LeyLand Cypress Browning
Hi, I have 3 Leyland Cypress that are over 15 years old. I noticed last year that they are turing brown from the bottom up. Up to last year, the y seem to be fine. Twenty feet over my neighbor has a border of younger leylands that are in perfect condition. The trees are over 15 feet tall and get full sun on the upper portion of the tree. I haven't noticed any insects. There is ivy growing on the ground near the trees. Any suggestions?
There are several insects and diseases that can impact Leyland cypress, not to mention problems caused by improper planting, root damage, drought, and other abiotic problems.
In general, Leyland cypress grow best in full sun and can grow to be about 60-70 feet tall. They are not that winter hardy here during cold winters. In the shade the trees will grow slowly and lose inner foliage. Trees are susceptible to canker diseases when stressed. There is no control other than pruning dead branches during dry periods. http://extension.umd.edu/hgic/plants/seiridium-and-botryosphaeria-canker-leylands-trees
Looks like there is lack of sunlight, the trees are thin, and there may be root competition for moisture and nutrients, etc. The trees will grow slowly in a shaded area and lose inner foliage. All you can do is prune dead wood. Mulch to conserve moisture, no thicker than several inches, and keep away from the base of the trunks. Water the trees during dry periods. To prevent root competition you can remove every other tree. Do not let ivy grow up the trunk and into the branches. This can deny photsynthesis and cause some decline.
You may also want to consider removal and plant native trees or shrubs that match the site.