Evergreen dying

Asked June 13, 2017, 1:16 PM EDT

Hi we have these in our yard when we moved in about 8 years ago. About 2 years ago, the bushes started to look dead in one area and the spot is growing. My husband thought we trimmed it too much at one point but the top where we trimmed more the leaves are still growing...any insight why the leaves are retrieving from one end of the other. We also have another evergreen where it has similar problem but we didn't trim that one too much (the tall one on the picture). We had another one that we took down due to same problem but it's from another end of the yard, so I don't think it's a bug issue?

Nassau County New York leyland cypress

4 Responses

There are quite number of afflictions that can cause devastating damage like this in conifers. To begin with, some conifers will not regrow needles if you cut them back too deeply, particularly in the less actively growing, lower parts of the tree.
It would be helpful to know (if you know) what types of plants you have as well as what the damaged needles look like when they first begin to discolor (do they have spots, uniform yellowing, evidence of insect activity, browning beginning from the tips?) Do you see any webs, holes or other signs of insect activity on the trunks or in the branches? Any funny growth at the base of the tree?
If you do not know the plant type, please send us a good close up of the healthy needles and we will do our best to get to the bottom of your problem. Sorry to give you extra work but we'd like to make as good a diagnosis as possible at a distance.

I don't see any holes or insect or funny growth at the bottom. The back and the top of the wide tree have green leaves and are growing fine. But the front bald spot just get bigger and bigger. They first just turn brown and then no new leaves in the spring. I have included a few close up shots for the two plants. I only see one name tag on one of them. Thanks for your help

The plant identity is very helpful as the Naylor's blue cypress (x cupressocyparis 'Naylor's Blue') is a sturdy plant that has relatively few problems. The die back in random distribution on the plant suggests that your plant has a canker caused by either Seiridium unicorne or Botryosphaeria dothidea fungi. The link to the heavy cutting back may not be misplaced as these fungi attack plants that are stressed by environmental factors such as drought, freeze, wounds or heavy pruning. We certainly get all of these in our area!
The canker begins as browning of needles and then die back of a more extensive area, typically an entire branch, distributed randomly on the plant.
These fungi can survive the winter cold and then the spores spread in wet weather or by spray from irrigation. This canker affects many woody ornamentals so the spread to your other shrubs is consistent.
I am sending you a link to a well written fact sheet on these fungal cankers from the University of Alabama https://www.uaex.edu/publications/pdf/FSA-7536.pdf

The fact sheet has recommended treatment including the cutting back of the affected branches and improvement in care so that the plants are less stressed and susceptible. I strongly suggest that you have an arborist look at these plants and make an on site diagnosis before taking any extreme measures. Your county cooperative extension may also provide "bring in" diagnostic services that are convenient to your home. Here is a link to the webpage for Nassau County's Cornell Cooperative Extension: http://ccenassau.org/

You should also be aware that Leyland cypress is fast growing but not a long lived plant, usually about 20 years. You may want to consider replacing these if they are reaching that age. Even with containment of a canker, the affected areas will not grow back.