Murase Plaza Invasive Plant Mitigation

In collaboration with Ash Creek Forest Management, the City’s Parks & Recreation crews are beginning a multi-year project to mitigate the proliferation of invasive lesser celandine at Memorial Park’s Murase Plaza.  The three-year restoration project is designed to restore Murase Plaza’s native prairie ecosystem.

Completing this work requires the controlled use of herbicide, as manual disturbance can stimulate the plant’s growth. The first herbicide treatment is scheduled to take place early morning on Wednesday, Jan. 26.

“With the size of the patch at Murase Plaza, the use of herbicide is the only viable control option,” said Dustin Schull, Parks Supervisor. “Tubers of the plant break off and spread easily when you attempt to remove the plant manually, which will cause the infestation to further spread.”

To ensure the safety of people and pets visiting the park, temporary closure signs will be posted along the application areas. These signs will be removed later in the day when the area becomes safe for public re-entry. Ash Creek specialists are spraying during the early morning in order to minimize exposure and drift. 

The herbicide is being applied by Oregon Department of Agriculture licensed pesticide applicators. The initial treatment is expected to take place twice each spring for a three-year period. Afterward, in the spring of 2024, native grass and wildflowers are being seeded at the location.

A herbaceous perennial plan in the buttercup family, lesser celandine forms dense patches, overwhelming lawns and leading to the exclusion of many low-growing wildflowers. It flowers in March and April. The plant has eight glossy, butter-yellow petals, and is borne singly on delicate stalks that rise above the leaves. When in bloom, large infestations of appear as a green carpet with yellow dots, spreading across the forest floor.

For more information on this project, contact Christopher Delk, Park Maintenance Specialist, at cdelk@ci.wilsonville.or.us.