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Ministry of Agriculture

Plum Pox Virus (Sharka)

Plum pox virus (PPV) is considered to be the most serious virus disease of stone fruit, with the potential to devastate stone fruit production. The fruit from infected trees becomes severely blemished and unmarketable. The disease has caused severe damage to the fruit industry in Europe. PPV is spread by several species of aphids as well as by infected propagative material.

Plum pox virus has never been found in British Columbia. It was first detected in North America in Pennsylvania in 1999, and in Ontario in 2000. Surveys conducted by the Canadian Food Inspection Agency (CFIA) in 2000 determined that PPV was generally present in Southern Ontario at a low incidence. PPV was also detected in one Nova Scotia orchard. The illegal movement of Prunus spp. planting stock or budwood is suspected to be the cause of this disease being introduced to North America.

In 2006, PPV was detected in New York and Michigan, the first detections outside of Pennsylvania in the USA. By 2010, the outbreaks in Pennsylvania and Michigan were considered to be eradicated.

Symptoms

Symptoms of plum pox virus are variable depending on the strain of virus, the host species and even the host cultivar, and may take several years to develop. On plum, leaf symptoms include pale green spots, rings and lines. Usually only some of the leaves on a tree are affected. Fruit symptoms include rings and blotches which become harder to detect as the fruit ripens, as well as sunken lesions. The pit may also be marked with rings or spots. Affected fruit have poor flavour due to low sugar content. Infected trees have a tendency to drop much of their fruit prematurely, resulting in a "blue carpet" of fruit on the ground.

Symptoms on peach include chlorotic vein-clearing and banding, along with leaf twisting or distortion. Fruit symptoms include rings, lines and spots, which may disappear at ripening. Apricot leaf symptoms are less conspicuous, but fruit of some cultivars are severely marked and may be misshapen, with poor flavour. The pit is often marked with rings or spots.

Plum Pox Virus Images from Ontario

plum pox virus symptoms on peach plum pox virus symptoms on peach
Plum pox virus symptoms on peach fruit.
Photo Courtesy of Neil Miles, University of Guelph		 Plum pox virus symptoms on peach fruit.
Photo courtesy of Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)
plum pox virus symptoms on peach leaf plum pox virus symptoms on peach leaf
Plum pox virus leaf symptoms on peach leaf.
Photo courtesy of OMAFRA		 Plum pox virus leaf symptoms on peach leaves.
Photo courtesy of OMAFRA

National Survey

A national survey and eradication program for PPV has been conducted annually by the CFIA since the disease was first detected in Canada. In Ontario, the disease remains under intensive surveillance and eradication. In Nova Scotia, PPV is now considered to be eradicated, with no positive samples in the last 3 years. In British Columbia, a comprehensive survey (2000-2003) covering all peach, nectarine, apricot and plum blocks, as well as nurseries was conducted, and no PPV was detected. Since then, a B.C. survey has been conducted every 4 years, focusing on propagative sources.

For detailed information on survey results, refer to the CFIA website at: http://www.inspection.gc.ca/english/plaveg/pestrava/ppv/surv/surve.shtml

Regulatory Action

Regulatory action by the CFIA following the detection of PPV in Ontario and Nova Scotia has included the following:
  1. Establishment of quarantine zones around infested areas. This resulted in prohibitions and restrictions on the movement of specific Prunus species susceptible to PPV, to prevent introduction into non-infected areas by movement of plant material. The Niagara quarantine area in Ontario remains in effect.
  2. Removal of infected trees. All PPV positive trees must be removed. If the percentage infection in a block of trees exceeds a threshold, then the whole block must be removed.
  3. The Plum Pox Virus Compensation Regulations provide monetary compensation to tree fruit and nursery producers who are impacted by the PPV eradication program.

Prevention

  • Plant only virus-free material from a reliable source.
  • Report any unusual symptoms in plum, apricot, nectarine or peach trees to CFIA or the B.C. Ministry of Agriculture. Early detection is the best defence!

More Information

If you think you have seen symptoms of PPV in British Columbia, or want more information, please contact Gayle Jesperson, Plant Pathologist, B.C. Ministry of Agriculture, Kelowna.

Also visit the following websites for more information on PPV, including periodic updates on the Canadian and US surveys:

Updated April, 2010