Red Oak Tree foliage problems

(Question)

Hi
I have a red oak tree that is about 15 years old (I planted it 9 years ago) .. It is about 6 meters and was previously doing very well. Not this year. I’ve noticed this year that many branches have little or no leaves and there are holes in the ones that are there. There is no sign of gypsy moths but I thought that would be the most logical answer.

I also noticed that a number of the younger oak trees in my neighbourhood are looking sparse although not all have holey leaves… could it be something else?

Do you know what the root cause is and what I can do as a remedy? I don’t want to lose this tree.

Thank-you!

(Answer)

Thank you for your inquiry to the Toronto Master Gardeners, Laura.  We love tree lovers.

Since you have inspected the tree and found no evidence of Gypsy Moths, you are probably right.  According to the City of Toronto website, the cold winter and the elimination program for this pest have combined to reduce numbers.  Just to be sure, I would take a twig or branch with a few leaves (in a sealed bag) to your local nursery and ask the most experienced tree person to give an opinion.  It pays to ask for the in-house expert.

Red oak is a hardy tree.  Some might say not to worry because the cold winter has caused quite a delay in everything this year.  However, there are some things you can do to help your tree thrive.  If it has been attacked or stressed in any way, you will want to give it a spa treatment:

  • Cut back any dead, weak, thin or crossing branches.
  • Give the area around your tree a couple of inches of compost.  Don’t dig it in; let the worms do the heavy lifting.
  • Lay down some good natural mulch.
  • Give it plenty of water.

Two excellent guides to pruning all sorts of shrubs and trees are:

  • Pruning Made Easy: A gardener’s visual guide to when and how to prune everything, from flowers to trees  by Lewis Hill
  • The Pruner’s Bible: A Step-by-Step Guide to Pruning Every Plant in Your Garden by Steve Bradley

If your tree is still not doing well in a month or so, I would consult a certified Ontario arborist. https://www.treesaregood.org/findanarborist