Faithful Texas reader Carolyn White planted live oaks 39 years ago. Her trees are very big now and suckers keep coming up from the roots. She wants to know if there is any product she can use to keep the suckers from sprouting without harming her trees. The answer is.......perhaps. But before deciding which product to use or whether to use any at all, you need to determine exactly why a tree is suckering. Here are five possibilities.
Reason #1. You have a tree that naturally suckers from the roots. Beech, birch, black cherry, black gum, black locust, box elder, and poplars all do this on their own.
Reason #2. You have a tree that suckers a lot while it's young, but gradually decreases this as it ages. Crepe myrtle is a good example. (See photo above.) You'll see lots of suckers coming up from the base (it is naturally a multi-trunked tree, after all). Just prune them off. As the main trunks get old and thick, suckering will get less and less.
Reason #3. You inadvertently cut a root of the tree while digging. The root responds by sending up a sucker. Example -- crepe myrtle.
Reason #4. You tree is under stress from weather, compacted soil, etc. Example: live oak.
Reason #5. You just cut down a large, healthy tree. Suckers then grow from the roots remaining in the ground until the end of time. Examples -- crepe myrtle, Bradford pear, black gum, sassafras, fruit trees.
For reasons #1-3, you might want to try a product called Bonide Sucker Punch. It contains a plant hormone that, when applied to a sucker, inhibits its growth for 6 months or so without harming the parent tree. Follow label directions carefully. Or just cut off the suckers as they sprout. For reason #4, you can use Sucker Punch, but I'd also want to consult with a certified arborist to see if the source of the stress can be alleviated.
Sucker Punch is useless for treating reason #5. In this case, you don't want to temporarily suppress sucker growth. You want to stop it for good by killing the remaining root system. For that, you need to apply a systemic herbicide containing triclopyr called Bayer Brush Killer Plus.
DO NOT apply Brush Killer Plus to the root suckers of any tree you don't want to kill!
Beetle Alert! The USDA urges everyone to be on the lookout for a beetle that threatens up to 70% of our nation's trees. No, not this guy....
This ugly guy below.
Meet the Asian longhorned beetle. It arrived in the U.S. from Asia around 1996 inside packing material. Its tunneling larvae kill maples, ash, willow, horse chestnut and other trees. Right now, it's a serious problem in New York, Massachusetts, New Jersey, and Ohio, but there's no reason it can't move south, primarily inside infested firewood, logs, and lumber. Signs of its presence are pencil-sized, perfectly round exit holes in the trunks, piles of sawdust at the base of the trees, and prematurely yellowing or dropping leaves. August is the peak time for mature beetles like the one shown above to emerge from trees. If you see one, please report it to www.asianlonghornedbeetle.com. And please never buy firewood that doesn't come from a local source.