Mushroom Pest and Disease Control A Colour Handbook John T. Fletcher B.Sc, Ph.D Regional Advisory Pathologist, Agricultural Development and Advisory Service, UK Richard H.Gaze B.Sc National Mushroom Specialist, Agricultural Development and Advisory Service and Horticultural Research International, UK With contributions from P. F. White, HNC, LIBiol Horticultural Research International, UK Professor Danny Rinker, University of Guelph, Ontario, Canada Professor Albert Eicker, University of Pretoria, South Africa Dr Helen Grogan, TEAGASC, Kinsealy Research Centre, Dublin, Ireland MANSON PUBLISHING Copyright © 2008 Manson Publishing Ltd ISBN: 978-1-84076-083-4 All rights reserved. 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Tel: +44(0)20 8905 5150 Fax: +44(0)20 8201 9233 Email: [email protected] Website: www.mansonpublishing.com Commissioning editor: Jill Northcott Project manager: Julie Bennett Copy editor: Carolyn Holleyman Cover design: Ayala Kingsley Layout: DiacriTech, Chennai, India Colour reproduction: Tenon & Polert Colour Scanning Ltd., Hong Kong Printed by: Grafos S.A., Barcelona, Spain Plant Protection Handbooks Series Alford:Pests of Fruit Crops – A Colour Handbook Alford:Pests of Ornamental Trees, Shrubs and Flowers – A Colour Atlas Biddle & Cattlin: Pests and Diseases of Peas and Beans – A Colour Handbook Blancard:Cucurbit Diseases – A Colour Atlas Blancard:Tomato Diseases – A Colour Atlas Blancard:Diseases of Lettuce and Related Salad Crops – A Colour Atlas Fletcher & Gaze: Mushroom Pest and Disease Control – A Colour Handbook Helyeret al:Biological Control in Plant Protection – A Colour Handbook Koikeet al:Vegetable Diseases – A Colour Handbook Murrayet al:Diseases of Small Grain Cereal Crops – A Colour Handbook Wale et al:Pests & Diseases of Potatoes – A Colour Handbook Williams: Weed Seedlings – A Colour Atlas Contents About the Authors 4 Chapter 6 Viral Diseases 109 Introduction 110 Preface 5 Names of mushroom virus diseases 111 Epidemiology of mushroom virus diseases 112 La France disease 114 Chapter 1 Mushroom Growing 7 Mushroom virus X disease 120 Introduction 8 Vesicle virus 123 Culture 8 Mushroom growing systems 18 Buildings 20 Chapter 7 Moulds that Compete with Mushrooms 125 Introduction 126 Chapter 2 Disorders: Symptoms, Causes, and Trichoderma compost mould 127 Identification 22 Penicillium mould 127 Introduction 23 Smoky mould (Penicillium implicatum, Names of disorders 23 P. chermesinum,and possibly Causes of disorders 24 P. fellutanum) 128 Symptoms in relation to crop development 24 Pythium – black compost 131 Biotic factors responsible for disorders 25 Other moulds 133 Abiotic factors responsible for disorders 27 Action points for control of mushroom moulds 139 Identification of disorders 28 Chapter 8 Pests 140 Chapter 3 Effective Pest and Disease Control 35 Introduction 141 Introduction 36 Mushroom flies 141 Pest and pathogen management 37 Sciarids or fungus gnats 143 Practices and operations 38 Phorids 147 Farm design 50 Cecids 151 Chemical control 50 Other flies 155 Cultural and environmental control 57 Mushroom mites 157 Action points during compost production Nematodes 162 and cropping 59 Minor pests 165 Genetic resistance 61 Organic production 61 Chapter 9 Abiotic Disorders 166 Introduction 167 Chapter 4 Fungal Diseases 63 Pinning disorders 167 Introduction 64 Whole mushroom distortion 169 Wet bubble or Mycogone 65 Mushroom stems 170 Dry bubble or Verticillium 70 Mushroom caps 172 Cobweb or Dactylium 76 Mushrooms at harvest and post-harvest 175 False truffle 80 Trichoderma diseases 84 Further Reading 177 Aphanocladiumcap spotting 90 Other diseases 91 Glossary 178 Chapter 5 Bacterial Diseases 93 Introduction 94 Appendix 1 Registered Pesticides 182 Blotch, Bacterial blotch or Brown blotch 94 Ginger blotch 99 Appendix 2 Checking the Chlorine Content of Mummy disease 100 a Hypochlorite Disinfectant 185 Pit 102 Drippy gill 103 Appendix 3 Some Useful Conversions 186 Bacterial soft rot 104 Internal stalk necrosis 106 Index 187 Post-harvest browning 108 4 About the Authors John Fletcher graduated in Horticultural Botany at Richard Gaze graduated in Horticulture at Wye the University of Reading followed by a PhD in plant College of the University of London. Following pathology at the University of Birmingham. He initial jobs in the protected crops industry in joined the National Agricultural Advisory Service Denmark, he joined the National Agricultural (subsequently the Agricultural Development and Advisory Service and developed a special interest in Advisory Service) and worked on many diseases the mushroom crop. This lead to him becoming the during his 34 years but specialized in those of Agricultural Development and Advisory Service glasshouse and mushrooms crops. In 1969 he spent National Mushroom Specialist, a position he held a year as a research fellow at the University of for 20 years and subsequently for a further 6 years Guelph, Ontario, Canada where he researched when he transferred to Horticulture Research tomato diseases but also made the initial discovery of International at Wellesbourne. He produced a the effectiveness of the benzimidazole fungicides for regular News Letter on the mushroom industry for the control of mushroom pathogens. He is a Past ADAS and in 2000 he became the editor of the President of the British Society of Plant Pathologists, Mushroom Growers Associations Mushroom received the British Crop Protection Councils Award Journal, a position he held until its closure in 2006. for services to British crop protection and the He was awarded the MGA Sinden Award for his Mushroom Growers Association Sinden Award for services to the Industry both as an adviser and his contribution to research and advice on the researcher. He is still involved in mushroom control of mushroom diseases. In recent years he has consultation work and advises ADAS as well as been consulted by mushroom growers in the UK and being an Associate Fellow of Warwick HRI and other countries and spent 5 months at La Trobe member of the Horticultural Development Council University, Melbourne, Australia working on Mushroom Panel. various mushroom pathogens and moulds. 5 Preface Mushrooms are a very important crop and are Finer grades of peat are used in casing, and sugar grown commercially in many countries. China beet lime, a by-product of sugar production from grows more types of mushrooms than any other sugar beet, is very commonly used as the lime source. country and is the largest overall producer These changes have resulted in wetter casing, and in accounting for some 32%. Worldwide, Agaricus turn, this can have a major effect on disease bisporus,the Paris mushroom, button mushroom or incidence. Wetter casing is considered by some to be white mushroom (the subject of this book), is one of the main factors in the international increase probably the most widely grown. It is eaten both in cobweb disease. Bulk production of compost and fresh and processed, especially canned. Modern its distribution to growers has accentuated the production methods are highly mechanized, Trichoderma compost mould problem. requiring detailed knowledge and a high level of The discovery of Mushroom virus X disease, management skill for successful and continuous which shows many of the features of La France cropping. Inevitably investment and production disease but with an apparent absence of virus costs are high and returns have not kept pace with particles, has resulted in a renewed interest in ‘virus inflation, though the crop is still one of the most diseases’ of the crop. Research facilities are essential valuable in many of the countries where it is grown. if such new diseases are to be understood and In the USA alone in 2003–2004, the Agaricuscrop controlled. Unfortunately there has been decreasing was valued at 880 million dollars and was produced support for research and extension in many by only 125 growers. Twenty-six of these, who countries, largely as a result of the withdrawal of produced over 10 million pounds each (c. 4.5 million government funding. The global industry urgently kg), accounted for 65% of the total production. The needs to reassess its research and extension situation in Europe is similar where there is also a requirements in order to make the best use of trend for the numbers of producers to decrease decreasing international resources. whilst farm size increases. Pesticide (fungi and insects) resistance has affected Fifteen years have passed since the publication of the control of sciarid flies and diseases such as the second edition of the book Mushrooms: Pest and Cobweb and Verticillium. The numbers of pesticides Disease Control(published by Intercept, Andover, available to mushroom growers has decreased and is Hants, England) and this is a major revision of that likely to decrease further. Biological control of pests book. During this time the mushroom industry, and pathogens has not developed at the pace worldwide, has undergone many changes. In the predicted some years ago. There are still no USA, fresh mushroom production has increased by biologically active products available for the control 14% over the last 10 years, while processed of fungal pathogens, although sciarid control with mushrooms have decreased by a similar amount. In nematodes is now an established practice. Europe, there has been a significant shift in the In addition to all these problems and changes is importance of the crop. In Poland for instance, the growing public concern for the environment. production has increased considerably whereas in Compost odours, run-off water from compost yards, the UK it has decreased by over 50% in the last 5 the use of disinfectants and pesticides, the possible years. Cultural developments have continued at a contamination of water courses near to farms, have rapid pace, and the production of compost in bulk, all added to perceived environmental problems up to and including fully colonized compost, is now associated with mushroom production. Industries in common practice. The use of bins or bunkers in the many countries have addressed many of these early stages of composting has had major effects, potential problems but at a cost. Returns for the both culturally, and on the biology of the process. product sometimes barely cover costs, and in 6 PREFACE countries where the crop is mainly marketed through is therefore vitally important that the national list of supermarkets there is constant pressure to improve approved products is consulted before a choice of quality, while returns remain constant or even in chemical is made and that it should be used at the decline. The high cost of harvesting continues to be rate shown on the label. The product labels must be a major factor and has resulted in the use of cheap read very carefully before using a chemical and the labour as well as the expansion of the industry into stated safety recommendations must be strictly countries where labour is less expensive. followed at all times. The most toxic pesticides and Against this background, effective pest and Formalin require the operator to wear full protective disease control is essential if farms are to remain clothing including the correct respirator filter. The viable. The aim of this book is the same as that in product label also gives a harvest interval and this, Mushrooms: Pest and Disease Control, namely to together with the correct rate, will insure that the provide information on the problems of the crop and treated mushrooms do not have undesirable the best ways to overcome them to remain in residues. business. In this respect, all the chapters have been It is hoped that this book will be of value to the revised, some in a major way, and many colour mushroom industry in every country where the crop pictures added. Inevitably there is some duplication, is grown. The metric units used in this book are not for instance in methods of pest and disease control, in common usage in all countries and with this in where the same or similar points are made for mind Appendix 3, which contains conversions to various problems. However, in a new Chapter 3 other units, has been included. details of processes and procedures with checklists We express our appreciation to the many people are given, and referred to more briefly under specific who have contributed in one way or another to the problems. information contained in this book. In particular, we In order to preserve and get the best results from wish to thank Dr Helen Grogan for her very the decreasing number of pesticides available to the significant research contribution during the past 12 industry, it is vital that growers are totally familiar years. We also thank Judy Allan, John Burden, Alan with the label recommendations; not only those that Clift, F.J. Gea, Geoff Izard, Martmari van Greuning, refer to biological efficacy but also the safety instruc- Brian Oxley, Steve Newton, Peter Romaine, Greg tions. The industry may one day have to manage Seymour, and Andrew Tinsley for information and without pesticides, and the development of pest- or photographs and in particular Dr Peter Mills for the pathogen-resistant strains of spawn still seems to be use of photographs (78, 101, 122, 130–140, a long way off. For these reasons alone, it is vital that 146–150, 156, and 159) that belonged to the Glass- growers use all means available to them in the house Crops Research Institute and Warwick/HRI. management of pest and pathogen populations. We are also extremely grateful to Professor Fred Last Finally, a word of caution: the international and Pat Fletcher for their very useful comments on, situation regarding the registration of pesticides for and help with the preparation of the manuscript. use on the crop is ever-changing. There is also no Finally we are very grateful for the contributions universal agreement on which pesticides should or which are also acknowledged in the appropriate should not be registered. Each country makes its places in the book, by Professor Danny Rinker for own decision. With the present speed of change, it is his North American perspective, to Jane Smith for likely that some active ingredients mentioned in this help with the pest section, and to Professor Albert book will have been withdrawn from use in some Eicker for his contribution to the moulds chapter. countries by the time the book is published. In addition, the rate of use of formalin suggested in this book is the maximum permissible rate for the UK; John T. Fletcher this rate may not be permissible in other countries. It Richard H. Gaze 7 CHAPTER 1 Mushroom Growing • INTRODUCTION • MUSHROOM GROWING SYSTEMS • CULTURE Tray systems; Shelf systems; Bag and block Compost: the ingredients; Composting; systems; Deep trough system Compost smells; Compost analysis; • BUILDINGS Mushroom compost: the selective medium; Spawning, spawn-running and phase III compost; Casing; Cropping; Pests and pathogens 8 MUSHROOM GROWING Introduction Mushroom culture is a remarkable system of biological manipulation whereby the organisms that are most likely to be harmful are minimized, and those that are beneficial are encouraged. A suitable medium, the compost, is the end product of a complex but controlled biological process involving fungi, bacteria, and actinomycetes. When well prepared, it is a living ecosystem that is suitable for the growth of mushrooms. Mushroom mycelium, once introduced into the compost, affects the system substantially and the development of other microorganisms may be minimized by competition and probably antagonism. However, mushroom compost is not a selective medium in the strict sense, and other fungi introduced at the completion of composting and before mushroom spawn may also grow well, often at the expense of mushroom mycelium. This book is almost entirely about the white mushroom, Agaricus bisporus(also known as A. brunnescens), with occasional reference to the closely related species Agaricus bitorquis. Many readers will have an intimate knowledge of mushroom growing and the different production systems used. This chapter is included for those without such knowledge. Abrief description is given of the production processes, the different systems and the overall environment in which mushrooms grow. An additional aid to understanding is the inclusion of a glossary of terms on pages 178–181. Culture Compost: the ingredients fertilizers such as urea or ammonium nitrate which provide additional carbohydrate and nitrogen. The predominant raw material for mushroom compost, or mushroom substrate as some prefer to call it, is straw. Wheat straw is generally used, although Composting straw from other crops, such as barley, rice and oil seed rape, is also suitable. In the USA, hay is a major The process of changing these mixtures into a suitable ingredient of mushroom compost. Traditionally, medium for mushroom production by composting, mushroom producers obtained wheat straw as horse or fermentation, takes place in distinct phases. litter from stables. Baled straw mixed with poultry Initially the ingredients are mixed and wetted (phase manure called ‘synthetic’ compost, is widely used as a 0), composting begins (phase I), it is pasteurized and substitute for horse litter. More complex mixtures composting completed (phase II), and finally it is include crushed corncobs, cotton seed meal and colonized by mushroom mycelium (phase III). CULTURE 9 Prewet or phase 0 centre of a compost stack commonly reaches The purpose of this phase is to mix and wet the raw temperatures (70–75˚C), high enough to kill pests material to begin the composting process during and pathogens in the manure or straw. The material which various microorganisms break down the is turned several times by mechanical compost straw. With the increased use of baled straw, a turners, often every other day, but some of the outer prewetting and blending phase has become more layers may not reach the middle and consequently do common. During this process the raw material is not achieve high temperatures. Within the last thoroughly wetted and made into large heaps which decade or so, the use of specially built bunkers with are moved frequently (1). This initial wetting and underfloor ventilation, and sometimes with an open mixing phase occurs over a period of 7 days. or partially open top or under a roof, has become widespread (3). The compost is put into these Phase I bunkers after a short prewet. The continuous supply After the wetting and mixing phase, the compost is of air from below and the insulation provided by the made into long narrow stacks or windrows in which walls result in the bulk of the compost reaching the composting process continues. Traditionally the temperatures of 80˚C or more. It is normal to take windrows of phase I compost are made up in the the compost out of the bunkers at 2- or 3-day open or under the protection of an open-sided shed intervals and put it back, thus allowing additional (2). The phase I process takes a further 7 days. The mixing. Generally, phase I bunker compost is produced in two or three fewer days (i.e. 11–12 days compared with 14 days) than that produced by the 1 traditional methods. Prewet/phase I composting methods are still being actively developed to further improve productivity and reduce odour pollution. Large quantities of water are used in the two early stages of compost production and excess water is generally collected in large containers. The water contains large amounts of organic material which ferments, especially in hot weather. It then becomes anaerobic, producing unpleasant smells. This water, often referred to as ‘goody water,’ must be well 1 Straw bale breaker with a chicken manure hopper on a aerated and it can then be recycled and used to make mixing line at the beginning of the prewet operation. more compost. It can contain large quantities of 2 3 2 Traditional phase II windrows. 3 Phase I bunker with underfloor ventilation holes in the lines in the concrete.