The branch cankers do look like black knot. This is a common disease of wild cherry trees in forest and landscape settings. While this disease does affect tree health, it's rarely catastrophic on its own. Light to moderate infections typically result in reduced growth and localized branch dieback. Trees with extensive infections on major limbs or the main stem can become weakened over time, and in those cases, there is an increased risk of canopy loss. I woods and natural settings, we view black knot as a natural stressor that influences cherry survival and stand dynamics. Management is generally not practical or necessary in wild areas unless cherry regeneration or timber quality is a specific objective.

If these trees are near neighborhoods with other susceptible trees, there is a large possibility the disease spreading to susceptible ornamental cherry and plum trees. In that case, pruning and sanitation of the infected wild trees may be warranted. See this fact sheet for more information about management practices: https://portal.ct.gov/CAES/Fact-Sheets/Plant-Pathology/Black-Knot-of-Plum-and-Cherry