By the time I learned that apple trees, and fruit trees in general, take well to pruning, my apples and pears were well beyond reach.  Fortunately, a family dog scratched all the bark off several of them resulting in death, so we were able to start over.  (A chicken wire cylinder would have prevented that - so another lesson learned too late).   On the new ones we learned that snow ABOVE the tree wrap makes rabbits happy and trees dead.  Build a complete fence around very young trees early - those rabbits are active right after fall planting.

Now, late February, early March, is the time to prune most trees, apples included.  Spring sap will help heal the cuts and renovation invigorates the tree.  Tree structure is visible without the impediment of leaves.  If there is disease or death, marking those branches in the fall can be helpful for spring pruning.  

For apples trees which are intended for harvest, restraining them to reachable heights is an achievable goal, especially while they are young.  While cutting the main leader is typically NOT what to do when pruning, it IS the solution to controlling heights in fruit trees.  Keeping the branches reaching at an angle reaching outward and not so much up is the goal.  

When looking at where to cut on any tree, consider how to let light and air in and encourage growth out and up.  Cut back to an, outward facing bud on the branch.  Cut diagonally above the bud, not leaving an awkward stump to encourage entrance for insects and disease.

When cutting major branches, for example dead ones or lower ones, to allow for maintenance underneath, cut back only to the branch collar leaving the collar materials to create a natural growth over the pruning wound.  (Maintenance underneath an apple tree would include removing dropped apples and leaves to diminish the chance of disease and insects persisting to the next season.)

Geriatric apple trees take well to restoration through dynamic pruning.  Go for dead, damaged, diseased and crossing first.  Then open up for light and air.  This might be a multi-year process as removing more than 1/4 of the tree in any one season is discouraged for the health of the tree.  Select upward angled branches - horizontal ones can be wet and vertical ones tend not to fruit.  Never forget to take those before and after photos!  

Fruit pruning is an important topic and the U of M has some excellent resources.  

Visit the U of M Extension for three short but effective videos.  

Many late winter/early spring days call us to get outside and pruning is the perfect activity: it needs doing, it requires lots of motion and decisions and signals the start of a new season.  

Photo Credit: Dyck Arboretum (1), deepgreenpermaculture.com (2), North Dakota State University (3)