Canker and Dieback Diseases of Leyland Cypress

ANR-1160, New Oct 1999. Austin Hagan, Extension Plant Pathologist, Professor, Entomology and Plant Pathology, Auburn University

Canker and Dieback
Diseases of Leyland Cypress
Within the last decade, Leyland cypress has been widely used in residential and commercial landscapes across Alabama not only as a specimen tree, screen, or hedge, but also as a Christmas tree. Popularity of this tree, which is a hybrid of the Monterey cypress (Cupressus macrocarpa) and the Nootka falsecypress (Chamaecyparis nootkatensis), is due in large part to its graceful columnar to pyramidal shape, its attractive dark green foliage, and its rapid growth rate. Mature Leyland cypress may reach a height of 70 feet or more. In its native England, Leyland cypress reportedly has suffered from relatively few damaging diseases. However, in recent years, several threats to the health and beauty of Leyland cypress have emerged in Alabama landscapes and on Christmas tree plantations.

Leyland cypress is best adapted to fertile, moist, well-drained soils. Unfortunately, this tree is often planted on poorly drained sites where it is not well adapted. In addition, Leyland cypress, which is relatively shallow-rooted, may be weakened when exposed to prolonged periods of drought during Alabama's blistering-hot summers. Finally, poor planting and maintenance practices as well as extremely close plant spacing further increase plant stress and the risk of fungal-incited canker and dieback diseases, including Seridium canker and Botryosphaeria, or Bot, canker.

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