Over 40 years ago, a mystery vigilante released a fungus to control blackberry in Australia. But why?

SashaFoxWalters/Getty Over the summer of 1983–84, a fungus called Phragmidium violaceum was introduced to Australia.

It was done secretly, deliberately and illegally.

And it was done for one purpose: to kill blackberry plants.

I’m a historian, not a detective.

My recent research on the illicit introduction of violaceum (also known as ‘blackberry rust’) doesn’t identify a culprit.

But it does shed light on one of Australia’s most significant and mysterious breaches of biosecurity over the past half-century.

Like so many other animals and plants, blackberry was deliberately introduced to Australia from Britain.

The earliest records date to the 1840s.

The plant was valued for its abundance of juicy fruit as well for its uses as a hedge.

Few herbivores other than tough-lipped deer and goats can eat the thorny plant.

But its delicious berries are prized by all sorts of animals, from foxes to fairywrens .

Every Australian knows common mynah birds are bad, rabbits are worse and feral cats kill native animals unchecked.

But how do we decide what makes an introduced species “good” or “bad” – and will we ever concede that some species are here to stay? With the help of humans and animals, blackberry spread rapidly.

By the late 1880s, it was becoming recognised as a serious agricultural weed.