RUSSIAN WHEAT APHID: TACTICS FOR FUTURE CONTROL A RESOURCE FOR AUSTRALIAN GRAIN GROWERS AND ADVISERS JULY 2017 SOUTH Title: Russian Wheat Aphid: Tactics for Future Control Project Code: ACO00020-B Authors: AgCommunicators ©Grains Research and Development Corporation 2017 ISBN: 978-1-921779-41-1 (online only) Contact • Telephone: 02 6166 4500 • Email: [email protected] • Internet: www.grdc.com.au • Facebook: www.facebook.com/theGRDC/ • Twitter: https://twitter.com/theGRDC All Rights Reserved This publication is copyright. Except as permitted under the Australian Copyright Act 1968 (Commonwealth) and subsequent amendments, no part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic or otherwise, without the specific permission of the copyright owner. Disclaimer Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Grains Research and Development Corporation. 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Authors Paul Umina1,2, Greg Baker3, Owain Edwards4 1 cesar, 293 Royal Parade, Parkville, VICTORIA 2 The University of Melbourne, School of BioSciences, Parkville, VICTORIA 3 South Australian Research and Development Institute, Waite Campus, Adelaide, SA 4 CSIRO Land & Water, Centre for Environment and Life Sciences, Underwood Ave, Floreat, WA Editors Belinda Cay, Deanna Lush AgCommunicators, 272 Magill Road, Beulah Park, SA Acknowledgements Tony Craddock, Mick Faulkner, Maarten van Helden, Garry McDonald, Julia Severi, Samantha Ward, and Craig Ruchs. 2 RUSSIAN WHEAT APHID: TACTICS FOR FUTURE CONTROL Contents Executive Summary ....................................................................................5 1.0 Introduction .......................................................................................7 2.0 Global distribution ..............................................................................8 3.0 Incursion into Australia ........................................................................9 4.0 Identification .....................................................................................10 5.0 Hosts ..............................................................................................12 6.0 Feeding behaviour ............................................................................12 7.0 Symptoms ........................................................................................15 8.0 Vector for disease .............................................................................16 9.0 Yield loss .........................................................................................18 10.0 Reproduction ....................................................................................19 11.0 Dispersal .........................................................................................21 12.0 Environmental influences ...................................................................22 13.0 Monitoring ......................................................................................23 14.0 Case study - RWA dynamics in 2016 .....................................................24 15.0 Management for 2017 and beyond ......................................................26 15.1 Assessment of risks ..........................................................................26 Weather ..........................................................................................26 Crop agronomy ................................................................................26 15.2 Controlling volunteers and alternative plant hosts ...................................26 15.3 Natural enemies ............................................................................... 27 15.4 Chemical management ......................................................................28 15.5 Insecticide seed treatments ................................................................29 15.6 Genetic resistance ............................................................................30 16.0 Ongoing monitoring of spread ............................................................32 17.0 FAQs .............................................................................................. 34 18.0 References .....................................................................................36 RUSSIAN WHEAT APHID: TACTICS FOR FUTURE CONTROL 3 Russian Wheat Aphid management – An integrated approach to control in Australia based on assessment of risk Monitoring • Monitor crops regularly throughout the season, checking • Preserve populations of predators and other beneficials to and recording population trends. help control aphid numbers. • Crops can be infested under warmer conditions in autumn, • Managing the green bridge over summer and autumn will during the early stages of establishment, from wingless reduce the refuges which enable aphids to carry over from aphids walking off nearby senescing hosts. one season to the next. Grass weeds and cereal volunteers • Intensive monitoring of early-sown crops, including cereals should be targeted. sown as pasture, should occur for the first 4-8 weeks after sowing. Chemical management • Populations frequently start to increase as temperatures • Adopt a threshold-based management strategy. Chemical warm in spring or typically from tillering onwards. control is warranted if infestations exceed thresholds of 20 • Stressed areas of the paddock are often the first to be per cent of seedlings infested up to the start of tillering and infested and hence monitoring may specifically target these 10 per cent of tillers infested thereafter. Crop/yield loss may areas first. be minimised through protection of the top three (major yield contributing) leaves. Symptoms • If spraying is warranted, use softer chemistry (e.g. • Russian wheat aphid (RWA) can be detected in cereal pirimicarb) where possible to encourage natural predators crops by visual examinations. Plants will show characteristic and beneficial insects, especially early in the season. symptoms such as chlorosis; necrosis; wilting, stunting; leaf • Avoid prophylactic insecticide applications. streaking with whitish, yellow and purple longitudinal leaf • Chlorpyrifos and pirimicarb are currently registered for markings; trapped awns (which give a hooked appearance); control under two Australian Pesticides and Veterinary stunted growth; rolled leaves and heads that fail to flower. Medicines Authority (APVMA) Emergency Use Permits. • Growers should first inspect inside the leaf rolls and newest Keep chlorpyrifos for heavy infestations. Good spray leaves for aphid infestations. coverage and consideration of weather conditions (temperature, rainfall) in the 24 hours prior and shortly after Environmental conditions application are important. • RWA is primarily associated with cereal production regions characterised by warmer, drier climates. Seed treatments • It is less prevalent in higher rainfall areas, with heavy rainfall • Neonicotinoid seed treatments are expected to provide reported to cause 50 per cent mortality. effective early season control of RWA. Preliminary evidence • Despite having a significantly higher tolerance to cold indicates the length of protection is expected to be temperatures than other cereal aphids, the population equivalent to that observed for other cereal aphid species. growth of RWA will be reduced with the onset of cold and • Prophylactic use of neonicotinoid seed treatments is wet conditions. discouraged and use should be targeted at those situations • Frequent spring rainfall and dry/hot summer conditions (no deemed to be of higher risk (early sowing, especially early green bridge) will lower the risk of RWA infestations. sown barley crops; or areas where volunteer cereals and/or live aphids are identified prior to sowing). Management • Wherever possible, save pesticide options until periods Report sightings of peak aphid activity, during early crop establishment in • Grain growers and advisers across Australia should remain autumn or during spring when populations are likely to vigilant and keep a look out for unusual aphid activity in increase and protection of the flag leaf is vital to maximise cereal crops. suspected infestations in areas where RWA grain fill. Currently registered foliar applied insecticide has not been confirmed should be reported to your state sprays do not provide any meaningful preventative activity. or territory’s department of agriculture or primary industries.