We’re always willing to try something new here at Wild Mob. After all, you don’t learn without a little experimentation!
Recently, we’ve been experimenting with a new weed control method on Brampton Island. We’ve been aSALTing an invasive infestation of sisal plants with just that… plain ol’ salt!
The sisal situation
There are several large infestations of sisal on Brampton Island.
The actual history of how it got there to begin with has been lost over the years. Our skipper Steve reckons it was introduced into islands before WW2 for making sisal hemp for ropes.
We’ve been focusing on a patch on the northern side of the island, adjacent to the walking track leading to the Old Jetty Site. The area of infestation is approximately 80 square metres.
Why it’s a huge problem
Sisal hemp aggressively destroys native species through prolific reproduction. Sisal hemp bulbills (a type of seed which germinates on the plant) are also able to float, and can sustain really extreme conditions.
Worse yet, the seed stalk of the Sisal plant can produce more than 500 bulbills! When the stalk drops, the bulbills scatter around the main plant and readily take root and continue growing. Nasty!
In the past, the Queensland Parks and Wildlife Service have used chemical herbicide to control the sisal.
Problem is, it’s really hard to be discriminate when using herbicide. There is always the risk that native plants will also succumb to the herbicide.
As some infestation are also close to turtle nesting areas, there is a risk that herbicides will leach into the surrounding sand and ultimately impact turtle eggs.
Brampton sisal ‘asalt’
Naturally, we wanted to try something a little different. We started trialling using salt to kill the sisal plants in August 2017.
First, we cut off all the fleshy leaves around the plant using a cane knife. We then scooped out a hole in the centre or heart of the plant, and packed about a cup of coarse pool salt right into the centre.
So far, they’re looking good! The mature treated plants have browned off and there is no sign of any new growth. Better yet, some of the smaller plants have started to decompose back to ground level.
There’s more testing to be done. But if successful, this could be a new, almost completely unobtrusive method to getting on top of the infestation. It may also be able to be used on other invasive weeds in the GBR islands.
We’ll update you in the coming months on our progress. Watch this space!
Keen to get involved? We’re running a special trip to Brampton next March. Conservation work by morning, learning to standup paddleboard by afternoon! Find out more here.