Callisto, a new herbicide from Syngenta, offers another weapon for control of major broadleaf weeds in corn. The postemergence herbicide controls tough weeds such as cocklebur, pigweed, lambsquarters, ragweeds and waterhemp.

Callisto can be applied until corn is 30" tall, offering both postemergence and residual weed control at a use rate of 3 oz/acre. In addition, company research has found that tankmixing 0.25 lb/acre of atrazine with Callisto delivered extended control of cocklebur and morning-glory and resulted in stronger residual activity.

At a time when some weeds exhibit increasing tolerance to triazine herbicides and ALS inhibitors, Callisto offers a new mode of action. It is both xylem- and phloem-mobile, which means it moves from the site of contact to growing points in shoots and roots. It inhibits the HPPD enzyme that helps the plant manufacture pigments needed for survival. Weeds appear bleached, stop growing and die in two to three weeks.