Boxwood Blight

Boxwood blight

4 host plants

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

Boxwood blight causes leaf spots with dark centers and yellow halos on boxwood foliage. You'll notice rapid defoliation and stem cankers that girdle branches. The disease spreads via water splash and contaminated pruning tools. Remove infected plants immediately, disinfect all tools, and improve air circulation around plantings.

To limit spread and movement of the pathogen, all confirmed infected plants should be destroyed. Isolate and contain new shipments of boxwood for at least a 30-day observation period.

Quick Reference

Causal Agent
Boxwood blight
Host Plants
4
Spread
Rain splash, contaminated tools and nursery stock, insect vectors.
Favorable Conditions
Cool wet conditions (10-20°C / 50-68°F); rain, overhead irrigation, and dew c...

Management

Vulnerability Window

Fall through spring in cool wet climates (October-May); March-April peak in PNW.

What Triggers Infection

Cool wet conditions (10-20°C / 50-68°F); rain, overhead irrigation, and dew critical for leaf wetness; sporulation occurs at high humidity (>90%).

Cultural Controls

  • To limit spread and movement of the pathogen, all confirmed infected plants should be destroyed.
  • Isolate and contain new shipments of boxwood for at least a 30-day observation period.
  • Locate the isolation area well away from existing blocks or outgoing shipments, and scout weekly.
  • Break up large blocks of Buxus with non-host species to limit exposure and potential losses due to this disease.
  • Do not reuse or recycle or compost infected plants, media, or containers.
  • Professional composting is fine.

Host Plants (4)