I planted 6 Holstrum Arborvitae, 3 foot, and 3 Little Giant Globe Arborvitae, about 45 days ago, for a customer. They were in very good shape when I planted them. The customer, she is a mowing customer, took me over to them today. On the surface they appear to be doing very well. She opened them up and the whole inside of the plants are brown with branches falling off on touch. The soil was very clay but we amended it to 50% bagged compost. Any ideas as to what may cause this? I've seen minimal temporary die back before but nothing like this. We have had a reasonable amount of rain and the customers root water them once a week.