Control Techniques

Spotted Knapweed
Spotted Knapweed
Spotted Knapweed

Without a doubt, exotic weeds are very aggressive invaders, that once established, don't like to leave. Controlling these hardy weeds requires the use of various methods. Using a combination of the following control methods has proven to be the most effective approach in exotic weed control.

Biological Agents

What is the one of the worst nightmares for a weed? - Being attacked by its natural enemies!

Introducing insects and pathogens (fungus), begins the natural process of weed control. Biological agents rarely destroy a weed infestation; instead, they weaken a plants' health and reduce seed production, allowing native plants an opportunity to compete.


Cultural control refers to management practices that prevent weed spread and promotes competition from other native plants. Examples may include native plant seeding, burning, flooding, hand pulling, and limiting livestock grazing or recreational uses in an infested areas.


Chemical treatment is most effective on new infestations. Some weeds, however, can survive repeated chemical attacks, utilizing the food reserves stored in their extensive root system.


Mowing, chopping, plowing - very effective short-term control. Repeating mechanical treatment weakens plants making them susceptible to disease and competition from other native plants and depletes food reserves.