Black knot is a common, often serious, disease of plums and cherries in Kentucky. Ornamental Prunus species, as well as wild plums and cherries, may also be affected. This disease is aptly named for the conspicuous black knotty growths that form on infected branches. Knots that were obscured by foliage during the growing season will be readily evident now on bare branches.
This fact sheet on black knot discusses symptoms, cause, disease development, and management options.
Black Knot (PPFS-FR-T-04) is available online.
For additional publications on fruit diseases, visit the UK Plant Pathology Extension Publications webpage.
By Cheryl Kaiser, Plant Pathology Extension Support, and Nicole Gauthier, Plant Pathology Extension Specialist