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• <br />In late March of 2000 portions of Refuse Pit 1 (RP -1) and the 2/3 topsoil pile located northwest of <br />RP -1 were treated with herbicide to control cheatgrass. Test areas on RP -1 included a total of 0.5 <br />acres treated with Oust at a rate of 0.6 oz. per acre and 1.4 acres with Roundup Pro at 12 oz. per <br />acre. Three weeks following application a diverse seed mixture of native grasses, shrubs, and forbs <br />shown in Table V.1 3a was broadcast over the treatment area followed by light harrowing. <br />The majority of the north 2/3 topsoil pile was also sprayed using 12 oz. per acre of Roundup Pro. <br />Three weeks later a more aggressive seed mix was broadcast over the treated area followed by <br />light harrowing (see 2000 Annual Reclamation Report). <br />Initial inspections showed marginal response from the seeding effort. On RP -1 the effects of the <br />Roundup Pro only lasted the first growing season. Additional cheatgrass germinated later in the <br />year due to no long term control mechanism. Oust treatments resulted in longer term effects but <br />with only marginal lasting change in the long term plant community. One aspect that may have <br />limited the success is the use of native species which are not aggressive enough to persist with <br />cheatgrass. Also, subsequent years following the first two years of growth were exceptionally dry <br />• which typically favors cheatgrass. <br />• <br />Similar results occurred on the north Refuse Area 2/3 topsoil pile. The effects of the Roundup Pro <br />only lasted the first growing season. Adequate seed bank of cheatgrass provided a dense stand <br />the following fall. This site typically produces some of the densest stands of cheatgrass in the area. <br />Excessive competition from the cheatgrass resulted in essentially no long term benefit from the <br />treatment. <br />Since this study Oust has fallen from favor with the BLM. It would be difficult to obtain additional <br />approval for its use. <br />TR65 (6/2007) V -51 <br />