Cankers form on trees and other woody plants as the result of infection by fungal or bacterial pathogens. Dieback, decline, structural failure, or plant death can result. Plants stressed by poor planting practices, improper maintenance, extreme weather, insect damage, mechanical damage, or other wounds are at increased risk for infection by canker causing pathogens.
Obtaining the right type of sample is critical for proper diagnosis of canker diseases. Samples can be submitted to a local county Extension office; county agents may be able to make the diagnosis or they can facilitate sample submission to a University of Kentucky Plant Disease Diagnostic Laboratory.
This publication details several methods for obtaining appropriate samples. Step-by-step techniques for sampling from twigs, branches, and trunks are depicted with color images.
Canker Sampling of Trees and Woody Ornamentals (PPFS-OR-W-27) is available online.
For additional publications on woody ornamental diseases, visit the UK Plant Pathology Extension Publications webpage.
Nicole Gauthier, Extension Plant Pathologist