I recommend you have your trees inspected by a tree doctor, a certified arborist to find our whats up. The yellow needles are toast so if the loss of them will distort the tree, I suggest you remove them and begin with a clean canvas. Trees under stress from lack of water become vulnerable for a variety of ills, such as pest and disease. So it takes a pro to diagnose and care for them. Best And Happy Yardening, Nancy
Evergreen Trees Are Yellow
Question From: S. Farley - NEW MEXICO
Q: We recently bought a house that had been unoccupied for over a year. The evergreen trees look yellow and am sure they weren't watered during that time (and we like in a high desert area with little rain). Do you have any suggestions on bringing them back to life?