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2.3 RECOMMENDED MANAGEMENT <br />2.3.1 Prevention — Inhibiting the spread of knapweeds will crucially depend on the <br />early detection and rapid response. Human activities are the largest contributors to the spread <br />of knapweed. Vehicles have been shown to pick up seeds when driven on unpaved roads and <br />off-road, especially under dry conditions. Consequently, vehicles entering and leaving the <br />quarry should avoid driving through infestations, especially when flowering. If these vehicles <br />do enter infected areas, the under carriage of the vehicles will be washed prior to leaving the <br />site. The construction equipment used on site for the day-to-day operations will only need to <br />be washed prior to transporting equipment to a new uninfected site. Construction equipment, <br />fill dirt and gravel are common sources of weed seed. Where construction, road building, <br />maintenance or some other major disturbance is planned, monitor bimonthly the first year and <br />monthly for the following three years. Do not drive or walk through infested areas during this <br />time. <br />2.3.2 Mechanical Control — Mowing: Mowing should be done in the spring before <br />seed set. It should be followed by a fall herbicide treatment. Hand pulling: Tenacious and <br />vigilant hand pulling can control diffuse knapweed. Since regrowth can occur from crowns, the <br />entire crown portion of the plant must be removed. Flowering plants must be bagged and <br />disposed of in a manner to prevent seed dispersal. Hand pulling should only be used in areas <br />with single plants or small infestations. Pulling should be three times annually. First in the <br />spring when the soil is moist, second in June focusing on bolted plants, and third just before <br />seed dispersal. Herbicides should be applied either before the mature plants set seed or to <br />rosettes in the fall. All treated areas should be monitored and new rosettes restored annually. <br />Treated areas should be planted with desirable grass species to help prevent reinfestation. <br />2.3.3 Chemical Control — Herbacides: Applying herbicidal treatments during the early <br />spring as plants are emerging followed by a second spot application as necessary. Some <br />herbicides such as Transline and some types of 2,4-D should not be used near water or in areas <br />with high water tables and sandy soils, to prevent contamination of water supplies and aquatic <br />plants. Herbicides such as picloram that are persistent in the soil should not be used in areas <br />that will be reseeded. Application instructions for all herbicides should be reviewed before use <br />to insure that they are appropriate for the location and species being treated. Especial <br />attention should be paid to safe distances for use near water. <br />2.3.4 Biological Control — Insects: Species of insects that have been most effective on <br />knapweed include the root beetle (Sphenoptera jugoslavica) and the flower weevil (Larinus <br />minutus). Larinus minutus has two sites of attack: larvae feed on the seeds, and the adults <br />damage leaves of bolting plants. <br />