Australia's flaky frontier has again been exposed as authorities across the north grapple with yet more invaders.
Ehrlichiosis in dogs, Japanese encephalitis virus, fall armyworm - they have all spread quickly around Australia in recent years.
One of the world's worst weeds is now becoming well established in the Northern Territory since it was found in July 2019.
Aerial surveys last year have revealed the fast growing Siam weed had spread 100km from the initial infestation site to cover more than 10 properties.
It was first found at Tully River in far north Queensland in 1994 and has since spread to Townsville-Thuringowa, Mossman and Mt Garnet areas in that state. One infestation has been found near Rockhampton.
A native of central and South America, experts say Siam weed has the potential to spread across northern Australia and down the eastern and western coastlines.
Only this week there was the awful discovery of banana freckle just outside Darwin.
It took more than five years to eradicate that plant disease at a cost approaching $30 million.
Plant biosecurity officers are undertaking surveillance across the Top End to determine how widespread this latest outbreak is.
The Consultative Committee on Emergency Plant Pests met on Friday to consider a national response to the find.
In better news, the discovery of a colony of small ants down south on the Victorian border was not the feared electric ants which are worrying Queensland.
Meanwhile, Territory land owners have been warned to keep a lookout for Siam weed infestations which are toxic to cattle.
Siam weed grows and spreads best in the wet season and kills around 3000 cattle annually in the Philippines.
The parachute seeds are dispersed by wind and water and contain fine barbs which readily stick to clothing and fur. Siam weed is easily spread long-distances through contamination of vehicles, equipment and produce.
It blossoms in June-July with pinkish-white flowers and is identifiable by its large stem and leaves both of which resemble a 'pitch-forking' pattern.
The department's Siam weed project officer Tom Price said: "Siam weed is highly invasive and is toxic to livestock. It can also cause skin complaints and asthma in allergy-prone people."
The case of a banana freckle at a rural residential property in the Top End has now been confirmed using sequencing results from an interstate laboratory.
Banana freckle is a devastating fungal disease of banana leaves and fruit.
The Phyllosticta cavendishii strain of fungus was detected on Dwarf Cavendish bananas at the infected property in the Batchelor region.
The banana plants have only been grown on the infected property for the past three years since the disease was thought eradicated in 2019.
Plant biosecurity officials in the NT are now working with industry to support a small number of nurseries, commercial growers and rural property owners to manage this pest.
The NT Government is also working with the Commonwealth, state and territory governments through the national response arrangements.
MORE READING: Australia's moat no barrier to all the world's nasties.
NT chief plant health officer Dr Anne Walters said: "Banana freckle is a serious threat to the industry.
"Territorians may feel concerned that banana plants will need to be destroyed, we are not at this level of threat.
"Our focus at this point is surveillance and further advice on what we can do to protect the Territory's industry will be made available in due course.
NT Farmers Association chief executive Paul Burke said: "In any of these incursions it's important we all work together.
"This is a plant disease but we can't forget about the human element, that is - looking after our growers and their employees."
And finally, there was biosecurity relief when a colony of exotic-looking tiny red ants were discovered living inside a water meter at Echuca, on the Murray River.
When the homeowner found the unusual ants, he immediately contacted Agriculture Victoria and included a series of pictures.
Agriculture Victoria leading biosecurity officer Emily Hill said the state's entomologists weren't able to categorically determine their identity so visits were made to the site.
"Thankfully, in this instance, the ants sampled were found to be a native species that were morphologically similar to electric ants.
"Electric ants are highly aggressive and can rapidly spread through a variety of landscapes, displacing native species and causing injury to livestock, wildlife, pets and people with painful bites," she said.
Ms Hill said these exotic ant species - which are present in Queensland and under an eradication program there - could come into Victoria in a variety of ways and quickly spread through human activity with the movement of plants, plant products, garden waste or machinery.
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