Boxwood Blight: A Spreading Threat in Georgia—How to Diagnose and Respond

Boxwood Blight: Identification, Spread, and Management

Boxwood blight (Calonectria pseudonaviculata) is a serious fungal disease spreading in Georgia, affecting American and English boxwoods. Korean boxwood shows some resistance but can be an asymptomatic carrier.

Key Symptoms

• Dark leaf spots with white centers
• Black streaks on stems
• Rapid defoliation starting at the bottom
• White sporulation on leaf undersides in humid conditions

Why Accurate Diagnosis Matters

Volutella blight and Macrophoma blight cause similar symptoms but require different management. Only a lab test can confirm boxwood blight. Submit samples through your local UGA Extension office (call 1-800-ASKUGA1). Homeowner samples cost $10; commercial samples (via landscapers) are free.

If Confirmed: Eradication Is the Only Option

1. Remove ALL infected plants, including roots and fallen leaf litter.
2. Bag and dispose of debris—do not compost.
3. Replant with non-host species or resistant Korean boxwood cultivars.
4. Avoid planting susceptible English boxwood nearby.

Seasonal Patterns

The disease spreads rapidly in cool, wet fall and spring weather. Hot summer temperatures slow it, but it returns aggressively in autumn.

Fungicides Are Largely Ineffective

Control with fungicides is extremely difficult and not recommended for homeowners. Prevention through sanitation, resistant cultivars, and early detection is the best strategy.

Resources

• UGA Boxwood Blight Update
• NCSU Boxwood Blight Overview