Subject: Notice of Priority Tree Removals at William Land Regional Park due to Infestation of Mediterranean Oak Borer Beetle
Dear Friends and Care-Holders of William Land Regional Park,
Two Vally Oak trees (IDs 28592 & 28690) within William Land Regional Park have been identified as being infested with the Mediterranean Oak Borer Bettle (MOB), scientifically known as Xyleborus monographus.
(graphic included below to identify the trees’ exact locations within the park).
This beetle poses a severe threat to oak trees because it carries a disease-causing fungus with it that leads to the decline and death of infected trees. There is no cure or effective treatment for the disease at this time and complete eradication of the beetle is not possible.
While Mediterranean Oak Borer is a newcomer to the City of Sacramento it is not new to California. Our city arborists have a wealth of experience to draw from which will enable us to take swift and decisive action to minimize the spread of this beetle and its disease-causing fungus within our city. The City’s arborists are working closely with CalFire staff and a variety of experts to evaluate the scope of the overall situation citywide and determine what resources will be needed to implement an effective long-term management plan. The consensus amongst the experts is that swift removal of infected trees and careful disposal of the wood is vital to reducing losses to the oak population. While the desire to save an infested tree is understandable, removing the affected tree and disposing of the wood is the most effective and responsible course of action when the following concerns are considered:
- Rapid spread and difficulty of detection: MOB beetles can quickly infest neighboring trees before visible symptoms appear, making early detection challenging. By the time an infestation is noticed, it may already be too late to save the tree.
- Limited pesticide effectiveness: Pesticides are generally ineffective against MOB beetles once they’ve bored into the tree. The beetles spend most of their life cycle inside the wood, protected from surface-applied treatments.
- Risk of re-infestation: Even if pesticides successfully eliminate the current infestation, weakened trees remain susceptible to future attacks from other pests or pathogens.
- Environmental concerns: Repeated pesticide applications can harm beneficial insects, contaminate soil and water, and potentially affect human health.
- Vector control: Infected trees serve as breeding grounds for MOB beetles, increasing the risk to nearby healthy trees. Removing the infested tree eliminates this source of infestation.
- Economic considerations: The cost of ongoing pesticide treatments and monitoring may exceed the value of saving a single tree, especially when considering the potential loss of surrounding trees.
By promptly removing infested trees, we can better protect the overall health of our oak populations and ecosystems. This approach, while difficult, represents a proactive stance in managing this destructive pest and preserving our valuable oak resources for future generations.
Attached with this email is additional information regarding the Mediterranean Oak Borer Bettle provided by the University of Californian, Division of Agriculture and National Resources.
If you have any questions or concerns, please feel free to reach out me. I am here to help.
Sincerely,
Shawn C. Aylesworth
Manager, Park Maintenance Division
Youth, Parks and Community Enrichment
City of Sacramento
5730 24th Street, Bldg 3
Sacramento, CA 95822
(916) 808-4070