Hello Jim,

Additional pictures would be helpful. Are these ornamental pears or pears meant for bearing fruit?

Are there any visible signs of damage or distress?

Hello Jim,

The greenish mold is just lichen. This wouldn't be the cause of the problem. There appears to be several shoots that are damaged at the top of the tree. This could be winter dieback. I can't tell from the pictures if there are leaves on the distressed branches. If there are leaves there that are spindly or shriveled it could be indicative of herbicide damage (potentially related to the lawn care).

I’m referring to the branches at the top of the tree you’re asking about. They appear not to have leaves. You can cut into the branch and see if there is a ring of green tissue under the bark or you can examine the leaves.

Hello Jim,

There doesn’t appear to be a clear cause for the injury, which leads me to believe that it is dieback from winter injury, especially since the other branches on the tree seem okay. You should prune out the dead branches and monitor the growth in the rest of the season and next year.