So many Leylands. So many problems. Tall, elegant Evergreens are often used for aesthetic borders for privacy barriers and relatively quick screening because a healthy specimen can grow 3-4 feet tall and 2-3 wide in one year. Key in on the term healthy. This species has been planted A LOT in the landscape, often incorrectly. Add stress to an already disease-susceptible organism and it’s a pretty sure bet that you will be looking at a problem in the not-too-distant future. Two points to emphasize 1) Know Before You Grow and 2) Plant the Right Plant in the Right Place at the Right Time. Meet these two criteria and you will see significant progress in saving your wallet and your very last nerve.

As with any tree, shrub, perennial or annual, plant it in the garden according to what space the adult plant will be, not how they look in the containers you’ve brought them home in. Leyland Cypress (X Cupressocyparis leylandii) trees must be planted at least 10 to 15 feet apart, and they STILL will need thinning out due to the trees’ rapid growth. A well-placed and correctly planted Leyland in the appropriate environment can grow to be 100 feet wide and 50 feet tall. When they are planted as a privacy screen, they are placed close together to grow into one another. That reduces the air circulation needed in the canopy to dry the branches and leaves and increases the tendency toward disease. Several different kinds of diseases like Phytophthora root rot, Armillaria root rot, Cypress (Seiridium) canker, Botryosphaeria canker/dieback, Passalora needle blight, algae on foliage, and internal browning, as well as other problems.

Leyland cypress need full, all-day sun to be their best self. They will struggle in shade and their vigor will suffer, causing them to thin out and become more susceptible to diseases and pests. Soil water management is another essential criterion. Internal soil drainage, not just surface water drainage, is an important factor for this plant. Too much water inside the soil leads to root rotting fungal diseases, and too little water leads to stress. And stress leads to – you guessed it – disease.

I often get the question “what can I spray on it” when disease takes hold to the point that the plant owner notices that their treasure is succumbing to a problem. With Leyland cypress, often using chemical controls at this point isn’t realistic because the application isn’t going to be effective, and control of the disease isn’t really going to occur. Severely infected trees are not going to recover and should be removed. If an infected plant is closely placed in a row of the same species of plants, disease can and does spread right through the row. It’s like offering up a smorgasbord to pests and pathogens to “come an’ get it”.

If your design goal is privacy screening, consider moving away from identical rows of the same plant toward the diversity of mixed screens. That means planting multiple species, preferably with different leaf shapes, textures, growth forms and characteristics in clusters of threes and fives, in varied layers to break the smorgasbord lunch line and control the spread of disease.

For more information with some useful disease info and images for comparison take a look at these fact sheets from our colleagues at the Universities of Georgia and Clemson.