Management of Leyland Cypress in the Landscape
Today, I want to share information about one of the most popular landscape trees over the last decade, the Leyland cypress.
First, why are these trees so popular? I would say that 9 out of 10 times I see Leyland cypress in the landscape, it is for border control. Many clients will plant these trees in order to have a dividing line between neighbors. The popularity is aided by the quick growth rate of these trees. Young Leyland cypress can grow 3- 4 feet per year and can end up over 40 feet in height.
In addition, they can have a nice natural oval or pyramid shape without any pruning. The foliage of the trees is pleasing to many folks that grow them too. Keep in mind that sometimes how and where we plant these trees can lead to problems. I will be sharing information from a UGA publication by UGA Extension Plant Pathologist, Dr. Alfredo Martinez and Dr. Jean Woodward and also Mila Pearce, UGA Homeowner Specialist Plant Pathology.
There are important issues to consider when deciding to plant Leyland Cypress on your property. They are considered to be somewhat insect pest free, but there are issues associated with this landscape tree. First, I have seen Leyland cypress damaged by bagworms in summer months. Second, they have a shallow root system so they can have problems in time of drought. If you remember back in 2007, we had an extreme drought that lead to many counties imposing outdoor water bans. About August of that year, my phone rang off the hook with clients losing up to 30- 40 Leyland cypress at one time. In addition, you may remember in early spring 2007, we had about two weeks in April of cold weather that possibly caused freeze injury to their bark. All of this made the trees more susceptible to the damaging canker issues that can plague these trees.
Many times, too, the homeowner starts these trees on a bad path by how and where they plant them. Most of the trees I see are planted too close together. I know the thought process is to get a dense row of trees to block all views to your backyard or pool area from neighbors, but they need to be planted more apart than I see them. I would plant them on 10- 12 foot centers instead of the very short distance trunk to trunk that I normally see. If you fear you won’t have a border soon enough, plant them on two staggered rows. Remember, these trees get big and get big quick, so giving them space to grow will fill up soon. You also need to plant them in well- drained areas to try to limit the chance of root rot such as Phytophthora root rot. The pathogen seems to bother root systems of younger trees more than mature trees. The issues are seen more in areas where soil drainage is poor on a property.
One of the more damaging diseases of Leyland cypress is Seiridium canker. You can see it as yellowing or browning of foliage on one or more top or lateral branches, according to UGA publications. You will see it more in spring, but can see it any time of year. You can look closer and see cankers on the stem and branches. The cankers can be sunken with raised margins and areas can be discolored with some oozing of resin.
To help combat this potential problem, in hot and dry summers, you can irrigate around the base of the trees every 7- 14 days depending on the soil composition according to our data. You can also mulch several feet beyond the lowest limb to help control water loss. You may want to pay special attention to trees planted in areas that can heat up even more such as around paved areas or cement. Keep in mind to not over- water due to the root rot issues associated with Leyland cypress.
Finally, Leylands can be a great landscape tree if given room to grow, planted correctly in the beginning and monitored during stress times. This summer and early fall has been some of those stressful times for Leyland cypress. Many Leyland cypress in the area have died do to our lack of moisture this year.
Timely good deep irrigations with soaker hoses can be beneficial for these trees in times of moisture stress. If you choose to irrigate any of your landscape items, make sure you are in line with our local irrigation rules by your water provider. For more information, contact UGA ExtensionGordon County at 706- 629- 8685 or email gbowman@uga.edu.