Burning Bush Branch die off
We have a mature Burning Bush on the South side of our house in Arvada and have never had any problem with it. A few weeks ago we started to notice that some of the branches had leaves that were drying up. We took a branch to our local garden center and they said it was not mites, and they weren't sure what was causing it, but that their burning bush had the same problem. They suggested that we run our hands down the branch and remove the dead leaves, but that was it. Any idea what might be causing this. The bush is well established and previously very healthy.
I suggest you begin at the tip of the affected branch and follow it down towards the soil to see if there are any clues there. What you're looking for is mechanical injury which may have damaged the tissue that conducts water into the upper portion of the plant.
Also look at the base of the plant to see if you can see any sawdust or bark missing there. Sometimes voles chew off the bark.
You might also try carefully removing an inch or so of soil from around the base of the plant to see if you find roots wrapping around the "trunk". This compresses the conductive tissue and can reduce or prevent water movement and could cause the symptom you describe.
If none of these steps uncover anything then I suggest you wait and see what happens. If the affected branch breaks when bent, it is dead and should be cut out. It's possible that some roots were injured during the very dry summer last year and the resulting root damage is finally appearing.