Efficacy and residual effects of Topramezone and Dicamba herbicide on weed control in selected crops. Siabusu Largewell A Dissertation Submitted to the University of Zambia in Partial Fulfillment of the Requirement for the Degree of Master of Science in Agronomy (Plant Science) The University of Zambia, School of Agricultural Sciences Department of Plant Science June 2020 i DECLARATION I, Siabusu Largewell, hereby declare that all the work presented in this dissertation is my own and has never been submitted for a degree at this or any other University. Signature: ………………… Date: …………………. i APPROVAL This dissertation is approved as fulfilling part of the requirements for the award of the degree of Master of Science in Agronomy (Plant Science) by the University of Zambia. Examiner Signature Date ………………………………. …………………………….. …………………… ………………………………. …………………………….. …………………… ………………………………. …………………………….. …………………… ii DEDICATION This dissertation is dedicated to my wife, Siabusu M. Nchimunya, my two sons, Chileleko and Chaabilo and my parents Mr and Mrs Siabusu. iii ACKNOWLEDGEMENT I wish to thank the Almighty God for seeing me through this far by grace in my studies. God has indeed given a definition to my life. I wish to extend my gratitude to my supervisors, Dr. T. T. Kambikambi for her mentorship and patience and Dr. D. M. Lungu for his support and guidance during my research, I, therefore acknowledge their great contribution through their visits, comments and corrections during the research work and completion of this dissertation. I wish to thank my classmates for all the knowledge shared during my short time with them. I also thank members of staff of the Plant Science Department for their contributions during the initial and final stages of the research work. Special thanks go to the ZARI director, Mr. Moses Mwale for granting me the privilege to study. I wish to thank the former APPSA coordinator, Mr. Laston Milambo for his support and encouragement for me to pursue my studies. I thank Dr. Mweshi Mukanga from ZARI for all the support and encouragement. My gratitude is also extended to Dr. Richard Chanda from SCCI for assisting me with data analysis and support. I am also grateful to ZARI/ APPSA for awarding me the scholarship that made it possible for me to pursue my studies. Thanks to BASF for enabling me to study their product Finally, I must express my profound gratitude to my wife for providing me with unfailing support and continuous encouragement throughout my years of study and through the process of researching and writing this thesis. This accomplishment would not have been possible without them. Thank you. iv TABLE OF CONTENTS DECLARATION............................................................................................................................ i APPROVAL .................................................................................................................................. ii DEDICATION.............................................................................................................................. iii ACKNOWLEDGEMENT ........................................................................................................... iv TABLE OF CONTENTS ............................................................................................................. v LIST OF TABLES ..................................................................................................................... viii LIST OF FIGURES ..................................................................................................................... ix LIST OF APPENDICES .............................................................................................................. x ABSTRACT .................................................................................................................................. xi CHAPTER 1 : INTRODUCTION ............................................................................................... 1 1.1 Background ............................................................................................................................... 1 1.2 Statement of the Problem .......................................................................................................... 2 1.3 Justification ............................................................................................................................... 2 1.4 Objectives ................................................................................................................................. 3 1.4.1 Overall Objective ................................................................................................................... 3 1.4.2 Specific Objectives ................................................................................................................ 3 1.5 Research hypothesis ................................................................................................................................ 3 CHAPTER 2 : LITERATURE REVIEW ................................................................................... 4 2.1 Weeds ...................................................................................................................................................... 4 2.2 Methods of Weed Control ....................................................................................................................... 5 2.2.1 Preventative Weed Control .................................................................................................... 5 2.2.2 Cultural Weed Control ........................................................................................................... 5 2.2.3 Mechanical Weed Control ..................................................................................................... 5 2.2.4 Biological Weed Control ....................................................................................................... 6 2.2.5 Chemical Weed Control ......................................................................................................... 6 v 2.3 Topramezone and Dicamba mixture herbicide- Stellar Star ................................................................... 6 2.3.1 Topramezone.......................................................................................................................... 7 2.3.2 Dicamba ................................................................................................................................. 8 2.4 Herbicide Classification .......................................................................................................................... 9 2.4.1 Classification Based on Translocation ................................................................................... 9 2.4.2 Classification Based on Time of Application ...................................................................... 10 2.4.3 Classification Based on Method of Application .................................................................. 10 2.4.4 Classification Based on Specificity ...................................................................................... 11 2.4.5 Classification Based on Site of Action................................................................................. 11 2.5 Herbicide Persistence ............................................................................................................................ 12 2.5.1 Soil Factors .......................................................................................................................... 12 2.5.2 Climatic Factors ................................................................................................................... 13 2.5.3 Herbicide Properties............................................................................................................. 14 2.6 Crop Rotation ........................................................................................................................................ 15 2.7 Strategies to reduce crop injury risk from herbicide residue ................................................................ 16 2.7.1 Tillage .................................................................................................................................. 16 2.7.2 Planting more tolerant crops ................................................................................................ 17 2.7.3 Conducting herbicide bioassay ............................................................................................ 17 2.8 Phytotoxicity ......................................................................................................................................... 17 CHAPTER 3 MATERIALS AND METHODS ........................................................................ 19 3.1 Experimental site .................................................................................................................................. 19 3.2 Experimental Design with treatments ................................................................................................... 19 3.2.1 Field experiment .................................................................................................................. 19 3.2.3 Meteorological data ............................................................................................................. 20 3.3 Green house experiment ........................................................................................................