Besides spreading via infected pruning equipment, insects and water are also known vectors. Viral Diseases Viruses are smaller than bacteria. As such, they rely on living organisms for dispersal in the garden. There are currently no chemical solutions for curing roses infected with a virus. The best control is to remove the rose, replace the surrounding soil, and inform the nursery or mailorder firm where you obtained the plant.
Serious infestations can greatly weaken plants, producing stem die back and unproductive growth.
A weakened plant will most likely experience winter damage in colder climates. Damage usually begins as a black or brown splotch. Shortly after, the leaf tissues surrounding this spot turn yellow. This is because fungi feed only on dead tissue. Under most conditions, the leaves must remain wet a minimum of seven hours before infection can occur.