A mango dieback disease affecting orchards in the Northern Territory has growers in Western Australia on alert as harvest approaches. Mango twig tip dieback (MTTD), first detected in Darwin crops in 2017, is estimated to cost the Darwin mango industry US$7 million per year.
The disease begins as dark lesions on twigs, later spreading to leaves, branches, and sometimes entire trees. Reports suggest up to 90 per cent of Kensington Pride orchards in the Darwin region have been affected.
Steve Angel, the largest mango producer in WA with 120,000 Kensington Pride and R2E2 trees near Kununurra, said his farm operates under strict quarantine. "We allow no foreign vehicles into the orchard," he explained. Visitors must disinfect their footwear, and machinery is sterilised before entry. "Anyone who comes from Darwin, or any reps or whatever, has to walk through a foot bath. It's not the answer, but it's just preventative maintenance. We're just trying to stop it from coming here. Whether we're successful or not, I don't know."
Despite these measures, Angel noted that growers had "no real control" over whether the disease might cross into WA, given the regular transport between the NT and WA.
Australian Mango Industry Association chief executive Trevor Dunmall said WA growers should not be overly concerned. "With regards to mango twig tip dieback, they shouldn't be too worried. Western Australia has very sound biosecurity measures, so the movement of plant material into northern Western Australia is not happening."
Research from the NT Department of Agriculture and Fisheries (DAF) has linked the disease to two fungal species, Lasiodiplodia and Neofusicoccum. These fungi are typically harmless but can become pathogenic when trees are stressed by extreme heat. There is no cure yet, but NT DAF is conducting trials and applying fungicide sprays in orchards before harvest.
"There is no uncontrolled plant or fruit movements from NT to WA, and before harvesting fruit, NT producers conduct in-field fungicide sprays," a DAF spokesperson said.
The WA Department of Primary Industries and Regional Development (DPIRD) said it is working with NT authorities to manage risks. "WA mango growers are encouraged to employ good orchard hygiene and use plant material from reputable sources to reduce the risk of mango twig tip dieback being introduced into WA. All consignments of mango plants must be certified as treated with fungicides and insecticides prior to entry."
MTTD differs from dieback in WA's south-west, which is often caused by Phytophthora fungi and usually affects other tree species.
Source: ABC News