Plum Pox Virus (PPV) or Sharka is a virus of stone fruit. PPV was first detected in the United States in 1999 in Pennsylvania, and later in New York in 2006.
There are seven individual strains of PPV. Only one of these, strain D, is known to occur in New York. PPV-D causes Plum Pox disease in peach, nectarine, apricot, and plum.
Long distance spread of PPV is the result of moving infected nursery stock or propagative material to a new region. Grafts and budwood are also ways of moving infected material. Secondary transmission, or short distance spread, is by aphids.
Once it is in an orchard, there is no cure for PPV. Infected trees must be removed and destroyed. The best prevention practice is to only use virus free stock.
Newly infected trees are rarely symptomatic and visually symptoms are often not apparent until three or more years after infection. It is critical that symptomless trees be regarded seriously as they will act as a silent virus source.
Visual symptoms may appear on leaves, fruit, flowers, and the stone (seed). The leaves have yellow or light green patterns, bands, or blotches on them. The fruit may have similar symptoms. The symptoms are distributed unevenly within the tree.
In New York PPV-D impacts stone fruit industry by reducing fruit yields and the marketability of fruit. The fruit trees are rendered useless for fruit tree production and shortens the productive lifespan of orchards.
Worldwide, PPV is estimated to have a $600 million impact on the apricot, peach, and plum industries.
Staff from the Department survey and sample orchards in and around the impacted areas to detect PPV and to direct mitigation efforts. In 2018, 100,246 samples were collected from 802 acres of commercial orchard and 2573 acres along the Niagara river. No PPV was detected.
All samples are sent to the lab at the New York State Agricultural Experiment Station, Cornell University, in Geneva, New York. Over 2500 Prunus tree leaves are screened on a daily basis for the presence of the Plum Pox Virus in New York State. The leaves are tested using the Enzyme-linked Immunosorbent Assay (ELISA) test.
Monitoring for PPV is an ongoing effort to eradicate and exclude this pest from New York.
There is a state quarantine for PPV in place to restrict the movement of regulated items. The quarantine includes parts of Dutchess, Niagara, Orange, Sullivan, and Ulster counties. All parts of the plants are regulated which includes but is not limited to the leaves, fruit, roots, stems or any propagative material, and nursery stock.
Industry and the public can help stop the spread of PPV by allowing regulatory officials to survey and sample host trees by granting access to homeowner and commercial orchards. When purchasing trees, they can be obtained from areas free of PPV. When suspect infections are found, they can be reported to the Department for further investigation.