The following pests are the exotic pests that pose the greatest threat to the Australian papaya industry. The climate of Australia’s papaya producing regions would allow each of these pests to survive, spread, and establish, should they be introduced, causing serious problems for producers.
Make sure that you and your workers are familiar with these pests and monitor your orchard regularly. Any suspicious plant pests or fruit symptoms that you have not seen before should be reported immediately to the Exotic Plant Pest Hotline on 1800 084 881, or to your state or territory department of agriculture.
More information on these pests are included in the fact sheets in the links.
These high priority exotic pests were identified through the development of the Industry Biosecurity Plan for the Papaya Industry. This document includes a complete list of exotic papaya pests and is available from Papaya Australia.
Paracoccus marginatus. Photo by Peggy Greb, USDA Agricultural Research Service, Bugwood.org
Papaya mealy bug
Small yellow-white insect that feeds on the sap of papaya and numerous other plants
Feeding causes leaf chlorosis, leaf distortions and can cause early fruit fall
While feeding, the mealy bugs produce honeydew which encourages sooty mould to develop. This reduces the marketability of fruit
The papaya mealy bug occurs in southern and south eastern Asia, Central America, Mexico and Florida as well as some African countries
The pest could be introduced on plants and plant material from overseas and potentially people who have recently visited an infected papaya orchard
Papaya is affected by a number of endemic (eg Two spotted spider mite T urticae) and exotic spider mites (eg T piercei and T truncates which both occur in Asia)
Spider mites feed on the plant’s sap causing leaves to become covered with spots of lighter green. Spider mites also produce silk webs on the undersides of leaves
Together these symptoms are diagnostic of spider mites
Feeding also causes reduced fruit quality and yield
All spider mites are very small (usually only 0.5 mm long). The colour of adults can assist in identification – Adult T urticae are a yellow-green or red colour with two dark spots, while adult T piercei and T truncatus are usually a dark red colour without spots
If pests or plant symptoms are found that are not normally present on your property, they may be new not only to your property, but to the region, or even Australia. Knowing how to recognise their presence and promptly report new pests is essential for containment and eradication programs.
Qfly. Photo by GT O’Loughlin, Department of Agriculture, Bugwood.org
Endemic fruit flies
The Queensland fruit fly (Qfly) (Bactrocera tryoni) and Mediterranean fruit fly (Med fly) (Ceratitis capitata) are significant threats to papaya production and accessing vital export markets. Qfly is widespread throughout Queensland and has a limited distribution through south-eastern Australia. Medfly is restricted to Western Australia. Further information can be found at www.preventfruitfly.com.au
Potyvirus, Strain P. Photo by Dr Jose R Liberato DPI&F, PaDIL
Papaya ringspot virus
Disease is caused by a virus that is spread by various aphids or by planting diseased plants
Virus causes yellow patterns to develop on leaves and leaf rolling to occur
Green ring-shaped markings develop on the skin of infected fruit and oily streaks develop on the plant’s stem. Trees may also become stunted if infected when young
Some mites may also cause leaf yellowing but obvious rings on fruit are tell-tale signs of the virus
Infection causes reduced fruit set and reduced vigour as well as reducing fruit quality and taste
There is no cure for this disease
Virus affects papaya, watermelon, pumpkins and cucurbits
Occurs in most tropical and subtropical countries including Australia
In Australia the virus is restricted to south east Queensland
A quarantine area exists in the south eastern corner of Queensland extending from the border north to Lowmead (24º30’ S) and from the coast west to near Theodore (150º E). Quarantine area details