Oaks should be pruned while they are dormant. If you have not pruned your oaks or scheduled an arborist, now is the time before they break bud in the spring.
By Thomas deHaas OSU and Colette Gabriel ODA Ohio
March 21st, 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 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.
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 following 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:
In addition, attached is another BYGL article:
So either contact an arborist or prune you 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)
ISA at the link below:
Be safe and happy pruning.