Plum pox

Plum pox potyvirus

Plum pox

Plum pox

Legal Status: Notifiable Organism
Status in New Zealand: Not in New Zealand
Organism: Micro-organism

This virus is not in New Zealand.

If you suspect you have seen symptoms of this virus call 0800 80 99 66.

Description

Plum pox virus (PPV) affects various members of the genus Prunus (stone fruit trees). PPV has also been transmitted artificially to a wide range of other plant species.

The virus has four main types or strains; the most severe and easily transmitted in the M strain.

The extent and type of symptoms caused by the virus depends on the species and variety of the affected tree, time of year, climatic conditions and strain of virus. PPV can cause a wide range of leaf, flower and fruit symptoms on affected trees.

In some peach varieties affected trees may have dark pink stripes on flower petals. Leaf symptoms include random yellow flecks on the minor veins, yellow blotches, rings or dead area that drop out creating holes. Fruit of sensitive varieties of peach and nectarine may have yellow of red rings. Fruit of apricots and plum may have raised centres giving them a bumpy appearance. Apricots may also develop distinctive rings on the pits, this symptom is a very clear indication of PPV.

Some trees may show no symptoms or symptoms after a number of years. In these cases infections are only discovered through laboratory testing.

Photos

Impact

This virus significantly reduces stone fruit production in areas where it is established. Plum pox can also have additional economic impacts as it can cause fruit to be unmarketable.

Spread

PPV was first noticed in Bulgaria in 1915. The virus has since gradually spread through most of Europe, parts of Asia and Egypt. Programmes to eradicate recent findings in the USA and Canada are continuing.

Aphids can transmit plum pox between trees in close proximity. Studies indicate that atleast 14 aphid species are capable of transmitting the virus. In New Zealand two of the most important aphid species capable of transmitting PPV are Brachycaudus persicae (Passerini) and Myzus persicae (Sulzer) (Scott & Emberson, 1999).

Aphids have been shown to carry the virus on their stylets for several kilometres if starved during flight. PPV can spread very quickly in nurseries, where material is planted close together enabling aphid to move easily from plant to plant. The virus is spread over longer distances by the movement of affected nursery stock and propagation materials.

Management

Biosecurity New Zealand has stringent importation requirements to stop the arrival of the virus to New Zealand. Preventing entry to New Zealand is the most effective measure against establishment. New stone fruit nursery stock imports are comprehensively tested for PPV whilst held in quarantine. The prospects for eradication of a PPV outbreak diminish with the time from initial incursion to detection.Therefore it is important to report immediately any trees showing suspect symptoms to Biosecurity New Zealand by telephoning 0800 80 99 66. Eradication requires complete destruction of infected trees, and would probably involve removal of entire orchard blocks where infected trees were found. Intensive monitoring of stone fruit for the virus would be needed, using laboratory tests. Additional measures would include controls on movement of plant material, certification of nursery stock and changing to crops not affected by the virus. Aphid control may not be a practical approach, given that an individual aphid can infect a tree within seconds. The programme would have to continue over multiple years.

Attempts to produce resistant stone fruit varieties by conventional breeding have had limited success. A variety of plum with good resistance to PPV that has been developed overseas using genetic engineering is not commercially available.

Useful Resources


www.aphis.usda.gov (offsite link to www.aphis.usda.gov)

Page last updated: 22 October 2008