Viburnum hedge was about 5' high. Landscapers cut it back a foot. The next week the leaves were half brown and the insides of the plant dried up and dying. Was told my plants are going into shock. They are 8 years old, very lush to start with. No watering issues here. I think something leaked from the machinery on my plants. An old plant like this could not go into shock from trimming, right? If so, the leaves on top would not be half dead, or would they?