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• <br />Boysen Reservoir, Wj+oming: <br />In 1995, Russian knapweed cover was influenced by suppression treatment where <br />percent Russian knapweed cover was similar among the Roundup, mowing, and control <br />treatments and averaged 52% (Table 4}. Russian knapweed cover w•as 32 and 48% less <br />from the Escort and Curtail suppression treatments, respectively. In general, more <br />Russian knapweed was harvested from the Roundup and mowing suppression treatments <br />than all other treatments and the control (2.6 times more Russian knapweed than from the <br />Escort treatment and 5.2 times more than from the Curtail treatment; Table 4). The least <br />Russian knapweed was harvested from the Curtail treatment. Russian knapweed was <br />controlled best by Curtail (89%) and Escort controlled more Russian knapweed (59%) <br />than Roundup (25%) and Roundup more than the control (6%) and the moH~ng treatment <br />(4%), which were similar. Cover and biomass of seeded grasses varied with suppression <br />treatment where the average cover of all seeded grasses within the Curtail, Escort, and <br />Roundup treatment were similar and approximately 13% greater than in the mowing or <br />control treatments (Table 5). Average seeded grass biomass in the Curtail, Escort, and <br />Roundup treatments were approximately 20 and 11 times greater than in the mowing and <br />control treatments, respectively. Seeded grass biomass also varied with seeded grass <br />species where harvested crested wheatgrass biomass was 5 times greater than harvested <br />streambank wheatgrass and thickspike wheatgrass and 40 times greater than Russian <br />wildrye (Table 6). Bareground cover also varied with suppression treatment (Table 5) and <br />seeded grass species (Table 6), Greatest bareground was observed with the Escort <br />treatment which was 22% greater than the Curtail treatment, 25% ereater than Roundup, <br />and 27% greater than the mowing or control treatments. The least bareground occurred <br />where crested wheatgrass .vas sown and bareground within the crested wheatgrass plots <br />was 6, 8, and 9% less than in the streambank wheatgrass, thickspike wheatgrass, and <br />Russian wildrye plots, respectively. <br />A4ost importantly in 1995, a suppression treatment by seeded grass interaction was <br />observed for Russian knapweed biomass and percent control, and seeded grass cover and <br />biomass and these are the most appropriate effects to discuss; although, the previous <br />discussion about treatment or seeded grass effects is an aid to better understand the <br />interactions. There were no differences for Russian knapweed biomass among seeded <br />grass species within any suppression treatment or the control (Table 7). Approximately 10 <br />times more Russian knapweed was harvested within the Roundup plus Russian wildrye <br />combination compared to the Curtail plus Russian wildrye management system. About <br />94% less Russian knapweed was harvested from the Curtail plus streambank wheatgrass <br />management system compared to other streambank wheatgrass plus suppression treatment <br />combinations. 1`tore Russian knapweed w•as controlled when Curtail was combined with <br />any seeded grass species compared to any other suppression treatment combined with any <br />grass species except that Russian knapweed control from Curtail combined with thickspike <br />wheatgrass was similar to Escort plus thickspike wheatgrass (Table 8). For example, <br />when Curtail w+as combined with Russian wildrye seeding, 34-84% more Russian <br />knapweed was controlled compared to other suppression treatments combined with <br />Russian ~~•ildrye; Curtail plus crested ~+heatgrass controlled 32-92% more Russian <br />knapweed than other suppression treatments plus crested wheatgrass; 42-92% better <br />-8- <br />