What is happening to my Leyland cypress trees?

Asked March 30, 2015, 3:21 PM EDT

Do your programs offer off-site evaluations of trees? I live next to the Newark Reservoir in Nonantum Mills and for the last year or so, my Leyland cypress trees are turning brown. I had a tree service out here, and a year ago they stated it was normal. The trees are looking worse now. I think something else is going on with them. I have 25-foot Leylands all lined up in the backyard for privacy. I am noticing sun coming through them now. I am not sure what to do or if I need to cut out some of the branches. I am concerned that I may lose the whole row. If you have a program out there that can help me and maybe send someone out to do a critical study, please let me know.

New Castle County Delaware

3 Responses

Leyland cypress trees have been used extensively in our area as a windbreak and privacy screen, but were often planted too close together. I suspect that now that your trees are grown, they are a bit crowded and stressed due to fluctuations in rainfall and soil moisture. Is the drainage good? Leyland cypress suffered last winter and this past winter from cold temperatures and wind. Since the whole row has branches dying back, it is most likely not a disease or insect pest issue.

Unfortunately, Leyland cypress trees do not grow back their shape really well when they are trimmed. You may want to consider taking out every other tree to open up the air circulation. Otherwise, you could just trim out the worst affected branches to make the trees look better and also increase air circulation. I know pruning is a challenge for 25-foot tall trees, which is why I suggest actually taking out every other tree.

There are many good tree service companies, but make sure they have a certified arborist who will try to save your trees.

If you want to send a branch sample in to the lab, the form and information are available at this link: University of Delaware Plant Diagnostic Clinic

There is a Master Gardener program in which they will come out to your property, but there is a fee. The contact number for New Castle County is 302-831-2667.

Hello Nancy, thank you so much for taking the time to answer my questions. At this point, I think it is best that I call the Master Gardner program and pay the fee. That way I could see if there is anything else going on the property that could contribute to the problem. It could be very well that I need to take out every other tree but if there is more to it, I would like to do know if I need to pull all the trees due to some disease. I think it would be a wise investment to pay the fee for the simple facts that it could save me time, money and man hours in the future . I use the trees for privacy and I like the fact that they are fast growers. Lets say that I need to pull the trees out and replace later due to disease, would you suggest replacing them with Green Giant Arborvitae's? I will call the number next week and schedule. Again, thank you for taking the time to respond back to me. Greg Cowchok 302-287-8026

Hello, Greg,

I understand your concern for the privacy screen that the row of leyland cypress gives. Other considerations are the site, slope of the property, and soil drainage. You may also want to check the trees for bagworm insect pests. Whatever you decide to do, please know that there are many evergreens that look off color now due to the winter. There may be some improvement over the next month. The NCC Master Gardener volunteers are a great, knowledgeable group, and I'm sure they will be glad to help you.