W W W.DPI.NSW.GOV.AU WEEDS OF NATIONAL SIGNIFICANCE CABOMBA Cabomba CONTROL MANUAL control manual Current management and control options for cabomba (Cabomba caroliniana) in Australia JN: 9408 WEEDS OF NATIONAL SIGNIFICANCE Cabomba control manual Current management and control options for cabomba (Cabomba caroliniana) in Australia This publication is copyright. Except as permitted under the Copyright Act 1968 (Commonwealth), no part of the publication may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owner. Neither may information be stored electronically in any form whatever without such permission. The information contained in this publication is based on knowledge and understanding at the time of writing (April 2009). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of New South Wales Department of Primary Industries or the user’s independent adviser. The product trade names in this publication are supplied on the understanding that no preference between equivalent products is intended and that the inclusion of a product name does not imply endorsement by the NSW Department of Primary Industries over any equivalent product from another manufacturer. Recognising that some of the information in this document is provided by third parties, the State of New South Wales, the author and the publisher take no responsibility for the accuracy, currency, reliability and correctness of any information included in the document provided by third parties. ALWAYS READ THE LABEL Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this publication. Parts of the chemical use pattern quoted in this publication are approved under permits issued by the Australian Pesticides and Veterinary Medicines Authority and in force at the time the publication was prepared. Persons wishing to use a chemical in the manner approved under permit should obtain a copy of the relevant permit from the APVMA and must read all the details, conditions and limitations relevant to that permit, and must comply with the details, conditions and limitations before using that chemical. © The State of New South Wales NSW Department of Primary Industries 2009 ISBN 978 0 7347 1976 8 Written by Elissa van Oosterhout Design by N Parker Orange, April 2009 For copies of this manual contact: NSW DPI Bookshop on (02) 6391 3801 or 1800 028 374, [email protected] Acknowledgments Principal author and compiler Elissa van Oosterhout, NSW DPI National Cabomba Technical Reference Group Tom Anderson Greg Brown, Sunshine Coast Regional Council Tony Cook, DPI, NSW Toby Grant, Benalla Rural City Council Phil Moran, Noosa & District Landcare Russell Rainbird, Sunshine Coast Regional Council Shon Schooler, CSIRO Steve Wingrave, Department of Natural Resources, Environment and the Arts (DNREA), NT Reviewers Chris Allan, Sunshine Coast Regional Council Geoff Black, Sunshine Coast Regional Council Rod Ensbey, NSW DPI Stephen Johnson, NSW DPI Phil Moran, Noosa & District Landcare Andrew Petroeschevsky, NSW DPI Russell Rainbird, Sunshine Coast Regional Council Shon Schooler, CSIRO Mark Scott, NSW DPI Wayne Tennant, Goulburn Murray Catchment Management Authority Birgitte Verbeek, NSW DPI People and organisations that provided information Geoff Black, Sunshine Coast Regional Council Greg Brown, Sunshine Coast Regional Council Steve Costin, Aquatic Weed Technologies Commercial Diving Contractor Toby Grant, Benalla Rural City Council Phil Moran, Noosa & District Landcare Larissa Montgomery, Benalla Rural City Council David Officer, DPI, NSW Ross Paulger, Seqwater Russell Rainbird, Sunshine Coast Regional Council Shon Schooler, CSIRO Wayne Tennant, Goulburn Broken Catchment Management Authority Steve Wingrave, DNREA, NT Rod Wood, Brisbane City Council CABOMBA WEED CONTROL MANUAL 3 4 WEEDS OF NATIONAL SIGNIFICANCE Foreword Although the current Australian distribution of cabomba is relatively small, cabomba is an insidious aquatic weed capable of rendering most Australian water bodies dangerous, lifeless and useless. Control of cabomba is currently limited by a lack of registered herbicides and biological control agents. The process of registering a safe and effective herbicide for use in water takes lengthy consideration, as does the process of finding and testing biological control agents. Both of these processes are currently under way and supported by State and Federal governments, with the hope of having a herbicide and a biological control agent available in the near future. In the meantime, managers of cabomba are restricted to physical control methods such as shading, drawdown, and manual and mechanical removal. There are also a number of situations where physical control methods are the only option, given public attitudes towards the use of herbicides. Given these restrictions, over the past 10 years managers faced with cabomba infestations have pioneered and improved the available physical control methods. Advances have been made in the efficiencies of mechanical removal systems and the development of plant and machinery to support diver-operated suction dredging. Credit is due to the contractors and managers involved—particularly those associated with the Lake Macdonald and Ewen Maddock Dam infestations in south-east Queensland. Noosa & District Landcare, along with CSIRO and NSW DPI, has recently made great efforts to improve shading techniques, and the insights gathered over the course of these developments have been recorded and presented in this manual. This publication brings together current experience and available information on the management and control of cabomba in Australia. The text has been reviewed by many of the people involved in the management of this weed. I would like to particularly thank those managers and contractors who have put their time and experience forward for the sake of this manual. I believe it is the most comprehensive resource for cabomba control in Australia, and indeed a very useful reference for the control of submerged aquatic weeds in general, with nothing similar yet published in Australia. Neale Tweedie Chair National Aquatic Weeds Management Group CABOMBA WEED CONTROL MANUAL 5 Contents INTRODUCTION 8 A Weed of National Significance ____________________________________________8 Impacts of cabomba______________________________________________________ 8 Current distribution _____________________________________________________ 12 Potential distribution ____________________________________________________ 12 Legal status of cabomba in Australia________________________________________ 13 References and further reading ___________________________________________ 13 PART 1: THE CABOMBA PROFILE 14 Physical characteristics___________________________________________________ 15 Reproduction and spread ________________________________________________ 18 Growth habits __________________________________________________________ 19 Habitat and conditions for growth _________________________________________ 21 Taxonomy _____________________________________________________________ 22 Similar-looking plants ___________________________________________________ 23 References and further reading ____________________________________________ 25 PART 2: MANAGING CABOMBA 26 Introduction ___________________________________________________________ 26 Containment and prevention of spread _____________________________________ 32 Early detection _________________________________________________________ 34 Herbicides _____________________________________________________________ 34 Biological control _______________________________________________________ 38 Aquatic revegetation ____________________________________________________ 38 References and further reading ____________________________________________ 39 6 WEEDS OF NATIONAL SIGNIFICANCE PART 3: SHADING 40 Floating blankets _______________________________________________________ 41 Benthic blankets ________________________________________________________ 43 Water dyes ____________________________________________________________ 46 Riparian vegetation _____________________________________________________ 46 Aquatic revegetation after shading_________________________________________ 46 References and further reading ____________________________________________ 47 Case study: Floating blankets on a small dam at Kin Kin, south-east Queensland ____ 48 Case study Benthic blankets in Lake George, USA _____________________________ 52 PART 4: DRAWDOWN 54 Introduction ___________________________________________________________ 54 High risk of spread ______________________________________________________ 54 Refuges/depressions ____________________________________________________ 55 Does drawdown work?___________________________________________________ 55 Follow-up after drawdowns _______________________________________________ 56 References and further reading ____________________________________________ 57 Case study: Drawdown in Lake Benalla, Victoria _______________________________ 58 PART 5: MANUAL REMOVAL