Symptoms of citrus greening.
Huanglongbing, also known as ´citrus greening´, is a bacterial disease that is lethal to citrus. Huanglongbing and the psyllid insects that transmit the disease are not known to occur in Australia. It is prohibited matter in Queensland under the Biosecurity Act 2014.
Huanglongbing occurs in many parts of the world, including Asia, parts of North, Central and South America, and Africa. Closer to Australia, it is found in Indonesia, East Timor and Papua New Guinea. Huanglongbing is a serious threat to citrus production areas worldwide.
The psyllid insects are the Asian citrus psyllid (Diaphorina citri) and the African citrus psyllid (Trioza erytreae).
Please help by looking for and reporting any suspicious symptoms.
|What causes huanglongbing?|
Huanglongbing is caused by Candidatus Liberibacter bacteria. The bacteria live in the host plant´s food conducting tissue (phloem), where they impede the movement of nutrients.
|What does it look like?|
In citrus, leaf symptoms include:
Citrus fruit s symptoms are:
All species and cultivars of citrus are affected, such as orange, grapefruit, mandarin, tangelo, kumquat, lemon, lime, pomelo, trifoliate orange and tangelo, and native citrus. Mock orange or orange jasmine (Murraya spp.) can also be a host plant.
|Spread of disease|
Long-distance spread can occur by the movement of infected citrus planting material, or by the movement of plant material infested with huanglongbing infected psyllids.
Movement of other host plants such as orange jasmine (Murraya spp.) and curry leaf (Bergera koenigii) also pose a risk of introducing huanglongbing-infected Asiatic citrus psyllids.
The Australian Quarantine and Inspection Service closely regulates approved importations of host plant material and monitors for illegal plant movement.
Tropical storms and cyclones could also lead to long distance spread of Asiatic citrus psyllids from Indonesia and Papua New Guinea to northern Australia.
|Management and quarantine|
Regularly check citrus for the presence of huanglongbing symptoms such as leaf yellowing on one branch or sectors of the tree and uneven blotchy mottling of leaves, leaf drop, dieback and misshapen fruit. Report suspicious symptoms.
There are simple steps you can take to protect your farm:
There are no impacts on human health from huanglongbing-affected plants and fruit. Although bitter tasting, the fruit is safe to eat.
|Reference and acknowledgement|