Why Winter is the Best Time to Prune Your Oak Trees

As snow blankets the ground and temperatures drop, most homeowners shift their focus away from yard work. But for oak tree owners, winter is the ideal season to schedule professional pruning. While it might seem counterintuitive to think about tree care during the colder months, pruning oaks right now offers significant benefits—most importantly, it dramatically lowers the chances of your tree contracting a devastating disease called oak wilt.

What Exactly is Oak Wilt, and Why is Winter the Safest Time to Prune?

Oak wilt is caused by the aggressive fungus Bretziella fagacearum. This pathogen is one of the most serious threats to oak trees in Michigan, capable of killing a healthy, mature oak in just weeks once infection takes hold.

The oak wilt fungus spreads in two primary ways. Above ground, tiny sap-feeding beetles - commonly called picnic beetles - pick up fungal spores while feeding on an infected tree and carry them to fresh wounds on healthy trees. These beetles are most active in spring and summer and will seek out wounds made during pruning or from broken branches after storm damage. Below ground, the disease can also travel through naturally grafted root systems, allowing it to jump from tree to tree in a stand of oaks, sometimes creating expanding pockets of dead oaks in neighborhoods and woodlands.

Trees in the red oak group - such as northern red oak, pin oak, and black oaks - are especially vulnerable. They often succumb within a single season, sometimes in as little as a few weeks. White oak group members (bur oak, white oak, swamp white oak, and chinquapin oaks) tend to be more tolerant and may linger for several years with progressive decline, but they can still die eventually.

Because picnic beetles are inactive in cold weather and oak trees are fully dormant, the risk of new above-ground infections drops almost to zero during winter. Arborists generally recommend avoiding any oak pruning or wounding between mid-April and mid-October. Once we’re safely past that high-risk window - typically from November through March in Michigan - winter becomes the perfect opportunity to give your oaks the care they need without inviting oak wilt into your landscape.

What Kind of Pruning Should You Do in Winter?

A professional winter pruning session for oak trees can include:

• Removing water sprouts and suckers that rob energy from the tree
• Thinning the canopy to improve light penetration and air flow
• Crown raising low branches for road clearance and lawn maintenance
• Safely removing dead, diseased, dying, or crossing branches
• Overall structural improvements to reduce wind and ice-loading stress
• Crown reduction to clear from houses, garages, light poles or street signs

All of this tree pruning work promotes long-term health, improves appearance, and makes your oaks less likely to be damaged during summer storms - without exposing fresh cuts to beetle-borne spores.

Take Action Now - Schedule Your Dormant-Season Oak Pruning

Don’t wait until spring when the risk returns. Contact Owen Tree and Lawn Care today to have one of our ISA Certified Arborists assess your oaks and schedule dormant-season pruning. A relatively small investment now can protect your majestic oaks from oak wilt and keep them thriving for years. Your trees - and your landscape - will thank you when warmer weather finally arrives.