Most successful weed management plans use a number of methods: herbicides, mechanical, cultural, and when appropriate biological control. Use of multiple methods at the same time is called Integrated Pest Management - or IPM.
Biological control of weeds is the use of one organism to control another. Classical biological control is the introduction of control agents - usually insects - into a region that is not part of their natural range, to permanently reduce the populations of selected weeds. They are used to REDUCE, not GET RID OF the weeds.
HOW BIOLOGICAL CONTROL WORKS
Biological control agents or bio-agents may control weeds by destroying seeds, leaves, root, or stems; by weakening or stressing the weed; and/or by limiting the weed's ability to reproduce.
Bio-agent feeding may also help weaken weeds through damage scars.
Once established and feeding in your weed infestations, bio-agents will continue to attack your weeds throughout the growing season.
BIOLOGICAL CONTRAL BASICS ADVANTAGES:
Target specific
Continuous action
Long-term cost effectiveness
Gradual in effect, environmentally friendly
Can move on their own (even into steep or difficult terrain)
BIOLOGICAL CONTROL BASICS DISADVANTAGES:
Initial high costs
Long time until results seen
Uncertain results
Uncertain "non-target" effects in the environment
Can not be removed
Environmental conditions can have an effect on the establishment of the bio-control agents
THINGS TO KNOW:
Effectiveness of agents cannot be guaranteed
Will not work every time in every situation
Will not "eradicate" the weed (no complete kill)
May not provide the desired level of control
Sometimes it might take years before you see biological control impact
SOME QUESTIONS TO ASK YOURSELF:
Do I want eradication? - biological control is not a good fit with this goal.
Do I want to reduce weed abundance? - depending on weed and control agent - maybe.
How soon do I need results? Yesterday? 1 to 2 seasons? Within 5 years?Biological controls take years to show results.
Do I have lots of money, time, or people? Other management tools such as herbicides, mechanical or cultural control may help you achieve your goals soomer.
Do I have little time or money? If you can't manage your weeds in any other way, biological control may be better than nothing.
SPOTTED KNAPWEED
Knapweed Agents - Seedhead feeders are everywhere in Kootenai County and are becoming more widespread. Work in Canada shows the best control if seedhead feeders and root feeders are combined.
Local Programs: Contact your State Department of Agriculture, County Noxious Weed Office, Local Cooperative Weed Management Area (CWMA) or Extension Agent.
USING LIVESTOCK FOR WEED MANAGEMENT
Prescription grazing - is carefully controlled grazing to meet land management objectives. It can reduce weeds in crop systems, control weeds in tree crops, remove weeds in sensitive areas, and control weeds on range lands.
KEYS TO PERSCRIPTION GRAZING:
Timing of grazing - when weeds are most susceptible and taste the best to the animal, generally early spring in North Idaho.
Frequency of grazing - Depends on the weed species; life span, reproduction, longevity of seeds in the soil, and how it react to grazing.
Stocking rate - How many aninmals do you need on how much acreage? It depends on the density of the weed infestation, the palatability of the weed, and your specific goals.
Pick the right animal for the job - Pick the correct species and breed for your weed. It is a myth that any old goat (or sheep, or cow) will do.
BIOLOGICAL CONTROL MAY BE AN OPTION FOR YOUR WEED PROBLEM IF.....
You don't expect the weed to be totally eradicated
You don't need instant gratification
You are willing to check release sites for establishment and impact
You are willing to give the agents the time they need to work (2-5+ years) before resorting to other weed management options (spray, mechanical,cultural)
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