Septoria musiva isolated from cankered stems in hybrid poplar stool beds, Fraser Valley, British Columbia

B. E. Callan, I. Leal, B. Foord, J. J. Dennis, C. van Oosten

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Septoria musiva, a pathogen causing leaf spots and stem cankers, was isolated from cankered hybrid poplar stems (TXM 271–287 and TXM 271–286) in commercial stool beds in the Fraser Valley, southwest British Columbia (BC) in November, 2006 and January, 2007. The identity of this pathogen was confirmed both morphologically in culture and by using species-specific PCR primers, unlike earlier questionable reports of this pathogen in BC. A survey of stems larger than 1 cm diameter in one stool bed revealed that 199 out of 458 (43.4%) stems bore one or more cankers. Septoria musiva was isolated in culture from 44% of 50 cankered stems sampled in this stool bed. In the past, leaf spots on BC poplars have occasionally been attributed to Smusivabased on conidial morphology, but S. populicola is far more prevalent in natural and commercial cottonwood and hybrid poplar stands, and the latter pathogen is not associated with stem cankers. The conidial size range of these two species overlaps, which adds uncertainty to earlier diagnoses of S. musiva based on morphology alone, especially since it had not previously been isolated from cankers collected in BC. This isolation and PCR-confirmed identification of S. musiva documents the first record of its association with a high incidence of stem cankers in commercially grown hybrid poplars in BC.


Septoria musiva; S. populicola; Mycosphaerella populorum; M. populicola; Davidiella populorum; Populus trichocarpa x Populus maximowiczii; hybrid poplar; cankers; stool beds; British Columbia; PCR; culture



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