Upper Snake River CWMA

Biological Controls

Biological weed control involves the deliberate introduction and establishment of natural

 enemies to reduce the target plant's competitive or reproductive capacities. Insects are the

 most common agent released against noxious weeds. However, plant pathogens, such as

 fungi, are increasing in use. Sheep and goats have been effective in reducing densities and

 limiting spread of specific weed species. Biological control can be a slow process, often

 requiring 5 to 20 years to be effective. Its purpose is not eradication but a reduction in

 densities and rate of weed spread to an acceptable level. It is most effective on dense weed

  infestations over large areas.
 

  The Teton River Corridor Integrated Weed Management Project helped private

  landowner efforts to control Canada thistle along the Teton River corridor and

  adjacent lands in Teton Valley, Idaho.  Teton Regional Land Trust, based in Driggs,

  Idaho, initiated the project because of the negative impacts Canada thistle can have

  on wildlife habitat and the productivity of agricultural lands.  The project took an

  integrated approach by using biological control insects and herbicide.  The Land

  Trust released seven colonies of Urophora cardui (stem gall fly) and twelve colonies

  of Ceutorhynchus litura (stem mining weevil) in six locations along the Teton River

  corridor.  In addition to biocontrol releases, approximately 1060 acres along the

  Teton River corridor were treated for Canada thistle with the herbicide Milestone. 

  The project resulted in approximately 23 public contacts.

  For more information on biological controls of Noxious weeds click on the following links:

• Idaho State Department of Agriculture www.agri.state.id.us/Categories/PlantsInsects/NoxiousWeeds/Bio_Contro.php
• Cornell University Biological Controls http://www.nysaes.cornell.edu/ent/biocontrol/