Intensive on-ground control on the lower Fitzroy River in the Kimberley has seen over 99 per cent of the so far identified infestation of the invasive weed Rubber vine, destroyed.
The project, jointly funded by State NRM Strategic grants program and Rangelands NRM, has enabled ‘Team Rubbervine’ led by John Szymanski, to cover approximately 25,000 hectares in the past three years searching for and controlling the rubber vine infestations.
Team Leader John Szymanski said the control methods had been tuned to an ‘nth’ degree.
“All plants detected were controlled using either hand pulling, cutting the root by small axes, cut-stump with application of Vigilant Herbicide Gel or, in only a few instances, blanket spraying,” Mr Szymanski said.
Searchers are generally spaced at 10 metres apart and are applying the finest grid search pattern, designed to achieve 100 percent probability of detection.
“We have got to this point in the eradication process because of our previous work over the entire infestation area in eliminating remaining breeding rubber vine,” Mr Szymanski said.
The project has incorporated a cycle of monitoring, evaluation, review and program of continuous improvement with annual on-ground activities informed by the analysis and evaluation of on-going data with that collected from the previous year.
The most recent phase of the eradication process of rubber vine in the Willare Infestation Area in 2013, commenced with the aerial search of the entire known infestation area.
“Despite flying double the hours of the previous year, including extra areas in the search and with closer more consistent track spacing, this year we found fewer large vine; 96 compared with 112 in 2012,” Mr Szymanski said.
The test of our progress will be when we replicate the same aerial search in 2014 and compare the results. I am sticking my neck out and predicting the number of plants found will be in single figures.
One of the best indicators of achievement towards the goal of eradication is the team are now marking Return Sites (micro sites which held a breeding rubber vine and associated offspring plants) as ‘Clear’. This means no plants were found at those sites.
In future years, a subsequent search of the same site, which is again marked as ‘Clear’, will designate that site as eradicated.
“A further indicator of achievement towards our goal, is that our work is now dramatically characterised by more searching, with less detection, and little control work. There are days we have not found a single vine and many days when we found only one or two,” Mr Szymanski said.
Mr Szymandski said this result was achieved through effective partnerships between the wide range of stakeholders engaged through the West Kimberley Rubber Vine Steering Committee.
“After completion of the 2014 works we will enter the end game or final phase of eradication. When environmental and other costs are considered, rubber vine has the potential to cost Western Australia many millions of dollars annually and we are well advanced to avert that cost,” he said.
Mr Szymanski also said one of the significant achievements of the last six months has been the involvement of two of the local Traditional Owners, Kelvin Mitchelson and Douglas (Dougie) McCasker. These have brought increased detection skills and also increased skills of non-Aboriginal team members.
“Where rubber vine has been removed, local plants are coming back and they are growing back stronger. It’s easier to access to get through for hunting without having to combat the rubber vine in the way. And you are getting more animals around, “Douglas McCasker from Team Rubbervine said.
Mr Mitchelson is currently investigating setting up a contracting business together with Mr McCasker and other community members to undertaken further eradication work.
“It was just a job to start off with, but now it’s going to be a career opportunity,” Mr McCasker said.
Rubber vine (Cryptostegia grandiflora), a weed of National Significance, is a woody perennial vine that colonises areas and aggressively forms impenetrable thickets, dense canopies. It smothers and chokes native vegetation, preventing both human and animal access and reducing biodiversity.
Rubber vine is only known to occur two locations in WA, on the lower Fitzroy River and lower Lake Argyle Catchment in the Kimberley. While not found in the Northern Territory, the weed has severely cost Queensland in loss of environmental and cultural values, grazing, tourism and recreation. In 1995, Rubber vine was estimated to cost the Queensland beef industry alone 18 million dollars annually.
Image: Control work on rubber vine