06/01/2026
🌳 What's Going On With This Tree Trunk?
If you've noticed black bark on the lower trunks of ornamental trees like this one, don't panic—it isn't always a disease.
In these photos, this appears to be a combination of:
✅ Sooty mold or algae buildup
✅ Lichen growth (the gray-green patches)
✅ Moisture retention from dense multi-stem growth
✅ Possible sunscald or old bark damage that has darkened over time
The good news? Lichens themselves do not harm trees. They're often a sign that the tree is growing slowly or that the area stays damp and shaded.
What should you do?
✔ Remove dead, crossing, or crowded branches to improve airflow.
✔ Keep the base free of weeds and debris.
✔ Monitor for cracking, peeling bark, or areas that feel soft.
✔ Avoid piling rock or mulch directly against the trunk flare.
✔ Water during drought periods, but don't keep the root zone constantly wet.
Pro Tip:
When ornamental trees become overcrowded with multiple stems, thinning a few interior trunks can improve air circulation and reduce moisture-related issues while highlighting the tree's natural structure.
📸 Have a tree in your landscape that you're concerned about? Drop a picture in the comments and we'll help identify what might be going on!
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