In March of 2007, the Urban Forestry Council adopted the policy developed by the Pitch Canker Task Force, a sub-committee of the California Forest Pest Council, which is advisory to the State Board of Forestry, in response to concerns related to the prevalence of the disease in San Francisco. The paper, in its entirely, is below.
Position Paper on the Retention of Pines Infected with Pitch Canker
(REVISED September 25, 2001)
The purpose of this document is to update the position of the Pitch Canker Task Force concerning when the presence of pitch canker justifies the removal of a diseased tree. Decisions concerning tree removal are often complex and the following information is a general policy statement and not a substitute for on-site professional hazard tree evaluation.
Monterey pine, along with many other pine species, is susceptible to pitch canker. The earliest symptom of pitch canker is dieback in the canopy, caused by infections on individual branches. Infections on large branches and the main stem of a tree can lead to top-kill and, in some cases, death of the entire tree. Trees differ in their susceptibility to pitch canker (see "What is Genetic Resistance?"), but nearly all will sustain some infections. Thus, when a tree shows early symptoms of pitch canker, it is not possible to predict how far the disease will progress in that tree. Recent research indicates that approximately 10% of Monterey pines are at least somewhat resistant to pitch canker; and will not sustain serious damage from this disease. Furthermore, some trees that do become heavily infected will recover from pitch canker.
Pitch canker infection is not a sole reason to remove a tree. The decision to remove a tree should be based on more general criteria, such as safety. Thus, if a tree has been deemed hazardous for any reason, it should be removed, regardless of its prospects for recovery from pitch canker.
Any recovery of the tree will be from living material. Infected trees may have numerous dead branches or the top section of the tree may be dead. Dead parts of the tree will not recover and will become increasingly weakened and unpredictable over time. Large dead material should be mitigated as soon as possible. Sometimes the tree may need to be removed even if it shows signs of recovery.
Most pitch canker affected trees will be found in areas where the disease is already present, and the above policy will be applicable. However, where pitch canker occurs in an area that is otherwise free of the disease, more aggressive efforts might be appropriate. To determine if this is applicable to your situation, contact your city forester, county agriculture commissioner, the Department of Forestry and Fire Protection, or your local U.C. Cooperative Extension office. Please keep in mind that county or municipal regulations may require that a permit be obtained prior to tree removal.
Photo: Martin Cathrae