Large crabgrass (Digitaria sanguinalis (L.) Scop) and yellow nutsedge (Cyperus esculentus L.) are problematic weeds in turf. It has been hypothesized that root absorption of mesotrione is necessary for effective control. Greenhouse studies were conducted to compare the effects of foliar-applied, soil-applied, and soil plus foliar-applied mesotrione at 0.14 or 0.28 kg ai/ha on large crabgrass and yellow nutsedge (foliar and soil plus foliar treatments included 0.25% v/v non-ionic surfactant). Large crabgrass and yellow nutsedge were evaluated visually for phytotoxicity 28 and 56 days after treatment (DAT) on a 0 (no control) to 100 (complete control) % scale. Plant foliage was harvested 28 DAT and plants were subsequently allowed to grow new foliage. Foliage was harvested at soil level and roots were washed free of soil 56 DAT. All plant biomass was oven dried and weighed. Soil-applied and soil plus foliar-applied mesotrione controlled large crabgrass and yellow nutsedge more effectively than foliar-applied mesotrione. Foliar-applied mesotrione was less effective at reducing large crabgrass foliar-weights than soil-applied or soil plus foliar-applied treatments. As hypothesized, root absorbed mesotrione from the soil is important for the effective control of both large crabgrass and yellow nutsedge.