The Leyland cypress tree is one of the most popular plants used in the landscape as a natural screen.
Unfortunately, increasing disease problems, improper plant placement, and the sheer prevalence of Leyland cypresses have all contributed to the need for alternative plant selection.
Leyland cypress trees are susceptible to a number of diseases, such as Seridium canker, Botryosphaeria dieback and Cercosporidium needle blight. Planting the trees too close together and planting them in unfavorable sites greatly increases the incidence and spread of disease. Certain insect infestations, such as bagworm and spider mites, have also become more and more common recently.
Other problems seen in Leyland cypress occur because they are often seen as the one and only solution to all screening needs in the landscape. They don't like having "wet feet," so placing them in poorly drained soils increases root diseases.
They require full sun to grow well, so those placed in shady areas often look thin and week. Many people don't realize that Leyland cypresses can grow 60 to 70 feet tall, which can lead to the trees having to be drastically topped when planted under utility lines.
In looking for an alternative natural screen, it is best to consider using several different trees as a substitute. Planting a variety of species well adapted to our climate conditions will result in healthier plants.
If you are looking for a tall, narrow conifer similar to Leyland cypress, consider an Arizona cypress for dry sites in full sun.
Green Giant arborvitae will work well in moist, well-drained sites in full sun. Japanese cedar, also called Cryptomeria, makes a good tall screen in partly shaded areas.
Consider broadleaved evergreens for dense screens that also have flowers or berries for seasonal color.
Alta, Bracken's Brown Beauty and Edith Bogue are all cultivars of southern magnolias that are tall and narrow and excellent for screens.
For a shorter screen, Little Gem can be used.
Sweetbay magnolias will tolerate moist soils, and cultivars Henry Hicks and Santa Rosa should work well.
Hollies can make good screen plants as well, and most can tolerate either sun or partial shade. Foster's holly is tall and narrow and would be good where width is tight. In less restricted spaces, lusterleaf holly and Nellie R. Stevens holly can be used.
Other broadleaf evergreens that can be used for a screen of up to 25 feet tall are fragrant tea olive, Fortune's tea olive and loquat.
In many cases, smaller screens of 6- to 15-feet tall are sufficient. For these, consider choices like wax myrtle, taller varieties of yaupon hollies, viburnums, cleyera, plum yew and taller cultivars of camellias and loropetalums.
It is important to remember to try and diversify your screening plants.
Having many different plants helps stop the spread of problems from one plant to the next. Even if one or two plants in the screen have a problem, removing them will not require removal of the entire screen.
If possible, try to have staggered rows of trees. This allows the plants to be spaced more widely, allowing for better air circulation, which will reduce disease and insect incidence.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.