Bacterial leaf streak (BLS) is one of the most significant foliar diseases affecting hard red spring wheat (HRSW) production in North Dakota. The most effective management tool for BLS is the use of host resistance; however, the adoption and availability of resistant cultivars is limited for HRSW producers. This has led to questions pertaining to the use of copper-based products to suppress BLS severity in HRSW production. Four field experiments were conducted from 2020 to 2022 in North Dakota to evaluate the efficacy of copper sulfate pentahydrate (CSP) applied at the flag leaf stage on reducing BLS severity and protecting HRSW yield and test weight. Experiments were conducted in a randomized complete block design with a split-plot arrangement with four replications. Three treatments served as the main plots (noninoculated, inoculated, and inoculated + CSP applied at flag leaf). Five HRSW cultivars varying in host resistance served as subplots. A high level of disease occurred across all experiments. A combined analysis suggested that the use of CSP did not provide adequate BLS suppression and did not protect HRSW yield or test weight regardless of HRSW susceptibility. The lowest mean yield loss was associated with the moderately resistant cultivar Boost (9%), and the highest was associated with the susceptible cultivar SY Rockford (19%). Variability in yield loss values among cultivars suggests that more research is needed to strengthen our understanding of BLS in HRSW.