What is Phytophthora ramorum?
Phytophthora ramorum is a plant pathogen that causes Sudden Oak Death (SOD) as well as a foliar/twig disease in other susceptible plants. While it is not uncommon for plants that contract Sudden Oak Death to succumb to disease, it is uncommon for foliar/twig host plants to die from infection. Foliar hosts, unlike bole hosts, are not a dead end for the pathogen. Many foliar hosts act as a breeding ground for the disease, allowing inoculum to build up on leaves, and then spread to new areas via natural or artificial means.
