What Is Sudden Oak Death
Phytophthora ramorum is known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon as well as being present in Europe. Very few control mechanisms exist for the disease and they rely upon early detection and proper disposal of infected plant material.
P. ramorum also infects a great number of other plant species, significantly woody ornamentals such as Rhododendron, Viburnum, and Pieris, causing foliar symptoms known as ramorum dieback or ramorum blight. Such plants can act as a source for new infections with the pathogen-producing spores that can be transmitted by rainsplash and rainwater.
Sudden Oak Death has caused a widespread dieback of numerous trees and plants. It has killed millions of trees and caused twig and leaf disease in other plants. It became a real problem in the United States in 2004 when some large West Coast nurseries shipped over a million infected rhododendrons and camellia plants to 21 states. This disease thrives in cool, moist environments, which is present in many nurseries, therefore, the disease thrives in nurseries, infecting the plants contained in them.
One of the major mechanisms of dispersal is rainwater splashing spores onto other susceptible plants and into watercourses to be carried for greater distances.
Hikers, mountain bikers, equestrians, and other people engaged in various outdoor activities may also unwittingly move the pathogen into areas where it was not previously present. Those travelling can help prevent the spread of the disease by cleaning their (and their animals') feet, tires, tools, camping equipment, etc., before returning home or entering another uninfected area especially if they have been in muddy soil. Additionally, the movement of firewood could introduce sudden oak death to otherwise uninfected areas. Both homeowners and travelers are advised to buy and burn local firewood.