Thorn In Your Side: Removing Invasive Parkinsonia Trees From Your Land


It's well known that Australia ecosystem is at constant risk from a wide variety of invasive plant species, but while many people fear the encroachment of cane toads, feral hogs and other highly visible invaders, the threat posed by invasive tree species is less well publicised.  Parkinsonia aculeata, more commonly known simply as Parkinsonia, is one of these alien trees, and it can deal serious damage to both surrounding wildlife and any animals or humans that run afoul of its wickedly sharp thorns.

Why are Parkinsonia trees on my land a problem?

Parkinsonia trees have a number of unusual properties which can make them obstructive or even dangerous trees to have on your land:

  • Aggressive growth: Growing closely together in densely packed thickets of trees, Parkinsonia colonies rapidly starve competing native plants of light and water. These thickets can also block access to waterways and provide safe havens for vermin. Parkinsonia grow rapidly, and their thin, wiry trunks and branches can endure wind and foul weather easily.
  • Seeds: Parkinsonia trees produce an enormous amount of seeds, which are tough and capable of lying dormant for long periods. This means they can be carried away by rivers and streams or consumed and excreted by animals, causing Parkinsonia infestations to spread over surprisingly wide areas. Wherever Parkinsonia seeds end up, they stand a good chance of surviving and thriving, as they can grow in a wide variety of soil types and can survive prolonged droughts.
  • Suckering: Even without seeds, Parkinsonia are sill capable of a form of reproduction in the form of suckers. These sprouts grow from the root systems of damaged or disturbed trees, and can rapidly replace trees that are improperly felled or uprooted.
  • Thorns: Parkinsonia is also commonly known as Jerusalem thorn, and the eponymous spikes are notoriously long and sharp. Particularly large thorns can puncture bike tyres and damage the hides of livestock.
  • Erosion: While these trees can grow in a diverse array of habitats, they prefer to grow by waterways and riverbanks, where their strong roots and rapid groundwater absorption can cause rapid soil erosion. 

This combination of nasty traits has allowed Parkinsonia to spread over wide areas of Australia in a relatively short space of time, and the tree is now listed as a Weed of National Significance by the Australian government. As you can see, if you have any of these trees present on your land, it's in your best interests to remove them.

How can Parkinsonia trees be removed?

Parkinsonia's thick coat of thorns and general hardiness make it a difficult tree to tackle head-on, but there are a few ways approaches you can choose from when the time comes to remove them:

  • Repeated felling: Parkinsonia trees are capable of remarkable regrowth, and younger trees will almost always survive being felled. However, repeated felling will deplete the trees of the energy and nutrients required for regrowth, and will eventually cause them to die. This technique is cheap and chemical-free, but can be very difficult to accomplish without professional tree felling services, particularly when dealing with larger thickets of trees.
  • Uprooting: Uprooting can be very effective, and smaller plants can be removed easily with a trowel or mattock. However, large trees and thickets will need to be mechanically removed with bulldozing or chain-pulling, which can be more expensive and may damage any beneficial plants remaining in the area. You must also ensure that uprooting is completed thoroughly with no hidden roots left behind, as even small fragments of root can sprout viable suckers.
  • Herbicides: A number of herbicides are suitable for Parkinsonia control; some can be sprayed  onto the foliage, while others must be applied directly to the bark or a hole cut into the stump of a felled tree. Follow the directions given with your chosen herbicide closely, and call in professional aid if you are at all unsure how to use them. Take particular care when using herbicide on waterside trees, as accidental contamination of freshwater can land you in legal trouble.


6 June 2016

Using Your Trees for Fun, Form and Function

Hi, my name is Christine. As a lifelong lover of the Shel Silverstein book "The Giving Tree," I have always been interested in the many different relationships one can have with a tree. I own a relatively large property with several trees, and I have worked hard to make those trees an essential part of my life. Some of my trees provide me with food, others provide me with energy-efficient shade that reduces my air conditioning bill and others create recreation opportunities for my kids in the form of treehouses or swings attached to the trees. Still other trees boost my property values just by being beautiful. If you want ideas about using your trees for fun, form and function, please explore this blog.