Clones of mature aspen (Populus grandidentata, P. tremuloides) can rapidly spread and become invasive in the absence of regular fire. Aspen trees resprout vigorously when top-killed by fire in globally rare inland pitch pine (Pinus rigida)/scrub oak (Quercus ilicifolia, Q. prinoides) barrens; thus, complete aspen kill (all trees in a clone) is desirable before introducing fire into barrens. Manual girdling may achieve complete kill but the scale of invasion can easily exceed the capacity to girdle. We evaluated dormant-season herbicide treatments by measuring aspen diameters and kill rates in an urban pine barrens preserve in east-central New York State. Chainsaw frill and drill/fill applications of glyphosate clearly outperformed stem injection of glyphosate capsules and basal bark spraying of triclopyr. Chainsaw frill was 95% likely to kill aspen smaller than 18.3 cm diameter whereas drill/fill was 95% likely to kill aspen smaller than 23.6 cm diameter. A single-cut chainsaw frill approach was fastest and incurred the lowest chemical cost, but mortality was limited to smaller trees. Drill and fill was effective regardless of tree size and drill effort, and a 20-cm drill-hole interval may provide the most cost-effective complete kill of mature aspen clones in barrens historically dominated by pitch pine and scrub oak.