Forestry Commission ARCHIVE DISEASES AND DISORDERS OF FOREST TREES A GUIDE TO IDENTIFYING CAUSES OF ILL-HEALTH IN WOODS AND PLANTATIONS by S C Gregory and D B Redfern Forestry Commission London: The Stationery Office © Crown copyright 1998 Crown copyright material reproduced under licence from the Controller of Her Majesty's Stationery Office and the Forestry Commission. Applications for reproduction should be made in writing to Crown Copyright Unit, Her Majesty's Stationery Office, St Clements House, 2-16 Colgate, Norwich, NR3 1BQ. Front cover, top left: Peridermium pini on Scots pine; pustules on a branch canker (see Figure 42 in main text). Front cover, top centre: Ramichloridium pini on lodgepole pine (see Figure 45 in main text). Front cover, top right: Oak leaves with spots and blotches caused by Apiognomonia errabunda (see Figure 60 in main text). Front cover, bottom left: Scots pine plantation in which most of the trees are dead or dying as a result of Bruncborstia infection (see Figure 46 in main text). Front cover, bottom centre: Fruit bodies of Lachnellula willkommii (see Figure 52 in main text). Front cover, bottom right: Atmospheric pollution injury in Norway spruce (see Figure 5 in main text). Back cover, left: Killing of shoot tip and buds of Sitka spruce by autumn frost (see Figure 30 in main text). Back cover, centre: Beech bark disease; " tarry spots" caused by Nectria infection (see Figure 63 in main text). Back cover, right: Breakage of a larch stem caused by Phaeolus schweinitzii decay (see Figure 71 in main text). Introduction 1 P A R T I A GUIDE TO DIAGNOSING TREE PROBLEMS 5 1. General considerations 5 2. Field investigation 6 2.1. Equipment and sampling 6 2.2. Symptoms and their assessment 7 2.2.1. Foliage discoloration and die-back 7 2.2.2. Resinosis, deformation and decay 8 2.3. Distribution of damage 10 2.4. Timing the occurrence of damage 10 3. Diagnosing the cause of damage 12 P A R T II KEY TO MAJOR DISEASES AND DISORDERS OF PLANTATIONS AND WOODLANDS 15 P A R T III NOTES ON COMMON DISEASES AND DISORDERS OF PLANTATIONS AND WOODLANDS 47 1. Abiotic disorders affecting several species 47 1.1. Planting failure , 47 1.2. General remarks on damage by climate and airborne chemicals 48 1.3. Injury by chemicals 49 1.3.1. Herbicides and fertilizers 49 1.3.2. Other types of chemical injury 51 1.4. Climatic injury 53 1.4.1. Frost 53 1.4.2. Winter injury 54 1.4.3. Wind 57 1.4.4. Drought 57 1.4.5. Lightning 59 1.5. Site 60 1.5.1. Waterlogging 60 1.5.2. Groundwater pollution and toxic soil 61 1.5.3. Lime-induced chlorosis 61 1.6. Genetic defects and chimeras 61 2. Root diseases of conifers 62 2.1. General 62 2.2. A rm illaria (honey fungus) 64 2.3. Heterobasidion cmnosum (Fom es) 66 2.4. Rhizina undulata 69 3. Diseases, disorders and pests of spruce 71 3.1. Frost 71 3.2. Elatobium abietinum (green spruce aphid) 76 3.3. Other causes of injury to young Sidra spruce shoots 77 3.4. Top-dying of Norway spruce 78 3.5. Nutrient deficiencies 81 CONTENTS 3.6. Chrysomyxa rusts 82 3.7. Cucurbitaria bud blight 83 4. Diseases, disorders and pests of pines 84 4.1. Potassium deficiency 84 4.2. Coleosporium tussilapinis 85 4.3. Lophodermium seditiosum 85 4.4. Lophodermella sulcipena 87 4.5. Peridermium canker 88 4.6. Shoot die-back 90 4.6.1. Tomicus piniperda (pine-shoot beetle) 91 4.6.2. Winter injury 91 4.6.3. Ramichloridium pini 92 4.6.4. Brunchorstia pinea 93 4.6.5. Browning and decline of Scots pine 96 4.6.6. Crumenulopsis sororia 97 4.6.7. Frost injury 97 5. Diseases, disorders and pests of larch 98 5.1. Meria laricis 98 5.2. Larch canker 99 5.3. "Larch die-back" 100 5.4. Ips cembrae 101 5.5. Minor causes of shoot die-back in larch 102 6. Diseases, disorders and pests of forest broadleaves 103 6.1. General remarks on diseases, disorders and declines of broadleaves 103 6.2. Insects and mites 106 6.3. Rusts 106 6.4. Apiognomonici errabunda 108 6.5. Leaf spotting and browning of sycamore 108 6.6. Diseases of Prim us 109 6.6.1. Foliage diseases 109 6.6.2. Die-back diseases 110 6.7. Bacterial canker and other poplar diseases 111 6.8. Beech bark disease 112 6.9.Dutch elm disease 114 6.10.Sooty bark disease of sycamore 116 6.11.Shoot diseases of willow 117 6.12.Bracket fungi and death of birch 118 6.13.Ink disease of Castanea and other Phytophthora diseases 119 7. Causes of physical damage 120 7.1. Damage by humans, other mammals and insects 120 7.2. Damage by non-living agents 121 8. Stain and decay 122 8.1. General 122 8.2. Wound-rot 122 8.3. Butt-rots 124 8.4. Phellinus (Fom es) pini; "Ring-rot" 127 1 INTRODUCTION A large number of diseases and disorders can affect forest trees in Britain. Confidence in identifying particular causes from this range of potential problems requires a combination of knowledge and experience that is not easily acquired without becoming a specialist in the field. Nevertheless, we hope that part I of this handbook will provide some useful guidelines by which managers and owners can investigate health problems in their trees. Straightforward field observations of the kind covered here can often allow crucial distinctions to be made between broad categories of disease; they can also provide solutions on which practical decisions can be based. Part II of the handbook is a key to the most common problems of plantation trees and in part III important features of some of the diseases and disorders covered in part II are summarized. Full details of these can be found in "Diseases of Forest and Ornamental Trees" by D H Phillips and D A Burdekin (Macmillan; 2nd ed; 1992), which also provides descriptions of the problems that are noted in the key but not treated in part III. The key and descriptions include some common diseases of trees that are not normally' regarded as major crop trees but which are frequently grown in commercial woodlands. However, street and garden trees are not dealt with specifically. Although these may suffer from some of the same diseases and disorders as plantation trees, symptom expression and pattern are often different, reflecting the different situations in which they are grown. For a comprehensive treatment of the problems of ornamental and amenity trees, we refer readers to "Diagnosis of Ill-health in Trees" by R G Strouts and T G Winter (HMSO; 1994). We have not dealt separately with Christmas tree plantations since, by and large, they are likely to suffer from the same diseases and disorders as forestry plantations of the same age. Methods used in the cultivation of Christmas trees probably expose them to higher risks of some forms of injury - herbicide damage, for example - and it should be acknowledged that some problems that are significant to Christmas trees but of trivial importance to forest crops have not yet been fully investigated. A common example is summer needle browning of Abies species, the cause of which is unknown. It is also relevant to note here that methods of chemical control have not generally been developed or approved for diseases of forest trees, as very few diseases would ever justify such treatment on a forest scale 2 DISEASES AND DISORDERS OF FOREST TREES in Britain. With the single current exception of stump treatment against Heterobasidion annosum (Fomes), forest diseases are either tolerated or managed; sometimes they can be avoided altogether by the choice of species or silvicultural technique. We have made several references to damage by insects. While many insect attacks are made quite obvious by the type of damage or the presence of the culprits themselves, other cases are not clearly insect- related and so could not readily be excluded from a general diagnostic guide. We are indebted to Mr T G Winter and Mr C I Carter for expert assistance with our brief coverage of insects. Further information can be found in "Forest Insects" by D Bevan (Forestry Commission Handbook 1; HMSO; 1987), and in "Christmas Tree Pests" by Clive Carter and Tim Winter (Forestry Commission Field Book 17; The Stationery Office; 1997). Finally, we should emphasize that we have concentrated on the commonest and most important damaging agents in woods and plantations. There are some uncommon diseases and disorders which can produce similar effects to those we describe. Consequently, not all forms o f damage will be identified by the key. If, on investigation, a problem looks serious, it may be advisable to seek confirmation of its cause from a specialist. NAMES The tree species for which we have used common names in the text are listed opposite with their botanical (Latin) names. The naming of pathogens and the diseases they cause has proved less straightforward as many do not have common names in Britain. Rather than contrive names in English, we have used the Latin name o f the pathogen - as in Lophodermium needle-cast and Crumenulopsis canker. However, although the use of Latin names is supposed to avoid the confusion and imprecision of common names, it frequently fails on the first count because the very accuracy of the system entails frequent revision of names by researchers.