Learn about your species of oak and local climate before beginning to prune.
Mar 14, If you have oaks in your landscape that need pruning and you live in an area of Minnesota where oak wilt occurs, pruning must be done before the oak wilt fungus and it's insect vector become active. Oak wilt is a fatal disease of oak trees that can be found in some counties of Minnesota.
If you live in an area where oak wilt occurs, it is critical to prune oak trees before the high risk infection period begins in April.
Oak trees should be pruned in the winter months when the trees are dormant and beetles are inactive to prevent the spread of oak wilt. Winter pruning is also great for arborists as the harder ground provides them easier access to trees and the bare canopy makes branches easier to see and bushlopping.clubted Reading Time: 6 mins.
When do insects come out where you live?
Sep 21, The University of Minnesota Forestry Department posts the oak wilt risk levels for pruning oaks: high risk in April through June, low risk in July through October, and no risk in November through March. You can safely prune Minnesota oaks in winter and take appropriate precautions as needed to protect the health of your tree. Oak trees are best trimmed in the winter between November and March.
Oak trees are dormant in winter and are less likely to be negatively affected by pruning when in winter dormancy.

That being said, branches which are dead, damaged, or diseased should be Estimated Reading Time: 8 mins. This will really depend on when you are asking the question.
Winter pruning is also great for arborists as the harder ground provides them easier access to trees and the bare canopy makes branches easier to see and handle.
The reason it is best to prune your oak tree in the winter months is because of a disease that gets spread to live tissue in the summer months. Oak Wilt is a disease fungus that is spread by insects which are most active from April to the end of bushlopping.clubted Reading Time: 7 mins. Nov 23, Never prune your oak tree in the spring time!
This is the time of year that oak trees have the greatest chance of contracting oak wilt fungus, and you really don’t want to expose your oak to that possibility. The riskiest time of year to prune your oak tree, according to some experts, is between February 1 and June 1.