Leyland Cypress Needle Blight: Cercospora Identification and Copper Treatment

Symptom Pattern

Leyland cypress hedges browning from inside out, spreading through trees, top growth still green. Classic Cercospora Needle Blight (Cercosporidium sequoiae).

Disease Progression

• Starts: Lower crown, near stem (browning needles)
• Spreads: Upward and outward
• Severe: Only upper branch tips remain green
• Mimics: Severe stress symptoms (interior yellowing/fall)
• Fruiting bodies: Tiny greenish pustules on needle upper surface/twigs
• Spores: Spring through summer, wind-dispersed
• Infection: Extended wet conditions

Host Range

Also affects: Juniperus, Thuja, Cupressus, Taxodium, Cryptomeria, Sequoia, and other conifers.

Control Protocol

• Copper-containing fungicides (e.g., Kocide — registered for ornamentals)
• Timing: 10-day intervals from bud break until new growth starts
• No fungicides specifically registered for Leyland cypress
• General ornamental registration applies

Cultural Management

• Improve airflow (selective thinning)
• Avoid overhead irrigation
• Remove severely infected branches
• Reduce canopy density for faster drying

Early intervention critical — advanced cases with only tip foliage remaining are difficult to recover.