Why Fill a Hollow Tree?

Filling of hollow trees, a process called "cavity filling," was practiced by arborists for many years.  Thanks to modern research, it has been discovered that cavity filling is not needed to support or improve the health of hollow trees.

Tree experts have found that cavity filling with cement can actually damage a hollow tree.  According to Bob Rouse, Staff Arborist at the National Arborist Association, "the column of cement created in the tree by a cavity fill doesn't move, just like a column on a building, but the tree is always moving.  It sways with the wind constantly.  The rubbing created by the swaying tree and the solid column of cement further damages the tree."

Decay organisms, such as rot fungi, that created the hollow in the first place, are able to take advantage of the new injuries created by the rubbing and invade the healthy tissue of the tree.

Rouse adds, "If that wasn't bad enough, the cement holds moisture, creating a favorable environment in the filled cavity for the decay organisms!"  Tree experts explain that it is much the same as when carpenters place a vapor barrier between a house's foundation and the wooden sills.   If they put the sills directly on the concrete foundation, the wood will rot rapidly.  If you place cement in a tree cavity, it will speed the wood decay!

If cavity filling is desired for aesthetic reasons, there ar some new synthetic foams that can by sprayed into the cavity by professional arborists.  These materials will bend with the swaying tree, but Rouse warns, "There is really no reason to fill a cavity; it doesn't improve the tree's health and doesn't offer any added support.  If structural support of a tree is required, a professional arborists will recommend  cables, braces, or tree guys, not cavity filling."

TREE EXPERTS RECOMMEND:

• NOT FILLING CAVITIES WITH CEMENT;

• SUPPORTING, IF REQUIRED, WITH CABLES, BRACES OR TREE GUYS

WE AT BURT'S TREE SERVICE ARE CONCERNED WITH THIS PRACTICE AND PRESENT THE INFORMATION ABOVE FOR THE BENEFIT OF YOUR TREES.

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