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Box Blight

Fungal

Plant disease guide — symptoms, causes, treatment, and prevention.

symptoms

Symptoms

  • circleBrown, circular leaf spots with dark edges
  • circleBlack streaking on stems
  • circleRapid, patchy leaf drop leaving bare sections in the plant
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Causes

Caused by the fungi Calonectria pseudonaviculata or Calonectria henricotiae, which thrive in warm, humid, still air and spread via water splash, tools, and contaminated plant material.

healing

Treatment

Prune out and destroy infected branches, clear fallen leaves from around the plant, and apply a labeled fungicide as part of an ongoing management program.

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Prevention

Improve airflow by thinning dense growth, avoid overhead watering, disinfect tools between plants, and consider resistant boxwood cultivars or alternatives in high-risk areas.