Leyland cypress trees are a very common and popular landscaping plant. I’ve seen them planted by people all over Georgia. However, there are a couple of issues that are commonly seen in Leyland cypress trees. Let’s talk about Leyland cypress trees, what some of those issues are, and what steps you can take to reduce the chances of your Leyland cypresses getting diseased.
Leyland cypress was bred in 1888. It is a cross of Alaska cedar and Monterey cypress. They can grow to be over 40 feet tall. When they are young, they grow very rapidly. They’ll grow at a rate of 3-4 feet per year. Later on in life, they will continue to grow very rapidly at rate of about 2 feet per year. They typically have a Christmas tree shape. In some places, people have even begun to grow them to be sold for Christmas trees. Typically, people plant them for a barrier or privacy screen.
Leyland cypress trees are relatively pest-free. They don’t have too many issues with insects or too many different diseases. However, because they have a shallow root system, they are often planted close together, and are commonly planted in poorly drained soils. They are commonly prone to a couple of canker diseases.
The two canker diseases that Leyland cypress trees get are Seiridium and Botryosphaeria canker. Seiridium canker is the most common and destructive of the two in Georgia. The symptoms from both diseases look very similar. You will see individual branches begin to die off. Sometimes you’ll see resin in spots on the branches because of the cankers. These cankers are essentially suffocating the branch, leading to the branch turning brown.
Stressed trees are going to be more susceptible to cankers. During times of drought, trees that are already infected will spread the disease much more quickly. Ice damage and spring freezes can create wounds where infection is able to occur. Trees that are near buildings that reflect sunlight will also be more stressed.
Unfortunately, with canker diseases there is not a fungicide that can be used to eliminate the pathogen. Even if there was, spraying a 40-foot tall tree is not practical. Once a tree has been infected the best treatment is to remove the dead branch and dispose of the branch. Try to keep plants from becoming stressed by laying mulch around their base. This will increase the moisture retained by the soil, and suppress competitive weed growth. During dry, hot summer days, water the trees if the soil has become dry. If trees are extensively damaged by cankers, then they will need to be removed. When planting Leyland cypress make sure to dig out an area 3-4 times larger than the diameter of the root ball. This will improve soil drainage, resulting in your trees being less stressed and less susceptible to root rot diseases. In addition, planting trees at least 15 feet apart will reduce disease incidence.
There are some alternatives to Leyland cypress trees. Green Giant arborvitae and Arizona cypresses are both trees that serve the same purpose in landscape and are more disease resistant. For anyone planting trees as a barrier or screen, I would encourage them to look into these alternatives.
If you have questions about Leyland cypress please contact your county Extension Office or email me at the address below. On July 25, the Union County Extension is putting on a Well Water Program. It will be at 5:30 in the Union County Civic Center. If you would like to attend, please RSVP with Union County Extension Office at 706-439-6030 or email me at Jacob.Williams@uga.edu.