The following is adapted from the University of California?EUR??,,????'???s IPM web site, www.ipm.ucdavis.edu and from Kansas State University?EUR??,,????'???s and U.C. Berekley?EUR??,,????'???s web sites (www.oznet.ksu.edu and www.berkeley.edu).

Due to climate and geography, each region of the country has diseases that pose unique problems for local trees. Here are four of particular concern for West Coast superintendents and arborists. Anthracnose and wood decay fungi, however, can be problems anywhere in the country.

This American sycamore is in the early stages of anthracnose disease (note defoliation along upper twigs). Anthracnose is a fungal disease that can affect trees in all regions of the country. Photo Courtesy of Theodore D. Leininger, USDA, www.forestryimages.org

Anthracnose

For new plantings, choose varieties that are resistant to the anthracnose fungi. Plant them widely apart to maximize air circulation and increase sunlight, both of which facilitate faster drying of leaf surfaces when trees are fully grown. Once symptoms develop or become severe, anthracnose cannot be effectively controlled during the current season.

Environmental factors also play important roles in managing anthracnose. Pay close attention to past and current conditions such as rain and irrigation to determine if anthracnose development is favored. Dry spring weather could mean that disease management is not necessary. A wet spring or an irrigation system that wets the foliage could result in disease outbreak that may warrant control.

Sudden Oak Death is a newly-identified fugus-like disease now active in northern and central California. (Other phytophthora species are active in other parts of the country.) The disease causes general wilting, as seen here on a tanoak. Photo Courtesy of Joseph O?EUR??,,????'???Brien, USDA, www.forestryimages.org

Sudden Oak Death

Sudden oak death is the name given to an epidemic, first detected in 1995, that affects three true oak species?EUR??,,????'??+coast live oak, California black oak and Shreve oak.

?EUR??,,????'??It?EUR??,,????'???s really meant for individual oaks or tanoaks that are at high risk for infection, such as those in the vicinity of infected California bay laurel trees,?EUR??,,????'?? U.C. Berkeley researcher Matteo Garbelotto explained.

Tree fungus of several varieties usually affects older or damaged trees. Photo Courtesy of www.ipm.ucdavis.edu

Fungal Infestation/Wood Decay

Wood decay is usually a disease of old, large trees. It is very difficult to manage, but a number of factors can reduce the risk of serious damage. First, trees should receive proper cultural care to keep plants vigorous. Minimize wood decay by protecting plants from injuries. Properly prune young trees to promote good structure and avoid the need to remove large limbs from older trees, which creates large wounds. Cut out dead or diseased limbs. Make pruning cuts properly: prune just outside the branch bark ridge, leaving a collar of cambial tissue around cuts on the trunk to facilitate wound closure, but avoid leaving stubs. Make cuts so that rainwater will drain.

Pitch Canker is a fungal disease that cause pines to ooze resin and ultimately die.

Pitch Canker

Pitch canker is a disease of pine trees that is caused by the fungus Fusarium circinatum. Douglas fir can also be infected, but this is rare and infected trees are not severely damaged. The disease was first observed in California?EUR??,,????'???s Santa Cruz County in 1986. Since then it has spread rapidly and now occurs in 18 coastal counties. Most pines native to California are susceptible to pitch canker, but Monterey pine (Pinus radiata) is the most widely affected host.

Pruning does not slow the spread of the disease in a highly infested area. However, pruning can be used strategically to enhance the aesthetic quality of a tree and thereby delay its removal from the landscape.