Ivy Survival Rings

Urban Forestry
Anticipated Budget: $55,000
Contractor: Olson Environmental
Contact: Urban.forestry@mercerisland.gov Phone: 206-275-7872

City contractors will be performing invasive weed work in select parks and public rights-of-way in the coming months. English Ivy (Hedera helix) thrives in the Pacific Northwest, to the great detriment of our native species. This vine creeps over low-to-the-ground plants, smothering all competition, and given a tall enough tree to climb, it can reach over 100 feet into the air.  The excess leaf mass and weight high in native trees makes them susceptible to windthrow, while ivy roots make the soil inhospitable for new seed germination through a process called allelopathy - changing the soil chemistry. The result is the loss of native tree canopy through poor conditions for new plants to grow, and the eventual destruction of existing canopy.

Mercer Island Public Works has long battled this weed in our parks and open spaces and intermittently performs work in our public rights-of-way to keep this weed from killing our mature trees. This year, city contractor Olson Environmental will be working on East and West Mercer Ways, as well as other select ivy hotspots to rescue our mature trees from Ivy. “Ivy Survival Rings,” is a technique where ivy vines are cut off from the lower section of a tree, severing the ivy in the tree from the roots, causing it to eventually die. Ivy is manually dug out from the base of the tree - no pesticides are used in this process. Homeowners adjacent to work areas will be receiving mailers before our anticipated start of work on April 10^th. This technique is easy to replicate in your own yard if you have an ivy problem.

Ivy control work is just a part of City efforts to protect and grow our Urban Forest. The city is seeing an increase in tree mortality due to pressures from invasive species, increased summer drought and heat, and novel pests like California Five Spine Ips Beetle and Sooty Maple Bark Disease. The City does its best to remove dead trees for public safety and to replant replacement trees (The city planted approximately 1,500 trees in 2023). Still, we need the help of the greater community to maintain and grow a thriving urban forest! The 2018 Tree Canopy Assessment tells us that 47% of the total urban forest is on single-family residential land use, and 85% percent of the plantable area is on single-family residential land.

Please join us in caring for our Urban Forest! You can learn more about the City's efforts and how to care for and plant your own trees at our urban forestry webpage. If you are interested in helping  the city to control this weed in our parks and openspace, please visit our volunteer page!

Contact: Urban.forestry@mercerisland.gov Phone: 206-275-7872

short URL : www.mercerisland.gov/ivyrings