Weed Management


 Control of exotic noxious weeds is accomplished by mechanical and chemical means. Roads and trails are pathways for weeds to take hold and spread so we concentrate on these areas.

Exotic plants are one of the greatest threats to native wildlife habitat. Controlling the spread of noxious weeds is necessary to maintain Refuge habitat integrity. If you would like to assist in our efforts, please contact us at lpo@fws.gov.

Combinations of biological, chemical, and mechanical methods are used to manage noxious weeds on Refuge property. An additional attempt to control leafy spurge was made by utilizing prescribed fire. Initial inspection indicates a reduced number of seed-head producing plants. Prescribed fire will continue to play a part to reduce the grass mass so the chemical and bio-agent efforts can be more effective. We have used the appetites of various root and seed head boring beetles and weevils, banded gall flies, seed head moths and their respective larvae to control and limit the invasion of non-native plant species.

Photographic points help us monitor the biological and chemical control efforts. Invasive plant species include: the thistle complex (Canada, bull and plumeless), sulfur cinquefoil, common bugloss, hound’s tongue, leafy spurge, St. Johnswort, dalmatian toadflax, yellow and orange hawkweed, common evening primrose and the Knapweed complex (diffuse, spotted and Russian)

Our Youth Conservation Corps crews assist with mechanical control along roadsides, in the riparian areas, and in campgrounds. They target diffuse knapweed, hound’s-tongue, common evening primrose, bull thistle, and common bugloss.

Transline (clopyralid) is an effective, selective herbicide that we use on our roadsides. It is active primarily on broadleaves, especially composites such as knapweed and hawkweed. We use Curtail (clopyralid + 2,4-D) on knapweed, Canada thistle, sulfur cinquefoil, and hawkweed infestations in some of our old homestead fields (Chester, Christianson, Starvation Flat, Samson Orchard, and the Cusick Flats Unit). Approximately 150 road miles are treated annually.

Eurasian milfoil was found in McDowell Lake in 2002. A survey was conducted in McDowell and Bayley Lakes as well as Potter’s Pond to determine the extent of the infestation. No milfoil was found in Bayley Lake, and only a small amount was near the boat launch in Potter’s Pond. These plants were hand pulled. In the fall of 2003 Potter’s Pond was drained to expose the milfoil and allow it to dry out and die over the winter. That treatment was successful. We then discovered more than 20 acres or about 65% of McDowell Lake had milfoil growing in the lake bottom. The lake was treated in the spring of 2006. Post treatment surveys in 2007 did not find any milfoil in McDowell Lake. Posted signs ask visitors to check their boats and trailers for any Eurasian milfoil..