Fungus on Redwood Trees

Redwood Canker

• The redwood tree (Sequoia sempervirens), also called the coast redwood or the California redwood, is susceptible to several species of fungal canker diseases. Redwood canker is brought on by the fungus Botryosphaeria dothidea and by fungi of the Cytospora and Seridium families. This disease also affects incense cedar, dawn redwood, giant sequoias and other species of hardwood and conifer trees. Redwood canker tends to attack trees that already are environmentally stressed.

Symptoms

• Fungus on redwood trees caused by redwood canker results in the dieback of twigs and branches, potentially including as much as one-third of the crown. This dieback occurs after the formation of cankers, characterized by the presence of dark depressions of rotting wood on the branches and twigs. These spots are surrounded by a circle of callused tissue and normally exhibit a collection of fungal ooze seeping from the canker. Fungal fruiting bodies of the disease will also be noticed inside the canker.

Wood Decay Fungus

• Wood decay fungi produce diseases known as heart or sap rots in a redwood tree, attacking the inner wood and structurally weakening the specimen. The disease is best distinguished by the fungal growths that pop from the bark of the tree. These shelf-like pieces jut outward several inches from the redwood and are more specifically known as conks or brackets. Armillaria mellea is another wood decay fungus that typically grows at or near the base of the tree and produces mushroom-like fruiting bodies.

Sudden Oak Death

• The disease sudden oak death, caused by the fungal pathogen Phytophthora ramorum, is extremely lethal to oak trees but typically causes only minor damage to the redwood species. The injury displays as a browning and withering of the leaves of the tree and the rotting and dropping of branches. Cankers and their accompanying oozing of sap may develop. Transmission of sudden oak death can be minimized by ensuring that plant material and wood emanating from coastal areas not be utilized in more inland locales.