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Locoweed toxicity in livestock is generally prevented by precluding access of animals to infested ranges during early spring and fall and/or by controlling locoweed populations through herbicide application.  Picloram is effective in controlling locoweed; however, aminopyralid may be a superior product because of its efficacy at lower application rates, lower off-target movement, and its ‘Reduced Risk' classification.  White locoweed (Oxytropis sericea), non-target grass, and non-target forb response to picloram+2,4-D ( P+D; applied at 64 fl oz product/a) and aminopyralid+2,4-D (A+D; applied at 24 fl oz product/a) were investigated at three locations in northern NM.  Three randomly selected 200m2 plots at each site were either not treated (control) or sprayed with P+D or A+D in early June 2009.  Both herbicides were similarly effective in reducing locoweed density, plant size, and biomass 15 MAT (months after treatment) compared to untreated rangeland.  Locoweed canopy cover was not different in P+D and untreated plots 15 MAT (P = 0.06) but was significantly reduced in A+D plots (-4.9% vs.-6.1%, P<0.01). A+D treatments had lower non-target forb canopy cover than their P+D counterparts 15 MAT (P = 0.03).  Grass biomass remained similar within treatments over time for control (-5 g/m2: P = 0.86), A+D (-12.2 g/m2: P = 0.67) and P+D (-16.2 g/m2: P = 0.57) plots, and was similar across treatments 15 MAT (control: 85.8g/m2, A+D: 94.6g/m2, and P+D: 93.0g/m2). Grass canopy cover increased in both herbicide plots (+15.2% in A+D: P < 0.05 and +13.8% in P+D: P < 0.05) relative to control plots 15 MAT. By the end of the study, control, A+D and P+D plots had 78%, 89%, and 85% grass canopy cover, respectively. Overall, both herbicides appeared to affect locoweed and non-target grasses similarly although A+D was less selective, killing a higher proportion of non-target forbs.