Dying Leland Cyprus

Asked April 5, 2018, 2:02 PM EDT

We have a number of Leland Cyprus that are all turning brown. They range in age fro 10-18 years. A number of the Cyprus are under the shade of Poplar trees. Are my trees dying? Is there anything I can do to help them? Most are primarily needed as. screen between a neighbor house. Thanks.

Montgomery County Maryland

1 Response

Unfortunately, Leyland cypresses are showing a lot of winter damage this year. These trees are also susceptible to several types of fungal diseases and insect damage (http://www.clemson.edu/extension/hgic/pests/plant_pests/trees/hgic2004.html). Leyland cypresses don’t tolerate sudden temperature fluctuations very well. We indeed experienced some of these very cold sudden temperature fluctuations this past December and January. The first winter damage symptoms begin showing up as browning and dieback. Since Leyland’s are often used for screening and windbreaks they are frequently exposed to temperature extremes and windy conditions that lead to drying out and cold damage.

There is no actual treatment for winter damage on Leyland cypress. Before pruning, allow the damaged tree to begin new spring growth.Often, if the damage did not injure the branch, new growth will emerge, and the browned needles will drop off naturally. If new growth does not emerge, the branch was severely damaged and should be pruned above where green color is still visible. Leyland cypress trees are tolerant of heavy pruning, but if more than one-third of the tree is damaged, the tree may need to be replaced. Thuja 'Green Giant' and hollies are a few choices you might want to consider for replacement screening.