Aerial transmission and strategies for control of Pythium on hydroponically grown cucumbers. Item Type text; Dissertation-Reproduction (electronic) Authors Goldberg, Natalie Pauline. Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 28/09/2021 21:57:02 Link to Item http://hdl.handle.net/10150/185247 INFORMATION TO USERS The most advanced technology has been used to photograph and reproduce this manuscript from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. 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AERIAL TRANSMISSION AND STRATEGIES FOR CONTROL OF PITH/UM ON HYDROPONICALLY-GROWN CUCUMBERS by Natalie Pauline Goldberg A Dissertation Submitted to the Faculty of the DEPARTMENT OF PLANT PATHOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1990 THE UNIVERSITY OF ARIZONA 2 GRADUATE COLLEGE As members of the Final Examination Committee, we certify that we have read the dissertation prepared by ___N_a_t_a_l_i_e __P_a_u_l_i_n_e __G_o_l_d_b_e_r~g __________________ ___ entitled Aerial Transmission and Strategies for Control of Pythium on Hydroponically-Grown Cucumbers--------------------------------- and recommend that it be accepted as fUlfilling the dissertation requirement for the Degree of Doctor of Philosophy Date Date Date Date Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. /'1';.. I ffo 3 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgement the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: d~f?C&J~ 4 This dissertation is dedicated to family and friends whose love, friendship, support and encouragement has helped me to achieve my goals. 5 ACKNOWLEDGEMENTS I wish to express my sincere appreciation and gratitude to Dr. Michael Stanghellini under whose guidance this research was conducted. I express thanks, not only for his scientific help and critical review of this manuscript, but also for his genuine personal interest, his excellent advice, his endless and contagious enthusiasm, and most of all for making my graduate research fun. I would also like to express my gratitude to Dr. Richard Hine, for his generosity, interest, friendship and for teaching me what Plant Pathology is really all about. Thanks are expressed to Dr. Robert Gilbertson, whose friendship was never ending and who always provided a great game of racquetball. And to Dr. Iraj Misaghi for continued support and sincere friendship. The kindness and generosity of Mrs. Pat Hine is also gratefully acknowledged and appreciated. Thanks also to Mr. Tom Kruk, whose sense of humor helped to bring pleasure to life without windows. Special thanks are given to Dr. Judy Brown and her family, Gary, Kevin and Katie, who are truly very precious friends. Thanks for everything, but most of all, thanks for picking me up when I was down and for readjusting my thinking whenever I was sure it wasn't worth the pain. The completion of this work would not have been possible without the help of my good friend and labmate, Mr. Scott Rasmussen. Thanks are extended for helping me with the hydroponic tanks and for always being willing to lend a hand whenever help was needed. Heartfelt thanks are extended to my many good friends I have made during my stay in Arizona. I would especially like to thank the members of Bad News, The Harvey Mason Fan Club and Triple Bypass, for providing good times and a lot of laughs. And to Terri Gerber, for helpful advice and encouragement; and to Jody Schneider, for her friendship and for giving me the opportunity to coach volleyball at Mountain View High School, a wonderful diversion without which this work would not have been possible. Finally, my appreciation is given to the University of Arizona and the Department of Plant Pathology for providing the resources necessary for me to carry out this research. 6 TABLE OF CONTENTS Page LIST OF ILLUS1RATIONS ...................................... 8 LIST OF TABLES ............................................. 9 ABS1RACT ................................................. 10 CHAPTERS 1. INTRODUCTION AND LITERATURE REVIEW ................. 12 History and definitions ..................................... 12 Types of hydroponic systems .............................. 13 Diseases in hydroponically-grown vegetables .................. 15 Disease symptoms ..................................... 20 Introduction and spread of pathogens ....................... 22 Methods of disease control ............................... 25 Objectives ........................................... 30 2. FIL1RATION AS A S1RATEGY FOR CONTROL OF PITHIUM APHANIDERMATUM IN RECIRCULATING HYDROPONICS ...................................... 31 Materials and Methods .................................. 32 Results and Discussion .................................. 36 3. INGESTION-EGESTION AND AERIAL TRANSMISSION OF PITHIUM APHANIDERMATUM BY SHORE FilES (EPHYDRINAE: SCATELLA STAGNALIS) ................. 42 Materials and Methods .................................. 44 Pathogen infestation of adult flies, pupae and larvae ......... 44 Germinability of oospores recovered from larvae, pupae, and adult flies ................................ 46 Germinability of oospores in insect frass .................. 46 Larval transmission of P. aphanidennatum ................ 47 Adult fly transmission of P. aphanidennatum ............... 35 7 Page Results .............................................. 48 Pathogen infestation of adult flies, pupae, and larvae ........ 48 Germinability of oospores recovered from larvae, pupae, and adult flies .. ,............................. 48 Germinability of oospores in frass ....................... 51 Larval and adult fly transmission of P. aphanidennatum ...... 51 Discussion ........................................... 52 REFERENCES CITED ........................................ 54 8 liST OF ILLUSTRATIONS Figure Page 1. Recirculating hydroponic system ............................ 33 2. Photograph of the 7-J.lITl filter cartridge used to study the efficacy of filtration of zoospore infested water on control of root rot of cucumber caused by Pythium aphanidennaP.jm .................. 35 3. Disease incidence in cucumbers resulting from the recirculation of water from (A) tank 1 which was artificially infested with Pythium aphanidermatum to (B) tank 2 and (C) tank 3 five days after receiving infested water passed through a 20-J,lm and 7-J.lITl filter, respectively ........................ 37 4. Efficacy of filtration of infested water to control root rot of cucumber caused by Pythium aphanidermatum in a recirculating hydroponic