2011-09-06_REVISION - C1980001 (2)

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September 6, 2011 Chris Keough Habitat Management, Inc. 14 Inverness Drive East Suite A -100 Englewood, CO 80112 Routt County Weed Program 136 6 Street/ PO Box 773598 Steamboat Springs, CO 80477 weeds@co routt. co.us Phone (970) 870 -5246 Fax (970) 879 -3992 Dear Chris, After reviewing the 2009 and 2010 reports of the control efforts and our phone conversation summarizing the 2011 control efforts I feel that you have made progress on the populations of Canada thistle (Cirsium arvense), musk thistle (Carduus nutans), whitetop (Cardaria draba); yellow and Dalmatian toadflaxes (Linaria spp.) and houndstongue (Cynoglossum officinale). A good start, however, relies on diligent and ongoing monitoring and weed control efforts to assure eventual success. Even when herbicide applications eliminate the current weed population the soil seed bank of these species may linger for sometime before germinating and growing. Whitetop seed may remain viable in the soil for over forty years. It is my recommendation that monitoring and herbicide treatment for these species be continued for two more years starting this fall. Canada thistle and musk thistle respond very well to September applications of Milestone at 7 oz. /acre and houndstongue first year rosettes are best treated with Escort at 1 %2 oz. /acre or Telar at 1 oz. /acre. Only with significant fall green up is whitetop successfully treated in the fall. Whitetop is best treated with a mixture of Telar at 1 oz. /acre and MCPA at 1 qt. /acre in late May through early June. The toadflaxes can be treated in late summer /fall or spring/ summer with Telar at l oz. /acre or Tordon and 2,4 -D, both at 1 qt. /acre. Two more years of diligent and timely monitoring and treatment are recommended, because of the years of relative neglect prior to your firm's management and treatment efforts. Gregory A. Brown Supervisor, Routt County Weed Program