Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1970 The ysS temic Activity and Phytotoxic Effects of Fungicides Effective Against Certain Cotton Pathogens. Robert Gene Davis Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Davis, Robert Gene, "The ysS temic Activity and Phytotoxic Effects of Fungicides Effective Against Certain Cotton Pathogens." (1970). LSU Historical Dissertations and Theses. 1776. https://digitalcommons.lsu.edu/gradschool_disstheses/1776 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 71-3408 DAVIS, Robert Gene, 1932- THE SYSTEMIC ACTIVITY AND PHYTOTOXIC EFFECTS' OF FUNGICIDES EFFECTIVE AGAINST CERTAIN COTTON PATHOGENS. The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1970 Agriculture, plant pathology University Microfilms, Inc., Ann Arbor, Michigan DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED THE SYSTEMIC ACTIVITY AND FHYTOTOXIC EFFECTS OF FUNGICIDES EFFECTIVE AGAINST CERTAIN COTTON PATHOGENS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Botany and Plant Pathology by Robert Gene Davis B.S., Mississippi State University, 1953 M.S., Mississippi State University, 1968 May, 1970 ACKNOWLEDGEMENT The contributions to this study by others is recognized and appre­ ciated. Dr. J. A. Pinckard suggested the problem and gave guidance throughout the duration of the study. Dr. S. J. P. Chilton, Dr. John B. Baker, Dr. A. D. Larson, and Dr. J. G. Lee, committee members, are extended special appreciation for their valuable assistance and advise during the study and in the prepara­ tion of the manuscript. Dr. Kenneth L. Kbonce gave counsel on experimental design and statistical analysis. Mrs. Peggy Denham, Mr. Ted 0. Ware, and Mr. Gerard T. Berggren, Jr., helped with some of the experimental work and the photography. Mrs. Jackie Lockwood and Miss Mary F. Bankston typed the manuscript. The Cotton Producers Institute provided financial aid during part of the work. The U. S. Department of Health, Education, and Welfare made available a National Defense Education Assistance graduate fellow­ ship during the final two years of the study. This support is gratefully acknowledged. ii TABLE OF CONTENTS Page ACKNOWLEDGEMENT................................................. ii LIST OF T A B L E S ................................................. V LIST OF FIGURES................................................. vil ABSTRACT....................................................... x INTRODUCTION ................................................... 1 LITERATURE REVIEW............................................... 2 MATERIALS AND METHODS ' 7 Test Organisms............................................. 7 Test Materials............................................. 8 Laboratory Evaluation of Candidate Fungicides.............. 8 Paper Disc Bioassays................................... 8 Bioassays of Test Materials Incorporated in Culture Media........................................... 9 Bioassay of Movement of a Fungicide in Cotton Seedlings. 10 Phytotoxicity and Systemic Activity Studies with Cotton Seedlings Grown in Culture Solution......................... 12 Solution Culture Procedures............................. 12 Preliminary Tests....................................... 14 Leaf Disc and Stem Segment Bioassays.................. 14 Benorayl Tes ts........................................... 15 Tests with a Selected Group of Fungicides.............. 16 Demosan Test ........................................... 17 Culture Solution Test for an Extended Growth Period. 17 Inoculatxon Studies............................ 18 Histological Studies ....................................... 19 iii Page RESULTS......................................................... 20 Laboratory Evaluation of Candidate Fungicides. ........... 20 Paper Disc Bioassays................................... 20 Bioassays of Test Materials Incorporated in Culture Media................................................... 20 Bioassay of Movement of a Fungicide in Cotton Seedlings. 21 Phytotoxicity and Systemic Activity Studies with Cotton Seedlings Grown in Culture Solution........................ 22 Preliminary Tests....................................... 22 Benomyl Tests........................................... 23 Tests with a Selected Group of Fungicides.............. 24 Demos an T e s t ........................................... 25 Culture Solution Test for an Extended Growth Period. 26 Inoculation Studies......................................... 27 Histological Studies ....................................... 28 DISCUSSION..................................................... 29 SUMMARY......................................................... 36 BIBLIOGRAPHY................................................... 38 APPENDIX....................................................... 41 VITA ........................................................... 81 iv LIST OF TABLES TABLE , Page 1. Chemicals tested for fungicidal or systemic activity against I). gossypina, P. parasitica, P. debaryanum, and R. solani ....................................... 42 2. Inhibition in paper disc bioassays of 17 test materials against D. gossypina, P. parasitica, P. debaryanum, and R. s o l a n i ............................................. 43 3. Inhibition of colonies of D. gossypina and R. solani grown on PDA medium seeded with mycelial suspensions of the organisms by paper discs containing various concentrations of Pimaricin........... 44 4. Effects of various concentrations of 16 test fungi­ cides incorporated into PDA medium on the radial growth of colonies of II. gossypina, parasitica, P. debaryanum, and R. solani. .. ... .......... 45 5. Hxe effects of various concentrations of Actidione, Demosan, Terrazole, and Tetracycline incorporated into PDA medium on the radial growth of colonies of I[. debaryanum and R, s o l a n i .......................... 49 6. D. gossypina spore bioassay of the movement of Benomyl in 3-week old cotton seedlings. Time of treatment with Benomyl 9:00 A.M................................. 50 7. Phytotoxicity and systemic activity of test materials in screening tests with cotton seedlings and in bio­ assays against R. solani.............................. 51 8. Analysis of variance for daily root elongation of cotton seedlings treated with various concentrations of Benomyl............................................. 52 9. Comparison of mean daily root elongation at various Benomyl concentrations and days for cotton seedlings grown for 5 days in culture solution containing Benomyl . 53 10. Comparisons of the effects of fungicide, fungicide concentrations, and time on mean daily root elonga­ tion of cotton seedlings grown for 4 days in culture solution containing various concentrations of Demosan, Pimaricin, potassium sorbate, Terrazole andVitavax .... 54 v TABLE Page 11* Comparisons of mean daily root elongation of cotton seedlings grown for 4 days in culture solution con­ taining various concentrations of Demosan, Pimaricin, potassium sorbate, Terrazole, and Vitavax .................. 55 12. Comparisons of mean daily root elongation at various days for cotton seedlings grown for 4 days in culture solution containing Demosan, Pimaricin, potassium sorbate, Terrazole, and Vitavax ............................ 56 13. Comparison of mean total daily root elongation and mean daily root length for cotton seedlings grown for 10 days in culture solution containing various concentrations of Demosan ............................... 57 14. Correlation coefficients for mean root elongation, root length, shoot height, shoot dry weight, and root dry weight of cotton seedlings grown for 10 days in culture solution containing various concentrations of Demosan . 58 15. Comparison of mean root length, shoot height, root dry weight, and shoot dry weight of cotton seedlings grown for 10 days in culture solution containing various concentrations of Demosan ............................... 59 16. Dry weights of shoots and roots of cotton seedlings grown 18 days in culture solution containing various concentrations of Demosan, potassium sorbate, and Terrazole................................................ 60 vi LIST OF FIGURES FIGURE Page 1« Cottori seedlings secured in culture container cover by opposing strips of polyvinyl............................. 61 2. The interior of a culture box used for growing cotton seedlings in culture solution...... ............... 62 3. A close-up view of the top of a culture box used for growing cotton seedlings in culture solution showing culture tube covers and aeration tubes................... 63 4. D. gossypina spores germinated in sap from cotton seedling grown in culture solution containing Benomyl. Photograph taken 6 hr following addition of sap to a spore suspension. (100X) ......... ............ 64 5. D. gossypina spores germinated in sap from cotton seedling grown in culture solution only. Photograph taken 6 hr following