Hi Kathleen, 

A trunk injury would not have caused the falling sap-like secretions, and your tree looks great from the photos. The 'sap' is actually honeydew, the waste from a sap-sucking insect. The honeydew rains down onto lower leaves and stems as well as anything else positioned beneath an infested tree. The sweet sticky goo is commonly colonized by black sooty molds which are harmless and mostly impact the aesthetics of the tree. 

Pests that create honeydew include aphids, adelgids, planthoppers (including spotted lanternfly), leafhoppers, whiteflies, mealybugs, psyllids, and soft scale insects. Although many of these insects can fly or jump, they need to remain fairly sedentary while feeding, and therefore are likely to be found close to honeydew residue.

Typically soft scale insects won't be fatal to the tree and you don't need to do anything. We provide a variety of control methods here - but given the height of the canopy, you might want to reach out to a certified professional arborist to see if they think treatment is necessary. 

Jamie