Tests of transmission of cynodon white leaf phytoplasma to sugarcane and maize in northern Australia

Cynodon white leaf disease is associated with cynodon white leaf phytoplasma in Cynodon dactylon growing in Darwin, Northern Territory. In order to effectively assess and manage the risk to agricultural crops posed by this phytoplasma, it is necessary to establish whether there is an insect species capable of transmitting it from C. dactylon to grasses like Saccharum spp. hybrids and Zea mays. We used field and cage trials to investigate transmission of cynodon white leaf phytoplasma in these grasses. No transmission of the phytoplasma occurred in any of the trials, even to C. dactylon, the known host, and the phytoplasma did not persist in the potential leafhopper vector, Chiasmus varicolor. These results suggest that C. varicolor is not a vector of cynodon white leaf phytoplasma and that some requirement for successful transmission was not met in our field trials. We do not have sufficient information to determine whether transmission to Saccharum spp. hybrids or Z. mays is possible. Our study demonstrates the techniques that can be applied to this problem and provides a starting point for further investigation using different transmission conditions and insect species.