Forty-seven isolates of Fusarium solani obtained from the roots of diseased and healthy conifer seedlings and forest nursery soil were tested for pathogenicity on young Douglas-fir germinants under controlled laboratory conditions. Isolate virulence varied widely; a few were highly virulent whereas many were classified as non-pathogenic. Isolates from the roots of conifer seedlings were generally more virulent than soil isolates; no significant differences in virulence between isolates obtained from diseased roots and healthy roots were found. We concluded that although some F. solani isolates commonly inhabiting forest nurseries have the potential to elicit disease, most are probably only slightly virulent or non-pathogenic.