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    Interested in what's new with Hawkweed biocontrol research?  Download the CABI Annual Report on Hieracium for 2010 here.

    Montana Hawkweed Identification Bulletin now available.  To order more copies, contact Montana State University Extension Publications by clicking here.


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    Check out our resources page with many guides, fact sheets, and regional maps to help you identify the hawkweed complex. 



    Established in 1948 as the Europe Station of the Commonwealth Institute of Biocontrol, CABI Europe-Switzerland has traditionally worked on the classical biological control of invasive insect pests and weeds of Eurasian origin, on behalf of the temperate areas of the world, particularly North America, Australia, and New Zealand.


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    hawkweed biocontrol consortium

    what is bio-control?

    When we use natural enemies to reduce invasive species populations, we refer to the natural enemies as "biological control agents," or sometimes "biocontrol agents."  Biological control can be defined as the use of living organisms to depress the population of a pest.  However, biological control could be more accurately called "biological suppression," i.e. reducing the population of the target weed to an acceptable level.  Often the goal of those who use biological control agents on rangelands is to suppress the alien weeds and at least partially restore the native plant community. 

    Biological control involves using living organisms, such as insects, pathogens, or grazing animals, to suppress a weed infestation.  Biological control attempts to recreate a balance of plant species with their natural enemies.  Since many serious rangeland weeds are invasive exotic species, they have few natural enemies on this continent.  Classical biocontrol focuses on introducing natural enemies from the weed's area of origin to local plant populations.  Biocontrol methods generally suppress host weed populations, but may not contain or eradicate them.  It is most effective on dense weed infestations over large areas.

    classical biocontrol testing

    Testing biocontrol in the greenhouse.

    This testing process usually takes between 5-10 years.  In parallel we generally quantify the impact of the agent on its host plant to ensure that only effective species are introduced.  Provided the agent shows a narrow host range, all available information is summarized in a petition for field release.  This petition is then submitted to the Technical Advisory Group (TAG), who reviews the document and then recommends to USDA APHIS PPQ (United States Department of Agriculture Animal Plant Health Inspection Service Plant Protection Quarantine) whether a release permit should be issued or not.  If a permit is not issued, usually more documentation is required.  This process alone can take up to two years. 

    For more information on hawkweed biocontrol insects, click here (link to biocontrol research page).