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The city of Covington's blackberry offensive

Covington delivers a big blow in its battle against invasive species with help from the Department of Natural Resources  - Eric Mandel
Covington delivers a big blow in its battle against invasive species with help from the Department of Natural Resources
— image credit: Eric Mandel

Blackberries are a healthy and beloved fruit. But they are also a menace in the city of Covington.

“We are not at war with blackberries, except when they encroach in mitigated wetland areas, which we are required to preserve,” said Ross Junkin, Covington’s Maintenance Supervisor.

The city of Covington recently struck its biggest blow against the tasty tormenter through a grant that paid for a Department of Natural Resources crew to remove the non-native plant, along with Boston ivy, Scotch broom, holly and other vegetation considered invasive species around the city. The removal took place over two weeks in April from six different locations. And though the major problem areas have been hit, the battle is not nearly won.

“It’s always a phased process with blackberries,” said Angie Feser, the city’s park planner. “You knock ‘em back, but (the DNR crew) made a huge dent in this and gave us a head start on the process.”

Two of the three types of blackberries that grow in the area are invasive — Himalayan and the Evergreen. The berries that grow on the invasives are much larger than the native, but they also grow to be 15 feet tall, with canes that spread another 40 feet. Covington’s moisture-filled and sunny climate makes for an ideal growth spot.

Others invasive species are annoying, Feser said, but don’t grow to be as big as a house.

“They grow extremely fast and all it takes is one seed from one berry,” she said. “If they didn’t have really delicious berries, people would be like, ‘Oh, they’ve got to go.’”

Blackberries are considered a nuisance because they typically grow taller than the ground cover, blocking the natural sunlight that would hit the native plants, while also sucking essential nutrients from the ground. The huge plants, with their prickly vines, also become barriers for both animals and humans.

The DNR’s biggest success came at Covington Community Park, Feser said, where huge swaths of area were overgrown with the plant.

“Knocking back blackberries is a really nasty job,” Feser said. “It’s a tough job. There are thorns and they are wicked to deal with.”

Blackberries can still be found throughout the park system, especially at Jenkins Creek Park, where there is limited access, Junkin said. Feser only needed to walk a block from City Hall to find a long thorny vine growing under some brush.

“It’s one of those things,” said Karla Slate, Covington’s communications and marketing manager. “I remember picking them as a kid and now they take over. They just keep growing and take over all the areas.”

The city typically counters the growth of blackberries with general mowing maintenance and herbicide spray, which is rarely used in parks. The city must indicate with flags or signs when an area is treated with herbicide.

The DNR pulled the invasive species’ from designated areas that were in need of maintenance, including one of the large stormwater pond facilities and an area designated as a mitigated wetland.

“We are always aware of areas in need of maintenance,” Junkin said. “With the limited funding and labor force we can’t always get to it in a timely matter. Vegetation, it doesn’t slow down for anybody.”

According to the Washington DNR, Scotch bloom, which was originally introduced from Europe as an ornamental and for erosion control, is “highly aggressive and forms dense, monotypic stands which reduce wildlife habitat and hinder revegetation of upland sites and wetland buffers.”

Meanwhile, the DNR says that English holly, a Christmas favorite, is spreading into native forest habitats.

“Having that added resource was great for controlling the invasive species so we can hopefully get a handle on them in the coming years,” Junkin said.

 

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