllidae) in North America. The Pan-Pacific Entomologist, 75:11, 55-57.
  4. Villegas, B., D.A. Mayhew, F. Hrusa, & J. Balciunas. 2000. Survey of Chaetorellia seedhead flies on Cirsium thistles in close proximity to Centaurea spp. in California. Pages 62-63 in D.M. Woods, ed. In, Biological Control Program Annual Summary, 1999. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, CA.
  5. Brennan, E.B., G.F. Hrusa, S.A. Weinbaum & W. Levison. 2001. Resistance of Eucalyptus species to Glycaspis brimblecombei (Homoptera: Psyllidae) in the San Francisco Bay Area. The Pan-Pacific Entomologist 77(4). 249-253.
  6. Sorensen, J.T., F. Hrusa & T. Tyler, 2001. Origin of the Sudden Oak Death (SOD) pathogen and its potential impact: a working hypothesis. California Plant Pest and Disease Report 19 (3-6): 47-57 + maps.
  7. Hrusa, F., B. Ertter, A. Sanders, G. Leppig, & E. Dean 2002. Catalogue of non-native vascular plants occurring spontaneously in California beyond those addressed in the Jepson Manual - - Part I. Madrono 49(2): 61-98.
  8. Ayres, D., F. Ryan, F. Hrusa, & P. Akers, 2005. Tumbleweeds of California: Who, what, where and how. Poster presented at the Annual Meeting of the California Invasive Plants Council.
  9. Gaskin, John F., Frederick J. Ryan, G. Frederic Hrusa, and Jason P. Londo, 2006. Genotype diversity of Salsola tragus and potential origins of a previously unidentified invasive Salsola from California and Arizona. Madrono 53(3): 244-251.

Papers currently in review

  1. Dean, E., F. Hrusa, G. Leppig, B. Ertter, A. &Sanders. (in review). Catalogue of non-native vascular plants occurring spontaneously in California beyond those addressed in the Jepson Manual Part II. Madrono (in review).
  2. Hrusa, G.F., & J.F. Gaskin, (in review). Salsola tragus sensu auct. California (Salsola sect. kali: Chenopodiaceae): characterization and status of Salsola australis R. Br. and the autochthonous species Salsola ryani sp. nov. Madrono (in review).