See:
Blackberry (Rubus spp.) - Armillaria Root Rot
Note Out of hundreds of samples there have been 19 that were diagnosed with Armillaria root rot by the OSU Plant Clinic.
The fungus has attacked the crown of these plants.
OSU Extension Plant Pathology Slide Set, 1964.
The fungus can be seen as white threads near the center of this picture.
OSU Extension Plant Pathology Slide Set.
See:
Blackberry (Rubus spp.) - Armillaria Root Rot
Note Out of hundreds of samples there have been 19 that were diagnosed with Armillaria root rot by the OSU Plant Clinic.