Guys: I don't condemn every hollow tree. It is always a balancing act to choose between compromised trunk strength and the customer's desire to keep the tree. If all you do is condemn a tree for having signs of decay, y'er not an arborist, you are a tree removal salesman. In this conversation, the arborist that works with the customer to give him the best match for his wishes is going to close the deal.
Points of consideration:
- How much of the trunk's diameter is gone? Some trees are infamous for being very hollow and still remaining viable for many years. Silver maples are notorious for being hollow and continuing to thrive. They tend to outgrow their decay. Others... not so much.
- What is the financial risk of having a tree collapse? Some customers like that tree almost as much as their porch, and much more than the fence out back.
- How many years does the tree probably have left before it must be condemned? If 15 years, then there is no hurry to remove.
- Will the tree be much more expensive to remove with the additional decay? (Almost always, especially if there is no access for an aerial device) Nobody likes climbing dead, rotten trees! Still, the customer should be informed.
- What treatments can be done that will reduce the risk or possibly extend the life of the tree? Cabling and bolting, as well as occasionally some insecticidal treatments will sometimes do wonders.
- Is crown reduction a viable alternative to removal?
Example: My children's babysitter was bugging me about a hackberry tree in her yard (a long time ago). I told her it was a tree in decline, but there was no immediate cause for concern. I suggested that hackberry trees have a tendency to break off at the base, but that her crown was still healthy, and very unlikely to drop branches on anyone. I pointed out that we should move the swing set, just to be safe, and that the tree was only going to fail during a big blowing storm (probably from the south-west), when all the kids were inside anyway. Otherwise, I said she should get years more out of that tree, and that we would see the crown dying back if it got worse. Furthermore, I suggested the tree would be cheaper to remove if we were only picking it up off the ground. She like the tree, and we decided to leave it alone.
That tree was crashed flat on the ground just one week later.
As predicted, a big storm from the southwest took it out, the swing set was out of the way, and no one was outside in the yard. And...it was cheaper, 'cause all we had to do was chop it up and put it in the truck.