Health of a tree
I have a very large oak tree in my yard. For the past few weeks the leaves on one of the tallest branches have died and fallen off. That branch is almost totally without foliage. Is this simply stress from weather or should the branch or entire tree be removed. If this branch or the tree falls. It doesn’t look too bad from the picture, but I can fill both bags on my lawn tractor 2-3 times per week with the leaves. Thank you
Jackson County Michigan
The symptoms you describe make me wonder if it is oak wilt. Oak wilt is a fatal disease that starts when a sap beetle with fungal spores on its body feed on a fresh wound on an oak tree. It then spreads through the root system to surrounding oaks, so it is important to control it using specific protocol to minimize spread. That said, there are look-alike diseases that should first be ruled out. This should be done by sending a branch sample of the symptomatic tree to MSU Plant and Pest Diagnostic lab to confirm or deny oak wilt. Go to their website (https://www.canr.msu.edu/pestid/ ) to read instructions on how to submit a sample.
If it does come back positive, you should refrain from cutting the tree down until a trench line has been cut between the sick tree and healthy surrounding oak trees. This severs root connections between the trees so that the pathogen cannot move from the sick tree into the healthy trees. Fungicide injections may be recommended if you have other oak trees you want to save, but the trench lines are most important. Later this fall, the tree should be cut down, and the wood should be burned, buried or chipped onsite to make sure it is not transported to a new area where it can infect healthy oak trees. If you want to use the wood for firewood, it can be securely tarped for a year until the wood is completely dry and de-barked. It does not harbor the oak wilt fungus in this state. Read more about oak wilt in this tip sheet: https://www.canr.msu.edu/news/smart-gardening-to-prevent-oak-wilt#:~:text=Smart%20Gardening%20to%20p...
The initial testing is not difficult or expensive, but it is really important to do. Oak wilt spreads readily and will move through large areas killing all of the oaks, so it is important to know what you are dealing with and how to manage it.