Crape Myrtle trunk problem
I have three crape myrtles, each with three trunks, and each one is slowly dying. The pattern seems to be the leaves turn red/orange early, and then the trunk is fully dead the next season. I've attached a few pictures of the bases that seem cracked. There is no weeding/mowing done near them, but seem to have issues. I'm trying to regrow a trunk from the suckers but wondering if i should just start over with a new tree? Third picture is the remaining healthy trio but i'm nervous it's showing early signs of the same problem?
Any advice would be greatly appreciated, thanks for your time.
Montgomery County Maryland
The trees looks like they have been planted too deeply and there is excessive mulch around the trunks. This can cause bark deterioration at the soil line which can lead to decline. Here is our publication on these types of problems https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs...
You should be able to see the flare at the base of the trunk where it joins the root system. When mulch is piled up against the trunk the bark decays and the entire plant may die. You can remove the mulch and the soil from the circumference of the trunk where the trunk flares out into root growth. It is up to you if you want to nurture the suckers. This can take several years. However, if the trees are in a prominent location in your landscape you should replant next spring. See the planting process https://extension.umd.edu/hgic/topics/planting-process
Also, some crape myrtles are marginally hardy here in cold winters. Look for hardiness and powdery mildew resistant varieties if you replant.