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GLT's Grow: Protecting Against An Oak Wilt Outbreak

Tree with oak wilt at ISU
Patrick Murphy
You can see the “staghorn” effect from removing oak wilt-infected dead wood from this tree on the Illinois State University campus.";s:

If you see a tree with yellowing leaves and it’s missing branches in the center, it could be an oak in trouble.

In this edition of our gardening program Grow, Illinois State University's Patrick Murphy tells GLT's Mike McCurdy that once an oak tree contracts this disease, it's fatal.

  • Oak wilt is a fungus that invades the water-conducting tissue of a tree below the bark, essentially shutting down the photosynthesis processes inside. It can kill quickly, in as little as four to six months. (Infected red oaks will die more quickly than white oaks.)
  • What to watch for? Bark will look blistered or ruptured like an ice crack. You might see some streaking near the inside of twigs, or even on the outside if the oak wilt is advanced enough. You’ll see yellowing or lime coloring in the foliage, or branches filled with dead or dying leaves.
  • Oak wilt can spread in many ways—through the roots, or even by your own tools if you’re not careful. Murph recommends cleaning your tools with Lysol to keep it from spreading. You can avoid an oak wilt outbreak by not planting too many oaks super close together. A little diversity between your trees might help stave off an outbreak.

Learn more about oak wilt and how to decide if a tree needs to go by listening to this week’s episode of GLT’s Grow:

GLT's Grow is your source for gardening advice and down-to-earth tips. Host Patrick Murphy and co-host Mike McCurdy are ready to take on all your gardening questions, so submit yours today.

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Ryan Denham is the digital content director for WGLT.