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Activated Resistance of Bentgrass Cultivars to Microdochium Nivale Under Predicted Climate Change Conditions

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Activated Resistance of Bentgrass Cultivars to Microdochium Nivale Under Predicted Climate Change Conditions Activated Resistance of Bentgrass Cultivars to Microdochium nivale under Predicted Climate Change Conditions by Sara Marie Stricker A Thesis presented to The University of Guelph In partial fulfilment of requirements for the degree of Masters of Science in Environmental Science Guelph, Ontario, Canada © Sara Marie Stricker, September, 2017 ABSTRACT ACTIVATED RESISTANCE OF BENTGRASS CULTIVARS TO MICRODOCHIUM NIVALE UNDER PREDICTED CLIMATE CHANGE CONDITIONS Sara Marie Stricker Advisor: University of Guelph, 2017 Professor Dr. Tom Hsiang The potential impact of predicted climate change on Microdochium nivale, which causes Microdochium patch on turfgrasses was investigated. Turfgrasses exposed to temperature fluctuations exhibited increased yellowing caused by M. nivale compared to a constant lower temperature incubation. The effect of increased CO2 (from 400 ppm to 800 ppm) on M. nivale hyphal growth, percent yellowing, and biochemical response was assessed for Agrostis spp. and Poa annua cultivars. The efficacy of the resistance activator, Civitas + Harmonizer, was assessed under conditions of increased CO2, two temperatures, and field conditions. Civitas + Harmonizer often decreased disease symptoms, and suppression varied by cultivar and environmental conditions. Elevated CO2 did not affect the growth of M. nivale, although evidence from growth room trials suggests it may decrease Microdochium patch disease severity in the future. However, the interactive effects of temperature, snow cover conditions, and moisture availability in the field under future conditions is unknown. ACKNOWLEDGEMENTS First and foremost, I would like to thank my advisor Dr. Tom Hsiang for welcoming me back into his lab and for his guidance, patience, and wry witticisms that kept me going. I am also very grateful for the opportunities I have had to participate in conferences and educational experiences throughout my time as a master’s student. Many thanks to other member of my committee, Dr. Annick Bertrand, for her enthusiasm, encouragement, and guidance. I thoroughly enjoyed my visit to Agriculture and Agri-Food Canada, and many thanks to Joseé Bourassa and Sandra Delaney for their statistical and technical assistance. Merci beaucoup! Additional thanks to Dr. Trygve Aamlid and the researchers at the Norwegian Institute of Bioeconomy Research (NIBIO) for sharing their insights on turfgrass disease trials in Scandinavia. I also owe a great debt of gratitude to Dr. Greg Boland for introducing me to the fascinating world of plant pathology. I am also grateful to my friends and family, especially my mom and sister who were always just a phone call away. Thank you to Nureen, for your unwavering confidence in me. I would also like to extend my sincere thanks to Anne-Miet Van Den Nieuwelaar, Matt Rudland, Jie Chen, and all of my colleagues over the years, for their friendship and assistance. I would especially like to thank Linda Jewell, for being my mentor during my undergraduate studies and for always being my Microdochium nivale buddy; and to Craig Moore for sharing your coffee with me and for our countless chats. Finally, thank you to my office-mates, Ryan Gourlie, Moez Valliani, and Nahed Mahrous, for tolerating my mess and for their willingness to listen to my rants. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS ..................................................................................................... iii TABLE OF CONTENTS ......................................................................................................... iii LIST OF FIGURES ................................................................................................................... x LIST OF ABBREVIATIONS AND ACRONYMS .............................................................. xiii Chapter 1 Literature Review ........................................................................................................ 1 1.1 Introduction .......................................................................................................................... 1 1.1.1 Turfgrass management .................................................................................................... 1 1.1.2 Cold acclimation and cold hardening ............................................................................. 2 1.1.3 Turfgrass diseases ........................................................................................................... 3 1.1.4 Pink snow mold .............................................................................................................. 3 1.2 Microdochium nivale ............................................................................................................ 4 1.2.1 Origin, distribution and host range of Microdochium nivale .......................................... 4 1.2.2 Microdochium nivale identification ................................................................................ 5 1.2.3 Life cycle of Microdochium nivale ................................................................................. 5 1.2.4 Effect of low temperature on Microdochium nivale ....................................................... 5 1.3 Management methods for Microdochium patch ............................................................... 6 1.3.1 Cultural control methods ................................................................................................. 6 1.3.2 Chemical control methods .............................................................................................. 8 1.3.3 Activated resistance ........................................................................................................ 9 1.4 Climate change and effects on turfgrass health .............................................................. 10 1.4.1 Winter de-hardening and environmental conditions ..................................................... 10 1.4.2 Effects of increased CO2 ............................................................................................... 10 1.4.3 Climate change and winter injury ................................................................................. 11 1.4.4 Influence of climate change on plant diseases .............................................................. 11 1.5 Turfgrass biochemistry under biotic and abiotic stresses .............................................. 12 1.5.1 Changes in free amino acids when under stress ............................................................ 12 1.5.2 Water soluble carbohydrate stress responses ................................................................ 12 1.6 Hypotheses and objectives ................................................................................................. 13 Chapter 2 Effects of Predicted Climate Change on Microdochium nivale ............................. 21 2.1 Introduction ........................................................................................................................ 21 2.1.1 In vitro effects of CO2 on Microdochium nivale .......................................................... 21 2.1.2 Effect of temperature on Microdochium nivale ............................................................ 21 2.2 Hypotheses and Objectives................................................................................................ 22 2.3. Materials and Methods ..................................................................................................... 23 2.3.1 Hyphal growth rates in agar tubes ................................................................................ 23 2.3.2 Effect of CO2 on Microdochium nivale ........................................................................ 23 2.3.3 Optimal growth temperature of Microdochium nivale ................................................. 23 2.3.4 High temperature exposure of Microdochium nivale ................................................... 23 2.3.5 Low temperature exposure of Microdochium nivale .................................................... 24 2.3.6 Statistical analysis ......................................................................................................... 24 2.4 Results ................................................................................................................................. 25 2.4.1 Effect of CO2 on Microdochium nivale ........................................................................ 25 2.4.2 Optimal growth temperature of Microdochium nivale ................................................. 25 2.4.3 High temperature exposure of Microdochium nivale ................................................... 25 2.4.4 Low temperature exposure of Microdochium nivale .................................................... 25 iv 2.5 Discussion ........................................................................................................................... 26 Chapter 3 Effects of Predicted Climate Change on Disease Caused by Microdochium nivale ........................................................................................................................................................ 33 3.1 Introduction ........................................................................................................................ 33 3.1.1 Effects of CO2 on plant diseases ................................................................................... 33 3.1.2 Grass response to changing temperatures ....................................................................
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