Question
I live in Durham, NC and have an arborvitae at the corner of my house.  The tree was planted in 2004 and has done well.  Over the last few weeks it has been dropping a lot of green leaves (needles).  Only thing new has been mulch.  It has been hot and dry here.  Any thoughts?  Thanks.

Answer
Since you did not say what type of mulch I will assume that you are correct. Mulch should be organic and nor more than 3 inches deep and not piled up on the trunk of a shrub. Some mulches will reflect heat and this will in turn cause the plant to wilt. IF it is not organic mulch I would remove it as soon as possible. (rock etc. ) Water the arborvitae with 1 inch of water--place a pan under the trees and turn the sprinkler on and when the pan has 1 inch of water in it stop. Do this every third day for a week then once a week.