DOCSLIB.ORG

U·M·I University Microfilms International a Bell & Howell Information Company 300 North Zeeb Road

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
U·M·I University Microfilms International a Bell & Howell Information Company 300 North Zeeb Road 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. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. U·M·I University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road. Ann Arbor. MI 48106-1346 USA 313 761-4700 800 521-0600 Order Number 9111934 Aerial transmission and strategies for control of Pythium on hydroponically-grown cucumbers Goldberg, Natalie Pauline, Ph.D. The University of Arizona, 1990 U·M·I 300 N. Zeeb Rd. Ann Arbor, MI 48106 NOTE TO USERS THE ORIGINAL DOCUMENT RECEIVED BY U.M.I. CONTAINED PAGES WITH PHOTOGRAPHS WHICH MAY NOT REPRODUCE PROPERLY. TIllS REPRODUCTION IS THE BEST AVAILABLE COPY. 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
Load more

Recommended publications
  • Phytopythium: Molecular Phylogeny and Systematics
    Persoonia 34, 2015: 25–39 www.ingentaconnect.com/content/nhn/pimj RESEARCH ARTICLE http://dx.doi.org/10.3767/003158515X685382 Phytopythium: molecular phylogeny and systematics A.W.A.M. de Cock1, A.M. Lodhi2, T.L. Rintoul 3, K. Bala 3, G.P. Robideau3, Z. Gloria Abad4, M.D. Coffey 5, S. Shahzad 6, C.A. Lévesque 3 Key words Abstract The genus Phytopythium (Peronosporales) has been described, but a complete circumscription has not yet been presented. In the present paper we provide molecular-based evidence that members of Pythium COI clade K as described by Lévesque & de Cock (2004) belong to Phytopythium. Maximum likelihood and Bayesian LSU phylogenetic analysis of the nuclear ribosomal DNA (LSU and SSU) and mitochondrial DNA cytochrome oxidase Oomycetes subunit 1 (COI) as well as statistical analyses of pairwise distances strongly support the status of Phytopythium as Oomycota a separate phylogenetic entity. Phytopythium is morphologically intermediate between the genera Phytophthora Peronosporales and Pythium. It is unique in having papillate, internally proliferating sporangia and cylindrical or lobate antheridia. Phytopythium The formal transfer of clade K species to Phytopythium and a comparison with morphologically similar species of Pythiales the genera Pythium and Phytophthora is presented. A new species is described, Phytopythium mirpurense. SSU Article info Received: 28 January 2014; Accepted: 27 September 2014; Published: 30 October 2014. INTRODUCTION establish which species belong to clade K and to make new taxonomic combinations for these species. To achieve this The genus Pythium as defined by Pringsheim in 1858 was goal, phylogenies based on nuclear LSU rRNA (28S), SSU divided by Lévesque & de Cock (2004) into 11 clades based rRNA (18S) and mitochondrial DNA cytochrome oxidase1 (COI) on molecular systematic analyses.
    [Show full text]
  • CANOPY and LEAF GAS EXCHANGE ACCOMPANYING PYTHIUM ROOT ROT of LETTUCE and CHRYSANTHEMUM a Thesis Presented to the Faculty Of
    CANOPY AND LEAF GAS EXCHANGE ACCOMPANYING PYTHIUM ROOT ROT OF LETTUCE AND CHRYSANTHEMUM A Thesis Presented to The Faculty of Graduate Studies of The University of Guelph In partial ful filment of requirements for the degree of Master of Science January, 200 1 Q Melanie Beth Johnstone, 200 1 National Library Bibliothèque nationale 191 of Canada du Canada Acquisitions and Acquisitions et Bibliographic Services seivices bibliographiques 395 Wellington Street 395, me Wellington Ottawa ON KIA ON4 Ottawa ON K 1A ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence dowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or seil reproduire, prêter, distribuer ou copies of this thesis in rnicroform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substanhal extracts fiom it Ni la thèse ni des extraits substantiels may be printed or othenvise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. ABSTRACT CAKOPY AND LEAF GAS EXCHANGE ACCOMPANYING PYTHIUMROOT ROT OF LETTUCE AND CHRYSANTHEMUM Melanie Beth Johnstone Advisors: University of Guelph, 2000 Professor B. Grodzinski Professor J.C. Sutton The first charactenzation of host carbon assimilation in response to Pythium infection is described. Hydroponic lettuce (Lactuca sativa L.
    [Show full text]
  • PROOF Biological Control of Pythium Root Rot of Chrysanthemum in Small-Scale Hydroponic Units
    PHYTOPATHOLOGY PROOF W. Liu et al. (2007) Phytoparasitica 35(2):xxx-xxx PROOF Biological Control of Pythium Root Rot of Chrysanthemum in Small-scale Hydroponic Units W. Liu,1 J.C. Sutton,1;∗ B. Grodzinski,2J.W. Kloepper3 and M.S. Reddy3 The capacity of several strains of root-colonizing bacteria to suppress Pythium aphanider- matum, Pythium dissotocum and root rot was investigated in chrysanthemums grown in single-plant hydroponic units containing an aerated nutrient solution. The strains were 4 −1 applied in the nutrient solution at a final density of 10 CFU ml and 14 days later the 4 root systems were inoculated with Pythium by immersion in suspensions of 10 zoospores −1 ml solution. Controls received no bacteria, no Pythium, or one of the Pythium spp. but no bacteria. Strain effectiveness was estimated based on percent roots colonized by Pythium and area under disease progress curves (AUDPC). In plants treated respectively with Pseudomonas (Ps.) chlororaphis 63-28 and Bacillus cereus HY06 and inoculated with P. aphanidermatum, root colonization by the pathogen was 83% and 72% lower than in the pathogen control, and AUDPC value was reduced by 61% and 65%. For P. dissotocum, the respective strains reduced root colonization by 87% and 91%, and AUDPC values by 70% and 90%. In plants treated respectively with Pseudomonas chlororaphis Tx-1 and Comamonas acidovorans c-4-7-28, root colonization by P. aphanidermatum was 84% and 80% lower than in the controls and AUDPC values were reduced by 66% and 57%; these strains did not suppress P. dissotocum. Burkholderia gladioli C-2-74 and C.
    [Show full text]
  • Rice Diseases and Disorders in Louisiana D E
    Louisiana State University LSU Digital Commons LSU Agricultural Experiment Station Reports LSU AgCenter 1991 Rice diseases and disorders in Louisiana D E. Groth Follow this and additional works at: http://digitalcommons.lsu.edu/agexp Recommended Citation Groth, D E., "Rice diseases and disorders in Louisiana" (1991). LSU Agricultural Experiment Station Reports. 668. http://digitalcommons.lsu.edu/agexp/668 This Article is brought to you for free and open access by the LSU AgCenter at LSU Digital Commons. It has been accepted for inclusion in LSU Agricultural Experiment Station Reports by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. Bulletin No. 828 July 1991 Rice Diseases and Disorders in Louisiana D. E. Groth, M. C .. Rush, and C.A. Hollier MIDL s 6 7 E36 n o .828 1 9 91 July Contents Page Acknowledgments...... ..... .. ..... ........................... .. ...... ................................... 3 Introduction ................... .................................................... ... .. ...................... 5 Rice Disease Identification . .. ....... ....... ...... ...... ...... ...... ...... ..... ..... ....... ...... 6 Guide to Identifying Rice Diseases Present in Louisiana.... .. .. .................. 7 Rice Diseases in Louisiana . ..... ....... ..... ....... .... .. ... ...... ....... ... .. .... ....... .... 11 Bacterial Leaf Blight ............................................................................ 11 Black Kernel............................ ... .. ... .....................................................
    [Show full text]
  • ABSTRACT REEVES, ELLA ROBYN. Pythium Spp. Associated with Root
    ABSTRACT REEVES, ELLA ROBYN. Pythium spp. Associated with Root Rot and Stunting of Winter Field and Cover Crops in North Carolina. (Under the direction of Dr. Barbara Shew and Dr. Jim Kerns). Soft red winter wheat (Triticum aestivum) was valued at over $66 million in North Carolina in 2019, but mild to severe stunting and root rot limit yields in the Coastal Plain region during years with above-average rainfall. Pythium irregulare, P. vanterpoolii, and P. spinosum were previously identified as causal agents of stunting and root rot of winter wheat in this region. Annual double-crop rotation systems that incorporate winter wheat, or other winter crops such as clary sage, rapeseed, or a cover crop are common in the Coastal Plain of North Carolina. Stunting and root rot reduce yields of clary sage, and limit stand establishment and biomass accumulation of other winter crops in wet soils, but the role that Pythium spp. play in root rot of these crops is not understood, To investigate species prevalence, isolates of Pythium were collected from stunted winter wheat, clary sage, rye, rapeseed, and winter pea plants collected in eastern North Carolina during the growing season of 2018-2019, and from all crops except winter wheat again in 2019-2020. A total of 534 isolates were identified from all hosts. P. irregulare (32%), P. vanterpoolii (17%), and P. spinosum (16%) were the species most frequently recovered from wheat. P. irregulare (37% of all isolates) and members of the species complex Pythium sp. cluster B2A (28% of all isolates) comprised the majority of isolates collected from clary sage, rye, rapeseed, and winter pea.
    [Show full text]
  • The Pennsylvania State University
    The Pennsylvania State University The Graduate School Department of Plant Pathology and Environmental Microbiology CHARACTERIZATION OF Pythium and Phytopythium SPECIES FREQUENTLY FOUND IN IRRIGATION WATER A Thesis in Plant Pathology by Carla E. Lanze © 2015 Carla E. Lanze Submitted in Partial Fulfillment of the Requirement for the Degree of Master of Science August 2015 ii The thesis of Carla E. Lanze was reviewed and approved* by the following Gary W. Moorman Professor of Plant Pathology Thesis Advisor David M. Geiser Professor of Plant Pathology Interim Head of the Department of Plant Pathology and Environmental Microbiology Beth K. Gugino Associate Professor of Plant Pathology Todd C. LaJeunesse Associate Professor of Biology *Signatures are on file in the Graduate School iii ABSTRACT Some Pythium and Phytopythium species are problematic greenhouse crop pathogens. This project aimed to determine if pathogenic Pythium species are harbored in greenhouse recycled irrigation water tanks and to determine the ecology of the Pythium species found in these tanks. In previous research, an extensive water survey was performed on the recycled irrigation water tanks of two commercial greenhouses in Pennsylvania that experience frequent poinsettia crop loss due to Pythium aphanidermatum. In that work, only a preliminary identification of the baited species was made. Here, detailed analyses of the isolates were conducted. The Pythium and Phytopythium species recovered during the survey by baiting the water were identified and assessed for pathogenicity in lab and greenhouse experiments. The Pythium species found during the tank surveys were: a species genetically very similar to P. sp. nov. OOMYA1702-08 in Clade B2, two distinct species of unknown identity in Clade E2, P.
    [Show full text]
  • Pathogens and Molds Affecting Production and Quality of Cannabis Sativa L
    ORIGINAL RESEARCH published: 17 October 2019 doi: 10.3389/fpls.2019.01120 Pathogens and Molds Affecting Production and Quality of Cannabis sativa L. Zamir K. Punja*, Danielle Collyer, Cameron Scott, Samantha Lung, Janesse Holmes and Darren Sutton Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada Plant pathogens infecting marijuana (Cannabis sativa L.) plants reduce growth of the crop by affecting the roots, crown, and foliage. In addition, fungi (molds) that colonize the inflorescences (buds) during development or after harvest, and which colonize internal tissues as endophytes, can reduce product quality. The pathogens and molds that affect C. sativa grown hydroponically indoors (in environmentally controlled growth rooms and greenhouses) and field-grown plants were studied over multiple years of sampling. A PCR- based assay using primers for the internal transcribed spacer region (ITS) of ribosomal DNA confirmed identity of the cultures. Root-infecting pathogens includedFusarium oxysporum, Fusarium solani, Fusarium brachygibbosum, Pythium dissotocum, Pythium Edited by: myriotylum, and Pythium aphanidermatum, which caused root browning, discoloration of Donald Lawrence Smith, the crown and pith tissues, stunting and yellowing of plants, and in some instances, plant McGill University, Canada death. On the foliage, powdery mildew, caused by Golovinomyces cichoracearum, was the Reviewed by: David L. Joly, major pathogen observed. On inflorescences,Penicillium bud rot (caused by Penicillium Université de Moncton, olsonii and Penicillium copticola), Botrytis bud rot (Botrytis cinerea), and Fusarium bud Canada Benedetta Mattei, rot (F. solani, F. oxysporum) were present to varying extents. Endophytic fungi present University of L’Aquila, Italy in crown, stem, and petiole tissues included soil-colonizing and cellulolytic fungi, such *Correspondence: as species of Chaetomium, Trametes, Trichoderma, Penicillium, and Fusarium.
    [Show full text]
  • Ecology and Management of Pythium Species in Float Greenhouse Tobacco Transplant Production
    Ecology and Management of Pythium species in Float Greenhouse Tobacco Transplant Production Xuemei Zhang Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Pathology, Physiology and Weed Science Charles S. Johnson, Chair Anton Baudoin Chuanxue Hong T. David Reed December 17, 2020 Blacksburg, Virginia Keywords: Pythium, diversity, distribution, interactions, virulence, growth stages, disease management, tobacco seedlings, hydroponic, float-bed greenhouses Copyright © 2020, Xuemei Zhang Ecology and Management of Pythium species in Float Greenhouse Tobacco Transplant Production Xuemei Zhang ABSTRACT Pythium diseases are common in the greenhouse production of tobacco transplants and can cause up to 70% seedling loss in hydroponic (float-bed) greenhouses. However, the symptoms and consequences of Pythium diseases are often variable among these greenhouses. A tobacco transplant greenhouse survey was conducted in 2017 in order to investigate the sources of this variability, especially the composition and distribution of Pythium communities within greenhouses. The survey revealed twelve Pythium species. Approximately 80% of the surveyed greenhouses harbored Pythium in at least one of four sites within the greenhouse, including the center walkway, weeds, but especially bay water and tobacco seedlings. Pythium dissotocum, followed by P. myriotylum, were the most common species. Pythium myriotylum, P. coloratum, and P. dissotocum were aggressive pathogens that suppressed seed germination and caused root rot, stunting, foliar chlorosis, and death of tobacco seedlings. Pythium aristosporum, P. porphyrae, P. torulosum, P. inflatum, P. irregulare, P. catenulatum, and a different isolate of P. dissotocum, were weak pathogens, causing root symptoms without affecting the upper part of tobacco seedlings.
    [Show full text]
  • Considering Cannabis
    October 2015 CONTROLLED ENVIRONMENT AGRICULTURE Consi dering Canna bis THE SCIENCE AND PRACTICALITY OF GROWING CEA’S TRENDIEST CROP. WILL YOU BE CAUGHT UP IN THE “GREEN RUSH” ? Page 10 PAGE 16 PAGE 24 PAGE 26 FIELD-GROWN FROM FOOTBALL GROWING LETTUCE Which TO FARMING A ORGANIC? These ones work in young man's journey are the best fertilizers hydroponic systems? into hydroponics 1 Reader Service Number 200 Reader Service Number 201 From Your Editor first time we’ve broken from the mold and pushed the boundaries of the traditional hor - ticulture industry. In June 2011, GrowerTalks was the first trade publication in our industry to openly discuss cannabis—a feature story Managing Editor Jennifer Zurko won a presti - gious national award for. Four years later, cannabis cultivation is more widespread and the topic is less likely to ruffle as many feathers—we think. Not knowing exactly where this story would take me, I set out with simply an open mind and a curiosity to explore the cannabis industry objectively and try to answer some questions I thought my readers would be cu - rious about. Naturally, I began my journey to learn Since sending out the first more about the industry in Burlington, Ver - mont, the place I call home. Vermont has a issue of Inside Grower four years ago, we’ve small, but tightly regulated, medical cannabis maintained a focus on the cultivation of edible program and it’s possible the state legislature will legalize the recreational use of mari - crops in controlled environments—and we’ll juana in 2016.
    [Show full text]
  • Biological Control of Soil-Borne Pathogens by Fluorescent Pseudomonads
    Nature Reviews Microbiology | AOP,published online 10 March 2005; doi:10.1038/nrmicro1129 REVIEWS BIOLOGICAL CONTROL OF SOIL-BORNE PATHOGENS BY FLUORESCENT PSEUDOMONADS Dieter Haas* and Geneviève Défago‡ Abstract | Particular bacterial strains in certain natural environments prevent infectious diseases of plant roots. How these bacteria achieve this protection from pathogenic fungi has been analysed in detail in biocontrol strains of fluorescent pseudomonads. During root colonization, these bacteria produce antifungal antibiotics, elicit induced systemic resistance in the host plant or interfere specifically with fungal pathogenicity factors. Before engaging in these activities, biocontrol bacteria go through several regulatory processes at the transcriptional and post-transcriptional levels. SUPPRESSIVE SOIL Imagine a place on Earth where an organism does not results from the activities of soil microorganisms that A soil in which plants do not suffer from infectious disease and is unlikely to become act as pathogen antagonists. There is evidence that each suffer from certain diseases or infected even though pathogens might be present. of the pathogens described in BOX 1 can be held in check where disease severity is Such exceptional places exist and are known as natural by antagonistic microorganisms in suppressive soils3,9. reduced, although a pathogen 1–3 might be present, and the host SUPPRESSIVE SOILS .They occur, for instance, in the Salinas Note,however, that the suppressiveness of some soils is plant is susceptible to the Valley (California, United States), the Chateaurenard not transferable; for a discussion of this observation, the disease; the opposite of a region near Cavaillon (France), the Canary Islands and reader is referred to specialized reviews2,3.Third,when conducive soil.
    [Show full text]
  • Microbial Suppression of Pythium Root Rot in Soilless Systems
    Microbial Suppression of Pythium Root Rot in Soilless Systems Cora McGehee B.S. Louisiana State University, 2015 A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science At the University of Connecticut 2018 Copyright by Cora Shields McGehee 2018 ii APPROVAL PAGE Master Thesis Microbial Suppression of Pythium Root Rot in Soilless Systems Presented by Cora Shields McGehee, B.S. Major Advisor_________________________________________________________________ Rosa E. Raudales Associate Advisor______________________________________________________________ Wade H. Elmer Associate Advisor_______________________________________________________________ Richard J. McAvoy University of Connecticut 2018 iii Acknowledgements I am beyond grateful to my major advisor Dr. Rosa Raudales for her hard work and dedication to the lab and innovative research projects. Her guidance and patience has made me into a stronger researcher and diligent worker. I also want to thank the other members of my committee Dr. Wade Elmer and Dr. Richard McAvoy for their time and generous advice. I want to thank Frederick Pettit, Shelley Durocher, and Ronald Brine for their assistance in the various greenhouse projects conducted. Thank you Margery Daughtrey for supplying isolates for experiments. Special thanks to Juan Cabrera, Sohan Aziz, Steve Olenski, Joy Tosakoon, and Carla Caballero for giving your time to help with experiments. Lastly a thank you to the office staff, Christine Strand and Nicole Gabelman for their assistance and kindness. Special thanks to the U.S. Department of Agriculture via the Connecticut Department of Agriculture Specialty Crop Block Grant # AG151260 for its support and funding of this work. Thank you to friends and family who supported me over the phone during this intense intellectual pursuit.
    [Show full text]
  • An Annotated List of Genus Pythium from India
    Plant Pathology & Quarantine 10(1): 120–132 (2020) ISSN 2229-2217 www.ppqjournal.org Article Doi 10.5943/ppq/10/1/14 An annotated list of genus Pythium from India Dubey MK1,2*, Yadav M1 and Upadhyay RS1 1Laboratory of Mycopathology and Microbial Technology, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi - 221005, Uttar Pradesh, India 2Department of Life Sciences, School of Basic & Applied Sciences, Galgotias University, Greater Noida- 203201, Uttar Pradesh, India Dubey MK, Yadav M, Upadhyay RS 2020 – An annotated list of genus Pythium from India. Plant Pathology & Quarantine 10(1), 120–132, Doi 10.5943/PPQ/10/1/14 Abstract Up-to-date information is presented based on an intensive search of literature records on the identity, occurrence, nomenclature, substratum, host ranges, geographical distribution and literature references of the genus Pythium from India. All Pythium species published until 2020 are included in this list. The survey result of all forms of analyses revealed that India has 55 species of Pythium belonging to the phylum Oomycota indicating the presence of rich mycoflora. Distribution of these Pythium species reported so far from freshwater and terrestrial habitats of various Indian states are listed alphabetically. The most frequently collected species are Pythium aphanidermatum, P. spinosum, and P. ultimum. The majority of these species were found as a parasite on a wide range of plants in both freshwater and terrestrial environment. Overall, this systematic checklist provides the total count of Pythium species, currently known to occur in India and it is also a valued addition for comparing Pythium diversity in India as well as the world.
    [Show full text]