Emerald Arborvitae Bronzing in Georgia: Environmental Stress

Nineteen 5–6 year old emerald arborvitae in NE Georgia show orange-bronze foliage from inside out after heavy rains. Planted on a slope with good drainage, they were green until a month ago.

Diagnosis

Not an infectious disease. Likely environmental stress from:

• Excessive rain (22+ inches above normal) causing temporary root hypoxia.
• Temperature fluctuations.
• Transplant shock (if recently moved) or seasonal bronzing.

Management

1. Watch and wait—do not spray horticultural oil, Miracle-Gro, or malathion.
2. Water only if dry several inches down.
3. Scout for bagworms inside foliage—hand-pick and destroy.
4. Re-evaluate in April/May for new green growth.

Why Not Treat?

Spraying stresses already-stressed plants. Bronze interior foliage is normal fall/winter coloration for many conifers. Healthy plants green up in spring.