The Australian sugar industry has supported joint research projects based at the Ramu Agri-Industries Limited (RAIL) estate in Madang Provence, Papua New Guinea (PNG), for many years. The projects aim to prepare the sugar industry for potential pest and disease incursions through diagnostic test development, pest and disease surveys, developing rapid and reliable resistance screening methods and obtaining resistance ratings for both Australian and PNG sugarcane cultivars. One of the target diseases is Ramu stunt, a serious viral disease characterized by stunting, failure to ratoon and various leaf streak symptoms. The insect vector is the island sugarcane planthopper Eumetopina flavipes. While the distribution of Ramu stunt appears to be limited to PNG, E. flavipes extends from PNG throughout islands in the Torres Strait and onto the Northern Peninsula Area (NPA) of Cape York on mainland Australia.
Through viral extractions, cloning and sequencing, the cause of the disease was shown to be a virus with homology to the genus Tenuivirus. Verification that the tenuivirus was the causal agent was obtained from caged transmission experiments using the insect vector to transmit the disease, with confirmation by symptomology, RT-PCR, sequencing and protein analysis. A diagnostic RT-PCR test was developed and validated on the RAIL estate. Surveys have been undertaken throughout parts of PNG and when the disease has been identified, partial viral genome sequencing was performed to assess the extent of genome variability between isolates. Several of the most genetically diverse isolates are now subject to whole genome sequencing.