Calotrope (Calotropis procera): a weed on the move in northern Queensland

Abstract

Calotrope (Calotropis procera) is an exotic woody shrub threatening the biodiversity and productivity of the rangelands in central and northern Queensland. It is widespread throughout the Gulf of Carpentaria region but is spreading into new areas where many land managers are not familiar with it. A collaborative research project funded by MLA has been initiated to better understand its rate of spread, ecology and invasiveness, as well as to improve the range of effective control options. To date, foliar herbicide trials have identified a limited number of chemicals that are effective in certain seasons. Soil applied herbicides are demonstrating good efficacy when applied by hand or aerially and work is continuing to refine effective rates. The susceptibility of plants to being cut off at ground level and several depths below ground is being determined to quantify the potential of mechanical control options. A site affected by a dieback phenomenon is being monitored to determine the fate of plants over time.