A friend of the gardens texted me pictures last week (see gallery below) of a damaged magnolia in their front yard and asked what to do with it. I thought it was a great chance to clear up some misconceptions regarding damaged shrubs and trees.
The trunk of this friend’s magnolia tree showed old damage from an unknown cause, as well as splitting bark, the presence of carpenter ants and soft rotting tissue. My friend naturally wondered if the ants were causing the damage and asked if they could treat for the ants and then bandage up the tree to help it heal. There were two misconceptions in one question! First of all, carpenter ants are opportunists. They take advantage of existing conditions and are attracted to the lovely soft rotting wood tissue caused by fungi, etc. Yum yum. In this particular case, the damage was caused by either some sort of human agent (i.e. overzealous weed whacker or misdirected mower) or an environmental cause. Wood eating fungi then moved in on now exposed wood and created the attractive ant housing development.
My friend’s solution of reinforcing/supporting the trunk via bandaging is one to which many people turn. A quick search of the internet will show a number of hobby farmers (and those looking to save a buck) looking to save that poor damaged tree. I found one online journalist who had “repaired” a couple of broken apple branches with similar methods. The only problem is these solutions DO NOT work. I think the average person thinks plants heal themselves in similar ways to humans. You know, take a broken bone, splint and bandage it, and it shall mend good as new. Not so, I am afraid. Trees do not heal like humans. They do not repair, replace and reconnect damaged cell tissue. They simply isolate the damage and move on through a process called compartmentalization. The break in the limb will remain forever damaged and will not regain strength, always needing to be propped up (and with ever bigger props as the tree outgrows the supports). It will forever remain a weak point, and potential re-injury will occur when supports are removed. This can been seen at Wellfield where a very large mature mulberry is supported with cabling and bolts. The tree will forever need these supports so shade seeking visitors may find respite.
As the winter snows/ice go, and violent spring winds come, the best option in most cases is careful removal of the damage through proper pruning. As I told our inquiring friend, the solution to his woes was to completely remove the tree and start over. There is no going back.
Josh Steffen, Horticulture and Facilities Manager
That wound is mostly compartmentalized. If salvaged, it the trunk should be able to support itself, regardless of the damage within. However, I would recommend lightening it up a bit for the process. Magnolias are innately stout anyway. I would not recommend salvaging such a trunk if it were to always require support. Another consideration is the bark inclusion between the two trunks. It might be an advantage to remove the damaged trunk, regardless of the damage, if doing so would benefit the other trunk. Those two trunks are just too close together. Unfortunately, that will leave a different kind of wound down at the base, in conjunction with the stub that is already there. Nonetheless, I would still not necessarily recommend removal of the tree, or even the trunk. It is hard to say without seeing the canopy.