|PSCHEIDT, JAY - Oregon State University|
|OHKURA, MANA - Oregon State University|
Submitted to: Pacific Northwest Plant Disease Management Handbook
Publication Type: Other
Publication Acceptance Date: 1/30/2023
Publication Date: 3/1/2023
Citation: Pscheidt, J.W., Ohkura, M., Weiland, G.E. 2023. Boxwood (Buxus spp.) - Boxwood Blight. Pacific Northwest Plant Disease Management Handbook. [online].Corvallis, OR: Oregon State University.
Technical Abstract: Boxwood blight is a serious disease of field and container boxwood in the Pacific Northwest. The disease is caused by the pathogen Calonectria pseudonaviculata. Boxwood with this disease show symptoms of leaf spots, defoliation, and black stem lesions. The pathogen is spread by rain splash on on contaminated equipment and clothing. Infected plants cannot be cured and must be destroyed. In the Pacific Northwest, disease is favored by cool temperatures (15-20C) and wet weather, which occur in spring and fall. Cool temperatures can compromise disease resistance in cultivars such as Winter Gem. Cultural control measures include reducing the amount of water applied through irrigation and increasing plant spacing to promote drying. Fungicides are also available for protecting plants, but will not cure the disease once it develops.