Are my trees sick?

Asked May 20, 2018, 7:46 PM EDT

My blue spruce have never really been well next to the Laurls and The cypress trees started to grow brown this year and we can’t figure out why. Can you please help?

Howard County Maryland

1 Response

Blue spruces, unfortunately, do not grow well in this area. They look great when they are young, but older trees decline from two common fungal diseases. There is no practical treatment. In your situation, recommend taking out the blue spruce and allow the laurels to fill in the space. It looks like they have a lot of healthy new growth.

There could be multiple things going on with the Leyland cypress. This was the 'go to' landscape plant for many years for evergreen screening in yards. In recent years it has become evident that they look great for the first 15 years or so, and then start to decline. Very often we see them planted too closely together, which leads to competition for water and nutrients. As the trees mature, lack of sunlight leads to the decline of interior branches.

Stressful conditions like drought or cold winters can make Leyland cypresses susceptible to different insect pests and diseases. Common problems include 'winter burn', which is a browning desiccation injury from drying winter winds. We have seen a lot of this type of injury in Leylands this year. Here is a recent article from our plant pathologist about this:

Much more serious are canker diseases and needle blight. Here is a page about these diseases and the symptoms to look for: No fungicides are effective for these diseases.

For the winter damage, there is not much you can do other than wait to see if new growth will develop then prune out areas that haven't recovered. Prune only to where there is green growth. (Do not cut into the wood with no foliage. It will not regrow.) Keep the trees well watered and mulched in times of drought. Avoid pruning when the trees are damp.

The bottom line is that Leyland cypresses look good for about 10-15 years and then they start to decline.