Dying Evergreen

Asked July 9, 2014, 11:32 AM EDT

Dear Expert, I have several evergreens (not sure about the type, it's 20-30 feet tall with pretty wide canapé ~20 feet in diameter, picture attached). Those were been planted pretty close to each other - within 10 feet or so and started to die in every-other pattern. It was not a big deal because open area created by the dead ones were taken by the neighbor trees. But now this pattern continues and I'm not sure if trees have enough width to cover the gaps. On the picture one dying tree is shown, it consists of 3 trunks, two are mostly dead. Should I remove dead ones right now to help the third trunk to survive? Any advice how to prevent it in the future? Thank you, Maxim

New Castle County Delaware evergreens leyland cypress evergreen diseases

5 Responses

Hello,

Thank you for contacting Delaware Cooperative Extension. You may receive a short survey after this question is answered.
The tree in the picture is a leyland cypress, commonly planted in our area, and often planted too close together. When they get large and there is not enough air circulation between them, disease and insects move in. However, much of what we have seen in the landscape this year is environmental stress, due to a combination of excessive water last year, and an extremely harsh winter. These trees have some dieback from fluctuating cold temperatures and wind. Leyland cypress do not grow back and fill in well after trimming, but trimming out the worst affected is about your best option. With the tree in the picture, I would recommend that you prune out the dead leads and try to keep the third going. Anything that you can do to reduce stress on the trees would help for the future. Water them once a week if we have a period of extended drought. Do not fertilize, it adds too much salt when roots may be poor.

My best,
Nancy

Dear Nancy, Thank you very much for the prompt and detailed reply! Should I trim dead leads now or wait till fall? If the whole tree dies, what kind of evergreen should I pick to fill the gap in my natural fence? As you see on the picture, neighbor trees are ~20-30 feet tall and do not leave a lot of room. But I still want to close an empty space. Am I asking too much? Thank you again, Maxim

Hello, Maxim,

You can go ahead and trim out the brown branches now. You can trim anytime up until October, you wouldn't want to encourage new tender growth going into the winter cold.
You may want to consider Green Giant arborvitae, or even our native red cedar, for replacement trees in that border area.

Nancy

Thank you again, Nancy! Would 3-4' Green Giant arborvitae or red cedar trees be comfortable in the shadow of the big 20-30' neighbors? Planting is in the fall or spring, right? Any fertilizer at planting? Thanks, Maxim

Hi,

After a bit more thought, the Green Giant might get too large. A better choice might be the Emerald Green arborvitae. The eastern red cedars would be okay in between. Planting in the fall, maybe the end of September, might be good.

Nancy