Please read the Summary in the section 03chapter3 of this documentDissertation (MSc)--University of Pretoria, 2005.Plant ScienceUnrestricte

Ahumada, Rodrigo

Dissertation (MSc)--University of Pretoria, 2005.Please read the Summary in the section 03chapter3 of this documentPlant ScienceUnrestricte

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Pathogens in commercial Eucalyptus plantations in Chile, with special reference to Mycosphaerella and Botryosphaeria species Submitted by Rodrigo Ahumada Submitted in partial fulfillment of the requirements for the degree MAGISTER SCIENTIAE In the Faculty ofNatural and Agricultural Science University ofPretoria Pretoria February 2003 PROMOTER: Prof. M. J. Wingfield CO- PROMOTERS: Prof. B. D. Wingfield Mr. G. C. Hunter (M.Sc.)                                                   © University of Pretoria DECLARATION I, the undersigned, hereby declare that the thesis submitted herewith for the degree Magister Scientiae to the University of Pretoria, contains my own independent work and has hitherto not been submitted for any degree at any other University. Rodrigo Ahumada February 2003    CHAPTER 3 BOTRYOSPHAERIA SPECIES CAUSING DIEBACK ON EUCALYPTUS SPP. 100 IN CIIll.E ABSTRACT 101 INTRODUCTION 102 MATERIALS AND METHODS 104 RESULTS 108 DISCUSSION 111 REFERENCES 113 SUMMARY 148 OPSOMMING 150    TABLE OF CONTENTS ACKNOWLEDGEMENTS 	 5 PREFACE 	 6 CHAPTER ] PLANTATION FORESTRY IN CHILE WITH PARTICULAR REFERENCE 8 TO DISEASE AND INSECT PROBLEMS 1.0 INTRODUCTION 	 9 2.0 FORESTRY PLANTATIONS IN CHILE 	 10 2.1 PINUS RADIATA 	 12 2.2 EUCAL YPTUS SPP. 	 12 3.0 	 MAIN SANITARY PROBLEMS OCCURRING IN COMMERCIAL 13 PLANTATIONS 3.1 PINUS PLANTATIONS 	 14 3.2 EUCALYPTUS PLANTATIONS 	 21 4.0 CONCLUSIONS 	 26 5.0 REFERENCES 	 27 CHAPTER 2 MYCOSPHAERELLA SPECIES CAUSING LEAF BLOTCH DISEASE ON 52 EUCALYPTUS SPP. IN CHILE ABSTRACT 53 INTRODUCTION 54 MATERIALS AND METHODS 55 RESULTS 58 DISCUSSION 62 REFERENCES 65    ACKNOWLEDGEMENTS I want to dedicate this thesis to my wonderful grandmother, with much 10ve.At 96 years you are a great example in faith and optimism. Thanks "Mamita" you are great! I want to thank the Lord for his constant love and guidance in the small and big things in my life. I really felt His support and care for both my family and myself. I want to give all my love and gratitude to my wife, Ana Maria, and my "super star" children, Rodri, Javi and Jose. They loved, supported and helped me unconditionally during this whole time. Thanks you for being a great family. Thanks also to the rest of my family from Chile, who supported us with their constant prayers and love. My mother, sister and brother have a special place in my heart. Similarly, our friends from Chile, who are like family, have meant so much to us during this time. This thesis would not be fmished without the great and professional support of my advisory team, Mike Wingfield, Brenda Wingfield and Gavin Hunter. Thank you Mike and Brenda for giving me the opportunity in the fust place. Thank you Gavin for spending many hours in the lab. listening and teaching. Thanks to all of you for your friendship and good disposition all the time. Thanks also to our other special friends in F ABI, you will always be in the hearts and minds ofour family. I would like to thank to Bioforest and the board for giving me the opportunity and fmancial support to pursue this dream. A special word of thanks goes to my manager and friend Eduardo Rodriguez, for his encouragement and support. I will not forget my collegues and friends from Arauco for much valued assistance during this period. 5    PREFACE Commercial plantations in Chile are comprised of exotic Pinus and Eucalyptus species, which make up approximately 2.1 million ha. Eucalyptus spp. represent about 17 % of the total, and the most widely planted species are E. globulus and E. nitens. Both species have been considered as relatively disease free in Chile, despite their susceptibility to several insects and diseases, elsewhere in the world. In Chile, leaf spot diseases are considered the most important sanitary problem associated with commercial Eucalyptus plantations and Mycosphaerella spp. appear to be the fungi causing the most significant damage. Botryosphaeria spp. have also been considered as a potential threat to Eucalyptus plantations, especially based on experience in other countries, where these fungi severely damage stressed trees. Very little research has been conducted on Eucalyptus diseases in Chile and the aim of this thesis was to expand our knowledge of this field. The more specific aim was to provide robust identifications for the species of Mycosphaerella and Botryosphaeria associated with disease symptoms in commercial Eucalyptus plantations in Chile. In the first chapter of this thesis, a general review of forestry activities ill Chile is presented. Special emphasis is placed on matters pertaining to tree health. Information is summarized separately for Pinus and Eucalyptus species and is organized in such a way that insect pests and disease problems are treated separately. A review of the available literature on tree pest and disease problems in Chile is provided to serve as a foundation for research undertaken in this thesis. Prior to undertaking studies in this thesis, very little research had been conducted on forest pathogens. In the second chapter of the thesis, I have undertaken a study to identify the most common Mycosphaerella spp. associated with leaf spot diseases in Chile. The taxonomy of these fungi is known to be very complicated and it was previously based exclusively on morphological characteristics. However, recent studies have applied DNA sequencing techniques to this process. My aim has thus been to use DNA sequence data, together with morphological characters to identify Mycosphaerel/a spp. associated with leaf diseases of Eucalyptus in Chile. Ultimately, the intention has also been to gain some perspective on the relative importance of the various species of these fungi in Chile and to reduce losses caused by them To achieve this objective, diseased adult and juvenile E. 6    globulus and E. nitens leaves were collected from plantations in Northern-central and Southern-central Chile. Species of Mycosphaerella were identified based on ascospore germination patterns, cultural characteristics and sequence data from the Internal Transcribed Spacer (ITS) region of the rRNA operotL Botryosphaeria spp. have thus far not been considered as serious pathogens in Eucalyptus plantations in Chile. This is despite the fact that they can be highly damaging elsewhere in the world. However, very little is known regarding their presence or potential to cause disease. The rapid growth ofcommercial Eucalyptus plantations has resulted in an increase in new pests and diseases. Ofthese, Botryosphaeria dieback disease has begun to appear in young and adult trees more frequently in Chile. Therefore, the aim of studies presented in Chapter III of this thesis, was to identify the Botryosphaeria spp. associated with dieback disease of commercial Eucalyptus plantations. Symptomatic branches were thus collected from E. globulus and E. nitens plantations in Northern-central and Southern-central Chile. Species of Botryosphaeria were subsequently identified based on morphological characteristics and sequence data from the Internal Transcribe Spacer (ITS) and ~-tubulin regions of the ribosomal RNA operon. A greenhouse pathogenicity triai was also conducted using the various Botryosphaeria spp. identified, to evaluate their relative importance in Chile. The primary aim of this thesis is to provide a better understanding of Mycosphaerella and Botryosphaeria species that are currently damaging Eucalyptus spp. in commercial plantations in Chile. The study is the first of its kind and it will hopefully also form a foundation for further studies of Eucalyptus diseases in the country. Knowledge of contemporary techniques to identify pathogens has also been learned and this will also be useful to forestry researchers in Chile in the future. 7    

Pathogens in commercial Eucalyptus plantations in Chile, with special reference to Mycosphaerella and Botryosphaeria species

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Pathogens in commercial Eucalyptus plantations in Chile, with special reference to Mycosphaerella and Botryosphaeria species

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