Picloram is a systemic herbicide used for general woody plant control, sold under the trade names Tordon and Grazon. It also controls a wide range of broad-leaved weeds, but most grasses are resistant. Picloram Pesticide Information Profile, Pesticide Management Education Program, Cornell University. A chlorinated derivative of picolinic acid, picloram is in the pyridine family of herbicides. Picloram can be sprayed on foliage, injected into plants, applied to cut surfaces, or placed at the bas… (More on Picloram)