|Phytophthora lateralis (a severe root rot disease of Chamaecyparis lawsoniana)
Why Phytophthora lateralis came to our attention during a bibliographic search on sudden oak disease (caused by another Phytophthora species), as significant tree mortality and severe losses are reported in USA on C. lawsoniana growing in nurseries, gardens and forests.
Where North America: Canada (British Columbia), USA (California, Oregon, Washington).
On which plants Chamaecyparis lawsoniana. Taxus brevifolia has also been reported as a host plant but it is less susceptible and tree mortality has only been observed in areas where C. lawsoniana trees were also infected.
Damage Root rot leading to tree mortality.
Transmission Root contact, zoospores in water, resting spores (chlamydospores) in the soil.
Pathway Plants for planting and wood of host plants (C. lawsoniana, Taxus brevifolia), infested soil from areas where P. lateralis occurs.
Possible risks In the EPPO region, C. lawsoniana is occasionally planted in forests but is a widespread ornamental tree. P. lateralis causes tree mortality in all cases and there is no curative treatment available. It could represent a serious threat, especially for the ornamental plant industry if introduced into the EPPO region. The isolated finding in France also suggests that there is a pathway for introducing the pathogen (may be through contaminated soil attached to C. lawsoniana or other non-host plants).
Source(s) DeNitto, G.A.; Kliejunas, J.T. (1991) First report of Phytophthora lateralis on Pacific yew. Plant Disease, 75(9), p 968.
Erwin, D.C. Ribeiro, O.K (1996) Phytophthora lateralis. In: Phytophthora diseases worldwide. American Phytopathological Society, St. Paul (US), pp 365-367. Plant Disease, 84(1), 4-14.
Hansen, E.M.; Goheen, D.J.; Jules, E.S.; Ullian, B. (2000) Managing Port-Orford-Cedar and the introduced pathogen Phytophthora lateralis.
Hansen, E.M.; Streito, J.C.; Delatour, C. (1999) First confirmation of Phytophthora lateralis in Europe. Plant Disease, 83(6), p 587.
Murray, M.S.; Hansen, E.M. (1997) Susceptibility of Pacific Yew to Phytophthora lateralis. Plant Disease, 81(12), 1400-1404.
Winton, L.M.; Hansen, E.M. (2001) Molecular diagnosis of Phytophthora lateralis in trees, water, and foliage baits using multiplex polymerase chain reaction. Forest Pathology, 31(5), 275-283.
USDA. Forest Service. Pacific Northwest Region. Ecology and management of Port-Orford-cedar. http://www.fs.fed.us/r6/siskiyou/poc1.htm
USDA. Forest Service. Pacific Northwest Region. Port-Orford-Cedar root disease by Roth, L.W.; Harvey Jr, R.D;; Kliejunas, J.T. http://www.fs.fed.us/r6/nr/fid/fidls/poc.htm
EPPO RS 2001/034, 2001/204
Panel review date 2006-03 Entry date 2001-02