Field surveys were conducted in 2016, 2017 and 2018 to build on previous distribution research. Waterhemp was located at 42 additional locations in seven Ontario counties and the province of Quebec. Greenhouse testing of populations collected between 2014 and 2017 has shown that 100% of the populations are resistant to Group 2 herbicides, 83% to Group 5, 87% to Group 9, and 28% to Group 14. This is the first reported case of a Group 14-resistant weed in Eastern Canada. Thirty-four field studies wereconducted at three locations over three years to identify efficacious PRE, POST, and two-pass herbicide programs for control of MR waterhemp in corn.Smetolachlor/mesotrione/bicyclopyrone/atrazine applied PRE provided 91% control of waterhemp, 8 WAA. POST-applied mesotrione + atrazine provided 92% control 8 WAA. All two-pass programs provided greater than 94% control of waterhemp 12 WAA. Ontario grain farmers have access to multiple effective options for controlling MR waterhemp in corn.