Providing practical information to help you protect your farm from biosecurity risks

Exercise tests readiness for ‘yellow dragon disease’ of citrus

March 31, 2015
HLB Leaf Symptoms (Florida)

HLB leaf symptoms on a tree in Florida. Photo: Stuart Pettigrew

Australia’s readiness for an incursion of the exotic disease of citrus, huanglongbing (HLB) or yellow dragon disease was boosted by a 2-day workshop, Exercise Yellow Dragon.

The exercise simulated an incursion discovered in Sydney of HLB and the insect vector that can spread it from plant to plant, the Asian citrus psyllid, a combination that has caused devastation of citrus crops elsewhere in the world.

HLB, also known as citrus greening disease, is not a human health issue, but it kills citrus trees. There is no known cure.

It is considered one of the most serious plant diseases in the world and affects orchards throughout Asia, the Middle East, South and Central America, the Caribbean and some southern states of the USA. It’s also present in regions close to Australia including Indonesia, East Timor and Papua New Guinea.

If HLB was to establish in Australia it would seriously threaten citrus orchards as well as backyard citrus trees, native citrus and ornamental citrus such as Murraya.

Plant Health Australia’s Dr Stephen Dibley said that the aim of the exercise was to assess the effectiveness of Australia’s planned eradication strategies for HLB and ACP, in a scenario where the disease was first detected in an urban setting.

Representatives from government and industry who would be involved in a citrus pest incursion participated in the workshop. Together they worked through the steps that would occur in a real eradication response.

“During the exercise we considered how aspects of a response would work in an urban environment,” Dr Dibley said.

ACP Nymphs (California) (2)

Asian citrus psyllid nymphs on a plant in California. Photo: Stuart Pettigrew

“This included eradication options, tracing of host material and other items that could carry the pests, and how to get the general community involved in the response.”

“People at the exercise recognised the importance of informing the public, who would be able to help in a response by checking citrus plants in their backyards, reporting anything unusual and abiding by quarantine zone restrictions,” Dr Dibley added.

Participants also heard first-hand accounts from a recent study tour to affected states of the USA and were shown the diagnostic facilities at the Elizabeth Macarthur Agricultural Institute which would be used to test for HLB in a real incursion.

Judith Damiani, Chief Executive Officer of Citrus Australia, said that Exercise Yellow Dragon had been very useful for everyone involved.

“You can sit at a desk and make plans for a theoretical incursion of a serious pest incursion like HLB, but a dress rehearsal like this makes everyone really consider all the details of how it would work,” Ms Damiani said.

“We feel that we are now better prepared to deal with the real thing, though of course we hope we never have to face HLB in Australia,” Ms Damiani added.

Exercise Yellow Dragon is part of the Citrus Biosecurity Project, which is funded by Horticulture Innovation Australia Limited and jointly managed by Plant Health Australia and Citrus Australia.