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Keynote address INTRODUCTION Emerging frontiers in forest pathology Michael J. Wingfield{ XE "Wingfield, M.J." } Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa If one uses the first text book on the topic as starting point, the study of tree diseases is a little more than 100 years old. Thus, Robert Hartig’s fundamental text published in 1874 and translated into English in 1894 as “Textbook of the diseases of trees” provided the first firm foundation for forest pathology. It is interesting, that it was not long after the publication of Hartig’s forest pathology text book that chestnut blight caused by Cryphonectria parasitica was first found outside its native range in the United States in 1904. At the time, this might have been considered co‐incidental, but it was clearly linked to growing trade, particularly between northern hemisphere countries and particularly including wood and wood products. Thus, outbreaks of devastating diseases such as white pine blister rust, Dutch elm disease and others caused by non‐native pathogens first emerged more or less during the same period of time. The study of tree diseases and the field of forest pathology have grown firmly during the course of the last Century. The causal agents of diseases of unknown aetiology have been discovered, new diseases have been recorded and the biology of the biology of many important tree pathogens has been elucidated. A suite of outstanding text books have been produced both for the teaching environment as well as for diagnosticians. Furthermore, we have celebrated the careers of many outstanding forest pathologists, working in many different parts of the world and contributing substantially to our understanding of tree pathogens and the diseases that they cause. While forest pathology has become a well‐established field of study and outstanding forest pathologists practice in many countries, there are causes for concern. In this regard, new and in some cases very serious tree diseases continue to appear regularly, both in natural forests and in plantation environments. This implies that in many situations, we are failing to manage the global threats to forests and forestry due to diseases. Ironically, there are also indications, at least in some countries that positions for forest pathologists and educators in this field are decreasing, rather than increasing in number. NEW TREE PATOHGEN TRENDS The threats relating to new diseases emerging from the accidental movement of pathogens from one area to another is well‐recognised. This is also a category of disease that continues to increase, despite global efforts to manage the movement of plants and plant products. A worrying trend that appears to be increasing is the adaptation of pathogens to new hosts. Apparent host and vector shifts, at levels previously unexpected are occurring for host specific pathogens. Novel pathogens are also emerging through hybridisation. The processes leading to host/vector shifts and hybridisation leading to the evolution of so‐called “new pathogens” are pathogens” are poorly understood and they deserve increased attention. FOREST PATHOLOGY OPPORTUNITIES New tree diseases and new categories of tree disease are emerging and this is a trend that is likely to continue to grow. This will also bring new and exciting challenges for forest pathologists. New tools and technologies continue to become available for research and these will clearly also enhance the depth and breadth of tree pathology investigations. Identification of tree pathogens and disease diagnosis is a field that has changed markedly during the course of the last two decades. The emergence of DNA‐based tools for these purposes is now commonly used and this will be increasingly true in the future. Many tree pathogens that have been treated as single species are now known to represent suites of cryptic taxa and this is already having a substantial impact on for example quarantine regulations. DNA based techniques have likewise made it possible to recongnise hybrids between species and they have shifted our understanding of pathogen population biology to new and exciting levels. Furthermore, diagnostics have become much more rapid and also more accurate. These are all areas that will grow substantially in the foreseeable future. For many years, quarantine efforts to restrict the movement of pathogens, was based on lists of names of undesirable organisms. It is now widely recognised that such lists have many flaws, many that have also emerged from the more sophisticated taxonomy and population biology tools now available. The focus has clearly shifted to understanding pathways that allow pathogens to move globally. Many opportunities remain to be explored in this domain and exciting new strategies are likely to emerge in the future In order to understand the importance and impact of climate change on tree health, there will clearly need to be a greater focus on team research. The importance of integrating the efforts of scientists from different disciplines has long been recognised. Yet there are disappointingly few examples of tree health research conducted by formally constituted and supported multidisciplinary teams. CONCLUSION Forest pathology is more important today than it has ever been in the past. The threat of tree diseases in their many different manifestations has increased steadily ever since they were first formally recognised. This trend is likely to continue to grow. The challenge for forest pathologists will be to fight for a fair share of biological science budgets for tree health research. This funding can then be expended to capture the many new and exciting opportunities and technologies that can contribute substantially to improving the current and future health of the world’s forests. Climate change is one of the most important issues facing the world and it will clearly also impact on tree health. Very little focused research has been conducted on the likely impact of climate change on tree diseases. This is a complex area of study but it is also one that will require the attention of forest pathologists globally. 34 PLANT HEALTH MANAGEMENT: AN INTEGRATED APPROACH | APPS 2009
INTRODUCTION Variability in pathogenicity of Quambalaria pitereka on spotted gums G.S. Pegg{ XE "Pegg, G.S." } A , A.J. Carnegie B , M.J. Wingfield C , A. Drenth A A Tree Pathology Centre, The University of Queensland/Primary Industries and Fisheries, Queensland, Australia, 4068 B Forest Resources Research, NSW Department of Primary Industries, New South Wales, Australia, 2119 C Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa, 0002 Quambalaria shoot blight (QSB) is a serious disease affecting the expanding eucalypt plantation estate in subtropical and tropical eastern Australia (1,2). Quambalaria pitereka has been isolated from foliage, stems and woody tissue of species in the genera Corymbia, Blakella and Angophora in Australia (1,2,3). Quambalaria pitereka affects the new flush of Corymbia foliage causing spotting, necrosis and distortion of expanding leaves and green stems. The aim of this investigation was to identify if variation in pathogenicity levels existed between isolates of Q. pitereka collected from a range of species and regions in NSW and Queensland. MATERIALS AND METHODS Isolates of Q. pitereka were collected from spotted gum plantations and Corymbia species trials in north Queensland (NQ), south east Queensland (SEQ) and northern New South Wales (NSW). Isolates used were: Q107 from C. torelliana (NQ), Q147 from C. citriodora (NQ), Q151, Q152 from C. variegata (SEQ) and Q191, Q200 from C. variegata (NSW). Spotted gum seedlings (1/2 sibling Woondum provenance) and cuttings were grown in steam sterilised soil mix and fertilised with slow release Osmocote ® (Native Trees) as required and irrigated twice a day for 10 minutes each using overhead sprinklers. Glasshouse temperatures were maintained at 25– 28°C during the day and 20–22°C overnight. Seedlings were grown for three months prior to inoculation with Q. pitereka. QSB Score (x/100) 35 30 25 20 15 10 5 0 Q107 Q147 Q151 Q152 Q191 Q200 Quambalaria pitereka isolate Figure 1. Comparison of pathogenicity of a range of isolates of Q. pitereka on spotted gum, Woondum provenance. DISCUSSION Variability in pathogenicity between isolates of Q. pitereka has not previously been studied. This preliminary study using isolates from a range of regions identifies only a small degree of variability. More extensive studies are needed to investigate the significance of pathogen virulence on disease development, especially in relation to selecting for disease resistance. Further studies are required to investigate Q. pitereka population genetics and potential variability in isolate virulence. ACKNOWLEDGEMENTS We thank Queensland Primary Industries Innovation and Biosecurity Program Investment, Forest Plantations Queensland, Integrated Tree Cropping, Forest Enterprises Australia and Forests NSW for providing the necessary funding for this research. Session 2A—Forest pathology/native Isolates of Q. pitereka were obtained from single lesions and grown on Potato Dextrose Agar (PDA) for 2 to 3 weeks in the dark at 25°C. A spore suspension (1x10 6 spores/ml) was obtained by washing plates with sterile distilled water (SDW) to which two drops of Tween 20 had been added prior to inoculation. Seedlings were inoculated using a fine mist spray (2.9 kPa pressure) generated by a compressor driven spray gun (Iwata Studio series 1/6 hp; Gravity spray gun RG3, Portland, USA), to the upper and lower leaf surfaces of the seedlings until runoff was achieved. All seedling trees were covered with plastic bags immediately after inoculation to maintain high humidity levels and to increase the period of leaf wetness. Bags were removed after 48 hours and plants watered using overhead irrigation systems twice a day for a period of 10 minutes. Sub‐samples of the spore suspension applied to the trees were placed onto PDA and incubated at 25°C for 48 hours to ensure that the spores were viable. REFERENCES 1. Carnegie AJ, 2007a. Forest health condition in New South Wales, Australia, 1996–2005. I. Fungi recorded from eucalypt plantations during forest health surveys. Australasian Plant Pathology 36, 213– 24. 2. Pegg GS, O’Dwyer C, Carnegie AJ, Wingfield MJ, Drenth A 2008. Quambalaria species associated with plantation and native eucalypts in Australia. Plant Pathology 57, 702–14. 3. Simpson JA, 2000. Quambalaria, a new genus of eucalypt pathogens. Australasian Mycologist 19, 57–62. Each treatment was replicated six times with a single inoculation per tree and assessed for disease incidence and severity 14 days later. A QSB score was then calculated to compare levels of pathogenicity between isolates. A comparison between isolates was done using ANOVA (StatView®). RESULTS Significant variability in pathogenicity was observed between isolates. Isolate Q152 was significantly more virulent than all other isolates. APPS 2009 | PLANT HEALTH MANAGEMENT: AN INTEGRATED APPROACH 35
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Keynote address A world of possibil
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Posters List of posters Poster no.
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Posters 21 First report of Leveillu
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Index Abkhoo, J....................
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