Even with proper care, Leyland Cypress can’t always thrive

Contributed Report

Leyland Cypresses are common visitors to the Goochland Extension Office lab. These nonnative, fast-growing evergreens are popular as a screening tree, but they are prone to a number of issues. Some issues are preventable. Homeowners who plant Leyland Cypress as a screening tree often give in to the temptation to plant trees very close–all the better to block an unsightly view, right? This approach can work if you are willing to thin the trees as they grow and age. Otherwise, they quickly begin to suffer the consequences of overcrowding.

Other common problems are less preventable. Leyland Cypress are prone to infestations of bagworm, scale, aphids, and mites, and fungal diseases like root rots and certain cankers. Recently, we had a client bring in some branches from his Leyland Cypress trees. The trees were still pretty young and had been planted a couple of years back, but they had never exhibited Leyland Cypresses characteristic rapid growth. Then in the last couple of weeks, the branches had started dying back. We couldn’t see anything under the microscope, and incubating the sample didn’t produce any signs of a pathogen. We discussed cultural practices with the client–were the trees mulched too deeply? Did the area drain well?—and still couldn’t find a smoking gun. s ubmitted by the Goochland e xtension Office

Finally we arranged for a site visit and found what we were looking for. A canker had formed on the main stem of each of the infected plants. Both Seiridium and Botryosphaeria canker attack Leylands and are incurable. In this case, the culprit was probably Botryosphaeria because the cankers were deep with little to no oozing, and the dead needles were retained by the branch. However, we don’t know for sure.

Unfortunately, there was nothing for the client to do other than remove the trees and replace them with another species. Because of the issues we often see with Leylands, we don’t recommend them. There are both native (Eastern Red Cedar, Southern Magnolia, American Holly) and non-native (Japanese Cryptomeria, Green Giant Arborvitae) replacements for Leylands available. Native trees are well adapted to our conditions and have the added benefit of supporting native insects and wildlife. Not all of these trees grow as fast as Leyland Cypress, but they will have fewer issues.

Use a mix of species in a screening planting to create a lovely multi-textured effect, cut down on pest issues, and reap the benefits of both fast- and slowergrowing species. But remember: proper spacing is still important! Have a question about a plant, insect, or soil? The Goochland Extension Office is here to help!

Give the office a call at (804) 5565841 and speak with either Bob or Nicole. Drop-ins are welcome at our office at 2748 Dogtown Road between 8:30 a.m. and 5 p.m., Monday through Friday.