Oak trees have long been venerable forest giants and an American landscape favorite. They're one of the best shade trees out there, and many varieties grow fast!

If you love oak trees as much as us, you’ve likely dreaded the deadly oak wilt disease.

Well, pruning oak trees in summer increases their risk of oak wilt. Read on to learn why.

Why You Should Avoid Trimming Oak Trees in Summer

Sap beetles – such as the picnic beetle, dusky sap beetle and strawberry sap beetle – buzz around your yard from April to August and are most active in June and July.

These beetles are attracted to the sap that seeps from wounds and holes in trees, like those from storm damage and pruning.  

After munching on a tree with oak wilt, these beetles fly to unaffected trees with pruning cuts or holes, carrying oak wilt spores with them and unknowingly infecting healthy trees. 

Because of this added risk, Davey experts avoid pruning oaks from April through August when the beetles and pathogens are active.

Some companies still do trim oak trees during this timeframe, which unnecessarily puts your trees and wallet in danger.

If pruning oaks must be done in the summer, then make sure the company you hire uses paint to treat fresh pruning cuts. This will reduce the possibility of attracting sap beetles. 

The Worst Case Scenario – What Happens Next

If one tree gets oak wilt, all oak trees in your yard are at risk, especially Red oaks.

You have to remove the infected tree and treat the other oak trees with a fungicide to protect them. And, your arborist may recommend a mechanical intervention since oak wilt most commonly spreads between root systems.

As you may have guessed, these treatments add up – as Emily in Akron, Ohio recently learned.

Last June, Emily had three red oaks pruned by a local tree company. This spring, Emily was devastated when her 100-year-old oak returned with fewer leaves and soon died.

The local tree care company didn't mention that pruning oaks in summer could lead to oak wilt. If Emily had known, she would have invested in a TCIA-accredited company with professional arborists to avoid these hefty removal and treatment costs.

Keep an Eye Out for Oak Wilt Symptoms

Oak Wilt Close Up1

If your oak was pruned from April through July, watch it for symptoms of oak wilt.

Now, in early August, is when you’ll start to see symptoms, such as the wilting, browning or excessive shedding of green leaves and branch dieback.

If you see these warning signs, scrape off 1-2 inches of bark on a branch that has wilted leaves or premature leaf drop. Under the bark, look for streaking, which is a tell-tale sign of oak wilt.

Symptoms on Live oaks include browning of leaf veins followed by leaf drop. If noticed early, the tree may be injected with a fungicide to help cure the infection. 

Suspect oak wilt? Contact your local Davey certified arborists to learn more about identifying and controlling this deadly disease.

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