For recommended pesticides, rates and times of application, see Extension Bulletin E-154, Fruit Spray Calendar. This is the most widespread and damaging raspberry virus. All commonly grown cultivars can be infected by the mosaic virus, except for Canby, which is resistant. The plants show a progressive stunting of growth and poor yield. Fruits on infected bushes are small and crumbly.
Growth is stunted, and fruit production is reduced.
A small, yellow-green aphid found on the undersides of leaves spreads this disease. Since the virus is pollen-borne, healthy plants can become infected by pollen from a diseased plant. This virus is widespread throughout the Michigan fruit growing area. Symptoms in raspberries are not very strong. A few leaves on infected bushes may show some pale ringspots in the spring, but these later disappear.