The most common viral diseases found in Minnesota include raspberry mosaic, leaf curl, and tomato ringspot. Raspberry mosaic disease can also infect plants without expressing any visual symptoms. Raspberry mosaic disease is caused by a complex of viruses and transmitted by the large raspberry aphid. Severe infection causes a reduction in stand vigor, fruit quality, winter hardiness, and stand yield. Raspberry leaf curl virus typically causes curling and distortion of dark green leaves.
Infected plants appear stunted and contain excessive branching.
Infected fruit is usually small, crumbly, and seedy. This disease is spread slowly by the small raspberry aphid. Severe infection causes a reduction in yield, fruit quality, and winter hardiness. Infected leaflets appear stunted, curied, and distorted. Yellow rings, line patterns, or veinal chlorosis commonly appear on the leaves of red raspberry plants.