Australian Lucerne Yellows Disease – Pathogen , vector and control A report for the Rural Industries Research and Development Corporation

The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable industries. The information should not be relied upon for the purpose of a particular matter. Specialist and/or appropriate legal advice should be obtained before any action or decision is taken on the basis of any material in this document. The Commonwealth of Australia, Rural Industries Research and Development Corporation, the authors or contributors do not assume liability of any kind whatsoever resulting from any person's use or reliance upon the content of this document. In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. iii Foreword Lucerne is a perennial, deep-rooted pasture legume of increasing worldwide significance due to its use in managing aspects of environmental sustainability, such as rising water tables and soil salinity. The production of lucerne seed is an important sector of Australia's pasture seed industry but is affected by the disease Australian lucerne yellows (ALuY). This disease has a severe effect on seed production, frequently causing death of plants and reduced vigour in those that survive. The disease also has led to the cutting or ploughing-under of seed crops, resulting in estimated losses of $7m annually to the Australian lucerne seed industry. The aim of the present work was to undertake the first comprehensive study of the disease in order to develop an understanding of the pathogen and how it is transmitted. Such knowledge is important in underpinning rational disease management approaches and several of these approaches have been tested. This report is an addition to RIRDC's diverse range of over 1500 research publications, forms part of our Pasture Seeds R&D program, which aims to facilitate the growth of a profitable and sustainable pasture seeds industry based on a reputation for the reliable supply, domestically and internationally, of a range of pasture species. Most of our publications are available for viewing, downloading or purchasing online through our website: iv Acknowledgments We thank Mr Don Gowanlock (University of Queensland) for his aid in interpretation of the electron micrographs. Abbreviations ALuY – Australian lucerne yellows TBB-tomato big bud DNA – deoxyribonucleic acid PCR – polymerase chain reaction RFLP – restricted fragment length polymorphism v Foliar and root symptoms are described for 'Australian lucerne yellows' (ALuY), a disease common in Australian lucerne seed crops. Using electron microscopy …