Overview
First discovered in North America in 1999, the Plum Pox Virus causes the most destructive disease of Prunus (a genus of trees and shrubs in the flowering plant family Rosaceae). The virus is more commonly called plum pox, PPV, or Sharka.
In October 1999, peach fruit showed symptoms of a disease and tests confirmed the causal agent of the disease.
The Pennsylvania Department of Agriculture announced that the virus was found in Adams County, PA.
Plum pox strains can affect a variety of fruits and nuts like:
- Peaches
- Plums
- Apricots
- Nectarines
- Almonds
- Cherries
It is possible for the virus to affect some Prunus and non-Prunus species. The strain of virus found in Pennsylvania is the D-strain.
Over 20 aphid species can spread the virus to healthy plants. It can also spread through infected nursery stock or grafting.
Plum Pox Virus
More commonly known as plum pox, PPV, or Sharka.
Plum pox severely damages fruit production in established areas. Tree yields can suffer. Some plum varieties report 80-100% premature fruit drop.Infected fruit may be unsightly and difficult to sell as table fruit.
Export of fruit is difficult; export of budwood and nursery stock is next to impossible.
Researchers have found Plum Pox Virus (PPV) in Europe, parts of Asia, Africa, and South America. The virus is well established in many European countries.
PPV is present only in restricted areas in some western European countries. Researchers found the virus in North America. They are working to remove it in the U.S. and Canada.
Host range depends on virus strain. The Plum Pox Virus (PPV) infects all Prunus species. In Europe, wild Prunus species are virus reservoirs. This is especially true for Prunus spinosa (blackthorn).
Test results show that PPV infected common weeds in Pennsylvania. These include white clover and some nightshades. But local field surveys have not found any non-Prunus hosts.
Symptoms depend on host species and cultivars, and on the strain of the virus.
Researchers identify strains with letters:
- D (strain found in Pennsylvania)
- M
- C
- Rec
- Ea
- W
Symptoms can appear one to several years after infection.
Aphids transmit the Plum Pox Virus (PPV) in a non-persistent manner, retaining it for no more than a few hours. Several species of aphid common in PA transmit the virus. Aphids do not pass PPV on to their offspring.
There is no seed transmission in Prunus with the D strain. Some reports say it occurs with the M strain. Long-distance spread is through the distribution of infected Prunus budwood and nursery stock.
Symptoms can be diagnostic, but laboratory testing should back up any diagnosis. Excellent laboratory methods and reagents are available for ELISA and RT-PCR. Bioassay on herbaceous or woody indicators are possible.
The virus scatters unevenly through a tree's branches. Researchers can detect the pathogen in infected flowers, leaves, fruit, wood, and roots.
The best control is preventing introduction. If we introduce it, we will exercise a strict policy of eradication.
Where eradication is not an option, we use less susceptible or tolerant cultivars. They can yield fruit even when plum pox is present, but researchers have developed altered plums that resist the Plum Pox Virus (PPV).
Contact Information
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