Cylindrocladium buxicola

Boxwood blight

Description

Boxwood blight (Cylindrocladium buxicola, also known as Calonectria pseudonaviculata) is a destructive fungal disease affecting boxwood plants (Buxus spp.). It causes leaf spots, defoliation, and stem lesions, leading to significant plant damage and sometimes death. The disease thrives in moist, warm conditions and spreads through infected plant material, tools, or water splashes. Effective management includes sanitation practices, fungicide application, and the use of resistant boxwood varieties. The fungus produces spores (conidia) that spread through water, wind, or contaminated tools. Spores land on boxwood leaves or stems in warm, moist conditions and penetrate the plant tissue. The pathogen grows, producing more spores that can infect surrounding plants. It survives in plant debris or soil over winter, waiting for favorable conditions to restart the cycle.

Symptom

Circular, brown to black spots on leaves, often with a darker border. Rapid leaf drop, leaving bare stems. Dark brown or black streaks on stems. In severe cases, plant branches or entire shrubs may die. The damage resembles that caused by the species Cydalima perspectalis. However, the leaves are not eaten, and other symptoms typical of larval feeding are absent.

Tree Species: Boxwood

Part of a plant- attacked: Tree trunk, Leaf / Needle, Branch

Pest significance: Very harmful

Pest Category: Fungi

Invasive Species: No

Present in EU: Yes