Common names:
Boxwood leaf boxwood drop
Boxwood blight
Box blight
Blight disease of Boxwood
Boxwood leaf drop
Pathogen causing this disease:
- Cylindrocladium pseudonaviculata
- Also called Cylindrocladium pseudonaviculatum or C. buxicola
Initial symptoms
Light brown spots with darker brown to purple edges develop on the leaves.
Foliar spots may continue to grow and merge until the whole leaf is affected.
Advanced symptoms
Leaves become bronze colored (take on a blighted appearance) and leaves drop rapidly (defoliation). A combination of humid conditions with temperatures between 64°F–80°F (18°C–27°C) favors infections.
Black streaks or lesions appear along the stems together with an angular, diamond-shape spot. This is a distinctive diagnostic characteristic of the disease.
Symptomatic container plants at nurseries, outdoors during winter. Notice excessive leaf debris.
Symptomatic plants at the greenhouse. Observe defoliated stems.
Roots of plants infected with C. pseudonaviculata remain intact and appear healthy, as shown here.
How the spores are spread
Spore masses can be observed on affected leaves and occasionally on affected stems with a magnifying lens. Spores are sticky. In high humidity, the fungal spores germinate and penetrate the host plant within 5 hours.
Volutella blight symptoms on boxwood are sometimes mistaken for boxwood blight.
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