OSU Logo

Everett Hansen

Everett Hansen

Professor, Emeritus
Ph.D., 1972, University of Wisconsin, Madison


Office/Lab: Cordley 1086/1085
Phone: 541-737-5243/5242


Research Area

Forest pathology, the biology and management of forest tree diseases; population biology of forest fungi; ecology, taxonomy and phylogenetics of Phytophthora.

Description of Research

I am retired, (and not taking new graduate students,) but the lab is still active, and my research interests continue, addressing both immediate forest management issues and fundamental questions of pathogen biology.  

  •  Work with laminated root rot caused by Phellinus weirii,  includes long-term studies of silvicultural strategies to lessen economic impacts of this widespread native disease of Douglas-fir, as well as ecological investigations of the roles the pathogen plays in determining forest structure and function in wild forests. 
  •  Root rot of Port Orford cedar (Phytophthora lateralis) is an introduced disease, spread in water and by human activity.  We support an intensive management effort by Federal land management agencies to limit the further spread of the pathogen and restore cedar on affected sites. Much of our effort is focused on breeding for resistance, and developing the biological basis for deployment strategies to use the resistant stock that is increasingly available from the program. 
  •  Sudden Oak Death (Phytophthora ramorum) is new in the west, devastating in California and localy destructive in Oregon.  This state has responded with an eradication effort that so far, is keeping the disease in check.  We support the eradication program by providing diagnostic and survey methods including molecular probes for the pathogen. Our research aims to clarify epidemiology in Oregon forests using molecular population genetics, spore trapping, and host range studies. Intriguingly, P. ramorum and P. lateralis are very closely related. 
  • Another avenue of research explores the evolutionary biology of Phytophthora species, especially the many new species we are discovering in Oregon forests and around the world.

Research Group Members

Faculty Research Assistants/Associates

Wendy Sutton
Paul Reeser

Graduate Students

No more students!

Hansen Lab Group
the lab group of 2013

Beaver Nation at WIFDWC 2011

"Hail Beavers!"

Recent Graduate Theses

Robin Mulvey, MS, 2010, Castilleja and Pedicularis are confirmed as telial hosts for white pine blister rust in whitebark pine ecosystems of Oregon and Washington

Sarah Navarro, MS, 2013, Pathogenicity of Phytophthora Species from Oregon Waterways

Laura Sims, PhD, 2014 Phytophthora Species and Riparian Alder Tree Damage in Western Oregon.

Joey Hulbert, MS, 2014. Boron to limit transport of Phytophthora ramorum in Douglas-fir logs.

Related Links

IUFRO Working Party 7.02.09 Procedings from the First International Meeting on Phytophthoras in Forest and Wildland Ecosystems

Forest Phytophthoras of the World

Recent Publications

E.M. Hansen, Paul Reeser, and Wendy Sutton. 2012. Phytophthora Beyond Agriculture. Ann. Rev. Phytopath. 10.1146/annurev-phyto-081211-172946

Donald J. Goheen, Katrina Mallams, Frank Betlejewski, and Everett Hansen. 2012. Effectiveness of Vehicle Washing and Roadside Sanitation in Decreasing Spread Potential of Port-Orford-Cedar Root Disease. West. J. Appl. For. 27: 170-175.

Everett M. Hansen, Paul W. Reeser, Wendy Sutton. 2012. Phytophthora borealis and Phytophthora riparia, new species in Phytophthora ITS Clade 6. Mycologia 104:1133-1142.

Brasier CM, Franceschini, S., Vettraino, A.M., Hansen, E. M., Green, S., Robin, C., Webber, J. 2012. Four phenotypically and phylogenetically distinct lineages in Phytophthora lateralis, Fungal Biology (2012), http://dx.doi.org/10.1016/j.funbio.2012.10.002

Aguayo, J., Adams, G. C., Halkett, F., Catal, M., Husson, C., Nagy, Z. Á., Hansen, E. M., Marçais, B., and Frey, P. 2013. Strong genetic differentiation between North American and European populations of Phytophthora alni subsp. uniformis. Phytopathology 103:190-199.

Richard C. Cobb, David M. Rizzo, Katherine J. Hayden, Matteo Garbelotto, João A. N. Filipe, Christopher A. Gilligan, Whalen W. Dillon, Ross K. Meentemeyer, Yana S. Valachovic, Ellen Goheen, Tedmund J. Swiecki, Everett M. Hansen, and Susan J. Frankel. Biodiversity Conservation in the Face of Dramatic Forest Disease: An Integrated Conservation Strategy for Tanoak (Notholithocarpus densiflorus) Threatened by Sudden Oak Death. Madroño Apr 2013 : 60: 151-164. doi: 10.3120/0024-9637-60.2.151

W.-x. Huai1,5, G. Tian1 E. M. Hansen2, W.-x. Zhao1*, E. M. Goheen3, N. J. Gr€unwald4 and C. Cheng1, 2013. Identifcation of Phytophthora species baited and isolated from forest soil and streams in northwestern Yunnan province, China. For. Path. 43:87-103. doi: 10.1111/efp.12015.

E.M. Hansen, P. Reeser, W. Sutton, L. Sims. 2012. Host and Habitat Index for Phytophthora Species in Oregon. 2: http://journals.oregondigital.org/ForestPhytophthora/article/view/3026

Reeser, P., W. Sutton, and E. Hansen. 2013. Phytophthora pluvialis, a new species from mixed tanoak-Douglas-fir forests of western Oregon U.S.A. North American Fungi 8(7): 1-8. http://dx.doi: 10.2509/naf2013.008.007

Peterson E., E. Hansen, and A. Kanaskie. 2013.  Spatial relationship between Phytophthora ramorum in tanoak forests and roads or streams: landscape features that have been associated with long distance dispersal of inoculum. For Ecol Man. Forest Ecology and Management 312 (2014) 216–224.

Oßwald, Wolfgang; Fleischmann, Frank; Rigling, Daniel; Coelho, Ana Cristina; Cravador, Alfredo; Diez, Julio; Dalio, Ronaldo; Horta Jung, Marilia; Pfanz, Hardy; Robin, Cecile; Sipos, György; Solla, Alejandro; Cech, Thomas; Chambery, Angela; Diamandis, Stephanos; Hansen, Everett; Jung, Thomas; Orlikowski, Lezzek; Parke, Jennifer; Prospero, Simone; Werres, Sabine. 2014. "Strategies of attack and defense in woody plant- Phytophthora interactions."  Forest Pathology44:169-190.

Ebba Peterson, Everett Hansen, Joseph Hulbert. 2014. Source or Sink?  The role of soil and water borne inoculum  in the dispersal of Phytophthora ramorum in Oregon tanoak forests. For Ecol Man. Forest Ecology and Management 322 (2014) 48–57.