Over the recent times, there is an increased concern about virus infections such as Prunus necrotic ringspot virus (PNRSV) and Prune dwarf virus (PDV) in various Prunus spp. In order to help the growers and nurseries to understand these virus infections, the following article was composed. Readers are suggested to review to Pallas et al., 2012 Phytopathology review article for further information and references.
Prunus spp. (Plums, Almonds, Cherries, Peaches, Apricots, Nectarines) are widely cultivated as fruit and ornamental crops. Virus diseases in Prunus spp. causes significant yield loss. Member of the genus Ilarviruses infect Prunus spp and are distributed worldwide. Prunus necrotic ringspot virus (PNRSV) and Prune dwarf virus (PDV) are two of the most economically important and prevalent viruses causing significant losses in cultivated crops.
PNRSV has a wide host range affecting all Prunus spp., hop and rose. PDV infects only Prunus spp. and reports indicate its occurrence in sweet cherry, sour cherry and peach.
PNRSV can reduce bud-take in nurseries, reduce fruit growth (10 to 30%), fruit yield (20 to 60%), delay fruit maturity and increase winter injury susceptibility in orchards. PDV causes up to 50% yield losses in sour cherry, low bud-take in nurseries (40 to 50%) and reduced growth of young trees. Synergistic effect of PNRSV and PDV, causing Peach stunt disease is the most damaging, leading to progressive decline and death of stone fruit trees.
PNRSV symptoms on leaves include chlorotic to yellow line pattern mosaic, necrotic spots and shot holes.
PDV symptoms on leaves include chlorotic rings, spots, mottle and line pattern.
- Serological assays such as ELISA (most common method of detection)
- Reverse transcription-PCR (Popular and highly sensitive assay)
- By grafting onto woody indicator hosts (less popular)
- Molecular hybridization using radio-labelled probes (less popular)
- Microarrays (less popular)
Effect of temperature on symptoms and detection: –
Temperature plays an important role in symptom expression by affecting the replication of virus in its host. When the day temperatures exceed 38◦C (100◦F) over a 12-day period, the new leaves emerging from an infected tree do not show any symptoms, thus making it difficult to perform visual diagnosis and detection by serological assays such as ELISA.
Seed and Pollen transmission are common means by which the virus spreads in an orchard or nursery. Some studies found thrips- and other arthropod- mediated transmission of virus. Such spread occurs when the insects feed on the pollen coming from a virus-infected tree.
Prevention is better than cure. Important method for controlling virus-infection is using certified virus-tested planting material. At Sunburst, we suggest testing a sample of nursery stock for virus infection before planting in the orchard for confirmation of disease-free status.
In case of virus-infected orchards, Sunburst is the only company in CA that offers remedial programs using the nutrient products from Fusion360 Inc. These programs have been proven to improve overall growth of the orchard. The last resort in diseased, heavily infested orchards is removal of virus-infected trees and planting with clean material.
If you have any questions, please contact Sunburst PDC using our online contact form, or call us at 866.762.8778.