The future health outlook bodes well for what many consider to be our finest native conifer in the PNW, Chamaecyparis lawsoniana, Port Orford cedar and its many cultivars. Port Orford cedars have been under seige for many years from its worst enemy Phytophtora lateralis, a soil-borne pathogen that is especially virulent in wet soils, and essentially spells a death-sentence to this majestic tree once its roots are infected. There is no cure, but there is a preventative practice known as plant resistance. Dr. Everett Hansen at Oregon State University has developed a Phytophthora lateralis resistant root stock. And now, thanks to the development and research labs of Monrovia, they have introduced into the trade numerous Port Orford cultivars grafted with the phytophthora resistant root stock. These grafted Port Orfords are known as The GUARDIAN ™ Series .
Through a generous donation from Monrovia, the Washington Park Arboretum will be trialing 6 GUARDIAN ™ Series Port Orford cultivars, as well as, the type species grown on its own root. We have chosen 5 known “hot-spots” (either cultured or symptomatic of phytophthora infested soils) throughout the arboretum. There are 2 specimens each of the cultivars and the type. We’ll be monitoring and reporting on their growth and health for a period of 5 years. Knowing the extensive research and development that has gone into The GUARDIAN ™ Series Port Orfords, after the 5-year trial, I expect a 100% survival-rate. Stay tuned for periodic updates on this exciting plant trial study.