Permaculture perspective/info on Uredo rangelii ( Myrtle rust ) & other pathogens

Discussion in 'Put Your Questions to the Experts!' started by Ashtoon, May 4, 2017.

  1. Ashtoon

    Ashtoon New Member

    May 4, 2017
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    The news that Myrtle Rust may have made it's way to New Zealand has me turned to gather research on the particular subject. I usually gather most plant/soil/nature research from various sources, but I do find myself turning to the vast amount of info that has usually been collected and organised under the label Permaculture. Along with my own experience as a landscaper/designer I find myself battling with (but also embracing) permacultural attitudes and concepts on invasives vs exotics etc and natural soil amendments and natural design to various problems encountered in the landscape.
    Basically, I'm continually researching to 'confirm my own bias' that nature just does it better.

    So the news that this 'invasive disease' has made its way to NZ has me stumped. The fact that it could (possibly) do some serious damage to some of our most cherished native flora such as Metrosideros excelsa (NZ xmas tree) is pretty worrying, but also interesting to me as to why it happens.

    Upon reading up on the pathogen, it supposedly originates from south America and made its way to Australia in 2010, so a lot of the readers of the site should know it well and have possibly dealt with it.

    Basically, I am after any/all information on the subject and most of all I want to try and understand the great proverbial 'why'.
    It has nothing to do with the soil, a lot of nz mytle family trees have been growing here forever obviously, yet here comes this invasive, blown in, and it could simply destroy well established native flora.
    It doesn't make any sense when thinking about diseases from a soil amendment or an unfit/poorly designed environment perspective.
    Are there really just 'bad ass' diseases out there that come to destroy? How can we use nature to combat such things? Are these plants going to just have to be treated for the rest of their lives to keep them alive? Is nature basically going to have to be on lock down to prevent the spread of such diseases?

    Thanks in advance for any sources and further reading/information.
  2. BajaJohn

    BajaJohn Member

    Apr 4, 2017
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    Hot desert/coastal
    This article is pretty basic but may provide a reasonable introduction. It also has links to other articles.
    The basic problem in many cases is that modern transportation has broken down the natural barriers such as oceans that existed in the world when much of our present flora and fauna evolved. Those barriers prevented myrtle rust from getting to New Zealand so the plants of New Zealand had no need to develop any resistance to that fungus. In other areas myrtle rust and it's host plants underwent millennia of co-evolution, honing predatory actions and the defences against them. By the time myrtle rust reached New Zealand, it was a vigorous and seasoned predator, normally kept in check by the equally vigorous, pathogen-related counter-attacks of the hosts it had evolved with. New Zealand plants haven't had an opportunity to develop countermeasures to myrtle rust simply because they haven't been exposed to it until recently. Consequently the New Zealand plants are easy prey for this new (to them) predator.
    There are similar examples occurring all over the world with all kinds of organisms. Many would argue that humans are an incredibly dangerous invasive species and they certainly fit the definition. It seems unlikely that the mechanisms that introduce invasive species to new habitats will diminish so the world will probably have to come to terms with the challenge until the organisms of the planet stabilize in a highly mobile environment.
    One of the mechanisms that combats novel invasive organisms is genetic variability. For example, some scientists believe they have evidence suggesting that some people survived the bubonic plague of 14th century Europe because they carried a certain gene that became much more common after the plague. Modern agribusiness thrives on cloning which significantly reduces genetic variability thus increasing vulnerability to new predators. Furthermore, the response to an infestation is often to destroy all of the host plants - even the apparently uninfected ones, thus removing any opportunity to identify resistant plants.

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