DNA Barcoding as a Tool for Surveying Cytospora Species Associated with Branch Dieback and Canker Diseases of Woody Plants in Canada

Background/Objectives: Branch dieback and canker diseases caused by Cytospora species adversely impact the health of woody plants worldwide. Results: During this survey, 59 Cytospora isolates were obtained from symptomatic trees and shrubs growing in southwest Ontario and Saskatchewan, Canada. A DNA barcoding approach combined with morphological characterization identified 15 known species of Cytospora associated with these diseases: C. chrysosperma, C. curvata, C. euonymina, C. hoffmannii, C. kantschavelii, C. leucosperma, C. leucostoma, C. nitschkeana, C. piceae, C. populina, C. pruinopsis, C. pruinosa, C. ribis, C. schulzeri, and C. sorbina. The most common species isolated from multiple hosts were C. sorbina (10), C. chrysosperma (8), C. nitschkeana (6), and C. pruinosa (6). A wide range of host associations, including non-conifer species, was observed for C. piceae. Conclusions: The obtained results contribute to the study of diversity, host affiliation, geographical distribution, and pathogenicity of Cytospora species occurring on woody plants in both natural habitats and agricultural systems. The findings support the effectiveness of using DNA barcodes in fungal taxonomy and plant pathology studies.