What is killing the Oak Trees?
Sudden Oak Death (SOD), ramorum leaf blight and ramorum dieback are all names for a recently-discovered plant disease caused by the fungus-like microorganism Phytophthora ramorum. This disease has killed tens of thousands of oak trees in the coastal areas of California and a small area of Oregon. The host list is broad and continues to expand. It includes common native and ornamental landscape plants like camellia, viburnum, pieris, rhododendron, pyracantha, mountain laurel, and leucothoe. SOD does not usually kill these non-oak hosts. Instead, depending on the plant, it may cause symptoms such as leaf spots, defoliation, twig and branch dieback, or blighting. These symptoms can be easily confused with those caused by other plant diseases or environmental stresses. Laboratory analyses are necessary to confirm the presence of SOD in all cases. Despite the name, Sudden Oak Death disease is not just restricted to oaks. Camellias, rhododendrons, Pieris, mountain laurel, viburnum, and lilac
