Phytophthora ramorum is a microscopic fungal-like organism (oomycete) which causes extensive damage and death to various species. Phytophthora translates to ‘plant destroyer’, and the genus has been responsible for some of the worst plant epidemics in history ⁠— including being the primary source of the infamous Irish potato famine in the 19th century. Spores easily spread in wind-driven rain and can travel for several miles. When they land on a tree they will begin to spread, breaking down leaf cells and eventually growing into the tree. As the phytophthora grows it blocks the tree's water transport system, eventually killing the tree. This process can occur quickly in certain species of tree, such as larch.