Final Report Effectiveness of mineral & vegetable oils in minimising the spread of non-persistent viruses in potato seed crops in GB Ref: R449 Reporting Period: April 2011 – September 2014 Report Authors: Greg Dawson1, Eric Anderson1, Ruairidh Bain2, Christophe Lacomme3, Maureen McCreath3, Adrian Roberts4, Jane 5 Thomas 1Scottish Agronomy Ltd, Arlary Farm, Milnathort. 2SRUC, Auchincruive Estate Ayr. 3SASA, Roddinglaw Road, Edinburgh. 4BioSS, JCMB Kings Buildings Edinburgh. 5NIAB Huntingdon Road, Cambridge © Agriculture and Horticulture Development Board 2015 While the Agriculture and Horticulture Development Board, operating through its Potato Council division, seeks to ensure that the information contained within this document is accurate at the time of printing, no warranty is given in respect thereof and, to the maximum extent permitted by law the Agriculture and Horticulture Development Board accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this document. Reference herein to trade names and proprietary products without stating that they are protected does not imply that they may be regarded as unprotected and thus free for general use. No endorsement of named products is intended, nor is any criticism implied of other alternative, but unnamed, products. Copyright, Agriculture and Horticulture Development Board 2015. No part of this publication may be reproduced in any material form (including by photocopy or storage in any medium by electronic means) or any copy or adaptation stored, published or distributed (by physical, electronic or other means) without the prior permission in writing of the Agriculture and Horticulture Development Board, other than by reproduction in an unmodified form for the sole purpose of use as an information resource when the Agriculture and Horticulture Development Board is clearly acknowledged as the source, or in accordance with the provisions of the Copyright, Designs and Patents Act 1988. All rights reserved. is a registered trademark of the Agriculture and Horticulture Development Board. is a registered trademark of the Agriculture and Horticulture Development Board, for use by its Potato Council division. All other trademarks, logos and brand names contained in this publication are the trademarks of their respective holders. No rights are granted without the prior written permission of the relevant owners. Additional copies of this report and a list of other publications can be obtained from: Publications Potato Council Tel: 02476 692051 Agriculture & Horticulture Development Board Fax: 02476 478902 StoneleighPark E-mail: [email protected] Kenilworth Warwickshire CV8 2TL Our reports, and lists of publications, are also available at www.potato.org.uk © Agriculture and Horticulture Development Board 2015 2 CONTENTS 1. SUMMARY ............................................................................................ 4 1.1. Aim ................................................................................................................... 4 1.2. Methodology ...................................................................................................... 4 1.3. Key findings ....................................................................................................... 5 1.3.1. Determine the effectiveness of treatment programmes in minimising potyvirus spread. ................................................................................................... 5 1.3.2. Determine the effect of tank mixes of mineral oils and common blight sprays .................................................................................................................. 6 1.3.3. The effect of mineral oils on crop inspections ........................................... 7 2. INTRODUCTION ..................................................................................... 9 3. MATERIALS AND METHODS .................................................................. 12 3.1. Field trials evaluating virus transmission 2011-13 ........................................... 12 3.2. Field Trials Evaluating Phytotoxicity and the Effects of Oil treatments on Visual Seed Crop Inspection ........................................................................... 24 3.3. Trials Investigating the Effect of Tank Mixing Oils with commonly used Fungicides for Foliar Blight Control .................................................................. 28 4. METHODS OF STATISTICAL ANALYSIS ................................................... 43 4.1. Virus Transmission Trials ................................................................................ 43 4.2. Seed Crop Inspection Trials ............................................................................ 43 4.3. Blight Control Trials ......................................................................................... 44 5. RESULTS ........................................................................................... 44 5.1. Vector and Transmission Pressure .................................................................. 44 5.2. Virus Transmission .......................................................................................... 58 5.3. Phytotoxicity and the Effects on Visual Seed Crop Inspection ......................... 93 5.3.1. SASA Edinburgh ..................................................................................... 93 5.3.2. NIAB Cambridge ..................................................................................... 95 5.4. Results of blight control trials ......................................................................... 101 6. DISCUSSION ..................................................................................... 135 6.1. Virus Control & Epidemiology ........................................................................ 135 6.2. Effects on Visual Crop Inspection for Certification ......................................... 137 6.3. Effects on Crop Yield ..................................................................................... 138 6.4. Effect on Blight Control .................................................................................. 139 7. CONCLUSIONS ................................................................................. 142 8. REFERENCES ................................................................................... 146 9. ACKNOWLEDGEMENTS ...................................................................... 147 © Agriculture and Horticulture Development Board 2015 3 1. SUMMARY 1.1. Aim The aim of the project was to investigate the potential for mineral oils to be used as a control method for potyviruses (non-persistent viruses) in seed crops subject to the GB Certification system of growing crop inspection and control programmes for persistent viruses (Potato Leaf Roll Virus, PLRV) and potato late blight (Phytophthora infestans). 1.2. Methodology 1.2.1. Determine the effectiveness of treatment programmes in minimising potyvirus spread. Four field virus transmission trials were established in each of the three years of the project. These were located in Fife, Edinburgh, Yorkshire and Cambridge. All trials were planted as randomised complete block designs. Each trial, with the exception of the Yorkshire site, had infector rows placed in equal proximity to the plots. There were different treatments at the four locations. The core treatments evaluated in Cambridge, Yorkshire and Fife were: • Untreated • Fortune (vegetable oil; @ 0.5% total spray volume) • Olie-H (mineral oil; @ 3.1% total spray volume) • Hallmark Zeon (75ml/ha) • Hallmark/Fortune (Hallmark Zeon 75ml/ha + Fortune 0.5%) • Hallmark/Olie-H (Hallmark Zeon 75ml/ha + Olie-H 3.1%) • Hallmark/Biscaya/SumiAlpha/Tepekki • Olie-H 3.1%/ Hallmark/Biscaya/SumiAlpha/Tepekki The integrated programmes with sequences including more than one product were devised to evaluate the integration of potyvirus control with measures targeting colonising aphids and persistent virus transmission (PLRV). At the Edinburgh site, the aim was to investigate the effect on virus transmission and acquisition of applying Fortune and Olie-H to four varieties susceptible to the most prevalent potyviruses (PVYN and PVA). Virus transmission was assessed by post- harvest virus testing of progeny tubers. This involved growing on the harvested tubers and measuring virus levels in the resulting leaves by ELISA. 1.2.2. Determine the effect of tank mixes of mineral oils and common blight sprays Two field trials were established in Ayrshire in each of the three years to compare the blight control achieved by commonly used blight control products with and without the addition of Olie-H 3.1% of the spray volume (6.25 l/ha in a tank mix in 200 litres of water per hectare). The first trial was to examine the effects at the rapid canopy expansion phase from rosette stage to full crop canopy. The second was targeted at canopy stable when full crop canopy had been achieved. © Agriculture and Horticulture Development Board 2015 4 1.2.3. The effect of mineral oils on crop inspection Observation plots were established to evaluate the impact of oil treatments on the visual inspection of seed crops. The plots were located at SASA, Edinburgh and NIAB, Cambridge. At each location variety / virus combinations were chosen to determine the effect of oil application on the visual assessment of