Black stuff growing on tree branches.

Asked July 17, 2018, 9:44 AM EDT

I recently moved into a house, so I don't know much about the trees currently there. However, one of my trees doesn't look right, seems to look unhealthy. There are not a lot of leaves on the trees and a lot of branches seem to fall down as I find them in my yard. Just yesterday, I picked up a fallen branch and noticed some black stuff that was all-around the branch. I don't know what type of tree it is, however I did ask the previous owners and they can't remember exactly the name but think it might be "plum krauter vesuvius" with quite certainty it is "plum" in the name. They did say it is an ornamental tree. I was wondering what the stuff growing on the branches are, because I see it on all the branches. Could this be the cause of the tree looking unhealthy? Is there a fix to the tree, or do I need to consider removing it?

Carroll County Maryland black knot ornamental plum tree

1 Response

These ornamental plums are not long lived. They can be susceptible to a lot of insect (Japanese beetles, borers, etc) and disease issues like cankers and black knot (right photo) http://extension.umd.edu/hgic/cankers-trees-and-shrubs
https://extension.umd.edu/hgic/black-knot-trees
as well as abiotic problems. These types of problems include poor planting techniques, girdling roots, drought, poor drainage etc. http://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs/...

The light spots on the trunk look like lichens and are not a reason for decline. You see them on mature trees and are an indicator of good air quality. http://extension.umd.edu/hgic/lichens-trees-and-shrubs

We recommend that you remove the tree and replant with another tree species. If you want to keep it, all you can do is prune the black knot (ugly stub pruning), any dead wood, keep well watered during dry periods, and make sure mulch is no thicker than several inches and away from the base of the trunk.

Here is some information on ornamental fruit trees and When to Remove a Tree
http://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs/...
http://extension.umd.edu/node/2273

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