DiseaseMedium Severity

Cedar Coryneum Blight

Coryneum berckmanii, C. thujina

A fungal leaf and twig blight disease affecting cedar and cypress species, also known as Cedar Leaf Blight, Cedar Twig Blight, or Berckman's Blight. The disease causes progressive dieback starting from small branches and can lead to tree mortality through repeated infections.

Peak Season: Primary infection: Moist spring weatherInitial symptoms: Upper crown during springSpore production: Following initial infectionSecondary spread: Throughout growing seasonOptimal conditions: Rain, fog, and cool weather
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Cedar coryneum blight symptoms

Identification & Symptoms

What to Look For

Small branches becoming reddish-brown and dropping
Larger limbs developing girdling symptoms
Black pustules (acervuli) on affected twigs
Foliage turning gray then brown
Dead twigs becoming entangled at base of tree
Yellowing and browning of foliage progressing upward

Potential Damage

Progressive branch drop starting with smaller twigs
Girdling of larger limbs leading to dieback
Accumulation of dead material at tree base
Crown thinning and aesthetic decline
Eventual tree mortality from repeated infections

Lifecycle

Infection first appears in upper parts of trees during moist spring conditions. Acervuli produce and release spores that are spread by windblown rain, fog, birds, and insects to infect lower branches. Disease spreads progressively through the tree with repeated infection cycles.

Professional Treatment Approach

1

Fungisol applications during early spring before infection period

2

Preventive treatments during wet weather periods

3

Remove and destroy infected branches to reduce inoculum

4

Sanitize pruning tools between trees and cuts

5

Improve air circulation around affected trees

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against cedar coryneum blight.

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