Why Is Your Oak Tree Languishing?

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When I bought a house with a cherry blossom tree in the front yard, I couldn't wait for that first blooming season to see the tree fill out. I knew that the tree needed care, but I wasn't sure how I was supposed to treat it. I called my local tree service and had them show me what it needed to keep it strong. I took all of the information they shared with me and everything else I've learned and created this site. I hope that the information here helps you take care of your blossoming trees so that you can enjoy their beauty every season.

Why Is Your Oak Tree Languishing?

18 January 2017
 Categories: , Articles

Has your oak tree started to look a bit worse for wear? Maybe entire branches seem to be dying or the leaves are beginning to curl. Perhaps there are black cankers (or sores) on the trunk. Chances are, your oak tree has one of several fungal diseases that affect oak species. Here's a look at the most common of these diseases and what to do about them.

Oak Wilt

Oak wilt is most common in red and white oaks, but it can affect pin oaks and live oaks, too. They symptoms typically appear in the spring as this is when the fungus starts to replicate rapidly. Leaves start to develop brown splotches white eventually extend over the entire leaf. Then, a few short weeks later, the leaves start curling and falling to the ground. 

Sadly, oak wilt is always deadly. Once trees start showing symptoms, most die within one year. White oaks may live a little longer than red oaks. Since there's no cure, it's usually best to have the infected tree removed sooner rather than later. Leaving it in place will only allow the fungi to proliferate and spread to other oaks, so it's best to contact a tree removal service.

Leaf Spot

If your oak tree's leaves have round black spots that look like warts or spots of tar, the tree may have a condition called leaf spot. There are a number of fungal and bacterial species that can cause this condition. The good news is that leaf spot is pretty minor compared to other common oak infections. It won't claim your tree's life, though you should take steps to treat it since it lowers your tree's immunity and might make it more susceptible to other diseases.

When autumn comes, rake up fallen leaves promptly so the fungus cannot reproduce in them. Have the tree trimmed so that air can blow more readily through the branches, keeping them dry. With any luck, the leaf spot disease won't re-appear the next year. If it does, you can have a tree care company spray your tree with fungicides to help fight the fungus.

Armillaria Root Rot

Take a look at the place where your oak tree's trunk meets its roots. Do you see any areas where the bark is peeling away to reveal white streaks? Do you see any brackets (mushroom-like growths) emerging from the tree's base? These are symptoms of armillaria root rot, which also causes branches to slowly die off and drop their leaves.

Armillaria root rot does often kill oak trees, but your tree may slowly decline over a number of years before succumbing to the disease. If you really value the oak tree, your tree care company may be able to inject it with fungicides to extend its life somewhat. However, if the tree does not have much value to you, it is wise to have it removed sooner to reduce the spread to other trees. 

Powdery Mildew Disease

If the underside of your oak's leaves start developing a powdery, white coating in the autumn, then the tree likely has powdery mildew disease. This is a rather minor condition that won't typically cause lasting damage to your tree.

If the whiteness on the oak leaves bothers you, consider having the tree sprayed with fungicide. This should eradicate the fungus within a matter of weeks. Otherwise, just rake up leaves at the end of the season and make sure dead branches are removed to increase airflow through the branches. The mildew disease should slowly diminish.

If you're still not sure what's going on with your oak tree, contact a professional arborist. They can examine your tree, diagnose its disease, and tell you where to go from there.