Leylands turning really brown

Asked May 4, 2018, 2:06 PM EDT

Hi, i'm trying to figure out why my leylands are so brown. Looks like they are slowly dying. My neighbors look similar. Is there anything known going on with leylands this year? Or can you identify if something else is wrong? I don't see canker sores (which is the only real thing i can find online) at Ace Hardware in Ellicott City suggested I try you. Thanks for any advice you may have.

Howard County Maryland leyland cypress trees browning and dieback on leylands

1 Response

There are likely multiple things going on.
Leyland Cypress were the 'go to' landscape plant for many years for evergreen screening in yards.
In recent years however it has become evident that they look great for the first 15 to 20 years or so, and then start to fail.
New growth this spring may flush out and and cover the problem, but you can always prune out any brittle, dead wood that you see. (The trees cannot grow green tips or branches back from the trunk area.)
There are multiple reasons for problems, but just like for us humans, stressful conditions like drought or cold winters can make them susceptible to different insect pests and diseases. Common problems include 'winterburn', which is a browning dessication injury from drying winter winds.
Here is a recent blog post about this: https://marylandgrows.umd.edu/2018/04/11/why-is-leyland-cypress-turning-brown-winter-took-its-toll/

Much more serious though are canker diseases. Here is a page about them: http://www.extension.umd.edu/hgic/seridium-and-botryosphaeria-canker-leylands-trees
Borers can also be a problem, again drawn to stressed or dying trees.
For these, there is not much you can do, other than to prune out affected areas and keep the trees well watered and mulched in times of drought.

cm