DiseaseHigh Severity

Coryneum Blight

Coryneum berckmannii, C. thujina (fungus)

A fungal blight disease also known as Cedar Leaf Blight, Cedar Twig Blight, or Berckman's Blight. Affects Oriental arborvitae, Italian cypress, and Monterey cypress in the Western Coastal United States, causing branch death and eventual tree mortality.

Peak Season: Infection begins during moist spring, progresses through growing season
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Coryneum blight showing characteristic shot-hole symptoms on leaves

Identification & Symptoms

What to Look For

Small branches become reddish-brown, many dropping
Larger limbs become girdled
Twigs with black pustules of fruiting structures (acervuli)
Foliage becoming gray
Dead twigs entangled at base of tree
Slightly sunken, dark, resinous, rough cankers on twigs and branches
Yellowing and browning of foliage
Gummy ooze at cankers

Potential Damage

Girdles twigs and branches starting with lateral twigs
Progressive branch death from top to bottom
Foliage discoloration and death
Accumulation of dead twigs at tree base
Eventual tree death from repeated infections
Reduced ornamental value

Lifecycle

Infection first evident in upper tree during moist spring. Following initial infection, acervuli produce spores which drop to lower branches or spread via windblown rain, fog, birds, and insects. Repeated infections lead to tree death.

Professional Treatment Approach

1

Remove infected branches promptly

2

Improve air circulation around trees

3

Avoid overhead irrigation

4

Fungicide injection for prevention

5

Disinfect pruning tools between cuts

6

Plant in well-drained locations

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against coryneum blight.

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Tebuject 16

Professional-grade treatment specifically effective against coryneum blight.

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