Pensacola News Journal

For: Saturday, June 21, 2003

By: Daniel E. Mullins

Extension Horticulture Agent

Santa Rosa County

Leyland Cypress Not Bulletproof

Leyland Cypress, that large growing evergreen conifer that has become so popular in Gulf Coast landscapes is not as trouble free as was once thought. Problems with established trees began cropping up 5 or 6 years ago and the incidence of damage from pests has increased every year since.

The Leyland Cypress (Cupressocyparis x leylandii) is an accidental hybrid of the Monterrey Cypress and the Alaska Yellow Cedar. The original hybrids were found in gardens in Leyland, England where these two species had been growing in close proximity. Interestingly, the two original parent trees do not overlap in their natural range.

These hybrids were found to be relatively easy to propagate by cuttings and caught on quickly for use as specimen trees and for screen plantings. The South Carolina Urban Forestry Newsletter contains some interesting comments about Leyland Cypress.

The rapid acceptance of this plant is said to be a landscape contemporary of the “Bradford” pear. Like the flowering pear, problems began to appear in Leyland Cypress plantings.

This spring in Santa Rosa County, we have identified several pest problems that required control measures. These have included Botryosphaeria canker and Phomopsis blight, as well as infestations by spider mites, scales and black twig beetles. Bagworms sometimes cause damage during the summer months.

Root problems are also common. On poorly drained, wet soils or where over watering occurs the trees are prone to become weakened and infected with root rotting fungi. This is a full sun loving plant and one that needs good air movement around the upper parts. Those planted in shady locations or under crowded conditions are sure to suffer eventually.

Most declining Leyland Cypress trees are probably due to overuse and being placed where they have little room to grow. Sometimes as gardeners, we tend to choose plants for a particular site based upon what we like best instead of choosing from a list of plant species that are best adapted to available light and soil conditions.

The current situation with Leyland Cypress reminds me of similar problems experienced with other species such as Redtip Photinia and Indian Hawthorn. They thrived the first few years in area landscapes and then began experiencing problems due to infection by a leaf spot disease. This problem has become serious on both species and is due in part, to overuse.

It is interesting to note that lists of substitutes for Leyland Cypress have been compiled in several Southeastern states. Since screen planting is the major use for this plant, the lists contains broadleaved and narrow leaved evergreens that grow to a similar size. Plant substitute recommendations will vary depending upon the region.

When a particular plant species or cultivar gets off to a good start and appears almost too good to be true there is often a temptation to use it in many areas of the landscape. Such repeated use is similar to a monoculture, which can encourage the development of insect and disease problems.

It is best to have diversity in the landscape. The use of several different well adapted species whose requirements match the site conditions, results in more healthy plants.

Some Leyland Cypress plantings will likely remain in good to moderate health, while others are expected to decline. Residents with these trees in the landscape are advised to allow plenty of space for air circulation and bright light. This might involve pruning nearby plants and even the eventual removal of every other plant from a screen planting that has become too dense. Avoid over watering by checking the irrigation system and redirect sprinkler heads to avoid wetting the foliage during irrigation.