Plum Pox Virus

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 infected propagative material.

Plum pox virus has never been found in British Columbia. It was first detected in North America in Pennsylvania during the 1999 growing season, and in Ontario in the spring of 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 tree fruit material (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.

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 British Columbia a comprehensive survey (2000-2003) covered all peach, nectarine, apricot and plum blocks that could be identified, as well as nurseries. No PPV was detected in British Columbia.

During the 2006 national survey, 942,196 samples were tested for PPV in Ontario and 4831 samples in Nova Scotia. There were 610 positive samples from 235 blocks in Ontario (Niagara area). A residential survey was also conducted, which involved 21,124 samples, resulting in 20 positives on 6 properties. No PPV was detected in Nova Scotia for the third year; the quarantine area in Nova Scotia will be lifted in 2007.

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

Regulatory Action

Regulatory action by Agriculture and Agri-Food Canada following the detection of PPV in Ontario and Nova Scotia has included the following:

Establishment of quarantine zones around 4 infested areas in Ontario and one in Nova Scotia. 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. Three of the quarantine areas in Ontario have since been lifted following eradication of PPV in those areas. The Niagara quarantine area remains in effect.
Removal of infected trees. All known PPV positive trees have been removed or ordered removed by CFIA. In some cases entire blocks of trees are being removed.
The Plum Pox Virus Compensation Regulations were published in June 2001.

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 veinclearing 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.

PPV Images from Ontario
Click on small images to view larger copies.

	Plum Pox Virus on Peach. Photo Courtesy Neil Miles, University of Guelph		Plum Pox Virus leaf symptoms on peach. Photo courtesy Gerry Walker, OMAFRA
	Plum Pox Virus symptoms on peach fruit. Photo courtesy Gerry Walker, OMAFRA		Plum Pox Virus symptoms on immature peach fruit. Photo courtesy Gerry Walker, OMAFRA

PPV Prevention

Plant only virus-tested material from a reliable source.
Report any unusual symptoms in plum, apricot, nectarine or peach trees. Contact BCMAL to determine if a sample should be taken for PPV screening. There is a very low probability that PPV has been introduced to BC, but it is also very critical to nip an outbreak in the bud or the whole stone fruit industry could be threatened.
Do not plant flowering plums, almonds or other susceptible ornamental species in close proximity to your orchard.

More Information:

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

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

Plum Pox Virus Page (Canadian Food Inspection Agency) - includes survey results, factsheets, ministerial orders and regulations, and news releases.
Policy on Importation and Domestic Movement of Prunus Plant Material (Canadian Food Inspection Agency)
Plum Pox Resources Page (West Virginia University)
USDA-APHIS Plum Pox Virus Page

November 2006

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