Huanglongbing

Huanglongbing is not present in the ACT or anywhere else in mainland Australia.

About the disease

Huanglongbing (also known as citrus greening disease) is one of the most destructive citrus tree diseases worldwide. Huanglongbing is one of Australia's national priority plant pests and there are strict quarantine measures in place to prevent its introduction into Australia.

Three bacterial pathogens can cause this disease. Vectors are the Asian citrus psyllid and the African citrus psyllid.

Why it is a problem

Huanglongbing is a bacterial disease that leads to tree decline and death. It is 100% fatal to citrus trees, has no known cure and destroys both crop yields and fruit quality.

What to look for

• Symptoms on trees include branch dieback and heavy flowering on diseased branches.
• Leaf symptoms include yellowing of leaves and shoots, small upright chlorotic leaves, asymmetric, blotchy and mottled leaves that cross the leaf veins and leaf symptoms randomly arranged in the canopy.
• Fruit will ripen unevenly, be bitter tasting and drop prematurely.

How it spreads

Huanglongbing is spread primarily through Asian Citrus Psyllid  and the African Citrus Psyllid. The psyllids feed on the sap of an infected citrus tree, become a carrier for the bacteria that causes the disease, and then transmit the disease to healthy trees when it feeds.

Additional transmission also occurs through the movement of infected plant material.

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