MANAGEMENT OF ANNUAL BLUEGRASS (Poa annua L.) USING POST-EMERGENCE HERBICIDES AND PLANT GROWTH REGULATORS A Thesis Presented to The Faculty of the Graduate School At the University of Missouri In Partial Fulfillment Of the Requirements for the Degree Masters of Science By JOHN B. HAGUEWOOD Dr. Xi Xiong, Thesis Supervisor Dr. Reid Smeda, Co-Advisor May 2014 The undersigned, appointed by the dean of the Graduate School, have examined the thesis entitled: MANAGEMENT OF ANNUAL BLUEGRASS (Poa annua L.) USING POST- EMERGENCE HERBICIDES AND PLANT GROWTH REGULATORS Presented by John B. Haguewood A candidate for the degree of Masters of Science And hereby certify that, in their opinion, it is worthy of acceptance. Major Professor: Dr. Xi Xiong Assistant Professor Thesis Committee: Dr. Reid Smeda Professor Dr. Anne McKendry Associate Professor Dr. Mark Ellersieck Research Professor ACKNOWLEDGEMENTS First and foremost I would like to thank my advisor, Dr. Xi Xiong, for giving me the opportunity to further my education with a graduate degree. I have learned more over the past four years than I could have every expected. Thank you for your patience, knowledge, motivation and friendship. Without your guidance, this would have never been possible. I would also like to thank Dr. Reid Smeda, who also provided me with tremendous support and a wealth of knowledge, especially with abstract and poster revisions. In addition, I would like to thank Dr. Anne McKendry and Dr. Mark Ellersieck for their input and encouragement on my research and thesis. I would like to thank Dan Lloyd, Steve Song, Natalie Pan, and Joe Schneider for their help and support during my thesis research. Without your assistance I may still be counting seedheads! Thank you for your friendship and your relentless work ethic over the past few years. To my fellow graduate students: Ashley, Spencer, Keller, Derek, Brett and Kristen. Thank you for your help during difficult classes, reviewing my poor writing, and listening to presentations. Your friendship made life much more enjoyable during the struggles of what is grad school. To my family, Doug and Linda and Danielle and Adam, thank you so much for the continual love and support and encouragement during these years. Finally, and most importantly, I would like to thank my best friend and fiancée Nicole Doerr. Your love and support is the strongest encouragement I have ever received, and it kept me motivated to finish. Thank you for being understanding, patient, and supportive even during the hardest days. You truly inspire me to be the best I can. ii TABLE OF CONTENTS Acknowledgements……………………………………………………………............... ii List of Tables………………………………………………………………………......... v List of Figures…………………………………………………………………………. viii List of Appendices………………………………………………………………………. x Chapter I: Literature Review……………………………………………………......... 1 Introduction.................................................................................................................. 1 Poa Biology…………………………………………………………………………. 4 Creeping Bentgrass (Agrostis stolonifera L.)………………………………………... 6 Annual Bluegrass Control……………………………………………………............. 7 Plant Growth Regulators…………………………………………………..………… 9 Herbicides…………………………………………………………………..…......... 11 Objectives…………………………………………………………………..…......... 16 Literature Cited…………………………………………………………………….. 17 Chapter II: Creeping Bentgrass (Agrostis stolonifera) Golf Green Tolerance to Bispyribac-sodium Tank Mixed with Paclobutrazol……………….………........ 24 Abstract………………………………………………………………….…….......... 24 Introduction……………………………………………………………….……........ 26 Materials and Methods………………………………………………….…………... 29 Results and Discussion………………………………………………….….……...... 31 Literature Cited…………………………………………………………….……...... 38 Chapter III: Suppression of Annual Bluegrass Seedheads with Mefluidide, Ethephon, and Ethephon plus Trinexapac-ethyl on Creeping Bentgrass Greens……………………………………………………………………………… 45 Abstract……………………………………………………………………………... 45 Introduction………………………………………………………………………… 47 Materials and Methods……………………………………………………............... 50 Results and Discussion…………………………………………………................... 53 Creeping bentgrass phytotoxicity……………………………………................. 56 Creeping bentgrass turf quality…………………………………………………. 57 Conclusion………………………………………………………………………….. 59 Literature Cited…………………………………………………………………….. 60 iii Chapter IV: Shoot growth and seedhead development of annual bluegrass (Poa annua L.) influenced by herbicide, PGR, and application timing stages………………………………………………………………………………... 70 Abstract……………………………………………………………………………... 70 Introduction…………………………………………………………………………. 72 Materials and Methods……………………………………………………………… 75 Results and Discussion…………………………………………………………….... 78 Treatment effects on shoot growth……………………………………………... 78 Treatment effects on seedhead development…………………………………… 80 Literature Cited…………………………………………………………………….. 85 Appendix……………………………………………………………………...………. 100 iv LIST OF TABLES Table Page Chapter II: 2.1 Oklahoma and Missouri research site characteristics…………………..…….... 40 2.2 Turf quality ratingsa of creeping bentgrass greens treated with bispyribac-sodium alone or tank-mixed with either trinexapac-ethyl or paclobutrazol in Oklahoma at 1, 2, 4, and 6 weeks after initial treatment (WAIT)……….................................. 41 2.3 Phytotoxicity ratingsa of creeping bentgrass greens treated with bispyribac- sodium alone or tank-mixed with either trinexapac-ethyl or paclobutrazol in Oklahoma at 1, 2, 4, and 6 weeks after initial treatment (WAIT)……..……….. 42 2.4 Turf quality ratingsa of creeping bentgrass greens treated with bispyribac-sodium alone or tank-mixed with either trinexapac-ethyl or paclobutrazol in Missouri at 1, 2, 4, 6, and 8 weeks after initial treatment (WAIT)……...………………….…. 43 2.5 Phytotoxicity ratingsa of a creeping bentgrass green treated with bispyribac- sodium alone or tank-mixed with either trinexapac-ethyl or paclobutrazol in Missouri at 1, 2, 4, and 6 weeks after initial treatment (WAIT)……………..… 44 Chapter III: 3.1 Influence of plant growth regulators (PGRs) on annual bluegrass seedhead formation per 900 cm2 area when evaluated at 2, 4, 6, 8, 10, and 12 weeks after initial treatment (WAIT) from Study 1 conducted in 2011 at Columbia Country Club in Columbia, MO. The number of applications did not significantly affect seedhead production, and hence data were pooled together..……………..…… 66 v 3.2 Influence of plant growth regulators (PGRs) on annual bluegrass seedhead formation per 900 cm2 area when evaluated at 2, 4, 6, 8, 10, and 12 weeks after initial treatment (WAIT) from Study 2 conducted in 2011 at Heritage Hills Golf Course in Moberly, MO. The number of applications did not significantly affect seedhead production, and hence data were pooled together………………….... 67 3.3 Influence of plant growth regulators (PGRs) on annual bluegrass seedhead formation per 900 cm2 area when evaluated at 2, 4, 6, 8, 10, and 12 weeks after initial treatment (WAIT) from Study 3 conducted in 2012 at Lake of the Woods Golf Course in Columbia, MO. The number of applications did not significantly affect seedhead production, and hence data were pooled together………….…. 68 3.4 Influence of single or sequential applications of plant growth regulators (PGRs) on creeping bentgrass phytotoxicity† at 3, 4 or 5 weeks after initial treatment (WAIT) from three Missouri golf course greens (Study 1, 2, 3). Study 1 and 2 were conducted in Columbia and Moberly, respectively, and Study 3 was conducted in Columbia in 2012………………………………………………… 69 Chapter IV: 4.1 Chemical treatments and rates applied at pre-boot, boot and flowering growth stage of annual bluegrass in greenhouse study……………………………….… 90 4.2 Influence of chemical compound and application at preboot, boot and flowering growth stages on annual bluegrass plant height (cm), color (1-9) and density (1-9) at 0, 4 and 8 weeks after treatment (WAT)……………………………………... 91 4.3 Influence of chemical compound applications at preboot, boot and flowing growth stages on annual bluegrass plant canopy area (cm2)……………………………. 92 4.4 Treatment and evaluation timing main effect on annual bluegrass seedhead counts at preboot or boot growth stages………………………………………………... 93 vi 4.5 Treatment by evaluation timing interaction on annual bluegrass seedhead counts when applications were made at the flowering growth stage. Consistent seedhead counts for the flower stage were assessed on 0 week after treatment (WAT) and ranged from 9.8 ~ 16.7 per plant………………………………………………... 94 4.6 Percent annual bluegrass seed weight per seedhead relative to the control following chemical treatments applied at preboot, boot, and flowering growth stages……………………………………………………………………………. 95 4.7 Chemical treatment main effects on annual bluegrass seed viability…………... 96 vii LIST OF FIGURES Figure Page Chapter III: 3.1 The effect of plant growth regulators (PGRs) on normalized difference vegetation index (NDVI) for Study 1 in Columbia, MO in 2011. Single or sequential applications did not interact with PGRs; therefore, data were pooled across the application time………………………………………………………………….. 63 3.2 The effect of plant growth regulators (PGRs) on normalized difference vegetation index (NDVI) for Study 2 in Moberly, MO in 2011. Single or sequential applications did not interact with PGRs; therefore, data were pooled across the application time. Abbreviations: trinexapac-ethyl, TE. Vertical bar represents the Fisher’s Protected LSD at P=0.05………………………………………………. 64 3.3 The effect of plant growth regulators (PGRs) on normalized