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 was conducted annually by the CFIA from 2000 to 2011. PPV was eradicated from Nova Scotia, but remains present in the Niagara area of Ontario. Since 2011, the CFIA has moved towards a Monitoring and Management Program.

In British Columbia, a comprehensive survey covering all peach, nectarine, apricot and plum blocks, as well as nurseries was conducted in 2000-2003, and no PPV was detected. Since then, a B.C. survey has been conducted periodically by CFIA focusing on propagative sources.

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 were removed to 2010. If the percentage infection in a block of trees exceeded a threshold, then the whole block was removed.
  3. The federal Plum Pox Virus Compensation Regulations provide monetary compensation to tree fruit and nursery producers who are impacted by the PPV eradication program.

Under the current Monitoring and Management Program, measures remain in place to help prevent further spread of PPV. Movement restrictions and propagation bans for the infested areas remain in place, as will strict import requirements. Targeted sampling of host trees inside and outside of the quarantine area will be carried out. Growers will be encouraged to use best management practices to manage the disease.

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

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

Prepared by:

Gayle Jesperson
Plant Pathologist
Plant and Animal Health Branch
Ministry of Agriculture,
Kelowna

Updated September, 2014