TreeSpecialist

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Personal Observations
by Pat Wentworth

It is not “hard science” or “pure research,” just things I have noticed mostly from observation and repetition………

Everyone has seen this before (if you haven't it's because you don't work on live oaks.) The live oak in the client's yard has hundreds if not thousands of root sprouts coming up all round the base of the tree. Sometimes they spread out from the tree to a radius of 12 feet or more. I've seen them so thick that they looked like an intentionally planted ground cover. The one thing you will always see with this condition is that the trunk of the tree comes out of the ground with very little flare at the base.


Base of live oak (Quercus virginiana)

Live oaks, like all trees, should have their trunk collar (the portion of the trunk that flares dramatically at grade) exposed. When it isn't, the tree will put out numerous adventitious roots that will quickly become root sprouts. Clients will have put too much mulch against the tree or around the base of the tree and root sprouts will occur. Or they will be raising the soil a little to allow the grass to grow just that much closer to the tree and root sprouts will occur. Or they will bury those exposed roots that they keep hitting with the lawn mower and root spouts are the result. Sometimes this condition is caused by weed blocking fabrics as well.

The cure for this problem is often more than that client is wiling to spend. The best way to approach the issue is to use an Airspade® to uncover the root collar.


Airspade® used to uncover root mat/ girdling roots

When this is done well, a twisted tangled mat of roots will be found just below the surface. Small roots can be carefully snipped off back down to the large root flares or back to the main trunk. Hand tools (hatchets, pruning shears, loppers) are the quickest way to remove them.


Removal of root mat and girdling roots with hand tools

Once cleared of the root mat, the root flares should be left exposed and above grade. The area can be left uncovered or covered with a light dusting (1/2 inch or less) of mulch.

Root mat / root-collar excavations are a hard sell because they’re tedious, time consuming, and therefore can be expensive. The real trick comes in figuring out how to bid the job before beginning. Any time you're excavating roots, you never know what you're going to run into or how long it will actually take.

For years, we've been told to plant trees at the same level they come in the container. This assumes that they were grown at the correct level from day one. A shallow moat is placed around the newly planted tree and a layer of mulch is added to keep the soil moist. What invariably happens is that too much mulch is used and the shallow moat collapses in on the tree burying it too deep.

We might be better off if we change planting specifications to plant trees 2 inches higher than the surrounding soil. By the time the well collapses, too much mulch is used, and the tree settles in the hole somewhat, it may wind up at the correct level instead of being buried 3 to 4 inches too deep. It would prevent a lot of girdling roots.