Other disorders of raspberries can cause symptoms similar to viruses. Positive identification of a bramble virus or virus complex cannot be based on foliar symptoms alone. Greenhouse and laboratory tests using specific scientific techniques are required for positive identification of viruses. No raspberry plants are immune, but black and purple cultivars are damaged more severely than red cultivars. The symptoms of mosaic vary considerably, depending upon the cultivar grown, which virus or viruses of the complex are involved, and time of year.
Symptoms are most evident on new canes during cooler weather of spring and fall.
Symptoms may disappear in the summer when temperatures are high. This is an important point to remember when considering control of virus diseases. Even though symptoms may disappear temporarily, plants remain infected for life. Infected canes are usually short and less vigorous than healthy canes. Leaves are mottled with yellowish or light green spots on a darker green background.