Profile

Scharka is a viral disease that affects trees and shrub species from the rose family (Prunus species). The virus causes changes in leaves, fruits and the stone.

Biology

In addition to infected planting material, the disease is also transmitted by various aphid species (non-persistent), which thus ensure the spread of the virus within a plant stand. Systemic infestation of a tree can take several years. By then, the distribution of the viruses in the plant may be very uneven. There is no transmission via seeds.

Host plants

The main hosts of the virus strains occurring in Austria are fruit-bearing Prunus species among the woody plants: apricot(P. armeniaca), peach and nectarine(P. persica), plum(P. domestica) and plum(P. salicina).

Almond(P. dulcis) can be infected, but hardly shows any symptoms. Wild Prunus species play a major role as secondary hosts, as they are a potential source of infection. Ornamental shrubs of the genus Prunus can also be infected.

There are major differences in susceptibility between varieties within a fruit species.

Scharka-tolerant varieties (Hanita, Cacacks Schöne, Toptaste, Tophit...) show hardly any symptoms of damage even when infected. Jojo is a Scharka-resistant variety that is often used as an intermediate graft to produce virus-free planting material, as an infected variety cannot grow on Jojo.

Distribution

Scharka disease (Plum pox virus) is widespread in Europe and is also found in Egypt, Tunisia, USA, Canada, Chile, Argentina, Brazil and several Asian countries (e.g. China, India).

Propagation and transmission

Transmission of the pathogen occurs through infected propagating material, vegetative propagation, and animal vectors(aphids).

Economic importance

Scharka is the most important virose in stone fruit cultivation and has great economic importance. Significant loss of quality due to fruit deformation or discoloration and changes in taste as well as yield losses of up to 100% are possible.

Prevention and control

Preventive measures:

• Purchase of certified planting material
• Examination of scions or rootstocks for latent infections
• no planting of host plants in infested areas
• use of tolerant or resistant varieties
• Vector treatment with approved plant protection products (see list of plant protection products approved in Austria)
• Sanitation measures: Removal of all plants with visually visible symptoms (it is necessary to remove also the rootstocks) and their destruction without damage
• Propagation quarters for scion or rootstock production: laboratory examination (screening) of the propagation quarters for latent infections by Scharka.

Phytosanitary status

Plum pox virus (PPV) is a Union regulated non-quarantine pest.

Services

Plant Health Services