Photo credit: Joseph O'Brien, USDA Forest Service, Bugwood.org
An emerging forest disease caused by the fungus-like organism, Phytophthora ramorum
Unknown. Experts speculate that it was transported on plant material.
P. ramorum is established in the natural landscape throughout parts of California's central coastal region and in a localized forested area in Curry County, Oregon. The pathogen has also become established in ornamental landscapes in the U.K. and Netherlands. In ornamental nurseries, the pathogen has been detected in Europe since the early 1990s and in North America since it was found in a California nursery in 2001. In 2003, P. ramorum was found in nurseries in Oregon, Washington, and British Columbia.
P. ramorum could injure and kill oaks and other economically and ecologically important plant species in Virginia forests. Although this disease often causes only mire branch dieback and leaf blight in nursery stock, it has killed millions of oaks in California forests since the mid-1990's.
In Virginia, nursery surveys are conducted annually for P. ramorum. The surveys are conducted in an effort to safeguard our natural ecosystems and protect the state nursery and forest industries from the potential losses associated with a widespread outbreak of P. ramorum.