Will Spreading Tar on the Bottom of a Tree Stop Suckers From Forming?

Tree Suckers

• Suckers, also called basal shoots, arise for two reasons. Some trees, like mimosas, spread by means of suckers, but they can also grow as a response to injury. They arise from either the roots or from the trunk's base and are clones of their parent tree. If left to grow, a sucker can become a full-sized tree and sap essential nutrients from its parent.

Manual Control

• Prune trunk suckers in the fall, when the tree is dormant to reduce the chance of them growing back. Clean dirt and debris off your shears and disinfect them with rubbing alcohol to prevent introducing pathogens into the bark. Cut suckers flush to the trunk. Ones coming up through the roots can be removed in the same manner if they are visible. If they are under turfgrass, mow over the suckers when you cut the grass. Alternatively, slit the sod around the sucker, find the root it is growing from and sever it.

Chemical Control

• If you feel chemicals are necessary, paint an herbicide containing triclopyr or glyphosate on the sucker after you cut it from the trunk or roots. Avoid spraying herbicides as they can harm the surrounding lawn. To reduce the number of suckers growing from the trunk, cut them off as they appear. In a few days, new shoots will appear from the cut's site. Dig them out and paint the wound with a tar-based wound dressing. Dig each shoot to a depth of 1/8 inch and only tar the wound. Don't tar the entire tree's base. According to Washington State University, there is evidence that wound dressings can accelerate decay and act as a food source for pathogens, so they should be used sparingly. Check your tree every few days and remove and tar any new shoots. According to arborist Mike Allen, this removal method can help reduce suckers over time.

Stumps and Suckers

• In response to being cut down, some trees, like poplars, send out numerous suckers from the roots and stump in an attempt to regrow the tree. Stumps rot naturally over time and as they do suckers stop growing. To speed up the rotting process, cut the stump as close to ground level as possible, cover it with soil and keep it moist. Cut suckers as they appear and paint them with an herbicide containing triclopyr or glyphosate.