Leyland Cypress Diseases: Treating Disease In Leyland Cypress Trees

Closeup of a Leyland Cypress Tree
(Image credit: CaronB)

Gardeners in need of quick privacy hedges love quick growing Leyland cypress (x

Cupressocyparis leylandii). When you plant them in an appropriate location and provide good culture, your shrubs may not suffer from Leyland cypress diseases. Read on for information about the main diseases of Leyland cypress trees, including tips on treating diseases in Leyland cypress plants.

Preventing Leyland Cypress Diseases

Prevention is easier than cure when it comes to diseases of Leyland cypress trees. Your first, best step toward keeping these attractive evergreens healthy is planting them in appropriate sites.

The second step is giving them the best care. A healthy, vigorous plant shakes off problems with more ease than a stressed plant. Leyland cypress disease treatment is often impossible or ineffective.

So, save yourself the time and effort involved in treating disease in Leyland cypress. Plant these shrubs in a sunny location in soil offering excellent drainage. Space them far enough apart to let air pass between them. Provide water during times of drought and check your hardiness zone. Leyland cypresses thrive in U.S. Department of Agriculture plant hardiness zones 6 through 10.

Diseases of Leyland Cypress Trees

If your shrubs are ill, you’ll have to learn something about the different Leyland cypress diseases to figure out what’s wrong. Diseases of Leyland cypress generally fall into three categories: blights, cankers, and root rots.


The symptoms of needle blight diseases include needles browning and dropping. Usually, this begins on the lower branches. These are fungal diseases, and the spores spread from branch to branch by rain, wind, and tools.

Placing the shrubs far enough apart to allow air and sun to get through the branches helps prevent needle blight. If it’s too late for prevention, prune out infected branches. Thorough application of a fungicide helps but is difficult on tall specimens.


If your Leyland cypress needles turn red-brown or you see cankers on the trunks or branches, the shrubs may have a canker disease, like Seiridium or Botryosphaeria canker. Cankers are dry lesions, often sunken, on stems and branches. Surrounding bark can show a dark brown or purplish discoloration.

Canker diseases are also caused by fungi and usually only attack stressed plants. When it comes to treating disease in Leyland cypress, fungicides are not effective. The only Leyland cypress disease treatment for this is to prune out infected branches, being sure to sterilize the pruners. Then start a program of regular irrigation.

Root rot

Root rot diseases cause dying roots leading to yellowing foliage. It is often caused by inappropriate planting in an area where the soil does not drain well.

Once a shrub has root rot, chemical Leyland cypress disease treatment is not effective. As with the other diseases, the best way of treating disease in Leyland cypress is to give the plants appropriate cultural care.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.