Mira:  Thank you for contacting the UVM Extension Master Gardener Helpline with your question about treating pruning cut wounds.   I'm glad you asked before applying a wound treatment because this practice is not recommended.  Sealing the wound may actually hinder the tree's ability to heal itself.   For many years tree wound sealants were used as a general practice, however, this is no longer the case.  

I am attaching a link to a fact sheet from UNH, regarding sealing tree wounds that you may find interesting.

Should I cover large pruning wounds with a tree wound dressing? | Extension (unh.edu)

You may have heard about the recommendation to treat oak tree wounds to avoid the fungal disease Oak Wilt.  However, Oak Wilt has not yet been found in Vermont, so this is not necessary.  (See the link from Vermont Invasives for the current status on Oak Wilt.)

https://vtinvasives.org/news-events/news/learn-how-to-spot-oak-wilt

I am also attaching a forestry fact sheet on pruning tips from the State of Vermont. This fact sheet is aimed for young trees, however, the basic proper pruning cuts apply to older trees, also.   Note that unless a tree has injuries, such as a broken branch, a dead limb, or crossing/rubbing branches, major structural pruning should be done when the tree is dormant during the winter months (never more than 25% of the tree should be removed).  If a branch has one of the problems stated above, the branch can be removed at any time.  This leaflet also addresses your wound sealant question.

https://fpr.vermont.gov/sites/fpr/files/Forest_and_Forestry/Community_Forests_and_Trees/Library/Pruning_Trees.pdf

I hope you find this information helpful!