I have noticed a lot of mature Leyland Cyprus dying. Do you know what is...
The Leyland cypress in the mid-Atlantic took a huge hit this winter. Many have suffered winterkill of branch tips and whole branches. Some have completely died. Many are still dying from the damage they sustained. There is nothing that can be done to reverse this damage. Prune out dead branches. Do not try to cure the problem by over-fertilizing, which will just stress the plants even more. A little slow release fertilizer or organic compost if okay. The most important thing to do is to prevent further stress as the plant attempt to recover, and this means watering them during droughts. If we do not get rain for 2-3 weeks or more, consider giving your Leylands a good deep watering.