Fruit flavour is altered resulting in tasteless, bitter fruit. The keeping quality, even of unmarked fruit, is often also reduced. Partial or complete fruit drop, 2-3 weeks before the normal harvest date, can occur, depending on the susceptibility of the affected cultivar. The virus is usually introduced into a nursery or orchard by either infected planting material or aphid vectors from infected trees on nearby orchards. Once in the orchard or nursery the virus is spread rapidly by aphid vectors, unless control measures are introduced.
Many aphid species are efficient vectors of plum pox.
Some researchers have reported transmission of the virus by pollen and seed, while others have not found this. Control Fruit trees in the orchard infected with plum pox cannot be cured. In Europe, the spread of plum pox is reduced by using only certified virus free plants, maintaining tight aphid control spray programmes and eliminating weeds which can be infected with the virus and act as reservoirs of infection. Once the virus is detected in the orchard, the major control method is to immediately rogue out trees which show symptoms and burn the plant material. Whole orchards have had to be removed.