First-of-its-kind agreement between Navy, Kitsap County to fight against aggressive plants

Knotweed growing alongside the road in Bremerton..jpg

Knotweed growing alongside the road in Bremerton.

SILVERDALE, Wash. — A first-of-its-kind agreement between the Navy and Kitsap County plans to take down aggressive, non-native plants growing wild on the landscape.

This three-year agreement focuses on surveying and managing state-listed noxious weeds which tend to outgrow native plants and can take over the countryside. Members of the partnership say these noxious weeds at one time could have begun as a plant in someone’s garden.

Tiffany Nabors is a biologist with Naval Facilities Engineering Command Northwest (NAVFAC NW) and Dana Coggon, Kitsap County’s Noxious Weed Control Coordinator, are leading the charge to manage these non-native plants. The agreement could serve as a blueprint for other military installations and their local counties.

“The landscape is out of balance,” Nabors explained. “The balance is thrown off because these noxious weeds out-compete the natural plants. They are aggressive and they spread everywhere.”

Nabors is a graduate of Western Washington University’s Huxley College of the Environment, a prestigious academic environment with a respected curriculum, with a Bachelor of Science degree in Environmental Science.  Tiffany joined NAVFAC NW through their professional development intern program in 2008.

The agreement allows the county to dispatch work crews to survey Navy lands for invasive species. After cataloging the plants on federal land, a strategic plan will be drawn up on how to combat the non-native plants. Currently the team is focusing their efforts on Naval Base Kitsap and Naval Hospital Bremerton.

The cooperative agreement proves to be the best value and meets the mutual interest of both parties. This partnership plans to aggressively fight these non-native plants from both sides of the fence line. Some of these noxious plants are fairly well known, like scotch broom and Himalayan blackberries.


Scotch Broom

“In the summer, you have probably been driving down the road, when suddenly your windshield is covered in a sea of yellow,” Nabors said. “That’s scotch broom.”  The seeds of scotch broom can remain viable in the ground for up to 60 years.


Eradication of some of these non-native plants across Kitsap County may simply prove impossible because they are virtually everywhere. The plant experts must triage to see what can be done with limited resources. The priority is to prevent any new infestation wherever possible while keeping known sites under control to shrink their foothold. The treatment protocol depends on the plant species. Some plants will be pulled, while others will be treated with herbicide to gain ground in control efforts.

“Natural resource managers in the past used to plant native plants without first eradicating the noxious weeds,” Coggon said. “Then the invasive species would mount a counter-attack. We have changed focus over the years to incorporate the removal of noxious weeds before planting desirable plants. Now, we have a more holistic approach to help heal the system.”

Coggon likened the past management approaches to placing a bandage on a cancer victim.  “In order to give the landscape a fighting chance, we must first cure the disease before we re-plant,” she stressed. “These plants are smart. They can change their genetic makeup in order to offset certain types of herbicide. Because of this, we have to change our approach as they change their molecular structure. It’s punch and counter-punch in this war on invasives.”

In 2016, Coggon served as the President of the State Association of County Noxious Weed Coordinators. Information about the partnership with the Navy was presented at the association’s annual convention. Other county coordinators from across the state expressed interest on how they might better coordinate their efforts with their federal land managing counterparts.

“Normally county coordinators don’t have access to Department of Defense lands, so weed issues continue to spread across fence lines,” Coggon explained. “The fence line means nothing to a weed.”

This agreement allows Kitsap County crews to survey for noxious weeds on Navy properties, map problems, and oversee on the ground controls. The agreement works in tandem with the Installation Natural Resources Management Plan to provide ecologically sound control practices for high priority weeds. Coggon, an adjunct faculty member for Washington State University, leads what she refers to as the “noxious weed triage crew” to remove the worst weed offenders.

One high priority weed in the crosshairs for control under this agreement is the invasive knotweed, considered one of the top enemy plant combatants. This aggressive plant tends to grow along the shoreline, displacing native plants critical for shoreline health. One challenge with knotweed is that it can grow up to 30 feet annually and can simply overrun an area.

Other noxious weeds on the target list are harmful to people and animals, like poison hemlock. Every part of the plant is poisonous, especially when ingested. Coggon recalls that someone in the Tacoma area ate poison hemlock root, mistaking it for a carrot, and died as a result.

Poison hemlock is extremely prolific, producing more than 1,000 seeds per plant, per year, spreading rapidly if left unchecked. This plant can render rangelands, grasslands and crops worthless. Dead stalks remain toxic for years. It is not yet widespread in Kitsap County, but can be found along roads, ravines, fields, ditches and empty lots.

According to a report issued in January, the state stands to lose $504.9 million this year alone from invasive species in Washington. The “Economic Impact of Invasive Species,” completed by Community Attributes Inc. of Seattle, looked at the potential economic damage from a select list of 23 invasive species. According to the report, scotch broom has a direct negative economic impact of $59.7 million across the state. Those economic losses include impacts to livestock ($15.8 million), timber ($42.9 million), and hunting ($971,000).

The report was written on behalf of the Washington State Department of Agriculture, in partnership with the Washington State Noxious Weed Control Board, and the Washington Invasive Species Council. The report looks at how invasive species impact jobs, wages and lost sales.

“It’s important for the Navy to work with Kitsap County. When you take invasive plants down on your side of the fence, your neighbors have a virtual seed bank ready to replenish the landscape,” Nabors said. “We want to be good neighbors. It’s not just a Navy problem. It’s everyone’s issue.”


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