Darwin researchers discover cause of mysterious mango disease

Darwin researchers discover cause of mysterious mango disease

Mango farmer Marshall Haritos once produced 18,000 trays of Kensington Pride mangoes from his Berry Springs property each season.

But over the last five years, a mystery disease has turned his once-profitable orchard into an operation that’s almost no longer viable.

After the inexplicable onset of mango twig tip dieback, the farm’s annual yield has slowly declined to 4,000 cartons — just a third of the harvest required to break even.

Marshall Haritos’s mango orchard has been impacted by mango twig tip dieback since 2020. (ABC News: Pete Garnish)

Mr Haritos said if the disease continued to plague his mango trees, he would soon be “out of money and incentive” to keep farming.

“[If] this keeps going for another year or two, I’m coming to the end of it. That’ll be it,”

he said.

Mango twig tip dieback causes a loss of foliage and fruit. (ABC News: Pete Garnish)

First identified in the Darwin region in 2017, mango twig tip dieback is a disease that does not impact fruit quality but can drastically reduce an orchard’s yield.

Research had so far failed to identify the exact cause and whether it was a viral, bacterial or fungal disease.

As scientists worked to narrow down the cause, Mr Haritos and other farmers tried fighting off the disease by changing fertilisers, using fungicides and even spraying trees with water — with little success.

“There must be a cure for this. I certainly haven’t found it,” Mr Haritos said.

Plant pathologist Dr Jane Ray (pictured) has also been part of the research into mango twig tip dieback. (ABC News: Anzaya Karim)

Now, researchers from the NT Department of Agriculture and Fisheries have made a breakthrough in the fight against mango twig tip dieback.

While they have not found a cure yet, a team of scientists has found two species of fungus, Lasiodiplodia and Neofusicoccum, are the likely cause of the disease.

Northern Territory chief plant health officer Dr Sally Heaton said the fungi, which was not “exotic”, could remain benign until a tree was stressed by environmental factors.

“That could be a whole range of things. Is it water, is it climatic, is it too hot, is it pruning?”

she said.

“These two fungi can turn pathogenic and seem to cause disease in the trees.”

Dr Stan Bellgard, the research team’s coordinator, said mango twig tip dieback had been a challenge to diagnose ever since it first emerged in the Top End eight years ago.

“Worldwide, when we looked at the literature, there was indeed at around this sort of time an emergence of a group of [similar] pathogens,” he said.

“What makes them very difficult to diagnose is they can be present and not cause infection.”

Leo Skliros, president of the Northern Territory Mango Industry Association, said the disease’s impact had been “substantial”, particularly on varieties such as Kensington Pride and Nam Dok Mai.

Leo Skliros has welcomed the scientific discovery but said it should have come sooner. (ABC Rural: Lydia Burton)

Mr Skliros believes the scientific discovery marks a “first step” after persistent advocacy from growers.

“I don’t think enough was done early enough to get to this stage — we should have been at this stage three or four years ago,” he said.

As researchers now turn to a cure for mango twig tip dieback, Dr Bellgard is hopeful farmers can play a role in managing the disease.

“The way forward is together,” he said.

“It’s going to require agronomic consultants, farmers who are willing to participate in the on-farm research, maybe in some way partitioning part of their orchard for particular aspects of the research.”

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