Summary of the final report
CSIRO Marine Research
for Department of the Environment and Heritage, June 2004
About the study
Invasive populations of C. taxifolia remain present in South Australia and NSW, and are likely to eventually be found in Victoria and WA. Currently available approaches to controlling the plant (principally altering salinity in the field) are expensive and not easily applied in many situations. We undertook to determine the feasibility of using modern genetic approaches to developing a species-specific biocide for use against C. taxifolia. Following discussions with plant geneticists, we developed, tested and experimentally proved the effectiveness of a prototype biocide that was based on an enzyme critical for photosynthesis.
Comparison of genetic and amino acid sequence information for C. taxifolia and other plants suggests that the biocide could be customized to be species-specific, though this was not attempted in this pilot study. Public consultation indicated that if the toxin was indeed species-specific and could be delivered in such a way that it affected only the targeted area, it would be publicly acceptable and used by managers. We conclude that a species-specific biocide for C. taxifolia is feasible and would be used. We recommend that the next stage of biocide development be undertaken, and that it focus on three areas:
- Identification and experimental validation of a biocide that disrupts a process other than photosynthesis. We have identified an osmoregulatory enzyme as a likely candidate.
- Experimental demonstration of genus or species specificity of the biocide.
- Development of a biocide delivery system that is practical in the field, and in particular, delivery in an "Osmocote"-like pelletized form.
- The next stage of biocide development should also include further consultation with the public and coastal managers, a formal hazard and risk analysis of the approach, and an exploration of regulatory issues that need to be addressed before field trials could commence. We estimate this work would take about 2 years to complete, at a cost of about $250,000 per year. If successful, it would be followed by field trials.