March 20th, 2023 is the first day of spring. With freezing temperatures this week, it may not feel like it, but spring is just around the corner. Most of our oaks will begin to leaf out mid to late April. So why the rush to prune? Two words: Oak Wilt.
Oak Wilt infestations are distributed throughout Ohio. The best assumption is to be cautious that Oak Wilt 'could be present' in your area. Trees that are pruned before they break bud have less of a likelihood to bleed and attract picnic beetle, that vector for Oak Wilt. So, prune oaks while dormant.
To our north, Michigan indicated many counties where Oak Wilt has been reported.
Oak wilt, caused by the fungus Bretziella fagacearum, previously known as Ceratocystic fagacearum, is a lethal disease of oaks and has been detected in 44 Michigan counties. One way oak wilt spreads is through disease spores carried on the bodies of sap beetles as they feed from tree to tree. These sap beetles are attracted to fresh wounds.
Source: https://www.canr.msu.edu/news/avoid_oak_wilt_by_not_pruning_oak_trees_april_october This article was published in 2014, so the infestations continue to grow.
The USDA Forest Service has created the following map related to Oak Wilt in the Northeastern and Midwestern States:
In addition, the USDA Forest Service Map shows infestations across the United States.
The best way to protect your oaks is to prune them when they are dormant which is usually October 15th to April 15.
The following fact sheet contains more details on Oak Wilt: https://ohioline.osu.edu/factsheet/plpath-tree-02
In addition, attached is another BYGL article: https://bygl.osu.edu/index.php/node/2081
So, either contact an arborist or prune your oaks yourself before they leaf out.
Remember, pruning can be dangerous! If you think the job is too big, call a professional.
You can search for an International Society of Arborists (ISA) at the link: https://wwv.isa-arbor.com/membership/benefitstools/findtcs
Be safe and happy pruning.