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Integrated Weed Management Recommendations <br /> Effective integrated management means using a variety of eradication methods that also includes restoration, <br /> prevention of seed production and dispersal, and monitoring. Maintain robust healthy native landscapes and restore <br /> degraded sites. Avoid soil disturbance. As with most biennials, prevent seed production in the first and second year <br /> of bull thistle growth. Prevent seed from dispersing, such as on contaminated equipment. Rest sites until they are <br /> effectively restored. <br /> CULTURAL CONTROL METHODS <br /> s�°ek Since bull thistle germinates in canopygaps,maintain or restore a competitive forb and cool <br /> and warm season grass assemblage to reduce spacing between plants.Use locally adapted <br /> and ecologically appropriate seeds whenever possible to improve competitiveness. <br /> Ensure annual species are included in the native seed mix as well as perennial.Incorporate <br /> soil amendments,soil microbes and mycorrhizal fungi in restoration efforts.Manage land <br /> I uses so they do not cause soil disturbance or create bare mineral soil. <br /> •?°wank 51IIIko'NPS — <br /> BIOLOGICAL CONTROL METHODS <br /> Horses, goats and sheep may eat flower heads on a few young individual plants, but <br /> seeds likely pass through their digestive tracks unaltered; cattle avoid bull thistle. Dense <br /> stands and large plants are usually avoided.Thus, bull thistle can become an "increaser" <br /> in over-grazed systems.Properly managed grazing can improve vigor of desired plants and <br /> indirectly reduce bull thistle. There is a biological control agent for this species, the bull <br /> thistle gall fly, Urophora stylato, but it was found to be ineffective in Colorado. Since it is <br /> y f"- not ethical to promote ineffective non-native insects in the state,this fly is not available in <br /> Colorado. For more information,visit the Colorado Department of Agriculture's Palisade <br /> P E&Cwmb4 OR Dept of Waku- __ Insectary website at www.colorado.gov/ag/biocontrol. <br /> Q - <br /> OiG7 .1%,q ij MECHANICAL CONTROL METHODS <br /> N Methods,such as hoeing,tilling and digging,are best for infestations smaller than 0.5 acres. <br /> y" '' '• Sever roots below the soil surface during the first year before the plant stores energy, <br /> and in the second year before seed production. Mowing, chopping and deadheading <br /> stimulates more flower production;these methods require consecutive years of season- <br /> long treatments. Flower heads and buds must be collected, bagged, and disposed of or <br /> "tF destroyed; seeds will mature and germinate if left on the ground. Prescribed fire that <br /> leads to high soil burn severity can damage roots and above ground biomass of bull <br /> thistle but also damages desired plants. Fire favors bull thistle and is not recommended. <br /> t/1 <br /> 0 U CHEMICAL CONTROL METHODS <br /> NOTE: The following are recommendations for herbicides that can be applied to pastures and rangeland. Rates are <br /> approximate and based on equipment with an output of 30 gal/acre. Follow the label for exact rates.Always read, <br /> understand,and follow the label directions.The herbicide label is the LAW! <br /> HERBICIDE RATE APPLICATION TIMING <br /> Aminopyralid* 6 oz.product/acre+0.25%v/v Apply to rosettes through bolting stage in spring,or to fall rosettes. <br /> (Milestone) non-ionic surfactant *Product not permitted for use in the San Luis Valley. <br /> Chlorsulfuron** 1 oz.product/acre(0.75 oz. Spring from bolting to bud stages.**This herbicide has residual <br /> (Telar) active ingredient/acre)+0.25% soil activity that will affect all broadleaf seedlings germinating after <br /> v/v non-ionic surfactant application has occurred. <br /> Clopyralid(Transline) 0.67-1.33 pints product/acre+ Apply to rosettes through flower bud stage in spring,or to fall rosettes. <br /> 0.25%v/v non-ionic surfactant <br /> Aminocyclopyrachlor 4.75-8 oz.product/acre+0.25% Apply from the seedling to the bolting stage. IMPORTANT:Applications <br /> +chlorsulfuron v/v non-ionic surfactant greater than 5.5 oz.product/acre exceeds the threshold for selectivity. <br /> (Perspective)* DO NOT treat in the root zone of desirable trees and shrubs.Not for use <br /> on grazed or feed forage.*Product not permitted for use in the San Luis <br /> Valley. <br /> Colorado Department of Agriculture-Conservation Services <br /> ' 305 Interlocken Parkway UUniversit�y <br /> Broomfield,CO 80021 <br /> Rev. 0 (303)869-9030 <br /> 11/16 '" www.colorado.gov/ag/weeds <br />