News and Opinion from Sisters, Oregon

Forest Service takes on weeds in Metolius Basin

Depending on weather conditions, the Deschutes National Forest will apply herbicides to invasive plants in an area adjacent to the Metolius River and the Metolius River Trail in late September.

The treatments will occur September 27-30, 2021, along the Metolius River Trail (trail 4020 on the west side and trail 4018, east side). The Sisters Ranger District will use Roundup Custom and Polaris to treat invasive non-native ribbongrass, reed canarygrass, perennial peavine, and yellow flag iris on about one acre of the Metolius River. In locations over 15 feet from water, Transline may be used on perennial


Treatments will take place in select locations from upstream of the confluence with South Fork Lake Creek downstream to Candle Creek Campground.

The method of treatment will be spot applications with a backpack or hand-sprayer by certified herbicide applicators. It involves application of herbicide to foliage of target invasive plants to minimize effects to native plants. The applied herbicides typically dry within an hour of being applied and do not pose a risk to human, wildlife, or animal health under the concentrations being applied, the Forest Service


The Metolius River Trail on both sides of the river will remain open during treatment, but the public should remain on the trails and are encouraged to keep dogs leashed during active treatments.

Ribbongrass, reed canarygrass, perennial peavine, and yellow flag iris are aggressive invasive plants overtaking native sedges, wildflowers, and shrubs within the river’s riparian habitats. These invasive plants out-compete most native species and present a major challenge to protecting unique native vegetation and habitat of the Metolius River. Restoring and protecting the Metolius Wild and Scenic River and its values including fish, wildlife, water quality, ecology, scenery, and cultural values is a priority of the Deschutes National Forest.

The two herbicides being used were approved through an environmental analysis in 2005 and a supplemental environmental analysis in 2012. Past treatments have been highly successful, and the population appears to be reduced by about 75 percent with each treatment, according to the Forest


For more information on the invasive weed project, contact Sisters District Botanist Elizabeth Johnson at 541-549-7727.


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