The Montana Department of Agriculture (MDA) confirmed rush skeletonweed (Chondrilla juncea) in recent weeks at several sites outside its historic invaded range in the state.
These include two plants in the I-90 median west of Three Forks, a few plants at two locations south of Dillon on I-15, and individual plants located where recent forest fires occurred near Wise River and Wisdom.
Rush skeletonweed, a Montana Priority 1B Noxious Weed, has limited presence in Montana and if found requires eradication or containment and education. Following these new sightings, county weed districts, Montana Department of Transportation, and MDA staff partnered to survey hundreds of miles of roadside looking for additional plants. Any plants found were mapped then all possible flowering parts were clipped, bagged, and incinerated. The remaining living plant material was treated with herbicide. Follow-up will be continued as long as necessary.
Rush skeletonweed is already present in western Montana, but it is increasing along I-90 in Missoula and Mineral counties. This summer, significant new infestations have been found and treated in Ravalli, Missoula, Flathead, and Lincoln counties, primarily in rangeland, open forests, and other natural areas. It has never been found in small grain fields in the state, but in Australia rush skeletonweed has reduced crop yields by as much as 70 percent once established due to strong competition for nitrogen and water, making establishment prevention in central and eastern Montana even more critical.
The easiest time to spot rush skeletonweed is September into October as the plant is flowering and producing seed. To learn more about identification, biology, and ecology, see the MontGuides – Rush skeletonweed.
To report a suspected rush skeletonweed plant, submit a sighting on EDDMapS or take multiple pictures and record accurate GPS coordinates, then submit to your local county weed coordinator, Montana State University Extension agent, and the Montana Department of Agriculture Noxious Weed EDRR Program at MTEDRR@mt.gov.
For additional rush skeletonweed resources and contact information, visit the MDA Early Detection, Rapid Response webpage here: agr.mt.gov/Noxious-Weeds.
The Montana Department of Agriculture is serving Montana Agriculture and growing prosperity under the Big Sky. For more information on department programs and services, visit agr.mt.gov.
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Montana Department of Agriculture
