Ash Tree Management Plan
Ramsey County Parks & Recreation created a management plan in response to the effects of emerald ash borer (EAB) on ash trees on county-managed land.
This plan includes a system-wide inventory and plan for ash tree removal and replacement within the department’s jurisdiction. This plan proposes to proactively remove or replace priority ash trees, starting at sites nearest EAB infested areas. This approach is more cost-effective and it allows for work to be done in phases.
EAB is an insect that attacks and kills ash trees. They spread through short distance natural flight and infested firewood transported long distance. The adults are small, iridescent green beetles that live outside of trees during the summer months. The larvae are grub or worm-like and live underneath the bark of ash trees. Trees are killed when larvae tunnel under the tree's bark.
EAB was first discovered in the United States in 2002 near Detroit, Michigan. In May 2009, the first cases of EAB were found in Minnesota within Saint Paul. The city of Saint Paul and its surrounding suburbs began creating management plans shortly after. Many cities are now nearing ten years of planning and management.
EAB has now locally infested most areas of Ramsey County. In 2010, Parks & Recreation began taking inventory of ash trees throughout golf courses and recreational areas of the park system. Between 2010–2012, around 350 ash trees located in parks and golf courses were treated with emamectin benzoate (trade name TreeAge). This treatment was effective for up to four years. Treatment of ash trees ceased after this initiative because of the high costs of ongoing treatment.
Ash tree management
The options for ash tree management include remove and replace, chemical treatment and biocontrol agents. Parks & Recreation has opted for removal and replacement, similar to many other counties and municipalities.
Benefits of removal and replacement approach:
- Removal and replacement is shown to be the longest term, most cost-effective measure.
- It generally takes 3–5 years for an ash tree infected with EAB to die. Removing these trees before mortality occurs reduces the number of dead and potentially hazardous ash trees.
- Replanting with varying tree species increases resilience to future pests and pathogens.
With assistance from the Tree Trust, an expedited removal and replacement timeline began in 2021. Due to a unique funding opportunity, 400 replacement trees have been made available to Parks & Recreation at no cost.
Designated sites will have selected ash trees removed from parking lots and other high priority areas in order to fully utilize these replacement trees. In some cases, it will be necessary to remove all ash trees from an area to facilitate planting. Signage will be posted on site as removal dates are confirmed.
In 2021, there were 455 ash trees removed and replaced with a variety of tree species - American basswood, disease resistant elm, redbud, yellow wood, honey locust, coffee tree, planetree, pin oak, red oak, birch and swamp white oak. The remaining 290 ash trees will be removed and replaced starting spring of 2022. Ongoing maintenance of these trees includes watering, stabilizing and protecting trees as needed to ensure establishment.