Controlling exotic plants poses a special dilemma because once an infestation is identified it is often already so large that containment is not only difficult, but also expensive. In Alaska parklands, a special emphasis is placed on early detection of infestations and prevention of new infestations. Land managers generally take an integrated approach, using a combination of the following four methods to contain weed infestations and eradicate them where possible.
- Hand-pulling and root removal works for small infestations of most species, but it's difficult, time-intensive, expensive, and requires repeated efforts.
- Cutting is effective for some species, like Melilotus alba (white sweetclover), but not others, like Cirsium arvense (Canada thistle).
- Herbicides are generally most effective in controlling weeds and stopping their spread, but they can be expensive and may have environmental impacts.
- Using organisms
such as introduced insects or diseases to suppress populations is effective
in slowing the spread of weeds but generally cannot eradicate the infestation
and is not an option until a species is well established.
White sweetclover currently threatening the borders of Wrangell-St. Elias National Park and Preserve is manually controlled twice a year
Yellow toadflax is contolled regularly from Kenai Fjords National Park 's Exit Glacier Road
