Massachusetts
Introduced Pests Outreach Project

Plum Pox Virus (Pest Alert 08/2006)

(Click on an image below to see the captioned full-size version)
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Scientific Name: Potyviruses: Potyviridae
Common Names: Plum Pox, PPV, Sharka, Sharka Disease

There are currently four known strains of PPV:

  • PPV-D: Found in peach, plum, apricot and nectarine.
    As of March 2008, only PPV-D has been found in North America.
  • PPV-M: Found in peach, plum, apricot and nectarine. Attacks peach more aggressively than other stone fruit species, is more effectively transferred by aphids, and is thought to be able to be transferred through seed.
  • PPV-EA: Found in peach.
  • PPV-C: Found in sour and sweet cherry.

Known Hosts:
Prunus species, including almond, apricot, cherry (sweet and tart), nectarine, peach, pear, plum, and wild species. In addition, more than 30 different annual, perennial, and woody species from nine different plant families have been found to be naturally infected with PPV or have been artificially infected in the lab. Susceptibility is dependent on the host and on the viral strain. For a complete list, see http://www.apsnet.org/publications/apsnetfeatures/pages/plumpoxpotyvirus.aspx.

Significance:
Plum pox virus has been a serious disease of stone fruit crops in Europe for almost a century. It was first discovered in the US in 1999, in the state of Pennsylvania, and has since been found in New York (2006), Michigan (2006) and Ontario, Canada (2000). Fruit from trees impacted by PPV can be rendered unmarketable, and there is no cure - infected trees must be removed and destroyed.

Pathways:
Within distances of approximately three miles or less, PPV can be spread by aphids, including the green peach aphid (Myzus persicae) and the leafcurl plum aphid (Brachycaudus helichrysi). For more details on aphid transmission of PPV see http://www.apsnet.org/publications/apsnetfeatures/pages/plumpoxpotyvirus.aspx. PPV is spread longer distances through the unintentional transport of infected stock or propagation materials.

Symptoms on Plum (including Prunus domestica):
Leaves with blotches, speckles or ring spots (Figure 1). Brown, dead areas can form and fall out, leaving "shot holes." Look for symptoms on young spring leaves.
Dark rings of brown form on unripe fruit (Figure 2), turning to red on maturing fruit. Fruits become deformed and bumpy. Severely infected fruit is shriveled with brown spots.
Pits may show white rings or line patterns.
In fall, brown cankers with purple borders may be visible on the green shoots of infected trees (seen in Hungary).
Plums tend to show more symptoms than other species, and are considered a good indicator host.

Symptoms on Peach (Prunus persica):
Pink stripes or streaking on the petals of specimens with large, showy flowers ("color-breaking", Figure 3) - a good early season characteristic.
Leaves with yellow ringspots or netting, veinal chlorosis, speckling, or blotches (Figure 4). Leaves may also become deformed, with brown patches.
Yellow or red rings or blotches on the skin of the fruit (Figure 5). Line patterns form when rings run together. Particularly obvious on the 'Encore' and 'O'Henry' cultivars.

Symptoms on Apricot (Prunus armeniaca):
Leaves with yellow or light green ring spot, blotches, netting, or vein yellowing (Figure 6). Symptoms are more difficult to see than those in plum or peach.
Fruit with large light-colored yellow or red rings or blotches, with line patterns that form when several rings run together (Figure 7). May become deformed or bumpy and develop brown patches. Distortion of flesh often extends to the pit, unlike peach.
Some fruit may show no outward symptoms but have white ring or line patterns on the pit surface (Figure 8).

Symptoms on Sour and Sweet Cherry (Prunus cerasus and P. avium):
Cherry trees infected with PPV-C have been found in Europe (a strain not currently found in the US).
Leaves develop yellow rings or blotches (Figure 9).
Fruits with yellow or brown rings, notched marks.

General symptoms for all fruit trees, and monitoring tips:
Early fruit drop.
Fruits with reduced sugar content.
Symptoms are often visible at the bottom of a branch, but not at the tip, and tend to be more visible in the spring.
Holding leaves up to the light can reveal vein yellowing when symptoms are mild.
Root suckers are considered a good source of PPV and should be monitored if an infected tree is removed but roots remain.
Many other herbaceous and woody species carry PPV, and can be used as indicators. For a complete list, see http://www.apsnet.org/publications/apsnetfeatures/pages/plumpoxpotyvirus.aspx

Similar diseases:
Bacterial spot causes brown leaf spots that can fall out, leaving "shot holes," but starts out as small water-soaked gray areas on the leaf undersides.
Rusty spot of peach creates orange to tan spots that discolor the fuzz on peach fruit and cause it to drop off, leaving bald patches.
X disease can cause red leaf blotches, and on peach causes yellowed summer leaves with brown spots that fall out and leave shot holes.
Thrip damage on plum fruit causes brown spots that look similar to those caused by PPV.
A number of other pathogens and nutrient deficiencies can cause symptoms that are similar to PPV. For more information, see http://msue.anr.msu.edu/uploads/files/plum-pox-issue-low.pdf

Fact sheets and references:
Plum Pox Virus Resource Page, Penn State University
http://extension.psu.edu/plants/tree-fruit/sharka

Plum pox virus page, Michigan State University Extension
http://msue.anr.msu.edu/news/history_biology_and_management_of_the_plum_pox_virus

Plum Pox Virus (PPV) on Ornamentals, Penn State University Cooperative Extension
http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/plum-pox-virus-in-ornamentals

Plum Pox - Potyvirus Disease of Stone Fruits, American Phytopathological Society
(includes extensive list of hosts and aphid vectors, and information about resistant cultivars)
http://www.apsnet.org/publications/apsnetfeatures/pages/plumpoxpotyvirus.aspx

PestTracker Invasive Pathogen: Plum Pox, Potyvirus Group (PPV), NAPIS
http://pest.ceris.purdue.edu/pest.php?code=FVPPVBE

Plum Pox Virus page, Canadian Food Inspection Agency
http://www.inspection.gc.ca/english/plaveg/pestrava/ppv/ppve.shtml

Descriptions of Plant Viruses: Plum pox virus, by Miroslav Glasa and Thierry Candresse
http://www.dpvweb.net/dpv/showadpv.php?dpvno=410

Plum Pox Photo Gallery, USDA
http://www.aphis.usda.gov/plant_health/plant_pest_info/plum_pox/downloads/plumpox-photos.pdf

last reviewed August 8, 2013


Massachusetts Department of Agricultural Resources
Massachusetts Introduced Pests Outreach Project is a collaboration between the Massachusetts Dept. of Agricultural Resources and the UMass Extension Agriculture and Landscape Program. This website was made possible, in part, by a Cooperative Agreement from the United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS). It may not necessarily express APHIS' views.