Holmstrup Arborvitae Declining: Environmental Stress Likely

Four Holmstrup arborvitae (planted June 2007) formed seeds, now have yellowing, dying leaves, scraggly droopy tops. Nursery couldn't diagnose.

Possible Causes

• Water extremes: Too much or too little.
• Nursery-origin stress: Problems from prior year often appear later.
• Twig blight (fungal): Phomopsis juniperovora or Kabatina juniperi cause dieback, cankers, death. Affects junipers, arborvitae, cedars, cypress, firs, larch, yews. Search both for details.

Assessment

Given multiple plants and no insects, environmental stress is more likely than fungal disease. Check soil drainage, watering history, and root health.

Action

• Ensure consistent moisture (not soggy).
• Prune dead tips.
• Fertilize lightly in spring with balanced slow-release.
• Monitor new growth.