Rubber Vine, the Rubbish

Photo by Colin G Wilson. Rubber vine smothering vegetation.
Viewed 30.03.2014

Rubber Vine, Cryptostegia grandiflora, endemic to the Island of Madagascar, was introduced to Northern Australia in 1917 in the hope of becoming a rubber source ( Huwer, McFadyen, 1999).  The shrub has since become a serious problem in the areas that it inhabits.

 Rubber vine generally invades waterways first where the seeds germinate in moist silt layers after rain fall. From there it expands outward invading hillsides and pastures forming dense and often inpenetratable thickets resulting in not only a decrease in biodiversity but a loss of grazing land and can make it difficult to muster stock.  In addition rubber vine creates habitat for feral animals, which poses further threat to native species.  Once the thickets are established the plant can cover trees up to 30m tall which choke out native vegetation (McFadyen, Harvey, 1990). The weed is poisonous to stock however it is rarely consumed, only when other feed is scarce.

There have been several mechanisms to conquer this weed. Chemical control is effective as rubber vine is susceptible to many herbicides however this method has proven to be uneconomical due to the vast areas of infestation.  In 1988, Euclasta whalleyi , a leaf feeding moth, also endemic to Madagascar was released as a potential biocontrol agent. It has been effective to a degree, increasing leaf litter which promotes grass growth amongst rubber vine which intern increases fuel loads for fire management. This creates opportunities to use fire as a part of the approach to manage this damaging weed (Tomly, Evans, 2004).

 

 In 1995 a rust fungus, Maravalia cryptostegiae, also from Madagascar was released to areas of the weed’s range in Queensland.  The results showed a rust-induced defoliation, producing an overall reduction in fecundity and biomass of the plant. Particularly in areas with low water tables weed growth decreased noticeably. At some sites both drought and rust induced stressed caused up to 75% plant mortality. This resulted in improved growth of indigenous grasses amongst thickets which creates ideal conditions in order to burn off and control the weed further. In order to gain full restraint over this economically and ecologically damaging weed would require the assistance of the landholders in which the rubber vine occupies.

 

 

Refereneces:

 

Huwer RK, McFadyen R.E, 1999, 'Biology and the host range of the hawk moth Nephele densoi Keferstein (Lep.: Sphingidaw) a potential agent for the biological control of rubber vine Cryptosteyia grandflora', Biocontrol Science Technology, Vol.9, no. 1, p.10.

 

McFadyden R.E, Harvey G.J, 1990, 'Distribution and control of rubber vine Cryptosteyia grandflora weed in North Queensland, Plant Protection Quarterly, Vol.5 no. 4, pp. 152-155.

 

Tomley A.J, Evans H.C, 2004, 'Establishment of and preliminary impact studies on, the rust, Maravalia Cryptopstegiae, of invasive alien weed, Cryptosteyia grandflora in Queensland, Australia, Plant Pathology, Vol.53, no. 4, pp. 475-484.