Australian Lucerne Yellows Disease
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Australian Lucerne Yellows Disease – Pathogen, vector and control A report for the Rural Industries Research and Development Corporation by Geoff Gurr, Leigh Pilkington, Murray Fletcher, Eric Elliott, Alex Nikandrow, Karen Gibb September 2005 RIRDC Publication No 05/033 RIRDC Project No US-85A © 2005 Rural Industries Research and Development Corporation. All rights reserved. ISBN 1 74151 132 1 ISSN 1440-6845 Australian Lucerne Yellows Disease – Pathogen, vector and control Publication No. 05/033 Project No. US-85A 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. This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186. Researcher Contact Details Geoff Gurr Pest Biology & Management Group The University of Sydney Orange NSW 2800 Phone: 02 63605551 Fax: 02 63605590 Email: [email protected] In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 1, AMA House 42 Macquarie Street BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6272 4539 Fax: 02 6272 5877 Email: [email protected] Website: http://www.rirdc.gov.au Published in September 2005 Printed on environmentally friendly paper by Canprint ii Foreword Lucerne is a perennial, deep-rooted pasture legume of increasing world-wide 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 project was funded from industry revenue which is matched by funds provided by the Australian Government. 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: downloads at www.rirdc.gov.au/reports/Index.htm purchases at www.rirdc.gov.au/eshop Peter O’Brien Managing Director Rural Industries Research and Development Corporation iii Acknowledgments We thank Mr Don Gowanlock (University of Queensland) for his aid in interpretation of the electron micrographs. Lucy Tran-Nguyen (Northern Territory University) and Deborah Hailstones (NSW Agriculture) provided technical support and advice; the Electron Microscopy Unit, University of Sydney supported TEM work; Ms Dorothy Noble (NSW Agriculture) guided bacteriology work and Ms Jan Gooden (South Australian Research and Development Institute) conducted ELISA tests on bacteria isolates. We thank also the University of Sydney technical staff Donna Read, Jenny Wickham, Karen Gogala and Raj Patel for assistance; biometricians Helen Nicol, Remy van de Ven and Arthur Gilmour for their advice; the landowners Kevin Rubie, Glen Rubie, Mark Green, Russell Glasson, DW Brett, RN and MA Sanderson and Trevor Smith for their cooperation; Aaron Simmons for field support; and Lucy Tran-Nguyen and Claire Streten (Northern Territory University) for supplying live Orosius argentatus. Abbreviations ALuY – Australian lucerne yellows TBB - tomato big bud DNA – deoxyribonucleic acid PCR – polymerase chain reaction RFLP – restricted fragment length polymorphism iv Contents Foreword............................................................................................................................................... iii Acknowledgments................................................................................................................................. iv Abbreviations........................................................................................................................................ iv Executive Summary ............................................................................................................................. vi 1. Detection and identification of a phytoplasma from lucerne with ‘Australian lucerne yellows’ disease .................................................................................................... 1 Introduction ......................................................................................................................................... 1 Materials and Methods ........................................................................................................................ 1 Results ................................................................................................................................................. 5 Discussion ........................................................................................................................................... 9 2. Reducing the immigration of suspected leafhopper vectors and severity of Australian lucerne yellows disease ................................................................................................ 12 Introduction ....................................................................................................................................... 12 Materials and Methods ...................................................................................................................... 13 Results ............................................................................................................................................... 16 Discussion ......................................................................................................................................... 21 3. The phytoplasma vector status of three leafhopper species ........................................................ 23 Introduction ....................................................................................................................................... 23 Materials and methods....................................................................................................................... 24 Results ............................................................................................................................................... 26 Discussion ......................................................................................................................................... 29 4. Management of Australian lucerne yellows disease by water, nutrient and antibiotic treatments.................................................................................................................... 32 Introduction ....................................................................................................................................... 32 Materials and methods....................................................................................................................... 33 Results ............................................................................................................................................... 34 Discussion ......................................................................................................................................... 36 5. Implications and Recommendations.............................................................................................. 37 Implications....................................................................................................................................... 37 Recommendations ............................................................................................................................. 37 6. References ........................................................................................................................................ 38 v Executive Summary Foliar and root symptoms are described for ‘Australian lucerne yellows’ (ALuY), a disease common in Australian lucerne seed crops. Using electron microscopy and molecular methods, a phytoplasma was detected in plants exhibiting symptoms but not in symptomless lucerne plants. DNA testing found the ALuY