Alternaria apple fruit spot: New Directions Christine Horlock QLD Department of Primary Industries & Fisheries Project Number: AP05002 AP05002 This report is published by Horticulture Australia Ltd to pass on information concerning horticultural research and development undertaken for the apple and pear industry. The research contained in this report was funded by Horticulture Australia Ltd with the financial support of the apple and pear industry. All expressions of opinion are not to be regarded as expressing the opinion of Horticulture Australia Ltd or any authority of the Australian Government. The Company and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this report and readers should rely upon their own enquiries in making decisions concerning their own interests. ISBN 0 7341 1632 2 Published and distributed by: Horticultural Australia Ltd Level 7 179 Elizabeth Street Sydney NSW 2000 Telephone: (02) 8295 2300 Fax: (02) 8295 2399 E-Mail: [email protected] © Copyright 2008 FINAL REPORT PROJECT AP05002 (31 October 2007) Alternaria fruit spot: New Directions Christine M. Horlock. Department of Primary Industries and Fisheries, Queensland Final Report AP05002 1 AP05002 Ms Christine M. Horlock Plant Pathologist, Delivery Department of Primary Industries and Fisheries, Queensland Applethorpe Research Station PO Box 501 STANTHORPE QLD 4380 This document is the final report for the Horticulture Australia Limited funded project “Alternaria fruit spot: New directions”, and as such contains the details of all scientific work carried out in this project. This report was prepared for submission on the 31st October 2007. Any recommendations contained in the publication do not necessarily represent current Horticulture Australia Limited policy. No person should act on the basis of the contents of this publication, whether as to matters of fact or opinion or other content, without first obtaining specific, independent professional advice in respect of the matter set out in this publication. Final Report AP05002 2 Table of Contents TABLE OF CONTENTS.......................................................................................................................2 TABLE OF CONTENTS.......................................................................................................................3 MEDIA SUMMARY..............................................................................................................................5 TECHNICAL SUMMARY....................................................................................................................6 INTRODUCTION..................................................................................................................................7 REVIEW OF RELEVANT LITERATURE .....................................................................................................7 Alternaria diseases affecting apples ...............................................................................................7 Alternaria leaf blotch (caused by Alternaria mali).........................................................................7 Alternaria fruit spot (caused by Alternaria species).....................................................................13 ALTERNARIA LEAF BLOTCH AND FRUIT SPOT IN AUSTRALIA ..............................................................13 Disease description.......................................................................................................................13 Distribution and importance.........................................................................................................14 1. PRESERVATION OF ALTERNARIA SPECIES COLLECTED FROM AUSTRALIAN APPLE LEAVES AND FRUIT...........................................................................................................16 2. ANALYSIS OF REPRESENTATIVE ALTERNARIA ISOLATES FROM AUSTRALIAN APPLE ORCHARDS ...........................................................................................................................17 2.1 IDENTIFICATION OF ALTERNARIA ISOLATES.........................................................................17 Identification of Alternaria isolates using morphology ................................................................17 Preliminary genetic analysis of Alternaria isolates......................................................................18 2.2 EFFECT OF IN VITRO FUNGICIDES ON THE IN VITRO GERMINATION AND GROWTH OF ALTERNARIA ISOLATES ......................................................................................................................19 Aim................................................................................................................................................19 Materials and Methods .................................................................................................................19 Results...........................................................................................................................................21 Discussion.....................................................................................................................................21 3. DETERMINING THE PATHOGENICITY OF ALTERNARIA ISOLATES FROM AUSTRALIAN APPLE LEAVES AND FRUIT................................................................................22 3.1 IN VITRO INOCULATION OF DETACHED APPLE LEAVES WITH ALTERNARIA ISOLATES ...........22 Aim................................................................................................................................................22 Materials and Methods .................................................................................................................22 Results and Discussion .................................................................................................................24 3.2 INOCULATION OF ATTACHED APPLE LEAVES WITH ALTERNARIA ISOLATES ..........................24 Aim................................................................................................................................................24 Materials and Methods .................................................................................................................24 Results and Discussion .................................................................................................................25 3.3 INOCULATION OF MATURE APPLE FRUIT IN VITRO WITH ALTERNARIA ISOLATES ..................26 Aim................................................................................................................................................26 Materials and Methods .................................................................................................................26 Results and Discussion .................................................................................................................26 4. METHODS FOR INVESTIGATING ALTERNARIA DISEASES OF TREE CROPS.............27 THE GENUS ALTERNARIA ...................................................................................................................27 ALTERNATA-LIKE SMALL-SPORED ALTERNARIA SPECIES ...................................................................27 IDENTIFICATION OF SMALL-SPORED ALTERNARIA SPECIES.................................................................28 Using morphological characters ..................................................................................................28 Using chemical (toxin or metabolite) production .........................................................................29 Using genetic characters ..............................................................................................................31 Using multiple methods.................................................................................................................32 PRACTICAL TECHNIQUES FOR USE IN AP06007...................................................................................33 Pathogenicity tests ........................................................................................................................33 5. PROJECT EXTENSION APPLICATION ...................................................................................37 Project Method .............................................................................................................................37 Final Report AP05002 3 Project Outcomes..........................................................................................................................37 CONCLUSIONS...................................................................................................................................38 TECHNOLOGY TRANSFER.............................................................................................................39 Grower meetings...........................................................................................................................39 Industry magazine articles............................................................................................................39 RECOMMENDATIONS – SCIENTIFIC ..........................................................................................40 RECOMMENDATIONS – INDUSTRY.............................................................................................41 ALTERNARIA DISEASE – POINTS FOR GROWERS TO REMEMBER...........................................................41