Technical Abstract: Early research suggested clipping Duncecap larkspur (Delphinium occidentale) reduced total alkaloid concentration. The objective of this study was to determine if clipping would reduce toxic alkaloids in tall larkspur (D. barbeyi). The study was replicated at two locations in the mountains of central Utah. In 1997 ten uniform plants in the bud elongation stage (40 cm in height) were selected at each site and clipped cm above the soil. The following year, one stalk from each plant was harvested on a weekly basis to evaluate the alkaloid response to clipping over the growing season. Toxic and total alkaloid concentration were measured and alkaloid pools in the entire stock were calculated. Clipping reduced stalk height to less than 50 cm (compared to over 100 cm in unclipped control plants), and some of the clipped plants were severely stunted (< 30 cm). The toxic alkaloid pools in the entire stalk of reduced-height and stunted plants were similar, but were only a third of those in undefoliated control plants. However, alkaloid concentration in stunted plants more than doubled, suggesting that a constant amount of alkaloid was concentrated in the smaller biomass of the stunted stalks. Clipping reduced subsequent vigor and the amount of toxic and total alkaloids in tall larkspur.