OK, So I have heard about a hundred different reasons why and when you prune an oak tree. Let me set it straight, It’s actually pretty simple. When you create a wound on a tree when pruning it, the wound will secrete sap. Bugs love sap! A bug, normally a beetle that does not have the ability to chew, will smell the sap and come to feed. This beetle may have been hanging out in a old oak, out in the woods feeding, the beetle picks up Oak Wilt spores on it body (picture a bee with pollen). When it comes to feed, it spreads the spore, these spores enter the wound and now you have a problem. Depending on the species of Oak, it can kill very quickly. How do you prevent this, well its nature, so 100% prevention is pretty much impossible, and there will always be the “weird scenario” that gets thru and toast’s a tree.
To prevent this, you work on oaks in the winter, it’s not because the sap drops or because the tree is dormant, the first frost is not the answer either. The best way to prevent the spread of the spore is to do it when there is very little chance of the beetle feeding on the sap, in the middle of winter. When the frost is in the ground, most bugs are under the frost line or they were frozen to death. How many times have we had a frost and a couple of real cold weeks and then, all of a sudden, we have 2 weeks of 60 degree temps! The bugs will be out and about feeding on whatever they can find; this is a typical Midwestern fall. People say after November or after first frost, these are wrong. Bugs do not work on a schedule and they do not get laid off. So yep, in the middle of winter, when there is 2 ft of snow on the ground and your nostrils burn every time you breath! That’s the best time to do it! So far, by sticking to this plan, I have never lost an oak. Not saying that this is the final rule, every situation is conditional. This is gives your tree its best chance to avoid the bugs. No bugs, no spread. Oak wilt can get into the tree via the root system, but we will touch on that later. So, when you see someone pruning an oak in the middle of summer, they are wrong, in October, they are wrong, in November, they are wrong. I stick to late December to middle March, based on the conditions outside of course. There are 2 main reasons why it is done improperly 1.They don’t care about your tree, just making revenue 2. They do not want to work in the freezing cold. Either do I, I do it because that’s the right thing to do.
There are a few other Certified Arborist in the area that prune them whenever. They know the reasons why it should be done in the winter, yet they do it and they know that it is wrong, these are the guys who became certified for the wrong reasons, just to flash a piece of paper in a face. If they practiced true arboriculture, They would not do this
