DiseaseHigh Severity

Botryosphaeria Branch Canker

Botryosphaeria species

A serious fungal disease affecting all redwood species, causing twig cankers and needle blight. Cool, damp spring weather favors spore spread, while hot, dry weather accelerates internal fungal growth and twig girdling. Trees grown outside their native environment are most susceptible.

Peak Season: Spore release: Early spring during wet weatherInitial infection: Cool, damp spring conditionsDisease progression: Accelerated by hot, dry summer weatherOverwintering: As mycelium in infected plant tissues
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Botryosphaeria canker symptoms

Identification & Symptoms

What to Look For

Purple, circular or oval spots on needles that expand to cover entire needle
Needles turn brown as spots expand
Purplish brown spots at base of needles becoming cankers
Cankers eventually girdle twigs
Tiny black stromata containing fruiting bodies in infected areas
Complete browning of distal portions after twig girdling

Potential Damage

Twig girdling leading to branch dieback
Progressive needle browning and drop
Multiple cankers developing on single twigs
Complete death of girdled branch sections
Weakening of tree structure through repeated infections

Lifecycle

Fungus overwinters in infected tissues as vegetative mycelium. Spores are released during early spring rains and fog, spreading by rain splash and wind. Spores penetrate needles through stomata, then move through leaf tissue to create twig cankers.

Professional Treatment Approach

1

Fungisol applications during early spring before spore release

2

Preventive treatments for trees under stress or grown outside native range

3

Address phosphorus deficiency with appropriate Mauget fertilizer treatments

4

Multiple fungicide applications during wet spring weather

5

Focus treatments on previously infected trees and susceptible locations

Recommended Mauget Products

Fungisol

Professional-grade treatment specifically effective against botryosphaeria branch canker.

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