NPS Photo

Pulling Canada thistle stresses the root system and helps prevent its spread.

Invasive exotic plants such as Canada thistle and leafy spurge, if not controlled, can choke out native vegetation. Aggressively invasive non-native plants are known as "noxious weeds."

Jewel Cave National Monument uses an integrated pest management (IPM) approach to control noxious weeds. IPM includes mechanical control (hand-pulling and cutting), chemical control (application of herbicides), and biocontrol (introducing insects which attack the plant).

To prevent contamination of water inside the cave, herbicide chemicals cannot be used in about half of the national monument.  The Cave and Karst Management Plan / Environmental Assessment (2007) established pesticide use zones based on the known geology and hydrology, and discussed the potential environmental effects of chemical treatment. 

Jewel Cave National Monument relies heavily on mechanical and biocontrol methods to control exotic plants. Hand-pulling removes part of the root system and stresses the plant. Cutting prevents the plant from producing seed. 

NPS Photo

Beetles have been released at 27 leafy spurge sites since 1994.

Biocontrol agents such as Apthona flea beetles are used to control leafy spurge. Flea beetles have been released at 27 sites within the monument since 1994.  In 2010, beetles will be released at up to 19 sites, depending on the availability of insects.

The NPS Northern Great Plains Exotic Plant Management Team (EPMT) assists the monument with chemical control of exotic plant species. EPMT treated approximately 15 acres of Canada thistle with Milestone herbicide in 2009, and will return in the fall of 2010. 

Also in 2010, the monument will begin limited use of a non-selective acetic acid vinegar herbicide to treat Canada thistle. This organic, food-grade herbicide has great potential to help reduce noxious weed infestations without impact to the cave.