Plum pox virus
Plum pox virus
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.
The expression of symptoms of Scharka depends on the Prunus species (tree, shrub species), variety, PPV strain (virus strain), season and location.
Symptoms on leaves include chlorotic spots, banding, or lightening of leaf veins. Leaf deformities are possible on peach. Leaf symptoms are particularly evident in spring. Attenuation of symptoms by high temperatures in summer.
Symptoms on fruit are chlorotic spots or rings. Fruit deformations occur on plums and apricots; underlying flesh is often discolored brown. The fruits have a tendency to gumminess.
Plums and apricots often show ring-shaped lightening at the stone.
The main hosts of the virus strains occurring in Austria are, among woody plants, fruit-bearing Prunus species: apricot(P. armeniaca), peach and nectarine(P. persica), plum (P.domestica) and plum(P. salicina).
Almond(P. dulcis) can be infected but shows few symptoms. Wild Prunus species play a major role as secondary hosts, being a potential source of infection. Ornamental shrubs of the genus Prunus can also be infected.
Within a fruit species, there are large varietal differences in susceptibility.
Varieties tolerant to Scharka (Hanita, Cacacks Schöne, Toptaste, Tophit..) show hardly any symptoms of damage even when infested.
Propagation and transmission
Transmission of the pathogen occurs through infected propagating material, vegetative propagation, and animal vectors(aphids).
Prevention and control
- 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.
Last updated: 17.12.2021