Siskiyou County WMA – California Invasive Plant Council

Chair: Jodi Aceves, Senior Deputy Agriculture Commissioner
530-841-4115, jaceves@co.siskiyou.ca.us

General contact: Daryl Lara, Vegetation Control Supervisor

Erin Lonergan, Forest Botanist, Klamath National Forest

Meetings: Twice per year at the Siskiyou County Department of Agriculture, Yreka

Outreach Summary:

Reprinting and circulation of “Selected Noxious Weeds of Northeastern California” a reference book for weed identification

Newspaper insert distributed through several papers in county and at other events.

In order to prevent the spread of knapweed species downstream, where agricultural lands could be impacted, or upslope to forests and rangeland, Siskiyou WMA treated populations of three knapweed species, reducing their density. Spotted, squarrose, and diffuse knapweed were mapped in and adjacent to U.S. Forest Service lands in the western part of the county using GPS/GIS, then mechanically or chemically treated. The acres infested by squarrose knapweed have been reduced from 1,600 acres to 30 acres. This reduction in density will prevent spread by vehicles, cattle, and mining equipment, which are vectors in this area. Project partners include U.S. Forest Service and Siskiyou County Department of Agriculture.

Perenial pepperweed was chemically treated in the Tule Lake and Lower Klamath Federal Wildlife Refuges, in the eastern part of Siskiyou County. Treatments began at the outlying portions of infestations and worked their way towards the center of the infestations. Follow-up treatments are ongoing. Project partners include Tule Lake Irrigation District, the wildlife refuges, private ranchers and farmers, and Klamath County, Oregon.

Siskiyou WMA partnered with California Department of Food and Agriculture, U.S. Forest Service, and Siskiyou County Department of Agriculture to control leafy spurge on Federal land along 60 miles of the Scott and Klamath Rivers. Two species of flea beetles and a longhorn beetle were used as biocontrol agents and were released at many sites along the rivers.

Chemical and mechanical treatments were initiated on a project area of approximately 30,000 acres of Musk and Scotch thistle. Because it is so large, this site was originally designated as a containment and biological control site. The site is predominantly infested with musk thistle, but Scotch thistle has been increasing significantly. Siskiyou County Department of Agriculture partnered with Trinity National Forest to initiate the project.