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Strain Differences in Fusarium oxysporum Causing Diseases of Douglas-Fir Seedlings. W. J. Bloomberg, Forest Pathologist, Canadian Forestry Service, Department of the Environment, Pacific Forest Research Center, Victoria, British Columbia; W. Lock, Technician, Canadian Forestry Service, Department of the Environment, Pacific Forest Research Center, Victoria, British Columbia. Phytopathology 62:481-485. Accepted for publication 13 November 1971. DOI: 10.1094/Phyto-62-481.

Axenically grown Douglas-fir seedlings were inoculated with Fusarium oxysporum isolates obtained in a nursery from roots of healthy Douglas-fir seedlings or from roots of seedlings infected with pre-emergence damping-off, postemergence damping-off, root rot, or corky root. All isolates killed all seedlings, but there were significant differences among isolates in the chronological pattern of mortality they produced. In seedlings growing in controlled environments in naturally infested soil, there was no significant association between any one disease caused by F. oxysporum and another. In nurseries, there were no significant correlations between the levels of one disease and another.