Kochia (Kochia scoparia (L.) Schrad.) and Biennial Wormwood (Artemisia biennis Willd.) Interference with Sunflower (Helianthus annuus L.) BY DEREK WILLIAM LEWIS A Thesis Submitted to the Faculty of Graduate Studies In Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Department of Plant Science University of Manitoba Winnipeg, Manitoba © Copyright by Derek W. Lewis 2012 ii THE UNIVERSITY OF MANITOBA FACULTY OF GRADUATE STUDIES ******* COPYRIGHT PERMISSION Kochia (Kochia scoparia (L.) Schrad.) and Biennial Wormwood (Artemisia biennis Willd.) Interference with Sunflower (Helianthus annuus L.) By DEREK WILLIAM LEWIS A Thesis Submitted to the Faculty of Graduate Studies in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE © Copyright by Derek W. Lewis 2012 Permission has been granted to the Library of the University of Manitoba to lend/sell copies of this thesis, to the National Library of Canada to microfilm this thesis and to lend or sell copies of the film, and to the University Microfilms Inc. to publish an abstract of this thesis. This reproduction or copy of this thesis has been made available by authority of the copyright owner solely for the purpose of private study and research, and may only be reproduced and copied as permitted by copyright laws or with express written authorization from the copyright owner. iii Table of Contents Abstract……………………………..……………………………………….……………vi Acknowledgements…...…………………………………………………………………viii List of Tables………………………….…………………………………………………..ix List of Figures………………………………………………………...……….…………..x 1.0 Introduction……………….……………………….………………………………..…1 2.0 Literature Review………………………………………………………………..…….3 2.1 The History of Sunflowers……….…………………………………………...…3 2.2 Sunflower Production Statistics.…….…………………………………………..3 2.3 Uses of Sunflowers…….…………………………………………………...…...4 2.3.1 Human Consumption…….………………………………………….......4 2.3.2 Livestock Feed and Forage…………....…………...………..………......4 2.4 Sunflower Morphology and Reproductive Biology……….………..………...…5 2.5 Sunflower Production Practices.………………………….……………..…...….6 2.5.1 Weed Management in Sunflowers………………….…………...………7 2.5.1.1 Mechanical Weed Management ………………………………..7 2.5.1.2 Cultural Weed Management ……………………….………..…8 2.5.1.3 Herbicidal Weed Management ……....……..…………….…10 2.6 Crop Yield Loss Related to Weeds…………….…………………………..…11 2.7 Weed Interference with Sunflowers..……………………….………………...11 2.8 Weed Interference Study Methods………………..……….……...…………..13 2.8.1 Additive Design Experiments……………………….…………...….…13 2.8.2 The Rectangular Hyperbola Yield Loss Model…………..……………14 2.9 Kochia ………………………………………………….…………….…..……15 2.9.1 Description of Kochia……………..…………….…….……………….15 iv 2.9.2 Biology and Growth of Kochia………………………………………..16 2.9.3 Geographic Distribution of Kochia……………………………………18 2.9.4 Herbicide Resistant Kochia……………………………………………18 2.9.5 Crop Yield Loss Caused by Kochia Interference………..………….…19 2.10 Biennial Wormwood……………………………………….….…………..….20 2.10.1 Description of Biennial Wormwood……………………………..…..20 2.10.2 Biology and Growth of Biennial Wormwood……….…………….…21 2.10.3 Geographic Distribution of Biennial Wormwood……………………23 2.10.4 Biennial Wormwood Management …..……………………….……..24 2.11 Experiment Objectives……………………………………………..……..….25 3.0 Effect of Kochia (Kochia scoparia L. Schrad.) Interference on Sunflower (Helianthus annuus L.) Yield ……………………………………………………………………26 3.1 Introduction………………………………………………….…………………26 3.2 Materials and Methods……………………………………….……………..….28 3.2.1 Experimental Locations………………….…………………………….28 3.2.2 Experimental Design and Plot Establishment..…………………….….39 3.2.3 Data Collection…………………………………………….………..…35 3.2.4 Statistical Analysis…………………………………………………….38 3.3 Results and Discussion……………………………………………………...…39 3.3.1 Kochia Seedling Recruitment………………………….….………...…39 3.3.2 Sunflower Yield and Yield Loss………………………….…………...39 3.3 3 Effect of Kochia Interference on Sunflower Growth and Development… ..……………………………………………………………………………..48 3.3.4 Effect of Kochia Interference on Sunflower Seed Quality ….……......52 3.3.5 Action Thresholds for Kochia Control in Sunflowers ………………..56 v 3.4 Conclusion.………………………………………………………………....….60 4.0 Effect of Biennial Wormwood (Artemisia biennis Willd.) Interference on Sunflower (Helianthus annuus L.) Yield ………………..……………………………………61 4.1 Introduction……………………………………………………………….……61 4.2 Materials and Methods……………………………………………………....…63 4.2.1 Experimental Locations …….…………………………………...…..63 4.2.2 Biennial Wormwood Seed Source …………...………………....…..64 4.2.3 Experimental Design and Plot Establishment .…….….…………….64 4.2.4 Data Collection …….……………………………….……………..…65 4.2.5 Statistical Analysis ..…………………………………………………66 4.3 Results and Discussion……………………………………………………...…67 4.3.1 Biennial Wormwood Seedling Recruitment ………………..…………67 4.3.2 Sunflower Yield and Yield Loss ……………...…………………...….68 4.3.3 Effect of Biennial Wormwood Interference on Sunflower Growth and Development …………………………………...........................…………...73 4.3.4 Effect of Biennial Wormwood Interference on Sunflower Seed Quality . ……………………………………………………………………………….76 4.3.5 Action Thresholds for Biennial Wormwood Control in Sunflowers….80 4.4 Conclusion.………………………………………………………….…………83 5.0 General Discussion…………………………………………………….……………..84 5.1 Kochia and Biennial Wormwood Interference in Sunflowers….…………..….84 5.2 The Effect of Environmental Conditions on Kochia and Biennial Wormwood Interference ...………………………………..………………………..……….......85 5.3 Integrated Weed Management in Sunflowers…………….…………………....85 5.4 Future Research……………………………….………..………………..….…87 6.0 Literature Cited…………………………………………………………….…………90 7.0 Appendix……………………………………………………………………………..97 vi Abstract Lewis, Derek W. The University of Manitoba, February 2013. Kochia (Kochia scoparia (L.) Schrad.) and Biennial Wormwood (Artemisia biennis Willd.) Interference with Sunflower (Helianthus annuus L.) Kochia and biennial wormwood are two weeds sometimes found growing in sunflower fields that may be difficult to control. Weed management in sunflowers is usually conducted using a combination of herbicides and mechanical weed control methods. Some farmers are growing sunflowers in reduced tillage systems, which may rely solely on herbicides to manage weeds; however, the spectrum of broadleaf weeds that can be controlled with herbicides is limited. Field experiments were conducted across southern Manitoba to determine the effect of kochia and biennial wormwood density and relative time of weed seedling recruitment on sunflower growth and development, yield and seed quality and to determine action thresholds for each weed. Early emerging kochia (plants that emerged at about the same time as the sunflowers) reduced sunflower yield by as much as 82%, which was greater than early emerging biennial wormwood plants, which reduced yield by as much as 27%. At low weed densities, each kochia plant reduced sunflower yield by 0.52% and each biennial wormwood plant reduced sunflower yield by 0.17%. As the density of early emerging kochia plants increased, sunflower height, stem diameter, leaf counts and head diameter were reduced in some of the experiments. Increasing densities of early emerging biennial wormwood plants had minimal effect on sunflower growth and development. Early emerging kochia and biennial wormwood plants both had the potential to vii reduce sunflower seed size and seed weight, while late emerging kochia and biennial wormwood (plants that emerged after the 4-leaf stage of the sunflowers) did not affect sunflower seed quality. The action threshold (5% sunflower yield loss) for early emerging kochia was 10 plants m-2 and the action threshold for early emerging biennial wormwood was 36 plants m-2 in the combined site-year analysis. Kochia or biennial wormwood plants that recruited after the 4-leaf stage of the sunflower crop did not affect sunflower yield, or seed quality. viii Acknowledgements There are many people I would like to acknowledge who have helped and supported me as I worked towards my goal of earning my Masters degree. Thank you to all of my committee members for their assistance over the past few years. Dr. Gulden, Dr. Entz and Dr. Francis Zvomuya were supportive and thoughtful members of my advisory committee. Thank you to the past and present members of the weed science lab who helped with the research; Mary Price, Don Sanders, Arron MacCauley, Yirga Kidane, Nia Perron, Melissa Pieniuta, John Stott and Luana Koucas. The help with hand weeding for weeks and counting and measuring plants is what made all of this research possible. Without them, collecting this amount of data would have been impossible for one person. Most importantly, thank you to my wife Nicole, and daughters Ava and Olivia, who sacrificed countless hours with me so I could go back to school and further my education. ix List of Tables Table 3.1. Soil texture, pH and organic matter content at the experiment locations investigating the effect of kochia interference on sunflower growth and development, yield and seed quality …………………………………….……………………….….….30 Table 3.2. Summary of the planting dates of sunflowers and kochia for each of the experiments........................................................................................................................31 Table 3.3. Summary of the nutrient status at each of the experiment locations prior to seeding each year and the fertilizer added to each of the experiments…………………..32 Table 3.4. Mean monthly temperature and precipitation during the growing season (May to