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Leafy Spurge <br />Pag <br />atone month intervals, wupied with fall grass seeding, Make the first application at the <br />beginning of June and a second application one month later. Occasionally, leafy spurge <br />will recover from these Roundup treatments. An application of 2,4-0 (2,0 quart/A) in <br />September can mntrol regrowth. Sow perennial grasses in late fall. <br />Tordon is the most effective herbicide for leafy spurge control. Treat large, readily <br />accessible areas with 1 quart/A for three to four consecutive years. More remote areas <br />may be treated with 2 quarts/A for two consecutive years or once every other year for <br />three years, depending on leafy spurge recovery after the first treatment. With either <br />treatment, monitor infestations. Retreat with 1 quart/A of Tordon when shoot control is <br />less than 75 percent. <br />Tordon may be tank-mixed with 2,4-D to provide adequate control. Apply 1 to 1.5 pints <br />of Tordon with 1 to 1.5 quarts/A of 2,4-D in spring when leafy spurge flowers. When this <br />application is made for three to flue consecutive years, leafy spurge shoot control is <br />generally 80 to 90 percent and cattle will feed in the area again. <br />Banvel/Vanquish/Clarity also is effective against leafy spurge. Apply 2 quarts/A in spring <br />for three consecutive years. Often control is not very good in the first year but improves <br />over the next two years. At that time, a maintenance schedule that uses low rates of <br />Banvel/Vanquish/Clarity + 2,4-D (4 to 8 ounces + 0.5 to 1 quart/A), or Tordon + 2,4-D <br />(1 pint + 1 quart/A) as needed can be used to keep infestations under control. Note: <br />Avoid using soil-active herbiades such as Tordon or Vanquish/Clarity near <br />windbreak plants or other desirable woody vegetation. Plant injury or death can <br />occur. Also, do not allow any herbicide to drift onto desirable woody vegetation for the <br />same reasons. <br />Recently, Plateau (imazapic) was registered to control leafy spurge in noncrop areas. It <br />can be used safely around trees but may temporarily Injure cool-season perennial <br />grasses. Apply Plateau at 8 or 12 fl. oz/A in fall, followed by 4 fl. oz/A the following <br />spring at flowering. Add a methylated seed oil at 2 pints/A to the spray solution. A liquid <br />nitrogen fertilizer solution may be added to the spray mixture to increase weed control, <br />but it may increase cool-season perennial grass injury. <br />Biological control. Sheep or goats can be used to help control leafy spurge. Research <br />from Montana State University indicates sheep may consume up to 50 percent of their <br />diet as leafy spurge. Introduce sheep to leafy spurge in early spring when the weed is <br />succulent. Goats will consume leafy spurge at almost any time during the growing <br />season. <br />Rotate pastures to prevent seed production and allow desirable forage plants to regain <br />vigor. If livestock graze leafy spurge after seed formation, hold animals in a corral for at <br />least seven days before moving them to an uninfected area. This reduces viable seed <br />passage. Sheep or goats followed by faA herbicide treatment may be an effective, <br />integrated means to use infested ground and control the weed. <br />The USDA is examining several insects for leafy spurge control. The Colorado <br />Department of Agriculture insectary has four flea beetles (Apthona nigriscutis, black-dot <br />Flea beetle; A. cyparissiae, brown-dot spurge Flea beetle; A. czwalinae, black spurge flea <br />beetle; and A. flava, copper spurge flea beetle) available for release. Their larvae feed on <br />leafy spurge root hairs and within roots, while adults feed on foliage. Other insects may <br />become available in the future. Most likely, a combination of insects will be necessary to <br />adequately control leafy spurge. Insects would be most advantageous in areas where <br />herbicide use is difficult or risky. <br />Recent research completed by Colorado State University showed that six to eight sheep <br />per acre grazing for 10 days in July over a period of five years decreased leafy spurge <br />density about 90 percent. When flea beetles grazed simultaneously in ]uly with eight <br />sheep per acre for 10 days over five years, leafy spurge density was decreased to zero. <br />Habitat requirements of the flea beetles vary. While all requirements are not well <br />understood, it is known that A. nigrisaitis prefers open, dry sites and coarse soils low in <br />http://wcvw.ext.colostate.edu/pubs/natres/03107.htm1 6/20/2005 <br />