Next time you are out for a drive along Mornington-Flinders Rd, take a short deviation along Meakins Road for a couple of kilometers
What was a tangled jungle of thick, invasive, exotic Karamu scrub (
Coprosma robusta) along road verge just a few years ago is now a mix of young native plants and plastic sheaths covering recent plantings.
Meakins Rd verge showing new native growth in foreground and the last section of Karamu in the background.
Credit for this outstanding success goes to our very own 'weedbuster', Michelle Stacey. Michelle has tirelessly
organised and coordinated the work coordinating a combination of machinery that chews right through the Karamu, chemical spraying, corresponding with local landowners, obtaining replacement tube stock, and organising volunteers into a number of planting days.
Michelle Stacey out early preparing holes for later planting by volunteers.
But this success is just one step towards achieving the complete eradication of an invasive weed before it reaches the stage where this becomes impossible.
Karamu is a fast-growing, highly-invasive New Zealand native vascular-plant to 6 m that. In addition to the Mornington Peninsula, it has gained footholds in the Dandenong Ranges, and Glenelg regions (
VicFlora 2019).
It has been assessed by
Agriculture Victoria (2019a) as a high threat to all plant communities that it invades, with the capacity to “
destroy understorey vegetation within 2-3 years” and the “
potential to displace all species within the ground and middle strata”.
As shown in the image to the right, the Meakins Road infestation had already started to kill mature gums and other trees before it was removed.
Mature eucalypts killed by the dense growth of Karamu along Meakins Rd.
Because of its rapid growth rate and attractive fruits that may be spread over large distances by birds and foxes, Karamu poses a serious threat to our remaining areas of natural bushland and habitat. It ranks in the top 20 invasive Victorian weeds (
White et al 2018), alongside such major weeds as Sweet Pittosporum (
Pittosporum undulatum).
This capacity for rapid and widespread devastation was demonstrated by recent Tasmanian experiences. A small initial Karamu infestation spread rapidly over substantial areas along the Derwent River, including across wetlands and into the river (
DPIPWE 2019). As a result, the Tasmanian government moved quickly to declare Karamu as a Noxious Weed.
The Landcare folks in Main Creek Catchment have applied to the State Government to list Karamu as a Threatening Process under the Flora and Fauna Guarantee Act (1988). If successful, this would enable a coordinated action plan to be developed to enable full eradication throughout Victoria.
That application was made in May 2019 and their Scientific Advisory Committee has given it serious attention. Sadly, the wheels of bureaucracy move ever so slowly, so we still await a final answer.
In the meantime, Landcare and Royal Botanical Gardens folk have found by genetic analysis that Karamu has started to hybridise with local indigenous species such as Prickly Currant Bush (
Coprosma quadrifida). Such hybridisation may pose a serious threat to the evolution of such native species.
Watch this space for further news. if you suspect Karamu may be growing in your area, please email me so we can build up a map for ensuring we treat all infestations before they become a major problem.
-Article and images by Greg Holland.