Clemson University TigerPrints All Theses Theses 7-2014 Potential susceptibility of Canna flaccida and two Canna hybrids to five species of Phytophthora Kristin Van Kampen Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Part of the Plant Pathology Commons Recommended Citation Van Kampen, Kristin, "Potential susceptibility of Canna flaccida and two Canna hybrids to five species of Phytophthora" (2014). All Theses. 1911. https://tigerprints.clemson.edu/all_theses/1911 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. POTENTIAL SUSCEPTIBILITY OF CANNA FLACCIDA AND TWO CANNA HYBRIDS TO FIVE SPECIES OF PHYTOPHTHORA A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Plant and Environmental Science by Kristin Leigh Van Kampen July 2014 Accepted by: Sarah A. White, Committee Chair Steven N. Jeffers William C. Bridges, Jr. Christina E. Wells ABSTRACT The costs and need for clean water are increasing for greenhouse, nursery, and agricultural businesses. Runoff from irrigated agriculture and specialty crops also can take a toll on the surrounding environment, because irrigation runoff water can contain high amounts of nutrients, contaminants, and plant pathogens. To assuage the pollution contributed to runoff water and reduce the overall volume of water used, nurseries are starting to reuse irrigation runoff water. For this to be possible, the water first should be treated before reuse. Constructed wetlands are a biological treatment option that employs vegetation to collect, filter, and store runoff water. Some wetland plants may have the ability to filter pathogen propagules from runoff without becoming infected and then becoming sources of pathogen inoculum. The purpose of this study was to evaluate the susceptibility of three wetland plants in the genus Canna. (C. flaccida, C. ×generalis ‘Carolina Pink, and C. ×generalis ‘Bird of Paradise’) to five species of Phytophthora (P. cinnamomi, P. citrophthora, P. cryptogea, P. nicotianae, and P. palmivora) that have been found in irrigation runoff water at ornamental plant nurseries. Plants were grown in Milli-Q water was amended with fertilizer and exposed to three isolates of a single species of Phytophthora. Six plants were exposed to one species of Phytophthora for each of the five species. Six plants were also grown but were not exposed to any species of Phytophthora. Zoospore presence and activity was monitored over the course of 28 days with leaf baits, and the infestation and infection of plant roots were evaluated at the end of each experiment. Roots from every Carolina ii Pink plant exposed to zoospores were infested, and 75% of the plants were infected. The leaf bait results for Carolina Pink plants indicated that zoospore activity did not decline during the 28 days in the presence of plants. Canna flaccida was less susceptible; 76% of the exposed plants were infested but only 23% were infected. The Bird of Paradise plants were even less susceptible to colonization by species of Phytophthora: only 33% of exposed plants were infested and 15% were infected. There was also a decline in leaf bait colonization in the presence of both Canna flaccida and Bird of Paradise plants when compared to treatment sets that contained Phytophthora only, even after plants were re-exposed to zoospores at day 14. Phytophthora cinnamomi was most successful at colonizing species of Canna plants, regardless of species or cultivar. The Carolina Pink cultivar cannot be recommended for use in constructed wetlands or vegetative buffers, because it was highly susceptible to species of Phytophthora and could potentially contribute to inoculum loads in recycled irrigation water. Canna flaccida and Bird of Paradise plants could be utilized in vegetative buffers, as they are less susceptible and seemed to help filter inocula from runoff water, as evidenced by decreased zoospore activity over time. iii ACKNOWLEDGMENTS I would like to thank Dr. Sarah White, my advisor, editor, and guide, for her direction and support throughout my research. I also would like to thank the rest of my advising committee: Dr. Steven Jeffers for aiding and educating me in plant pathology, Dr. Billy Bridges for helping me make sense of my data via statistics, and Dr. Christina Wells for her knowledge and support of my work. I am also grateful for my friends and co- workers who have helped me tremendously in the lab: Lynn Luszcz, Suzy Sharpe, Garrett Ridge, David Tyrpak, Alan Jones, and Ron Gossett. Special thanks go to my parents, who have demonstrated the importance of education and hard work; my family and friends, who have held me together and ensconced me with love; and, most importantly, to the One who created all things. iv TABLE OF CONTENTS ABSTRACT ............................................................................................................................. ii ACKNOWLEDGMENTS ......................................................................................................... iv TABLE OF CONTENTS............................................................................................................ v LIST OF FIGURES ................................................................................................................ viii CHAPTER ONE: INTRODUCTION AND LITERATURE REVIEW ............................................... 9 The Greenhouse and Nursery Industry ............................................................... 9 Economic Impact ............................................................................................. 9 Nutrient Requirements ................................................................................... 9 Fungicides ..................................................................................................... 11 Water Requirements and Water Quality ...................................................... 13 Constructed Wetlands as Vegetative Buffers ................................................... 17 Natural and Constructed Wetlands .............................................................. 17 Wetland Plants .............................................................................................. 20 Irrigation Techniques ........................................................................................ 27 Runoff Water ................................................................................................ 29 Pathogens in Runoff Water ............................................................................... 30 Species of Phytophthora ............................................................................... 30 Reproduction of Species of Phytophthora .................................................. .. 31 Taxonomy of Species of Phytophthora .................................................. ....... 32 Isolation of Species of Phytophthora .................................................. .......... 33 Species of Phytopthora in Nurseries ............................................................. 34 Effects of Species of Phytophthora .................................................. ............. 36 Treatment of Species of Phytophthora .................................................. ....... 38 Canna flaccida and Canna Hybrids ................................................................... 41 Research Objective ........................................................................................... 43 Literature Cited ................................................................................................. 44 CHAPTER TWO: POTENTIAL PATHOGENICITY OF FIVE SPECIES OF PHYTOPHTHORA TO CANNA FLACCIDA AND TWO CANNA HYBRIDS ..................................................... 56 Abstract ............................................................................................................. 56 Introduction ...................................................................................................... 57 Materials and Methods ..................................................................................... 61 Species of Phytophthora ............................................................................... 61 Plant Species ................................................................................................. 62 Potential Plant Susceptibility ........................................................................ 63 Pathogen and Water Temperature Monitoring ........................................... 64 Plant Harvest and Pathogen Isolation from Roots ....................................... 65 Statistical Analyses ........................................................................................ 66 Results ............................................................................................................... 67 Canna flaccida .................................................. ............................................. 68 v Table of Contents (Continued) Page Leaf Baits ................................................................................................... 68 Root Infestation and Infection .................................................................. 69 Plant Mass, Shoot Height, and Root Length ............................................