Callisto Xtra is a systemic herbicide and is absorbed through the foliage of emerged weeds and by soil uptake. When applied as a preemergence, weeds take up the product through the soil during emergence. When applied postemergence, susceptible weeds absorb the herbicide through the treated foliage and by root uptake from the soil. For best postemergence weed control, apply the product to actively growing weeds. Susceptible weeds which emerge soon after application may be controlled after they absorb the herbicide from the soil. Susceptible weeds cease growth soon after application with complete death of the weeds occurring within 2 weeks. Callisto Xtra is not effective for the control of many grass weeds. For control of grasses or additional broadleaf weed control, refer to the tank mixing recommendation section on this label.