In March 2015, a banana farm in Tully in Far North Queensland went into lockdown. Harvesting of fruit was stopped and movement of plant material, soil, equipment, vehicles and people on and off the farm were restricted.
More than 16,000 banana plants were destroyed. This sudden rush of activity was in response to the detection of a fungus called fusarium wilt tropical race 4 (TR4), which triggered state and national emergency plant pest response arrangements.
Fusarium wilt may be caused by several different strains of the fungal organism, and is commonly known as Panama disease. The most serious of which is tropical race 4 which has had a devastating impact on commercial Cavendish plantations internationally.
Some of the scientific information that underpins Biosecurity Queensland’s emergency plan, which was developed by DAF in consultation with the Australian Banana Growers’ Council, has come from the Banana Plant Protection Program, including work in developing disease diagnostics.
Developed and run by QAAFI and DAF, with funding from Horticulture Innovation Australia, the Banana Plant Protection Program has assisted the Australian banana industry to prepare for potential banana disease incursions into Australia.
Panama disease resistance has been a key target of the protection program. Last century, the Panama disease race 1 strain wiped out large-scale global production of the then ubiquitous Gros Michel bananas, which were replaced with the Cavendish variety. But while Cavendish is resistant to race 1, it’s highly susceptible to the TR4 strain.
Queensland’s banana growers have been bracing themselves for TR4’s arrival since 1997, when it was detected in the Northern Territory. Most of the territory’s small banana industry was wiped out as a result of that outbreak.
The detection of TR4 in far north Queensland, where most of Australia’s bananas are grown, had the potential for a similar devastating outcome in Queensland.
QAAFI’s Banana Plant Protection Program is one of a number of current projects working to mitigate the impacts of the disease as part of the multi-agency response to the detection of TR4 in Queensland.
Getting ahead of the problem
Australia’s proactive approach to disease management is rare in the international banana industry, but logical given the local industry’s historic attunement to biosecurity issues.
That history dates back a century, when the banana bunchy top virus was detected in northern New South Wales and south-east Queensland, where it has been carefully contained ever since. More recently, in 2001, there was an outbreak of the black sigatoka fungal disease in Tully, which was eradicated from the major production area in a world-first success.
In 2013, an outbreak of the banana freckle fungus in the Northern Territory was also met with an eradication program, the plan for which was developed by the Northern Territory Government with input from other state biosecurity agencies, and scientists who were working as part of the Banana Plant Protection Program.
“Nine years ago we started looking at banana freckle,” says Professor Andre Drenth, who leads the program. “Morphological and molecular studies indicated that there were three different pathogen species, one endemic and two exotic, for which we developed molecular diagnostic assays. Once we finished that work we had a way to identify all three of the freckle pathogens.”
When a tissue sample was sent in from a Northern Territory farm with an unknown disease in 2013, the test developed in that work identified it as one of the new exotic strains of the banana freckle pathogen.
“If we had not done that basic research, we wouldn’t have even started the eradication campaign, because we wouldn’t have been sure if it was endemic or exotic,” says Professor Drenth.
The Panama response
The re-emergence of TR4 in Australia’s main banana producing region is the next challenge for the Banana Plant Protection Program and the science behind the disease-containment plans used in Tully will now segue into work on Fusarium wilt resistance screening.
“We have been importing and screening a lot of varieties for resistance to Race 1, and we have trials set up in northern New South Wales, north Queensland and more recently in the Northern Territory to screen for resistance to TR4,” Professor Drenth said.
The Banana Plant Protection Program has established agreements with banana-breeding programs around the world in addition to those already established by DAF.
“Australia is one of the few places in the world where you can see material from all the breeding and selection programs around the world,” says Professor Drenth. “Collaborators like to work with us because we’re not a commercial threat to them, and we do provide scientifically rigorous screening and evaluation.”
Professor Drenth’s team now aims to develop commercially viable banana cultivars with full TR4 resistance and hopes new varieties that are resistant to both Panama disease race 1 and TR4 will be available to growers, if TR4 begins to impact significantly on production.
This project has been jointly funded by the Department of Agriculture and Fisheries, the University of Queensland and Horticulture Innovation Australia.
