Non-Peer ReviewedThe residual effects of three rates of picloram, chlorsulfuron, metsulfuron, metribuzin, and cyanazine, applied to a Vierdale loam (Heath Park), Helfort silty clay loam and Etomami clay (Somme) in 1985, were investigated on eight rotational crops. Picloram applied to cereals at the recommended rate of 0.024 kg/ha continued to suppress yields of lentils and field peas two years after application. Alfalfa, red clover and sweetclover were not affected, whereas canola yield increased due to the residual weed control provided by the herbicide. Chlorsulfuron residues adversely affected lentils, canola, red clover and sweetclover even at the lowest rate of 0.01 kg/ha but peas were not affected. Hetsulfuron residues from the 0.006 kg/ha rate injured lentils, red clover and sweetclover. The recommended rates of metribuzin (0.41 kg/ha) and cyanazine (1.44 kg/ha) for TT-canola did not have any carryover effects, whereas the 2× rates injured lentils, peas, and Tobin canola two years after application. Crested wheatgrass and smooth bromegrass were not
affected by any of the herbicides tested even 1 year after application. In general, the risk of injury to rotational crops was greatest at Meath Park (pH = 7.8, OM = 5.6 %) and least at Melfort (pH = 6.2, OM = 12 %)
