If this question does nothing else, it causes the individual to look closely at their plant. If ants have built a nest near the base, they should be able to see to. If the bark is splitting away, the plant may have been planted too deeply or latent cold damage may be a problem depending on the plant species - Azaleas, Citrus, Pittosporum and Elaeagnus, to name a few, have been notorious for this in the past years in Florida. While it is desirable to know if they are keeping competition down while the plant is small, the main point of this question is to find out how they are keeping the grass down around the plant if they are not pulling it out. Weedeater type machines will girdle a trunk and people tend to ignore this damage even when told to look for it.
Mowers can also do a job.
These would indicate galls or cankers which could be due to insects or disease, depending on the host plant. In North Florida, companies are selling peat muck under these names. While legal, it is an unfortunate practice, in my opinion. If the homeowner does not thoroughly mix it with whatever they are taking out of the planting hole, it will stay gummy when wet and as it dries it will crack apart. While you can never be sure of it, I suspect that some plants have been lost to this material as a result of its use in planting holes, especially in wet sites.