The common raspberry mosaic complex is widespread and may cause the greatest reduction in growth, vigor, fruit yield, and quality of any of the bramble viruses. Fruit yield may be reduced 50 percent or more. No raspberries are immune, however, black and purple raspberries are damaged more severely than red varieties. The symptoms differ with the cultivar grown, the virus or viruses involved, geographical location, and seasonal growing conditions. Symptoms are most evident in the cooler weather of spring and fall, being masked (or disappearing) when temperatures are high in summer.