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The Greener View: Tree House and Oak Wilt

Jeff Rugg on

Q: Would it harm a tree if I built a simple tree house in it? It would be nothing elaborate: a deck, three walls and a roof. I was thinking of the nails that would have to be used to make firm steps for my grandchildren and for the support braces.

A: A few nails or bolts in a tree trunk will not harm the tree. The tree needs to be solid to begin with, or else the holes could allow insects and water to enter the trunk. The ladder going up to the tree can be attached to the house instead of the tree trunk to reduce the number of nails into the trunk.

A tree house can be built so it is around a tree trunk without actually being attached to the tree. The weight of the tree house doesn't have to be entirely supported by the tree. Support posts can be used to prop up portions of the house or even the whole tree house.

A more serious problem to look out for are power lines, not just the ones running down the back yards but also the one to the house. The tree house would need to be built carefully so that the power line is out of reach of the house itself and the occupants.

A great source of books, plans, tools, photos, ideas and special tree house attaching bolts is a really cool website at:

Q: Do you think it would be OK to cut a few low branches from a live oak at this time? We have several live oaks that are about 10 years old. The branches are about five to six inches in diameter at the trunk. The lowest ones are about five feet above the ground, which is too low to walk under. Please, advise. Any information about young live oaks you can share with me it is appreciated (and really needed!)

A: Live oaks and the other oaks are very long-lived. They eventually need a proper branching structure that is above the street, driveway or house. Out in the landscape, the branches can be a lot lower, but five feet is kind of low because the ends of the branches are going to be even lower.

If the tree is not pruned while it's young, large branches will have to be cut off, which will not be attractive for many years to come, and it can be unhealthy for the tree. These five-inch diameter branches should probably have been pruned off when they were only two inches in diameter. The tree would have already healed the cut by now.


After planting in your yard, an oak (and most other shade trees) should be looked at and probably pruned yearly for the first five years. After that, they should probably be pruned once every five years until they are 30 to 50 years old. The mature tree will be able to go many years without pruning.

Oaks and live oaks in particular should not be pruned during the growing season if possible. They can get a disease call oak wilt. It is a fungal disease spread by beetles and root grafts with infected trees.

The beetles spread the disease from red oaks to live oaks. The live oaks don't produce the type of fungal growth necessary for the beetle to spread the disease, but once it is in the live oak tree, it is fatal.

The beetles feed on sap that comes from open wounds. If the sap is infected with the oak wilt fungus, the beetles can spread the disease. Pruning should be done when the insect is not available to spread the disease, which is normally the wintertime.


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