Hello, We had a golden tipped locust tree that was 15 years old that was...

Asked December 15, 2015, 10:25 AM EST

Hello, We had a golden tipped locust tree that was 15 years old that was snapped off during a tornado. We had the tree cut down and the stump ground out. However, we had little saplings growing around the edge of the ground stump. I wanted to grow the tree back, so I let one of the seedlings grow, which is about 6 feet tall. Here is the odd thing....it has these thorns on it that the original tree didn't have. What caused this mutation? We will be cutting it down in the spring, and I'm wondering if the other seedlings would be the same if I let them grow? Regards, Dolores Anderson

Medina County Ohio

1 Response

It appears that your original tree may have been grafted, which is the process of growing a desired upper stock on a different understock, including roots. This is very common in the nursery industry, particularly with fruit trees, although it is being done with all kinds of plant matter, including vegetables

In your case, the variety of locust that you bought likely a cultivar such as Sunburst Golden Locust have had many positive characteristics such as appearance, open "lacy" canopy, fall color and thornlessness. However, it also may have had few negative ones, for example, a fragile root system. By grafting the tree with desirable traits onto the stock of a tree with a vigorous root system, you get a far hardier tree.

However, the rootstock will be the same as the tree from which it was taken, along with its negative characteristics, including seed pods and thorns. In this case, it likely was a black locust or a honeylocust. These are notorious for throwing suckers. As for them, you have a couple of options. One possible remedy is to regrind where the original stump was, including nearby saplings. You can mow them if they are small enough, but you will have to be persistent. Root systems will continue to sprout saplings until the remaining reserves of carbohydrates are depleted, so it may take several mowings.

Another alternative is to use a non-selective herbicide and treat the stump of the sapling you are removing by painting it immediately after it is cut with herbicides such trichlor or glyphosate (e.g. Round-up), which will travel from the new cut through the roots and eventually kill them. You can paint the larger saplings with the herbicide and an old paintbrush, always making sure you paint new, "wet" wood so that the material will travel readily through the tree's remaining circulatory system. This too could take several applications until the roots are exhausted and eventually die.As always, be sure to wear gloves and to read the herbicide's directions completely and comply with all safety precautions.