Mature Arborvitae Branch Tips Drop Off Without Apparent Insect Damage

Question From: West Chester, Pennsylvania, United States
Q: I have a wall of 12 mature arborvitae about 30 feet tall. On summer mornings I would find lying on the ground cut ends of the tips of branchlets from the tree located at the far right end of the line. The cuttings were about 4 inches long and green with no apparent insect damage. I noticed the dropping stopped in early September. Do you have an idea of what might have caused this? In comparison to the others, the tree now looks a little sparse and less green. Using binoculars I couldn't find anything that might have caused the dropping. A friend suggested cutworms but I cant find anything on the net about cutworms affecting arborvitae. What's your opinion? Do you think I should fertilize or spray these trees in the spring? I haven't done either in a long while. Thank you.

A: If you value the tree I recommend you have a certified arborist do an onsite inspection to see what's up with your arb. If it is some sort of insect, you need to know what kind it is and the best time to treat it. Do it at the wrong time and it may not be effective. Also, whatever is causing the problem will probably spread to the other arbs. I would mulch the trees and keep them watered. Best And Happy Yardening, Nancy.