Septoria spp. Infection among North American Northwest Coast provenances of Black Cottonwood (Populus trichocarpa) : a field study of natural infection in a Fraser Valley plantation Cimolai, Tomas
Given the recent finding of Septoria musiva among poplars in a Fraser Valley plantation and nearby vicinity in British Columbia, we undertook a field study of Septoria spp. presence among black cottonwood (P. trichocarpa) trees which were being assessed in a British Columbian provenance study. For seven such provenances, S. musiva and S. populicola were found on leaves in frequencies of 3.9-33.3% and 65.8-85.3% respectively. There were no significant differences in the isolation frequency between provenances for either fungus (p>0.10). The provenances were then pooled into two large groups to account for higher and lower latitudes; the lower latitude (South Coast/USA) cluster was found to bear both S. musiva and S. populicola in lesser frequencies (p=0.03 and p=0.01 respectively). S. musiva was isolated from tree canker, but the presence of canker-like lesions on stem and branches did not correlate with the presence of either fungus overall (p>0.10). Endemic S. musiva among poplars in this plantation raises several concerns about the local epidemiology. Further studies to confirm our findings are warranted as are studies that further the understanding of the S. musiva-P. trichocarpa pathosystem.
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