Plastic – Use Under Tree

Q: Six years ago I planted a silver maple on my front lawn. About a year ago I noticed branches growing from the base of the trunk of the tree, almost at the soil line. I trimmed these branches off. The same thing happened again this year, branches growing at the base of the tree.

Last week I trimmed them again and happened to lift the plastic used for weed control around it. Wow! There are several roots ranging from two to eight inches in diameter on top of the soil with smaller roots branching off from them. Do I cover the roots and hope it will correct itself or is there something else that should be done?

A: Did you ever burrow under a bed quilt when you were a kid? It was fun at first, wasn’t it? A few minutes later your breathing became faster, you realized that you were suffocating and you quickly shot out from under the covers.

Your silver maple has been in a similar situation. At first it was warm and moist under the plastic you spread to control weeds. Then the roots grew larger and began to need more oxygen to respire. They became desperate and enlarged themselves to increase the surface area that absorbs oxygen. Could you hear them “gasping” when you removed the plastic sheet?

The branching at the tree base was a symptom of great stress affecting the tree but you didn’t recognize it. It is a good practice to control weeds under a tree but impervious plastic is the WORST material to use.

A woven weed control fabric is much better for weed management because it allows water and oxygen to penetrate to the roots. At this point I’d remove the plastic, cover the roots with soil conditioner, cover that with weed fabric and spread a layer of pine straw on top.

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