Exotic alert : Psyllid watch

Pest and diseases double threat: Asian Citrus Psyllid and Huanglongbing

Rebekah Niall, Plant Biosecurity Officer Preparedness

October 2015

Definition: An exotic plant pest is a disease-causing organism or an invertebrate not present in Australia and which threatens agricultural production, forestry or native and amenity plants.

The Asian citrus psyllid is a small citrus pest that, on its own, causes minor damage to citrus leaves. But don't be fooled! This modest psyllid is in fact one of the greatest threats to citrus production worldwide as it could be carrying the world's most devastating citrus disease: Huanglongbing (HLB).

Dying mandarin trees infected with Huanlongbing. The leaves are shredding off the branches — Dying mandarin trees infected with Huanlongbing. The leaves are shedding off the branches. Photo courtesy of Nerida Donovan, NSW DPI.

Huanglongbing, also known as citrus greening, is a bacterial disease that is fatal to citrus trees. Once a citrus tree becomes infected with HLB, there is no cure and whilst it can take a few years for symptoms to appear, the tree will eventually die.

Any fruit produced is bitter, hard, misshapen and unmarketable.

Many overseas citrus growers currently battling HLB have no choice but to try and stop the spread of the disease by removing infected trees, or else risk infecting their entire orchard.

Asian citrus psyllids only have to feed on an HLB-infected tree once and then they carry the disease for life. The infection is spread when the psyllid moves to feed on other citrus trees.

An important way to stop HLB being introduced into Australia is to stop the spread of the Asian citrus psyllid. HLB can also spread by grafting infected plant material, so budwood should only be imported into the country through legal channels and tested in post-entry quarantine before release. It is essential that orchards are planted with healthy, disease-free trees.

Information on how to recognise and protect your property from the Asian citrus psyllid and HLB is available from the NSW DPI website. Information about this, other exotic pests and biosecurity for citrus orchards is available in a manual developed by Stuart Pettigrew (HIA project) and is available from the Citrus Australia website.

If you suspect that you have found an Asian citrus psyllid or seen symptoms of HLB call the Exotic Plant Pest Hotline on 1800 084 881.

For more information, email Rebekah Niall or phone 02 6391 3535.