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What is it?
Plum pox virus, also known as sharka, is the most devastating viral disease of stone fruit in the world. This virus affects many wild and cultivated species of Prunus plants, including plums, peaches, apricots, nectarines, cherries and almonds.
Where is it found?
Plum pox was first discovered in Bulgaria in 1917 and has since spread through most of Europe; it is estimated that more than 100 million trees are now infected. The disease is also present in Turkey, Syria, Egypt , India, the United Kingdom, Africa, the former USSR and parts of the United States, Canada and South America.
What are its effects?
Trees infected with plum pox virus can show a range of signs on leaves, flowers and fruit depending on host species, locality and season. The disease develops slowly over several years, usually affecting one or two branches before spreading through the tree.
Fruit production drops by up to a third and fruit may drop prematurely; the presence of other viruses in the tree can increase the severity of plum pox infection.
Fruit from infected trees is deformed or blemished and marked with spots or rings; it is usually unmarketable because of its unattractive appearance, low sugar content, poor flavour and short shelf life.
Plum pox virus is spread by grafting diseased stock onto other trees, by aphids that suck sap and by seed. There is no cure or treatment for the virus and all infected trees in an area must be destroyed.
What’s the risk to Australia?
Plum pox virus poses a considerable risk to Australia’s stone fruit industries. To keep it out, all imports of stone fruit planting material are screened in quarantine facilities. Many stone fruit food products containing seeds require heat treatment to kill the seed and prevent the spread of the virus.
23 Apr 2007