Risk Background

Bacterial crown rot disease (Erwinia papayae and Erwinia caricae)

Poses a risk of introducing bacterial crown rot disease (BCR) into Australian territory caused by the bacterium Erwinia papayae and Erwinia caricae.

Erwinia papayae and Erwinia caricae are not present in Australian territory.

Erwinia papayae causes die-back in pawpaw plants. Symptoms include yellowing and necrosis along leaf edges followed by water soaked areas on the bases of leaf stalks, crowns and along leaf mid-ribs. Fruit symptoms include dark spots on the skin and water soaked flesh. Advanced symptoms of the disease include necrotic and water soaked areas that have developed on the stems of plants and have then spread to the internal tissues of the plant, causing die-back and the death of trees.

There is no evidence of this species being truly seed-borne. However, it is reported to spread to the internal tissues of fruits which could indicate its ability to access and potentially be transmitted via the seed.

Some species of Erwinia are known to be externally seed borne and internally seed borne. In order to effectively treat both the external and internal inoculums, treatment with sodium hypochlorite and hot water are both required.

BCR has been recorded in the following countries: Dominica, Fiji, Grenada, Guadeloupe, Indonesia, Japan, Malaysia, Mariana Islands, Martinique, Saint Lucia, Saint Vincent, Tonga, the US Virgin Islands and Venezuela.

Papaya dieback disease (Erwinia mallotivora)

Poses a risk of introducing papaya dieback disease (Erwinia mallotivora) into Australian territory caused by the bacterium Erwinia mallotivora.

Erwinia mallotivora is not present in Australian territory.

Erwinia mallotivora is a newly emerging pathogenic bacterium which has been identified in papaya plants from Malaysia. Early symptoms include brown spots along the main vein of infected leaves followed by water soaked lesions and greasy spots on the stems and fruits, and eventual death of the host plant. The disease is spread by rain splashes, insects, birds and people where the bacterium enters the plant through stomata, hydathodes, lenticels and wounds. Erwinia mallotivora is closely related to Erwinia papayae and Erwinia caricae and causes similar symptoms.

Papaya sticky disease (Papaya meleira virus)

Poses a risk of introducing Papaya Sticky Disease (Papaya meleira virus) into Australian territory caused by the pathogen Papaya meleira virus (PMeV)

Papaya meleira virus is not present in Australian territory.

Papaya meleira virus has been detected infecting papaya in Brazil and Mexico. PMeV is seed borne in Papaya carica and can be transmitted from one generation to the next through contaminated seeds. PMeV is of economic importance as it can cause complete crop loss in papaya plantations over relatively short time periods. It infects green papaya fruit causing an excessive exudation of latex, which rapidly oxidises, and darkens on the surface of fruit. This compromises the flavour of the fruit and causes them to become visually imperfect rendering them un-marketable.