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Conservation Week: Peter de Lange’s work protecting our trees

  • Myrtle Rust on Ramarama Awaroa Valley
    Myrtle Rust on Ramarama Awaroa Valley

It’s Conservation Week 2020 and who better to hear from than Associate Professor Peter de Lange, lecturer in our School of Environmental and Animal Sciences...

It’s Conservation Week 2020 and who better to hear from than Associate Professor Peter de Lange, lecturer in our School of Environmental and Animal Sciences who has spent many years researching and working in the field with other experts to find out more about the diseases threatening our native environment. He spoke on Radio New Zealand last week about issues surrounding ongoing effort to halt the spread of Myrtle Rust and Kauri Dieback – in particular how they got here, the impact they’re having on our trees and how experts are working on tackling them.

Peter de Lange

Peter is part of the Beyond Myrtle Rust research programme. He has found that Myrtle Rust is far more widespread that initially thought, and there is currently no way to control it.

“I got a fright, I was seeing 3 or 4 metre ramarama dead or dying....it was shifting already into the rata....

“We could spray, but each tree has its own ecosystem. We dont know what the cohabitants are and how important they are – some of those cohabitants might actually prevent Myrtle Rust attacking the host. You potentially could lose an ecosystem within an ecosystem if you lose ramarama.”

But there is a ray of hope, in the form of a tiny maggot.

“A [Unitec] student and Scion have been working in tandem with us, and we’ve found that tiny maggots actually eat rust. They’re not known to be native to New Zealand but they’ve arrived recently it seems and they are eating the rust spores. So it’s a potential biocontrol but whether it’s actually going to have a huge impact on controlling Myrtle Rust we don’t know, but hey, fingers crossed.”

“Our environment we depend on and the more that we strangle it, it’s like sitting in a tank and pulling out the oxygen. We are going to suffer if we don’t do something. We need the research, we need the confidence in people and to get out there and do something.”

On Kauri Dieback, Peter said “we know that sequencing data shows that at a minimum, Kauri Dieback has been in New Zealand for 600 years. However it cannot be denied, assuming it is a native disease, that something has happened to make it more virilent.”

Listen to the full interview with Peter de Lange

More about Myrtle Rust and Kauri Dieback:

Myrtle Rust

It is native to Amazonia, South America where it was discovered in the late 1800s but it has now spread by human agency to many countries around the world, from where it has further spread by wind movement.

In 2017, myrtle rust was detected on the New Zealand mainland and the Ministry for Primary Industries now considers it widespread in the country, attacking all members of the myrtle family it is currently a serious threat to ramarama and some species of rātā. Of the 28 species of native myrtles here it has so far been found attacking six of them, three seriously so.

Currently we have no practical cure for myrtle rust, and the rust is still actively spreading. Based on what happened in Australia it may be a decade before the full impact becomes apparent. Myrtle  rust is very easily spread - by the wind or on clothing.

"I felt like crying because all the ramarama down the Awaroa Valley (South Kawhia) had myrtle rust in them and were dying," he says. Peter spent much of his youth in South Kawhia bush, the destruction he saw there was he felt akin to losing a close friend.

Kauri Dieback

The fungus-like disease has been making headlines for years and is known as a type of pathogen, also called phytophthora.

Peter de Lange says previous research suggests not only that it's native to our country, but it's been here for hundreds of years. That said no one is certain why it has become so lethal to kauri. More research is needed.

Credit: RNZ website