Tree Preservation & Protection

Resources

The Town of Windsor has a wide variety of native and non-native trees which give Windsor a unique visual character. Trees are a source of beauty, provide shade and other environmental benefits, enhance property values, create a community identity, and in general, enhance the quality of urban life.

The Town of Windsor is committed to protecting existing trees and planting new trees. In accordance, the Town has adopted a Tree Preservation and Protection Ordinance, which regulates protection, preservation, maintenance, and removal of protected trees.

Additional information:

Mediterranean Oak Borer

The Mediterranean Oak Borer (MOB) is an invasive ambrosia beetle that was recently discovered within Sonoma CoMOB Infected Treeunty and has spread to trees within the Town limits. MOB infests oak trees, mainly valley oak, blue oak, and Oregon white oak. The beetles initially attack the crown of the tree and create tunnels (or galleries) in the branches, eventually invading the trunk and killing the tree. The infested trees can become a hazard when widespread galleries weaken the tree’s limbs and upper trunk.

The Town of Windsor values its heritage oak groves and is taking a proactive approach to decelerate the rate of MOB infestation. Vulnerable trees identified through thorough site assessments were treated in the spring of 2024 and will be monitored for efficacy over the next two years.

What to do if you believe your tree is infested with MOBMediterranean Oak Borer Beetle

  • Contact a certified arborist (ISA or ACSA) to have them inspect the tree and provide recommended treatment.
  • If the arborist recommends a removal, request a tree removal permit from the Town of Windsor’s Planning Department (native oak trees are protected trees).
  • Contact a licensed tree service company to perform the service/removal and ensure they have protocols in place for the removal and disposal of MOB-infested wood chips.

How you can help prevent/slow the rate of MOB infestation

  • Improving the overall health of the tree can make it less vulnerable to MOB. Ways to make/keep a tree healthy are:
    • Mulching—providing a layer of mulch around the base of the tree to reduce moisture loss.
    • Supplemental watering
    • Reduce competition by thinning stands (removing trees to allow others more room to grow) and pruning trees.
  • Don’t move firewood or infested material. Firewood can host invasive species (such as MOB). Instead, buy it where you’ll burn it. Visit https://www.dontmovefirewood.org/ for more information.

Timeline of Town’s Response to MOB

  • July 2023
    • Town is informed of a potential MOB infestation within Town limits and contacts Town Arborist.
  • August 2023
    • Field meeting with the University of California Cooperative Extension (UCCE), leading researchers of MOB. MOB presence confirmed along Conde Lane. Town staff receives informational presentation from Dr. Michael Jones (UCCE) on identification of the pest and possible mitigation methods.
  • September 2023
    • Five (5) trees infested with MOB were removed along Conde Lane.
  • October 2023
  • November 2023
    • One (1) tree infested with MOB was removed along Windsor River Road and Richardson Street.
  • December 2023
    • Town staff conducted an extensive assessment of all public spaces with heritage oak trees to evaluate their overall health and public safety risk. 
    • One (1) tree infested with MOB was removed along Hembree Lane and Pool Creek Lane. 
    • Two (2) trees showing early stages of infestation were pruned in the Town Hall oak grove on Old Redwood Highway. 
  • January 2024
    • Data collected from field assessments was presented to Town Council at the January 17, 2024, meeting, along with a proposed treatment program (link to video: https://windsor-ca.granicus.com/player/clip/1616?meta_id=106806). Town Council adopted an urgency ordinance amending Chapter 27.36 – Tree Preservation and Protection, of the Town of Windsor Zoning Ordinance to allow mitigation fees collected for tree removal to be used for emergency Mediterranean Oak Borer Treatment of heritage oak trees on public property within town limits. Council also approved a budget amendment to utilize unappropriated funds from the Tree Preservation Mitigation Fund and approved Amendment No. 1 to the Master General Service Agreement and Task Order No. 2 with Hagstrom and Sons Professional Tree Service to perform injection services on infested or vulnerable trees, as identified by Town staff.
  • March 2024
    • One (1) tree at Keiser Park and one (1) tree at Pleasant Oak Park were removed due to MOB infestations. Two (2) additional trees infested with MOB at Pleasant Oak Park were pruned.
    • Injection services performed by Hagstrom and Sons Professional Tree Service on infested or vulnerable trees, as identified by Town staff. Product used: TREE-äge® G4 (active ingredient: Emamectin benzoate). View the Safety Data Sheet for this product here .
  • August 2024
    • After closely monitoring the infested trees in the Town Hall oak grove, four (4) trees were recommended for removal for safety purposes. 
  • January 2025
    • A fungicide bark spraying was conducted by Hagstrom and Sons Professional Tree Service on 200 trees in Keiser Park, Town Hall Oak Grove, and the Town Green. Products used were Reliant Fungicide and Pentra-Bark (click titles to view the labels).
  • August 2025
    • One (1) tree in the Town Hall oak grove and one (1) tree in Vintage Oaks Park removed due to MOB infestations.
  • September 2025
    • Two (2) trees in the Town Hall oak grove were scheduled to be removed due to MOB infestations. Upon further inspection by industry experts, they were resprayed with the fungicide and are being closely monitored.
  • October 2025
    • Nine (9) trees along the SMART tracks on Eagle Dr. were identified by Town staff and the Town arborist as being dead from MOB. SMART was notified and the trees are pending removal by SMART.
  • March 2026
    • Three (3) trees along the Windsor Creek (Oakfield Lane) are scheduled to be removed due to MOB infestation, along with the safety pruning of several other trees. 
  • April 2026
    • A fungicide bark spraying was conducted using Reliant Fungicide and Pentra-Bark.
  • August 2026
    • One (1) tree in the Town Hall oak grove was removed after exhibiting signs of further decline.
    • Two (2) trees in Keiser Park were identified as being infested with MOB and are scheduled for removal. 


Information and Resources