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BLM>California>Bishop>Biological Resources>Invasive Species (Noxious Weeds)>Control and Prevention
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Control and Prevention of Noxious Weeds


Controlling weeds poses a special dilemma because once a weed infestation is identified, it is often already so extensive that containment is difficult and expensive. Biological control (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. Mechanical control, e.g. pulling weeds or using machines to dig them up is effective with smaller infestations if done carefully to avoid spreading seeds.  Chemical control can be effective in controlling weeds and stopping their spread especially when infestations are detected early. Cultural or ecological control, is the modification of the weed's immediate environment so that weed competition is depressed. Land managers generally take an integrated approach, using a combination of these methods which is referred to as Integrated Weed Management.


The best way to control noxious weeds is to prevent them from entering the land in the first place. Following are some general guidelines for preventing weeds from entering public lands and from spreading to new uninfested areas:

  • Commercial seed should be required to be free of noxious weeds and labeled accordingly.
  • Collect seed on the land and use local native seeds for planting.
  •  Tamarix stump

    Tamarisk stumps

    Consider seeding only in graded areas or areas where damage will occur, such as erosion, if seeding is not done.
  • Prohibit livestock lessees from supplemental feeding while their livestock is grazing on public land.
  • Keep livestock in a holding field for 24 to 48 hours before they are released onto open range.
  • When constructing or maintaining roads, inspect gravel pits and fill sources to identify weed-free sources.
  • Grazing animals should not be moved from infested to noninfested areas until after weed seed set.
  • Signs should be posted at trailheads containing weed awareness and prevention techniques.
  • Equipment or machinery should be cleaned before it is moved from a noxious-weed contaminated area to a noncontaminated area.

Here is what you can do to help prevent the spread of noxious weeds:

  • Refrain from picking wildflowers or plants. They may be noxious weeds. Picking them can spread their seeds.
  • Tell your family and friends about this problem.
  • Check with your local nursery or nature center before adding weed-like plants to your garden. Some varieties come in a hybridized or non-invasive variety. Be aware of what is in your own backyard.
  • Check with your local ranger or land manager before starting a backcountry hike. Find out how to identify problem weed species in the area. Report any infestations you may encounter.
  • Clean all camping gear, clothing, and shoes before leaving an area to avoid inadvertently taking seeds along to the next campsite, county, or state.
  • Do not camp in or hike through weed infested areas. Stay on designated trails.
  • Drive only on established roads or trails away from weed infested areas. Seeds can become imbedded in tire treads and travel to new areas.
  • For pack animals, use only feed that is certified weed free starting 96 hours before entering backcountry areas.
  • Remove weed seeds from the animals by brushing them thoroughly and cleaning their hooves.