Preparing the Australian sugar industry for exotic disease threats: final report 2009/033

Abstract

Previous field resistance trial data for downy mildew, Ramu stunt and Sesamia grisescens collected in PNG since the mid-1980s were accessed, analysed and information used as a foundation for project field resistance screening research. 2. Pot methods for moth borer resistance screening were reviewed, a visit to South Africa was made to view pot trial methodology and rapid test resistance screening research plans developed. 3. Field resistance screening trials for the moth borers (Sesamia grisescens and Scirpophaga excerptalis) and the diseases (downy mildew, (Peronosclerospora spp.) and Ramu stunt (tenuivirus)) showed promise in project research. Data collected has been analysed and resistance ratings for Australian commercial varieties assigned and loaded into SPIDNet. 4. A rapid resistance screen for the moth borers (manual infestation of test plants) and downy mildew (using oospores mixed into potting soil) show promise, but each method requires further refinement. 5. The causal agent of Ramu stunt was confirmed as a tenuivirus and a diagnostic assay validated. Suspect disease specimens can now be confidently assayed, should an Australian incursion occur. Some pathogen variation was noted around PNG; it is unknown if this will affect varietal resistance reactions. 6. Molecular tools for assaying for downy mildew were also developed; suspect disease specimens for DM can also now be confidently assayed. Significant DM pathogen variation in PNG was noted, with three taxa identified. One of these may be a new Peronosclerospora species. 7. The project has led to major steps forward in relation to knowledge of these pests and diseases. Our capacity to identify, manage and advise the Australian sugarcane industry with regard to PNG pests and diseases has improved greatly. The industry is now in a strong position to deal with the major pest and disease threats present in PNG.