Ask Mr. Smarty Plants

We are assuming that you are dealing with a Ficus caricus (common fig) with a Celtis laevigata (sugarberry), also known as hackberry, growing up through it. The bad news is that the hackberry is a plant native to North America, and therefore is probably better adapted to live here than the fig tree. The common fig is a temperate species from the Middle East and southern Europe. However, we can understand your desire to keep your 50-year-old fig tree. We agree that using poisons on that stump could very easily damage the roots of the fig. As long as you can keep it from leafing out, the hackberry will have to die, because it needs the leaves for manufacturing food for the tree's survival. However, you probably need to do some more damage to the stump now, to keep it from crowding the roots of the fig. Try digging down (gently!) around the roots of the hackberry, trying to identify the hackberry roots as opposed to the fig roots. With a pruning saw, saw off the hackberry roots as far from the stump as you can. Keep working the stump back and forth, trying to find roots that can be cut to free the stump from the ground. If you can get to the point that you can get the stump out of the ground in this manner, you should have disposed of the problem. Keep an eye on it, and if any sprigs come up, yank them out while they're little. In self defense, tree roots will often try to put out sprouts in a last gasp attempt to keep going. The fig has very extensive roots, going in all directions, so it probably has root capacity to spare if you accidentally damage one root, just try to avoid it if you can. Click this link for a page of images of the Ficus caricus. Below are some pictures of various parts of the hackberry, to hopefully help you identify which tree you are dealing with.

Celtis laevigata

Celtis laevigata

Celtis laevigata

Celtis laevigata