DiseaseMedium Severity

Coryneum Canker

Coryneum berckmanii, C. thujina

A fungal canker and blight disease affecting cedar, cypress, and arborvitae species, also known as Cedar Leaf Blight, Cedar Twig Blight, or Berckman's Blight. The disease causes progressive branch death and can lead to tree mortality through repeated infections.

Peak Season: Primary infection: Moist spring conditionsInitial symptoms: Upper crown during springSpore production: Following acervuli developmentSecondary spread: Throughout growing season via rain and windOptimal conditions: Cool, wet, or foggy weather
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Coryneum canker showing characteristic twig dieback and lesion formation

Identification & Symptoms

What to Look For

Small branches becoming reddish-brown and dropping
Larger limbs developing girdling cankers
Black pustules (acervuli) on affected twigs
Foliage turning gray then brown
Dead twigs accumulating at tree base
Slightly sunken, dark, resinous cankers on branches
Yellowing and browning foliage with gummy ooze

Potential Damage

Progressive branch mortality starting from upper crown
Girdling cankers on lateral twigs and larger branches
Crown thinning and aesthetic decline
Tree mortality from repeated severe infections
Accumulation of dead debris creating fire hazard

Lifecycle

Infection first appears in upper tree parts during moist spring weather. Acervuli develop and produce spores that are spread by windblown rain, fog, birds, and insects. Secondary infections occur on lower branches, creating progressive disease cycles that can lead to tree death.

Professional Treatment Approach

1

Fungisol applications during early spring before spore release

2

Preventive treatments during wet weather periods

3

Remove and destroy infected branches to reduce spore sources

4

Sanitize pruning tools between cuts and trees

5

Improve air circulation around susceptible trees

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against coryneum canker.

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