First Large Scale Flowering Rush Treatment in Pacific Northwest Completed

Flowering Rush in Silver Lake, Washington

Flowering Rush is emerging as a major threat to the water resources of the Pacific Northwest.  Researchers in Flathead Lake, Montana have been working on this invasive aquatic weed for a number of years.  The plant there infests signficant portions of the littoral area of the lake and in addition to limiting species diversity and impeding beneficial water use, has provided habitat for invasive predatory fish such as the invasive Northern Pike as they decimate native fisheries.

Flowering Rush has been present in Silver Lake in northwestern Washington State for a number of years.  Until recently, this location was thought to be the only place in Washington with a known infestation.  It appears now however that there are populations in the Yakama River and the Spokane River, so it is moving to the Columbia.  Flowering Rush is a Class A noxious weed in Washington State and it’s control is mandated by law.
The Whatcom County Noxious Weed Board received a grant from the Washington Department of Ecology to target the infestation in Silver Lake last year.  The first applications were made on Tuesday of this week.  Three large operations scale research plots were selected from the dense areas on the lake.  One plot was treated with Renovate OTF granular, a selective systemic herbicide that has functioned well in laboratory studies.  The second plot was treated with Renovate MAX G, a new combination pellet that contains two systemic herbicides.  The third plot was treated with Clearcast, a new ALS chemistry that holds considerable promise.
Water sampling will be ongoing through the next week to review levels in the treatment plots.  Evaluation of control measures will be ongoing through the coming season and beyond.  This is the first large scale application targeting this noxious aquatic weed in the region and it will be interesting to see the results and to fine tune treatment strategies that help us deal with this coming threat.

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