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Characterization and Evaluation of Aminocyclopyrachlor on Native and Invasive Species of Florida

Permanent Link: http://ufdc.ufl.edu/UFE0044236/00001

Material Information

Title: Characterization and Evaluation of Aminocyclopyrachlor on Native and Invasive Species of Florida
Physical Description: 1 online resource (103 p.)
Language: english
Creator: Greis, Anna L
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2012

Subjects

Subjects / Keywords: aminocyclopyrachlor -- invasives -- natives -- residual
Agronomy -- Dissertations, Academic -- UF
Genre: Agronomy thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Aminocyclopyrachlor is a synthetic auxin herbicide proposed for invasive species management and the release or restoration of native perennial grasses. As a component to natural areas restoration, it is also beneficial to understand the impact that herbicide residues have on native plant species. Studies were therefore initiated to determine the efficacy of aminocyclopyrachlor on several invasive grass species as well as the impact of establishment and growth of native species. Postemergence applications of aminocyclopyrachlor were evaluated under greenhouse conditions to determine the control of several invasive grasses including natalgrass (Melinis repens), torpedograss (Panicum repens), paragrass (Urochloa mutica), West Indian marshgrass (Hymenachne amplexicaulis) and cogongrass (Imperata cylindrica), as well as several native grass and broadleaf species. All invasive species showed less than 50% visual injury and no reduction in shoot growth or regrowth to aminocyclopyrachlor with the exception of cogongrass which showed a 25% reduction in regrowth biomass. Eragrostis elliottii was the most tolerant native grass evaluated. Aristida stricta and Eragrostis spectabilis were the most sensitive grasses with I50 values of 0.11 and 0.09 kg-ai ha-1, respectively. All other grasses were tolerant to rates below 0.19 kg-ai ha-1. All broadleaf natives were highly sensitive (<0.13 kg-ai ha-1) to rates of aminocyclopyrachlor except Garberia heterophylla which showed less than 50% injury at 0.24 kg-ai ha-1. To assess the impact of aminocyclopyrachlor soil residues on native species, seedlings of several common forbs, grasses, and tree species were transplanted into field plots treated with varying rates of aminocyclopyrachlor. Solidago fistulosa and Liatris spicata showed greater than 50% injury at all rates of aminocyclopyrachlor. Pinus palustris was tolerant to rates below 0.16 kg-ai ha-1, and Andropogon virginicus var. glauca showed no injury to aminocyclopyrachlor. Aminocyclopyrachlor caused significant injury to all other species at rates above 0.1 kg-ai ha-1. Utilizing plant species injury, optimal planting dates were determined for these species based on a 90 day half-life of aminocyclopyrachlor with grasses having the shortest plant back interval. To further investigate the potential of aminocyclopyrachlor for cogongrass control, a field study was conducted in Hillsborough County, Florida. Aminocyclopyrachlor was evaluated alone or in combination with imazapyr or glyphosate and compared to standard rates of imazapyr and glyphosate. Aminocyclopyrachlor alone showed initial control 31 WAT but no long term control 92 WAT of cogongrass. The addition of aminocyclopyrachlor to glyphosate or imazapyr did not improve control relative to glyphosate and imazapyr applied alone. Two additional experiments were established and found that imazapic and imazamox were ineffective for cogongrass control. Surfactant type and ‘Cogon-X’ did not influence the activity of glyphosate or imazapyr for cogongrass efficacy.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Anna L Greis.
Thesis: Thesis (M.S.)--University of Florida, 2012.
Local: Adviser: Macdonald, Greg.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2012
System ID: UFE0044236:00001

Permanent Link: http://ufdc.ufl.edu/UFE0044236/00001

Material Information

Title: Characterization and Evaluation of Aminocyclopyrachlor on Native and Invasive Species of Florida
Physical Description: 1 online resource (103 p.)
Language: english
Creator: Greis, Anna L
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2012

Subjects

Subjects / Keywords: aminocyclopyrachlor -- invasives -- natives -- residual
Agronomy -- Dissertations, Academic -- UF
Genre: Agronomy thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Aminocyclopyrachlor is a synthetic auxin herbicide proposed for invasive species management and the release or restoration of native perennial grasses. As a component to natural areas restoration, it is also beneficial to understand the impact that herbicide residues have on native plant species. Studies were therefore initiated to determine the efficacy of aminocyclopyrachlor on several invasive grass species as well as the impact of establishment and growth of native species. Postemergence applications of aminocyclopyrachlor were evaluated under greenhouse conditions to determine the control of several invasive grasses including natalgrass (Melinis repens), torpedograss (Panicum repens), paragrass (Urochloa mutica), West Indian marshgrass (Hymenachne amplexicaulis) and cogongrass (Imperata cylindrica), as well as several native grass and broadleaf species. All invasive species showed less than 50% visual injury and no reduction in shoot growth or regrowth to aminocyclopyrachlor with the exception of cogongrass which showed a 25% reduction in regrowth biomass. Eragrostis elliottii was the most tolerant native grass evaluated. Aristida stricta and Eragrostis spectabilis were the most sensitive grasses with I50 values of 0.11 and 0.09 kg-ai ha-1, respectively. All other grasses were tolerant to rates below 0.19 kg-ai ha-1. All broadleaf natives were highly sensitive (<0.13 kg-ai ha-1) to rates of aminocyclopyrachlor except Garberia heterophylla which showed less than 50% injury at 0.24 kg-ai ha-1. To assess the impact of aminocyclopyrachlor soil residues on native species, seedlings of several common forbs, grasses, and tree species were transplanted into field plots treated with varying rates of aminocyclopyrachlor. Solidago fistulosa and Liatris spicata showed greater than 50% injury at all rates of aminocyclopyrachlor. Pinus palustris was tolerant to rates below 0.16 kg-ai ha-1, and Andropogon virginicus var. glauca showed no injury to aminocyclopyrachlor. Aminocyclopyrachlor caused significant injury to all other species at rates above 0.1 kg-ai ha-1. Utilizing plant species injury, optimal planting dates were determined for these species based on a 90 day half-life of aminocyclopyrachlor with grasses having the shortest plant back interval. To further investigate the potential of aminocyclopyrachlor for cogongrass control, a field study was conducted in Hillsborough County, Florida. Aminocyclopyrachlor was evaluated alone or in combination with imazapyr or glyphosate and compared to standard rates of imazapyr and glyphosate. Aminocyclopyrachlor alone showed initial control 31 WAT but no long term control 92 WAT of cogongrass. The addition of aminocyclopyrachlor to glyphosate or imazapyr did not improve control relative to glyphosate and imazapyr applied alone. Two additional experiments were established and found that imazapic and imazamox were ineffective for cogongrass control. Surfactant type and ‘Cogon-X’ did not influence the activity of glyphosate or imazapyr for cogongrass efficacy.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Anna L Greis.
Thesis: Thesis (M.S.)--University of Florida, 2012.
Local: Adviser: Macdonald, Greg.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2012
System ID: UFE0044236:00001


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1 CHARACTERIZATION AND EVALUATION OF AMINOCYCLOPYRACHLOR ON NATIVE AND INVASIVE SPECIES OF FLORIDA By ANNA LIN GREIS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIR EMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2012

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2 2012 Anna Lin Greis

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3 To my family for all their love and support

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4 ACKNOWLEDGMENTS First and foremost, I would like to thank my major professor, Dr. Greg MacDonal d, for all the support and encouragement he has given me throughout my graduate school experience. He took a chance on a business major and for that I am truly grateful. His confidence in my abilities as a student and speaker gave me the confidence to be lieve in myself. Along with Dr. MacDonald, Dr. Jason Ferrell has taught me so much about agriculture, weed science, and research in general. I thank Dr. Ferrell for always being available to meet and discuss any questions I had as well as providing guid ance throughout my research. Thanks go to Dr. Brent Sellers for his presentation advice at providing input in my research and for being my forestry advisor my committ ee. I would not have been able to complete any of my research without the physical labor and moral support of my fellow graduate students and summer employees. A special thanks to Mike Durham for helping me in each step of my research, being a great study partner, as well as getting me addicted to coffee. I would also like to thank Sarah Berger and Neha Rana, who have become great friends and supporters both in and out of the office. I would not have been able to complete this degree without the endless s upport and encouragement of my parents and my brother Adam. My parents are my inspiration and I know that with their support I can accomplish all my goals. Throughout all of the ups and downs of this journey they have provided me with moral support, enco uraging words, and great advice for which I am so thankful. I thank my dad for providing me with professional guidance and always supporting me in my decisions in

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5 life. My mom has always believed in me and my abilities, even when I faltered, and for that I am truly grateful. Finally, I thank my fellow employees at the Marston science library, for giving me four hour escapes each week filled with lots of laughs and great conversation. I will be forever grateful to my supervisor Vanessa Jewett for giving me a summer job, at which I met Dr. MacDonald who opened the door to my weed science future.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 8 LIST OF FIGURES ................................ ................................ ................................ .......... 9 ABSTRACT ................................ ................................ ................................ ................... 12 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 14 ................................ ................................ ...................... 14 Controlling Invasive Species ................................ ................................ ................... 16 Aminocyclopyrachlo r ................................ ................................ ............................... 17 Native Ecosystems in Florida ................................ ................................ .................. 18 2 THE EFFECT OF AMINOCYCLOPYRACHLOR APPLIED POST EMERGENCE ON SELECTED NATIVE AND INVASIVE GRASS SPECIES UNDER GREENHOUSE CONDITIONS ................................ ................................ ............... 23 Background Information ................................ ................................ .......................... 23 Materials and Methods ................................ ................................ ............................ 25 Results and Discussion ................................ ................................ ........................... 26 Native Plants ................................ ................................ ................................ .... 26 Invasive Grasses ................................ ................................ .............................. 29 3 RESPONSE OF SELECT NATIVE SPECIES TO VARIOUS SOIL CONCENTRATIONS OF AMINOCYCLOPYRACHLOR ................................ ......... 50 Background Information ................................ ................................ .......................... 50 Materials and Methods ................................ ................................ ............................ 52 Results and Discussion ................................ ................................ ........................... 54 4 HERBICIDE EVALUATIONS FOR COGONGRASS CONTROL UNDER FI ELD CONDITIONS ................................ ................................ ................................ ......... 79 Background Information ................................ ................................ .......................... 79 Materials and Methods ................................ ................................ ............................ 81 Results and Discussion ................................ ................................ ........................... 83 5 CONCLUSIONS ................................ ................................ ................................ ..... 92

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7 LIST OF REFERENCES ................................ ................................ ............................... 95 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 103

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8 LIST OF TABLES Table page 2 1 Summary of the effect of aminocyclopyrachlor concentration on native species Experiment 1. ................................ ................................ ....................... 31 2 2 Summary of the effect of aminocyclopyrachlor concentration on native species Experiment 2. ................................ ................................ ....................... 31 2 3 Summary of the eff ect of aminocyclopyrachlor concentration on invasive species Experiment 1. ................................ ................................ ....................... 32 2 4 Summary of the effect of aminocyclopyrachlor concentration on invasive species Experiment 2. ................................ ................................ ....................... 32 3 1 Species used in revegetation study in Citra, Florida. ................................ .......... 57 3 2 The effect of aminocyclopyrachlor concentration on percent visual injury of selected native species 14 weeks after treatment. Experiment 1 ....................... 58 3 3 The effect of aminocyclopyrachlor concentration on percent visual injury of selected native species 10 weeks after treatm ent. Experiment 2 ....................... 58 3 4 The effect of aminocyclopyrachlor soil concentration on percent mortality of selected revegetation species 40 weeks after planting. Experiment 1.. .............. 59 3 5 The effect of aminocyclopyrachlor soil concentration on percent mortality of selected revegetation species 10 weeks after planting. Experiment 2. ............... 60 4 1 The effect of aminocyclopyrachlor treatments on cogongrass control over time in Hillsborough County, Florida ................................ ................................ ... 79 4 2 The effect of aminocyclopyrachlor treatment on cogongrass rhizom e biomass over time in Hillsborough County, Florida. ................................ .......................... 89 4 3 The effect of surfactants or additives on the activity of glyphosate or imazapyr tre atments on cogongrass control in Hillsborough Co unty, Florida. .... 90 4 4 The effect of selected imidazolinone herbicides on cogongrass control over time in Hillsborough County, Florida. ................................ ................................ .. 91

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9 LIST OF FIGURES Figu re page 2 1 Andropogon brachystachyus response to aminocyclopyrachlor concentration. Experiment 1 ................................ ................................ ................................ ...... 33 2 2 Aristida stri cta response to aminocyclopyrachlor concentration. Shoot growth 4 WAT for experiment 1. ................................ ................................ ..................... 34 2 3 Andropogon virginicus response to aminocyclopyrachlor concentration.. .......... 34 2 4 Eragrostis elliottii response to aminocyclopyrachlor concentration. Experiment 1 ................................ ................................ ................................ ...... 35 2 5 Eragrostis spectabilis response to aminocyclopyrachlor conce ntration. ............. 36 2 6 Panicum anceps response to ami nocyclopyrachlor concentration. E xperiment 1. ................................ ................................ ................................ ........................ 36 2 7 Sorghastrum secundum respons e to aminocyclopyrachlor concentration. Experiment 1 ................................ ................................ ................................ ...... 37 2 8 Garberia heterophylla response to ami nocyclopyrachlor concentration. E xperiment 1. ................................ ................................ ................................ ..... 38 2 9 Liatris spicata response to aminocyclopyrachlor concentration. E xperiment 1 .. 38 2 10 Pityopsis graminifolia response to aminocyclopyrachlor concentration. E xperiment 1. ................................ ................................ ................................ ..... 39 2 11 Solidago fistulosa response to aminocyclopyrachlor concentration. E xperiment 1 ................................ ................................ ................................ ..... 39 2 12 Andropogon brachystachyus respons e to aminocyclopyrachlor concentration. Experiment 2 ................................ ................................ ................................ ...... 40 2 13 Aristida stricta response to aminocyclopyrachlor concentration. Experiment 2 .. 41 2 14 Eragrostis spectabilis response to aminocyclopyrachlor concentration. Experiment 2 ................................ ................................ ................................ ...... 42 2 15 Sorghastrum secundum response to aminocyclopyrachlor concentration. Experiment 2 ................................ ................................ ................................ ..... 43 2 16 Hymenachne amplexicaulis response to aminocyclopyrachlor concentration. Experiment 1 ................................ ................................ ................................ ...... 44

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10 2 17 Imperata cylindrica response to aminocyclopyrachlor concentration. E xperiment 1 ................................ ................................ ................................ ..... 44 2 18 Melinis repens response to aminocyclopyrachlor concentration. E xperiment 1 .. 45 2 19 Panicum repens response to aminocyclopyrachlor concentration. E xperiment 1 ................................ ................................ ................................ ........................ 45 2 20 Urochloa mutica response to aminocyclopyrachlor concentration. E xperiment 1 ................................ ................................ ................................ ........................ 46 2 21 Hymenachne amplexicaulis response to aminocyclopyrachlor concentration. Experiment 2 ................................ ................................ ................................ ...... 47 2 22 Imperata cylindrica response to aminocyclo pyrachlor concentration. E xperiment 2 ................................ ................................ ................................ ...... 47 2 23 Melinis repens response to aminocyclopyrachlor concentration. E xperiment 2 .. 48 2 24 Panicum repens response to aminocyclopyrachlor concentration. E xperiment 2 ................................ ................................ ................................ ......................... 48 2 25 Urochloa mutica response to aminocyclopyrachlor concentration. E xperiment 2 ................................ ................................ ................................ ......................... 49 3 1 Pinus palustris (Longleaf pine) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) Experiment 1 .................... 61 3 2 Quercus laevis ( Turkey oak) response to aminocyclopyrachlor concentration in so il 14 WAP (weeks after planting). Experiment 1 ................................ .......... 62 3 3 Quercus virginiana (Live oak) response to aminocyclopyrachlor concentration in so il 14 WAP (weeks after planting). Experiment 1 ................................ .......... 63 3 4 Liatris spicata (Blazing star) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting). Experiment 1 ................................ .......... 64 3 5 Solidago fistulosa (Goldenrod) response to aminocyclopyrachlor concentration in so il 14 WAP (weeks after planting). Experiment 1 .................... 65 3 6 Andropogon virginicus var. glauca (Chalky bluestem) response to aminocyclopyrach lor concentration in soil 14 WAP. Experiment 1 .................... 66 3 7 Aristida stricta var. beyrichiana (Wiregrass) response to aminocyclopyrachlo r concentration in soil 14 WAP. Experiment 1 ................................ ....................... 67 3 8 Eragrostis spectabilis (Purple lovegrass) response to aminocyclopyrach lor concentration in soil 14 WAP. Exper iment 1 ................................ ...................... 68

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11 3 9 Panicum anceps (Spreading panicum) response to aminocyclopyrachlor concentration in so il 14 WAP. Experiment 1 ................................ ...................... 69 3 10 Pinus palustris (Longleaf pine) response to aminocyclopyrachlor concentration in so il 10 WAP (weeks after planting). Experiment 2 .................... 70 3 11 Quercus laevis (Turkey oak) response to aminocy clopyrachlor concentration in so il 10 WAP (weeks after planting). Experiment 2 ................................ .......... 71 3 12 Quercus virginiana (Live oak) response to aminocyclopyrachlor concentration in so il 10 WAP (weeks after p lanting). Experiment 2 ................................ .......... 72 3 13 Liatris spicata (Blazing star) response to aminocyclopyrachlor concentration in soil 10 WAP (week s after planting). Experiment 2 ................................ .......... 73 3 14 Solidago fistulosa (Goldenrod) response to aminocyclopyrachlor concentration in so il 10 WAP (weeks after planting). Experiment 2 .................... 74 3 15 Andropogon virg inicus var. glauca (Chalky bluestem) response to aminocyclopyrach lor concentration in soil 10 WAP. Experiment 2 .................... 7 5 3 16 Aristida stricta var. beyrichiana (Wiregrass) response to aminocyclopyr achl or concentration in soil 10 WAP. Experiment 2 ................................ ...................... 76 3 17 Eragrostis spectabilis (Purple lovegrass) response to aminocyclopyrachlor concentration in soil 10 WAP. Experiment 2 ................................ ...................... 77 3 18 Panicum anceps (Spreading panicum) response to aminocyclopyrachl or concentration in soil 10 WAP. Experiment 2 ................................ ...................... 78

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12 Abstract of Thesis Presented to the Graduate Schoo l of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science CHARACTERIZATION AND EVALUATION OF AMINOCYCLOPYRACHLOR ON NATIVE AND INVASIVE SPECIES OF FLORIDA By Anna Lin Greis May 2012 Ch air: Greg MacDonald Major: Agronomy Aminocyclopyrachlor is a synthetic auxin herbicide proposed for invasive species management and the release or restoration of native perennial grasses. As a component to natural areas restoration, it is also beneficial to understand the impact that herbicide residues have on native plant species. Studies were therefore initiated to determine the efficacy of aminocyclopyrachlor on several invasive grass species as well as the impact of establishment and growth of native s pecies Postemergence applications of a minocyclopyrachlor were evaluated under greenhouse conditions to determine the control of several invasive grasses including natalgrass ( Melinis repens ), torpedograss ( Panicum repens ), paragrass ( Urochloa mutica ), We st Indian marshgrass ( Hymenachne amplexicaulis ) and cog ongrass ( Imperata cylindrica ) as well as several native grass and broadleaf species. All invasive species showed less than 50% visual injury and no reduction in shoot growth or regrowth to aminocyclop yrachlor with the exception of cogongrass which showed a 25 % reduction in regrowth biomass. Eragrostis elliottii was the most tolerant native grass evaluated. Aristida stricta and Eragrostis spectabilis were the most sensitive grasses with I 50 values of 0 .11 and 0.09 kg ai ha 1 respectively. All other grasses were tolerant to rates below 0.19 kg ai ha 1 All

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13 broadleaf natives were highly sensitive (<0.13 kg ai ha 1 ) to rates of aminocyclopyrachlor except Garberia heterophylla which showed less than 50% in jury at 0.24 kg ai ha 1 To assess the impact of aminocyclopyrachlor soil residues on native species, seedlings of several common forbs, grasses, and tree species were transplanted into field plots treated with varying rates of aminocyclopyrachlor Solidag o fistulosa and Liatris spicata showed greater than 50% injury at all rates of aminocyclopyrachlor. Pinus palustris was tolerant to rates below 0.16 kg ai ha 1 and Andropogon virginicus var. glauca showed no injury to aminocyclopyrachlor. Aminocyclopyrach lor caused significant injury to all other species at rates above 0.1 kg ai ha 1 Utilizing plant species injury, optimal planting dates were determined for these species based on a 90 day half life of aminocyclopyrachlor with grasses having the shortest plant back interval To further investigate the potential of aminocyclopyrachlor for cogongrass control, a field study was conducted in Hillsborough County, Florida. A minocyclopyrachlor was evaluated alone or in combination with imazapyr or glyphosate and compared to standard rates of imazapyr and glyphosate. Aminocyclopyrachlor alone showed initial control 31 WAT but no long term control 92 WAT of cogongrass The addition of aminocyclopyrachlor to glyphosate or imazapyr did not improve control relative to glyphosate and imazapyr applied alone. Two additional experiments were established and found that imazapic and imazamox were ineffective for cogongrass control. S urfactant type did not influence the activity of glyphosate or imazapyr for cogo ngrass efficacy

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14 CHAPTER 1 INTRODUCTION The state of Florida has over 13 million ha of diverse natural areas ranging over 81 natural community types. M ore than 4,000 native species of trees, shru bs, and other flowering plants i n Florida are being displaced by over 900 escaped exotic species (Frank et al. 1997; Simberloff et al. 1997; Westbrooks 1998 ; Whitney et al. 2010 ). Florida is a prime area for invasive species due to its mild climate, many international ports, cultural div ersity, and previous lenient importation laws ( Anonymous 1999 ). Collectively th i s led to Florida becoming the epicenter for more exotic species than almost any other region in the US ( Anonymous 1999 ). In 1994, over 684,000 ha were impacted by the top sev en exotic species: Australian pine ( Casuarina equisetifolia L. ) water hyacinth ( Eichhornia crassipes ), hydrilla ( Hydrilla vertici l lata ), old world climbing fern ( Lygodium microphyllum ), melaleuca ( Melaleuca quinquenervia ), torpedograss ( Panicum repens ), a nd Brazilian peppertree ( Schinus terebinthifolius ) ( A nonymous 1999 ). Currently the top 10 most abundant invasive plants in Florida according to EDDSMaps are Brazilian peppertree, melaleuca, old world climbing fern, cogongrass ( Imperata cylindrica ) Japane se climbing fern ( Lygodium japonicum ) Chinese tallowtree ( Triadica sebifera ) Caesarweed ( Urena lobata ) Australian pine ( Casuarina equisetifolia L.) air potato ( Dioscorea bulbifera ) and mimosa tree ( Albizia julibrissin ). Invasive species are a leading cause of native species becoming protected under the Endangered Species Act with 54 endangered species exist ing in Florida (Pimentel et al. 2000; US FWS 2012). Important impacts of invasive plants are ecosystem modification through altering fire frequency and intensity, flooding, erosion and land

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15 stabilization, nutrient cycling and competition with native species W orst case scenarios result in species decline to the point of extinction (Henderson et al. 2006; Mauchamp et al. 1998; Westbrooks 1998). These impacts and several others have prompted the control and elimination of invasive species as a top priority. One of the major invasive plant species in the Southern US and thr oughout the world is cogongrass Cogongrass, Imperata cylindrica has invaded ove r 500 million hectares worldwide and over 500,000 ha in the US ( Holm et al 1977 ; MacDonald 2007 ; Holzmueller and Jose 2010 ). It is a prolific seed producer with over 3 000 seeds per plant (MacDonald 2009) and also propagates through rhizomes. Cogongrass w as brought to the US as possible forage but experimental trials eliminated this use due to silica accumulation in the cogongrass leaf tissue and poor nutritive quality (Hubbard 1944; Dickens and Moore 1974; Coile and Shilling 1993; Dozier et al. 1998; Mac Donald 2009). Cogongrass tolerates a wide range of soil and light conditions and can be found in varying environments from shorelines to upland forests, reclaimed mined land, and abandoned agriculture fields (Hubbard 1944; MacDonald 2009). Cogongrass is a lso a pyrogenic species, maintaining a thick layer of dry leaf thatch for fuel (Holm et al. 1977). Cogongrass fires are very intense and hot which eliminates the native species in the immediate area and provides openings for cogongrass spread (Eussen and Wirjahardja 1973; Seavoy 1975; Eussen 1980). It has been reported that cogongrass rhizomes may exude allelopathic substances that inhibit the growth of other plants (Eussen 1979; Boonitte and Ritdhit 1984 ; Casini et al. 1998). As cogongrass invades an are a, the rhizomes form a dense mat preventing the growth of native species an d eventually form ing a monoculture This in turn reduces native plant productivity, reduces nutrient

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16 availability, and decreases native species biodiversity ( Collins et al. 2007 ; Da neshgar et al. 2008; Daneshgar and Jose 2008 ). This is why cogongrass is considered one of the al. 2004; Plant Protection and Quarantine 2010 ). Controlling I nvasive S pe cies Integrated management plans utilize a variety of control options for invasive species control These include prevention, mechanical, biological, cultural, and chemical control options. Ideally these should be used in tandem to not only prevent the s pread of invasion but also to control and eliminate the invasive species once it has spread to natural areas. A complete eradication of a species once it has become established is extremely difficult ; therefore these control options are used to reduce the ir impact (Weber 2003). For many invasive species, the most and often only cost effective option is to use chemical control. The primary herbicides used in natural areas are glyphosate (Roundup 1 others), imazapyr (Arsenal 2 Chopper 2 Stalker 2 Hab itat 2 others), and triclopyr (Garlon 3 others ) due to their broad spectrum control on many invasive plants. Triclopyr is only effective on broadleaf species and has little to no soil activity. Glyphosate, the most common herbicide used for invasive s pecies control, possesses no soil residual activity and therefore provides no residual control. Conversely, imazapyr possesses considerable residual activity, which is desirable for long term control, however this may result in non target injury to native species or 1 Monsanto Company St. Louis, MO 2 BASF Specialty Products Raleigh, NC 3 Dow AgroS ciences LLC Indianapolis, IN

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17 prevent native species establishment (MacDonald et al. 2008). Herbicides that provide selective control plus soil residual ac tivity could change how land managers address invasive species management. Aminocyclopyrachlor Aminocyclopyrachlor is a synthetic au xin herbicide belonging to the pyrimidine carboxylic a cids class of chemistry. Aminocyclopyrachlor is formulated in the acid and methyl ester form -DPX MAT28 and DPX KJM44, respectively (Bukun et al. 2010). The methyl ester was the formulation initially tested however, the acid is now the current product under evaluation ( DuPont Crop Protection 2010 ). Aminocyclopyrachlor is a bsorbed through foliage and roots, translocates extensively throughout the plant, and accumulates in meristematic tissues ( DuPont Crop Protection 2010 ; Bell et al. 2011). Research has indicated it is both xylem and phloem mobile ( Bell et al. 2011). Once reaching the meristematic region, it acts similarly to other auxin mimic herbicides, causing stem and leaf epinasty and wilting (Senseman 2007 ). Aminocyclopyrachlor shows good herbicidal activity on broadleaf weeds and brush species It shows some activity on grasses, but is highly species specific Research indicates activity on several species in the Asteraceae, Chenopodiaceae, Convolvulaceae, Euphorbiaceae, Fabaceae, and Solanaceae families as well as woody plant species such as Acer rubrum Acer negund o Celtis occidentalis Salix alba Nyssa sylvatica Prosopis juliflora and Ulmus Americana ( Bukun et al. 2008; Claus et al. 2008 ; Armel e t al. 2009; Blair and Lowe 2009 ; Evans et al. 2009; Gannon et al. 2009; Montgomery et al. 2009; Roten et al. 2009; Tu rner et al. 2009; Westra et al. 2009; Wilson et al. 2009 ; Rupp et al. 2011 ). It also controls many ALS ( acetolactate synthase) PPO ( protoporphyrinogen oxidase) triazine and glyphosate herbicide resistant weeds (Blair and Lowe 2009; Turner et al.

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18 2009). As mentioned, aminocyclopyrachlor shows selectivity for many perennial gras ses and some broadleaf species which is important for the restoration of desirable native species ( DuPont Crop Protection 2010 ; Wallace and Prather 2011) One of the proposed uses of aminocyclopyrachlor is for the release or restoration of native perennial grasses ( DuPont Crop Protection 2010 ). Other desirable characteristics of this new herbicide include low use rates ai ha 1 ) low toxicity profile and favorable environmental profile ( DuPont Crop Protection 2010 ). In order to utilize a chemical in natural areas, it is important to understand the vulnerabilities of native species and unique ecosystems Nati ve Ecosystems in Florida Florida is home to a variety of ecosystems. There are 81 natural communities in Florida consisting of 13 million hectares of diverse natural areas encompassing forests, flatwoods, prairies, swamps, marshes, and waterways ( Myers an d Ewel 1990 ; FNAI 2010; Whitney et al. 2010). Within these ecosystems there are more than 4,000 native species of trees, shrubs, and other flowering plants ; 300 of which are endemic to Florida (Whitney et al. 2010). Florida temperate to subtropical clima te and 300 soil types, which comprise 7 of the 11 soil orders in the US, provide for a diverse range of nat ive habitats (Brown et al. 1990 ). South Florida has a subtropical climate while north Florida receives cold fronts in winter and has more varied tem peratures and rain than winters the Atlantic Ocean on its east coast, the moving warm water produces high humidity and abundant rain with 137 centimeters per year on a verage though this varies throughout the state (Carriker and Borisova 2008). The four major native plant communities that exist in the interior uplands of Florida are the high pine grasslands,

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19 flatwoods and prairies, interior scrub, and temperate hardwoo d hammocks (Whitney et al. 2010). High pine grasslands, also known as upland pines, sandhills, and pine rocklands, have existed on the southern coastal plain for more than 20 million years. M any species are unchanged for at least 2 million years including many endemic species to Florida (Whitney et al. 2010). At one time this ecosystem covered ove r 8 million hectares in Florida, but is now almost completely gone (Whitney et al. 2010). This ecosystem consists of a widely spaced canopy, typically longleaf pin e ( Pinus palustris ) sparse midstory of turkey oak ( Quercus laevis ) and scrub oak ( Quercus sp.), and diverse understory dominated by wiregrass ( Aristida stricta ) (FNAI 2010; Whitney et al. 2010). This is a fire dependent community, relying on frequent, low intensity fires to suppress hardwoods, stimulate seed release, provide sunlight for seedlings, and to keep dry litter at a minimum to prevent hot, damaging fires (Whitney et al. 2010; Myers 1990). Flatwoods and prairies, also known as savannas, grasslands and plains, were the most extensive grasslands in the southeastern US and covered half of Florida ( Edmisten 1963; Davis 1967 ; Abrahamson and Hartnett 1990 ; Whitney et al. 2010). Many of these natural systems have disappeared due to developme nt and conve rsion to agricultural fields ( FNAI 2010 ; Whitney et al. 2010). These prairies are characterized by a low, flat topography and relatively poorly drained sandy acidic soils They are dominated by a continuous layer of grasses and forbs with few scattered tr ees (Abrahamson and Hartnett 1990; Whitney et al. 2010). In the past, fires were frequent a s many of the grass species, including wiregrass, are fire dependent (Abrahamson and Hartnett 1990; Whitney et al. 2010).

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20 Interior scrublands are unique xeric commun ities on well drained, infertile sand formations in the coastal and interior areas of Florida (Whitney et al. 2010). The largest interior scrub is located in and around the Ocala National Forest and is though t to be over a million years old (Myers 1990; Wh itney et al. 2010). Much of the interior scrubland has been lost to development and citrus cultivation (Myers 1990). This is a pyrogenic natural community that depends on infrequent (every 10 to 50 years) high intensity fires (Myers 1990; Whitney et al. 20 10). Many scrub plants produce allelopathic chemicals or are home to toxic fungi that inhibit the reproduction of other plants and even their own seeds until the parent plant dies, making scrubland one of the most botanically unique and important ecosystem s in the United States (Whitney et al. 2010). Temperate hardwood hammocks occur along the southeastern coastal plain of the US (Platt and Schwartz 1990). Hardwood hammocks are categorized by three types: xeric, mesic, and hydric (FNAI 2010; Whitney et al. 2010). Xeric hardwood hammocks are an evergreen forest on well drained soils consisting of a closed canopy of oaks, often live oak ( Quercus virginiana ) and laurel oak ( Quercus laurifolia ) (FNAI 2010; Whitney et al. 2010). Mesic hammocks are a mixture of m any tree s pecies ranging from dry upland forests to wet bottomland forests (Whitney et al. 2010). Hydric forests consist of oaks and palms, generally live oak, laurel oak, cabbage palm ( Sabal palmetto ), and red cedar ( Juniperus virginiana ) (FNAI 2010; Whi tney et al. 2010). These hammocks are not fire dependent and where fire has been excluded due to burning restrictions and development new areas of hammocks have emerged (Whitney et al. 2010). Maintaining these natural communities are important, and many a reas are being restored to their natural state after being disturbed (Myers and Ewel 1990). Exotic

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21 species hinder these restoration efforts because habitat occupied by invasives is unavailable for native species recrui tm ent (Myers and Ewel 1990). Exotic sp ecies compete for nutrients, water, and light that would otherwise be available to native s pecies (Myers and Ewel 1990). Phosphate mining creates anthrosols ( human created soils ) that appear to provide favorable environment for invasive species while hind ering restoration efforts (Myers and Ewel 1990). In such areas where an ecosystem ha s been greatly altered, the control of the invading exotic species and restoration of its native properties are necessary to return the land to its natural state (Gordon 19 98). Therefore t he establishment of a self sustaining native plant community is critical to return a land to its natural state and prevent new invasions ( Shilling 2003; Ewel 1986). Invasive species control must be accomplished be fore native plant restorat ion techniques can be successful and u nderstanding the impact of herbicide residue potential is paramount for the success of a restoration effort If aminocyclopyrachlor is found to be effective on invasive species, this herbicide could change how land ma nagers address invasive species management for many areas. However before this can be accomplished several questions rise with respect to this herbicide and its activity under Florida conditions : How does aminocyclopyrachlor effect invasive and native pl ants post emergence; Does the soil residual of aminocyclopyrachlor impact native species transplant success; and can this chemical be used to control cogongrass infestations in Florida conditions. Therefore, the objectives of this research were to: 1) d ete rmine the efficacy of aminocyclopyrachlor on select native and invasive plants grown under greenhouse conditions ; 2 ) e valuate native plant tolerance to various soil

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22 concentrations of aminocyclopyrachlor ; and 3 ) e valuate the use of aminocyclopyrachlor for c ogongrass control under field conditions.

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23 CHAPTER 2 THE EFFECT OF AMINOC YCLOPYRACHLOR APPLIE D POST EMERGENCE ON SELECTED NATIVE AND INVASIVE GRASS SPECIES UNDER GREENH OUSE CONDITIONS Background Information In Florida, more than 4,000 native species are be ing displaced by over 900 invasive exotic species (Frank et al. 1997; Simberloff et al. 1997; Westbrooks 1998; Whitney et al. 20 10 ). Florida has become an epicenter for invasive species due to its mild climate, international ports, and historically lenient importation laws ( Anonymous 1999 ). Torpedograss, Panicum repens and cogongrass, Imperata cylindrica are two species that have historically been the most problematic exotic species in the state ( Anonymous 1999 ; EDDSMaps 2012 ). Cogongrass causes ecosystem destruction by outcompeting native species, as well as eliminating species during prescribed or natural burns due to its pyrogenic characteristics (Eussen and Wirjahardja 1973; Seavoy 1975; Eussen 1980). Two other invasive grasses impacting Florida are We st Indian marshgrass ( Hymenachne amplexicaulis ) and paragrass ( Urochloa mutica ). West Indian marshgrass and paragrass are category 1 exotic species on the Florida Exotic Pest Plant Council Invasive Plant List for central and south Florida (FLEPPC 2011). Ca tegory 1 invasives alter native plant ecosystems by displacing natives, changing community structur e and functions, or hybridizing with native species (FLEPPC 2011). Finding new herbicides to control these invasive species as they invade a natural area is When controlling invasive plants in natural areas, the response of native plants to the chemical treatment must be considered. Selectivity is key to finding a useful herbicide for invasive species management in natural areas. Two common herbicides

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24 used for grass control in natural settings are glyphosate and imazapyr, though limitations exist with both. Glyphosate is broad spectrum and therefore does not show sel ectivity to many native species, as well as possessing no soil residual activity mean ing long term control of invasive grasses is limited with this product (Cornish and Burgin 2005). Imazapyr, another broad spectrum non selective herbicide, possesses considerable residual activity. This is desirable for long term control of invasive species, but residual activity also impacts native plant recruitment over the long term (MacDonald et al. 2008). Therefore practitioners are always looking for new chemicals that will provide control of invasive species while minimizing non target injury/damage and encouraging the recruitment of desirable natives. Aminocyclopyrachlor is a synthetic auxin herbicide proposed for restoration of native perennial grasses ( DuPont Crop Protection 2010 ). The low use rate s and selectivity of this herbicide may allow for its use as a post emergence herbicide for invasive species control where native plants are present ( DuPont Crop Protection 2010 ). It is active on many broadleaf and brush species as well as some grass speci es, but appears to be highly species specific ( Bukun et al. 2008; Claus et al. 2008 ; Armel e t al. 2009; Blair and Lowe 2009 ; Evans et al. 2009; Gannon et al. 2009; Montgomery et al. 2009; Roten et al. 2009; Turner et al. 2009; Westra et al. 2009; Wilson et al. 2009 ; Rupp et al. 2011). Post emergence experiments on native species have been utilized for other natural area chemicals such as hexazinone, glyphosate, imazapyr, imazapic, 2, 4 D, and sulfometuron methyl (Lym and Kirby 1991 ; Kluson et al. 200 0; Ric hardson et al. 2003 ; Jose et al. 2010 ). However, little research has been conducted with aminocyclopyrachlor in this regard. Therefore, post emergence activity on a variety of

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25 native species and invasive grasses were conducted under greenhouse conditions t o determine potential invasive grass control and native plant selectivity Materials and Methods Native plant species were established from seed obtained from a native plant nursery 1 in Florida. Plants were grown under greenhouse conditions (30C day; 20 C night temperatures, natural sunlight) until they had vigorous growth and multiple leaves on the broadleaf species or multiple leaf blades on the grass species to adequate transplant size The number of native plant species evaluated was limited in the second experiment due to poor seed germination. Cogongrass plants were established from rhizomes obtained from naturally growing populations in Gainesville, Florida. Paragrass, West Indian marshgrass, and torpedograss were established from propagule cuttin gs of plants obtained from south Florida. Natalgrass was grown from seeds collected from an established natalgrass population in central Florida. All grasses were grown for 8 to 10 weeks to ensure a healthy root and/or rhizome mass and shoot growth accumul ation. Due to the natural aquatic environment of paragrass, West Indian marshgrass, and desirable moisture conditions. Experiment 1 occurred in spring 2010 and experiment 2 occurred in sum mer 2011. All species were grown in 0.5 L pots with commercial potting soil. Plant height (cm) was taken before treatment and due to the variability in native plant growth, native plants were grouped by height and distributed evenly among the six treatmen ts. 1 The Natives, Inc., Davenport, FL, USA. 2 Induce, Helena Chemical Company, Collierville, TN

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26 Herbicides were applied with a nonionic surfactant 2 (0.25% v/v) at a spray volume of 187 L ha 1 Treatments included aminocyclopyrachlor applied at rate s of 0, 0.0175, 0.035, 0.07, 0.14, and 0.28 kg ai ha 1 Visual estimation of injury (100 = complete death, 0 = no visual injury rating scale) was evaluated at 1, 2, 3, and 4 weeks after treatment (WAT). At 4 WAT aboveground biomass was harvest ed and dry weights obtained. The native grasses were cut to1 cm and the invasives to 2.5 cm height and allowed to re grow for 4 weeks. After 4 weeks, shoot regrowth was harvested, dried, and weighed. The experimental design was a 2 way factorial with aminocyclopyra chlor rate and plant species as main effects. Treatments were arranged in a randomized complete block design with 4 replications Analysis of variance (ANOVA) was used to test for treatment by experiment interactions. For both greenhouse experiments the re was a significant treatment by experiment interaction, so data are presented separately. A log logistic model for predicting dose response curves, as adopted from Seefeldt et al. (1995), was utilized for r egression an alysis to show spe c i es response to aminocyclopyrachlor rate and generate predictive I 50 values. Results and Discussion Native Plants Eight of the native species used in experiment one showed a response of increased injury corresponding to increasing levels of aminocyclopyrachlor based on visual evaluation. For shoot weight, nine of the eleven species were evaluated using regression analysis while Sorghastrum secundum and Garberia heterophylla did not have a consistent trend of shoot weight verses aminocyclopyrachlor application rate (Figu re 2 7 and 2 8 ).

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27 Grasses For visual evaluation Andropogon brachystachyus had an I 50 value of 0.22 kg ai ha 1 in experiment one (Table 2 1 Figure 2 1 ) and showed less than 50% injury in experiment two (Table 2 2 ). For shoot growth it had an I 50 value of 0.20 kg ai ha 1 in experiment one and greater than the maximum labeled rate of 0.28 kg ai ha 1 in experiment two. A 50% reduction of regrowth has been predicted at 0.19 kg ai ha 1 for Andropogon brachystachyus in experiment one Andropogon virginicus wa s tolerant to aminocyclopyrachlor with a visual I 50 value of 0.23 kg ai ha 1 and a shoot growth I 50 value of 0.24 kg ai ha 1 (Table 2 1 Figure 2 3 ). Re growth data are not shown due to damage across all rates caused by the cutting procedure and plant de ath seen across all rates and the untreated control. Visual data are not shown for Aristida stricta due to the lack of observable visual symptoms for both experiments. Aristida stricta had a shoot growth I 50 value of 0.11 kg ai ha 1 i n experiment one (Tab le 2 1 Figure 2 2 ) and no injury in experiment two (Table 2 2 ). However, Aristida stricta had an I 50 value greater than 0.28 kg ai ha 1 for experiment two. Greenhouse environmental issues such as uneven watering may have also caused the reduced shoot gro wth in experiment one when compared to experiment two. Eragrostis elliottii showed less than 5 0% injury at all rates of aminocyclopyrachlor, an I 50 value greater than the maximum labeled rate of 0.28 kg ai ha 1 for shoot growth and a high predicted I 50 of 0.25 kg ai ha 1 for shoot regrowth (Table 2 1 Figure 2 4 ). Overall, Eragrostis elliottii was the most tolerant grass species evaluated. Conversely, Eragrostis spectabilis showed greater than 50% injury at all rates of aminocyclopyrachlor and had a shoo t growth I 50 value of 0.12 kg ai ha 1 (Table 2 1 Figure 2 5 ). Regrowth was highly inconsistent and therefore was not regressed for this

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28 species. Significant plant injury was observed at even the lowest application rates, indicating that injury may have b een exacerbated by stress factors such as irrigation problems coupled with aminocyclopyrachlor damage. Panicum anceps had no visual injury at all rates of aminocyclopyrachlor but showed a shoot growth I 50 value of 0.17 kg ai ha 1 and a regrowth I 50 value g reater than 0.28 kg ai ha 1 (Table 2 1 Figure 2 6 ). Sorghastrum secundum injury had an I 50 value of 0.13 kg ai ha 1 in experiment one (Table 2 1 Figure 2 7 ) which is slightly lower than a half rate of aminocyclopyrachlor and showed less than 50% injury to all rates of aminocyclopyrachlor in experiment two (Table 2 2 Figure 2 1 5). For shoot growth and regrowth data, Sorghastrum secundum was not significantly affected by aminocyclopyrachlor with all I 50 values greater than 0.28 kg ai ha 1 The greater ov erall injury seen in experiment one may be due to a watering issue in the greenhouse because greater damage is seen across all species. Many of these species, such as Eragrostis species, Sorghastrum secundum Andropogon virginicus and Aristida stricta ar e common to xeric upland ecosystems in Florida (Grelen and Hughes 1984). These natural xeric sites are characterized by excessively drained soils (Florida Native Plant Society 2004). Overwatering in the greenhouse may have caused mold and disease, which was seen in some pots, thus stressing these species and leading to the increased damage observed. Broadleav es Garberia heterophylla was the least sensitive broadleaf evaluated with an I 50 value for injury of 0.24 kg ai ha 1 however shoot growth was inconsis tent across all treatments and no data were collected for this parameter. Liatris spicata had a visual injury predicted value of 0.08 kg ai ha 1 and a shoot growth predicted value of

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29 0.12 kg ai ha 1 Solidago fistulosa was the most sensitive species evalua ted with visual I 50 value of 0.02 kg ai ha 1 and shoot growth I 50 value of 0.09 kg ai ha 1 Due to the broad spectrum broadleaf weed control observed with aminocyclopyrachlor, the significant damage seen on these native broadleaf plants in the greenhouse was not surprising (DuPont Crop Protection 2010). Invasive Grasses All species had less than 50% injury at all rates of aminocyclopyrachlor at 4 WAT, therefore, I 50 values are not listed. For Hymenachne amplexicaulis regrowth I 50 values for all experim ents were above 0.28 kg ai ha 1 (Table 2 3 and 2 4 ). Imperata cylindrica was not regressed for regrowth due to data inconsistencies in experiment one however it had a regrowth I 50 value of 0.09 kg ai ha 1 in experiment two (Table 2 4 ). Melinis repens av erages of four means at three treatments are graphed for experiment one but significant injury due to cutting was seen at all rates above 0.035 kg ai ha 1 Therefore data cannot be analyzed for experiment one, but Melinis repens had an I 50 value above 0.2 8 kg ai ha 1 for shoot regrowth in experiment two (Table 2 4 ). Panicum repens was not regressed for shoot weight in experiment one, however it had an I 50 value at the highest rate (0.28 kg ai ha 1 ) in experiment two (Table 2 4 ). Urochloa mutica did not s how significant shoot growth reductions at all rates of aminocyclopyrachlor in either experiment. Shoot regrowth of Urochloa mutica in experiment one was also not affected by aminocyclopyrachlor, however in experiment two a predicted 50% reduction in regr owth was seen at 0.15 kg ai ha 1 Discussion For native species, grasses showed less injury and therefore a higher I 50 value than all broadleaf species excluding Garberia heterophylla Though native plants rarely exhibit uniform growth, the I 50 values s how a trend that grasses are

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30 more tolerant to aminocyclopyrachlor than native forbs. These results are to be expected, as grasses have been found to be tolerant to other growth regulating herbicides (Crafts 1946; Shinn and Thill 2002 ; Rinella et al. 2010) An experiment by DiTomaso et al. (2006) found an increase in annual grass composition and decrease in legumes in a grassland treated for two years with the growth regulator clopyralid. For the grass regrowth evaluation, most species had I 50 9 kg ai ha 1 In experiment 1, Eragrostis spectabilis was an exception to this high I 50 value trend while other species in both experiments showed damage from the actual cutting procedure. The invasive grasses had more consistent growth patterns than the native grasses. The I 50 values for all invasive grasses tested were > 0.28 kg ai ha 1 for initial growth evaluations. Imperata cylindrica and Urochloa mutica showed reduction in regrowth in experiment two. All other grasses evaluated had regrowth I 50 v kg ai ha 1 Overall, these five invasive grasses are not highly sensitive to aminocyclopyrachlor. Brecke et al. (2010) also found similar results that indicated torpedograss cannot be controlled by a post application of aminocyclopyrachlor. D ifferences in plant response in replicated greenhouse experiments have been noted in other greenhouse trials which emphasize the need for additional greenhouse and field trials to get a complete understanding of herbicide efficacy (Viswanath et al. 2011).

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31 Table 2 1 Summary of the effect of aminocyclopyrachlor concentration on native species Experiment 1. I 50 values reflect the predicted aminocyclopyrachlor concentration that would result in 50% visual injury 4 WAT, 50% reduction in shoot growth 4 WAT, and 50% reduction in shoot regrowth 8 WAT Species I 50 1 aminocyclopyrachlor values (kg ai ha 1 ) I 50 2 aminocyclopyrachlor values (kg ai ha 1 ) I 50 3 aminocyclopyrachlor values (kg ai ha 1 ) Andropogon brachystachyus 0.22 0.19 0.17 Aristida stricta 4 0.11 Andropogon virginicus 0.23 0.24 Eragrostis elliottii > 0.28 0.25 > 0.28 Eragrostis spectabilis 0.09 0.12 Garberia heterophylla 0.24 Liatris spicata 0.08 0.12 Panicum anceps > 0.28 0.20 Pityopsis graminifolia 0.04 0.18 Solid ago fistulosa 0.02 0.09 Sorghastrum secundum 0.13 1 I 50 aminocyclopyrachlor value for less than 50% visual injury 4 WAT 2 I 50 aminocyclopyrachlor value for reduction in growth 4 WAT 3 I 50 aminocyclopyrachlor value for reduction in regrowth 8 WAT 4 Species did not show a response Table 2 2 Summary of the effect of aminocyclopyrachlor concentration on native species Experiment 2. I 50 values reflect the predicted aminocyclopyrachlor concentration that would result in 50% visual injury 4 WAT 50 % reduction in shoot growth 4 WAT, and 50% reduction in shoot regrowth 8 WAT Species I 50 1 aminocyclopyrachlor values (kg ai ha 1 ) I 50 2 aminocyclopyrachlor values (kg ai ha 1 ) I 50 3 aminocyclopyrachlor values (kg ai ha 1 ) Andropogon brachystachyus > 0.2 8 > 0.28 Aristida stricta > 0.28 > 0.28 Eragrostis spectabilis > 0. 0 > 0.28 Sorghastrum secundum > 0.28 > 0.28 > 0.28 1 I 50 aminocyclopyrachlor value for less than 50% visual injury 4 WAT 2 I 50 aminocyclopyrachlor value for reduction in regrow th 8 WAT 3 I 50 aminocyclopyrachlor value for reduction in growth 4 WAT

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32 Table 2 3 Summary of the effect of aminocyclopyrachlor concentration on invasive species Experiment 1. I 50 values reflect the predicted aminocyclopyrachlor concentration that would result in 50% reduction in shoot growth 4 WAT and 50% reduction in shoot regrowth 8 WAT Species I 50 1 aminocyclopyrachlor values (kg ai ha 1 ) I 50 2 aminocyclopyrachlor values (kg ai ha 1 ) Hymenachne amplexicaulis > 0.28 > 0.28 Imperata cylindrica > 0.28 Melinis repens > 0.28 Panicum repens > 0.28 Urochloa mutica > 0.28 > 0.28 1 I 50 aminocyclopyrachlor value for reduction in growth 4 WAT 2 I 50 aminocyclopyrachlor value for reduction in regrowth 8 WAT Table 2 4 Summary of the effect of amino cyclopyrachlor concentration on invasive species Experiment 2. I 50 values reflect the predicted aminocyclopyrachlor concentration that would result in 50% reduction in shoot growth 4 WAT and 50% reduction in shoot regrowth 8 WAT Species I 50 1 aminocyclopyr achlor values (kg ai ha 1 ) I 50 2 aminocyclopyrachlor values (kg ai ha 1 ) Hymenachne amplexicaulis > 0.28 > 0.28 Imperata cylindrica > 0.28 0.09 Melinis repens > 0.28 > 0.28 Panicum repens > 0.28 0.28 Urochloa mutica > 0.28 0.15 1 I 50 aminocyclopyr achlor value for reduction in growth 4 WAT 2 I 50 aminocyclopyrachlor value for reduction in regrowth 8 WAT

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33 Figure 2 1 Andropogon brachysta chyus response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT; C ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression curves shown when applicable. Experiment 1 A B C

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34 Figure 2 2 Aristida stricta response to aminocyclopyrachlor concentration. Shoot growth 4 WAT for experiment 1. Means of 4 replications pr esent with standard error. Figure 2 3 Andropogon virginicus response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT for experiment 1. Means of 4 replications present with standard error. Regressio n curves shown when applicable. A B

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35 Figure 2 4 Eragrostis elliottii response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replicatio ns present with standard error. Regression curves shown when applicable. A B

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36 Figure 2 5 Eragrostis spectabilis response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression c urves shown when applicable. Figure 2 6 Panicum anceps response to a minocyclopyrachlor concentration. A) shoot growth 4 WAT; B) s hoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regressio n curves shown when applicable. A A B B

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37 Figure 2 7 Sorghastrum secundum response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT; C ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression curves shown when applicable. A B C

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38 Figure 2 8 Garberia heterophylla response to aminocyclopyrachlor concentr ation. A ) visual injury 4 WAT ; B) shoot growth 4 WAT for experiment 1. Means of 4 replications present with standard error. Regressio n curves shown when applicable. Figure 2 9 Liatris spicata response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT for experiment 1. Means of 4 replications present with standard error. Regressio n curves shown when applicable. A A B B

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39 Fi gure 2 1 0 Pityopsis graminifolia response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT for experiment 1. Means of 4 replications present with standard error. Regressio n curves shown when applicable. Figure 2 1 1 Solidago fistulosa response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT for experiment 1. Means of 4 replications present with standard error Regressio n curves shown when applicable. A A B B

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40 Figure 2 1 2 Andropogon brachystachyus response to aminocyclopyrachlor concentration. A ) visual i njury 4 WAT ; B) shoot growth 4 WAT; C) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Regression curves shown when applicable. A B C

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41 Figure 2 1 3 Aristida stricta response to aminoc yclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT; C) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Reg ression curves shown when applicable. A B C

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42 Figure 2 1 4 Eragrostis spectabilis response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT; C) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Regression curves shown when applicable. A B C

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43 Figure 2 1 5 Sorghastrum secundum response to aminocyclopyrachlor concentration. A ) visual injury 4 WAT ; B) shoot growth 4 WAT; C) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Regressio n curves shown when applicable. A B C

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44 Figure 2 1 6 Hymenachne amplexicaulis response to aminocyclopyrachlor c oncentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression curves shown w hen applicable. Figure 2 1 7 Imperata cylindrica response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression curves shown w hen applicable. A A B B

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45 Figure 2 1 8 Melinis repens response to a minocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression curves shown w hen applicable. Figure 2 1 9 Panicum repens response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with standard error. Regression curves shown w hen applicable. A A B B

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46 Figure 2 2 0 Urochloa mutica response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 1. Means of 4 replications present with stand ard error. Regression curves shown w hen applicable. A B

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47 Figure 2 2 1 Hymenachne amplexicaulis response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowt h 8 WAT for experiment 2. Means of 4 replications present with standard error. Regression curves shown when applicable. Figure 2 2 2 Imperata cylindrica response to aminocyclopy rachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Regression curves shown when applicable. A A B B

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48 Figure 2 2 3 Melinis repens response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Regre ssion curves shown when applicable. Figure 2 2 4 Panicum repens response to amin ocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 2. Means of 4 replications present with standard error. Regression curves shown when applicable. A A B B

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49 Figure 2 2 5 Urochloa mutica response to aminocyclopyrachlor concentration. A ) shoot growth 4 WAT; B ) shoot regrowth 8 WAT for experiment 2. Means of 4 replicat ions present with standard error. Regression curves shown when applicable A B

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50 CHAPTER 3 RESPONSE OF SELECT NATIVE SPECIES TO VARIOUS SOIL CONCENTRATIONS OF AMINOCYCLOPYRACHLOR Background Information Florida consists of 13 million hectares of diverse natural a reas encompassing a wide variety of ecosystems (Myers and Ewel 1990 ; FNAI 2010; Whitney et al. 2010). These natural ecosystems support a high diversity of 4,000 native plant species throughout the state (Whitney et al. 2010). The four major native plant co mmunities in the state are the high pine grasslands, flatwoods and prairies, interior scrub, and temperate hardwood hammocks (Whitney et al. 2010). Native grasses and broadleaves are important in maintaining a diverse ecosystem. There are several key spec ies that dominate the understory of these ecosystems. Wiregrass, Aristida stricta is a dominant species in longleaf pine ecosystems of Florida ( Brockway et al. 1998; Clewell 2003 ). According to Norcini et al. (2003) wiregrass is the most desirable speci es to include when restoring pineland habitats. In the northwestern panhandle of Florida, longleaf pine forest understories may also be dominated by bluestem ( Andropogon ) species ( Brockway et al. 1998 ). These two grasses, along with longleaf pine ( Pinus pa lustris ) are keystone species in these fire dominated ecosystems (Platt et al. 1988 ; Brockway et al. 1998 ). Their ability to carry a fire makes them ideal for these frequently burned habitats. Several other forbs and grasses are used for restoring degraded sites. Blazing star, Liatris spicata is a perennial wildflower found throughout the state of Florida. It is browsed by deer and its flowers are attractive to many species of butterflies and insects (Norcini et al. 2003). It has been shown to be adaptabl e to sand tailings in reclaimed mined sites (Norcini et al. 2003). Chalky bluestem ( Andropogon virginicus var. glauca ),

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51 and lopsided indiangrass ( Sorghastrum secundum ) are used for erosion control, livestock forage, and wildlife cover (Norcini et al. 2003) Silkgrass, Pityopsis graminifolia has been studied for use in restoring reclaimed phosphate mine sites in Florida (Pfaff et al. 2002). Lovegrasses such as Eragrostis elliottii and Eragrostis spectabilis are native pioneer grass species that can compete with invasive grasses while allowing smaller native plants to become established (Segal et al. 2001). Direct seeding and transplanting are the two main options f or reestablishing native species on a site. Direct seeding is the least expensive, however th ere are several complications with using this method. Native seeds are often light, with awns or hairs that make planting with conventional equipment difficult ( Pfaff et al. 2002 ). Many native species lack seed vigor and cannot outcompete established invas ive specie s ( Pfaff et al. 2002; Norcini et al. 2003). In addition, seed dormancy is a common occurrence with native seeds with germination occurring only during certain seasons ( Pfaff et al. 2002 ). Though planting containerized seedlings is more costly, it is a popular method for quickly re establishing native species (Glitzenstein and Streng 2003). When trans planting natives, it is important to understand the residual effects of an herbicide that ha s been previously employed on the site for weed control. Previous plant back studies have been conducted on native species in response to imazapyr, glyphosate, and hexazinone (Miller et al. 2002 ; Bar ron et al. 2005 ; Cornish and Burgin 2005; Jose et al. 2010). When herbicide residues persist in the environment t here is a risk that damage to the replanted species will result (Cornish et al. 1996 ; Cornish and Burgin 2005) An experiment conducted by Barron et al. (2005) evaluated imazapyr

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52 residuals on native species and found all species were highly injured at rat es above 0.56 kg ai ha 1 Aminocyclopyrachlor is a synthetic auxin herbicide proposed for natural areas management and the restoration of native perennial grasses ( DuPont Crop Protection 2010 ). This herbicide is active on many broadleaf and brush weeds an d has shown some activity on g rasses, though it is highly species specific. Some grasses that are intolerant of aminocyclopyrachlor are Bromus marginatus Nees ex Steudel, Leymus cinereus (Scribn. & Merr.) A., and Stenotaphrum secundatum Walt. Kuntze (Buk un et al. 2008; Brecke et al. 2010; Claus et al. 2008; Armel et al. 2009; Blair and Lowe 2009; Evans et al. 2009; Gannon et al. 2009; Montgomery et al. 2009; Roten et al. 2009; Turner et al. 2009; Wallace and Prather 2010; Westra et al. 2009; Wilson et al. 2009 ; Rupp et al. 2011 ) Aminocyclopyrachlor does possess soil residual activity wi th a half life ranging between 22 and 164 days in bareground studies ( DuPont Crop Protection 2010 ). If this chemical is to be used for restoration purposes i t is important to understand how native species respond to this product after re introduction into a treated landscape. Therefore the response of native species to various soil concentrations of aminocyclopyrachlor was evaluated. Materials and Methods F ield experiments were conducted in the summer of 2011 at the Plant Scien ce Research and Education Unit in Citra, Florida. The soil type is a Sparr sand (Loamy, siliceous, subactive, hyperthermic Grossarenic Paleudults taxonomic class) consisting of deep, somewhat poorly dr ained, slowly permeable soil ( Soil Survey Staff 2004 ). The field was prepared using conventional tillage practices and had no previous treatme nts

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53 of aminocyclopyrachlor. Aminocyclopyrachlor was applied at 0, 0.009,0.018, 0.035, 0.07, 0.14, and 0.28 kg ai h a 1 with a CO 2 backpack sprayer calibrated to deliver 187 L ha 1 Application s occurred on June 1 st 2011 and July 6 th 2011 for the first and second experiments, respectively. Immediately after application, the herbicide was incorporated into the top 8 cm of so il. Within 24 hours after application, the native seedlings were hand planted into each plot. A native plant nursery 1 supplied the native species used in both experiments. These included three tree species, four grasses, and two forb species ( Table 3 1 ) The plants were evaluated 10 and 14 weeks (Experiment 1 and 2) after treatment for percent mortality and plant injury 10 and 14 weeks (Experiment 1 and 2) after treatment where 0 = no injury and 100 = plant death. The experimental design was a 2 way f actorial with aminocyclopyrachlor rate and plant species as main effects. Plots were 3 by 6 m 2 and arranged in a completely randomized block design with 4 replications Data was subjected to analysis of variance to test for treatment by experiment intera ctions There was a significant treatment by experiment interaction (p<0.05), therefore data is presented separately. Regression analysis was used to predict I 30 and I 50 values for all species (Table 3 2 and 3 3 ). Due to initial transplant shock and act ivity of aminocyclopyrachlor, only 14 weeks after treatment for experiment 1 and 10 weeks after treatment for experiment two are shown to allow for greatest plant response and possible recovery. Plant back days were determined for each species based on a 9 0 day half life of aminocyclopyrachlor (estimated for Florida sandy soils) applied at 0.28 kg ai ha 1 maximum labeled rate 1 The Natives, Inc., Davenport, FL, USA.

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54 The equation used to predict plant back intervals is: Days =((LN(I 50 /0.28))/LN(0.5))*9 0. Results and Discussion Overall, experiment two showed less visual injury for all species as compared to experiment one. This could be due to transplant shock differences between the two experiments. To hinder reestablishment of invasive plants such as cogongrass, it is often important to establish tree species during the later control phase of restoration (Faircloth et al. 2005). Quercus virginiana had an I 50 value of 0.024 kg ai ha 1 in experiment 1 (Table 3 2 Figure 3 3 ) and 0.08 kg ai ha 1 in experi ment 2 (Table 3 3 Figure 3 1 2). Based on these values, plant back days ranged from 163 to 319 days after a 0.28 kg ai ha 1 application of aminocyclopyrachlor. Pinus palustris had I 50 values of 0.071 and 0.16 kg ai ha 1 (Table 3 2 and 3 3 ). The plant bac k time ranged from 73 to 178 days after treatment. Quercus laevis was regressed for experiment two only due to high injury rates for all treatments including the untreated in experiment one. Experiment two shows that Quercus laevis is a sensitive species with an I 50 value of 0.06 kg ai ha 1 and a plant back time of 200 days post treatment (Table 3 3 ). In experiment two, Quercus laevis was the most sensitive tree species evaluated. Mortality rates for all tree species were below 60% in experiments one an d two (Table 3 4 and 3 5 ). One of the uses of aminocyclopyrachlor is for the release or restoration of native perennial grasses and so it is important to determine which native grasses can be planted back into an area that has been previously treated with aminocyclopyrachlor for weed control (DuPont Crop Protection 2010). Mortality was less than 60% for most grass species in experiment one (Table 3 4 ) and all grasses in experiment two

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55 (Table 3 5 ). Andropogon virginicus var. glauca was the least sensitive species, showing no injury at all rates of aminocyclopyrachlor and therefore had a plant back time of 0 days. Aristida stricta was regressed in experiment one and showed high sensitivity with an I 50 value of 0.01 kg ai ha 1 and greater than 30% injury at all rates (Table 3 2 Figure 3 7 ). Based on the I 50 value, the plant back time was 433 days. Aristida stricta showed greater than 60% mortality at rates above 0.09 kg ai ha 1 (Table 3 4 ). This grass is very important for restoring longleaf pine ecosystem s so knowing the plant back interval is very important to reduce mortality and injury and increase the chance for survival and seeding (Whitney et al. 2010). Eragrostis spectabilis had higher injury in experiment one than experiment two which may be due to a combination of transplant shock and aminocyclopyrachlor damage because 60% injury is seen at the two lowest rates of aminocyclopyrachlor (Figure 3 8 ). In experiment two, injury was too low to enable prediction of an I 50 value. Panicum anceps also displ ayed a greater level of injury in experiment one and no injury in experiment two. In experiment one, Panicum anceps had an I 50 value of 0.096 kg ai ha 1 with a plant back time of 139 days (Table 3 2 ) and a mortality P 60 value of 0.21 kg ai ha 1 (Table 3 4 ). In experiment two, no injury over 50% was seen. Panicum anceps can be planted immediately after application (0 days) and show less than 50% injury. Aminocyclopyrachlor is known to control many broadleaf weeds ( Armel et al. 2009; Blair and Lowe 2009; Bukun et al. 2008; Claus et al. 2008; Evans et al. 2009; Gannon et al. 2009; Montgomery et al. 2009; Roten et al. 2009; Rupp et al. 2011; Turner et al. 2009; Westra et al. 2009; Wilson et al. 2009 ) and this injury is replicated on the two broadleaf native species evaluated. Injury of both Liatris spicata and Solidago fistulosa

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56 was significant at all rates of aminocyclopyrachlor and plant back dates for both species were greater than a year (Table 3 2 and 3 3 ). Mortality of Liatris spicata was greater than 60% at all rates in experiment one and Solidago fistulosa was sensitive with P 60 value of 0.024 kg ai ha 1 (Table 3 4 ). In experiment two, both species showed less than 60% mortality (Table 3 5 ). Solidago fistulosa showed 50% injury at all rates If rest oration to broadleaf natives is the goal, aminocyclopyrachlor may complicate the revegetation process.

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57 Table 3 1 Species used in revegetation study in Citra, Florida. Common Name Scientific Name Plant Volume Longleaf pine Pinus palustris 3.8 L pots L ive oak Quercus virginiana 3.8 L pots Turkey oak Quercus laevis 3.8 L pots Chalky bluestem Andropogon virginicus var. glauca 10.2 cm tublings Wiregrass Aristida stricta var. beyrichiana 10.2 cm tublings Purple lovegrass Eragrostis spectabilis 10.2 cm t ublings Spreading panicum Panicum anceps 10.2 cm tublings Blazing star Liatris spicata 10.2 cm pots Goldenrod Solidago fistulosa 10.2 cm pots

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58 Table 3 2 The effect of aminocyclopyrachlor concentration on percent visual injury of selected native speci es 14 weeks after treatment. I 30 and I 50 values reflect the predicted aminocyclopyrachlor concentration that would result in visual 30% and 50% injury. Plant back days for 50% or less injury Experiment 1 Plant Species R 2 aminocyclopyrachlor values (kg ai ha 1 ) I 30 I 50 Plant Back Time (days) 1 Pinus palustris 0.52 0.03 0.07 180 Quercus virginiana 0.68 0.02 0.06 200 Andropogon virginicus var. glauca 0.10 2 0 Aristida stricta 0.79 >0.0 0.01 433 Eragrostis spectabilis 0.19 Panicum ance ps 0.42 0.07 0.10 139 Liatris spicata Solidago fistulosa 0.51 >0.0 >0.0 1 Based on 90 day half life of aminocyclopyrachlor applied at 0.28 kg ai ha 1 2 Data not regressed Table 3 3 The effect of aminocyclopyrachlor concentration on percent visual injury of selected native species 10 weeks after treatment. I 30 and I 50 values reflect the predicted aminocyclopyrachlor concentration that would result in visual 30% and 50% injury. Plant back days for 50% or less injury Experiment 2 Plant Speci es R 2 aminocyclopyrachlor values (kg ai ha 1 ) I 30 I 50 Plant Back Time (days) 1 Pinus palustris 0.50 0.12 0.16 73 Quercus laevis 0.25 0.02 0.05 224 Quercus virginiana 0.39 0.03 0.08 163 Andropogon virginicus var. glauca 2 0 Erag rostis spectabilis 0.19 0.15 0 Panicum anceps 0.16 0.28 0 Liatris spicata Solidago fistulosa 1 Based on 90 day half life of aminocyclopyrachlor applied at 0.28 kg ai ha 1 2 Data not regressed

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59 Table 3 4 The effect of aminocyclopyrac hlor soil concentration on percent mortality of selected revegetation species 40 weeks after planting. Experiment 1. P 60 values reflect the predicted aminocyclopyrachlor concentration that would result in less than 60% mortality. Plant Species Regression e quation R 2 P 60 values (kg ai ha 1 ) Pinus palustris y= 1.279+33.78*(1 exp( 8.284*x)) 0.41 1 Quercus laevis 3 Quercus virginiana y= 2.07+31.17*(1 exp( 9.053*x)) 0.48 1 Andropogon virginicus var. glauca y= 0.6263+21410*(1 exp( 0.002*x)) 0.15 1 Ari stida stricta y= 40.74+72.63*(1 exp( 3.605*x)) 0.34 0.086 Eragrostis spectabilis y= 16.67+31.67*(1 exp( 94370000*x)) 0.10 1 Panicum anceps y= 4.208+103*(1 exp( 4.603*x)) 0.71 0.21 Liatris spicata y= 66.67+25*(1 exp( 2292*x)) 0.19 2 Solidago fistulosa y= 15.65+84.82*(1 exp( 31.48*x)) 0.68 0.024 1 Species exhibits less than 60% mortality at all rates of aminocyclopyrachlor in soil. 2 Species exhibits greater than 60% mortality at all rates of aminocyclopyrachlor in soil. 3 Data not regressed

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60 Table 3 5 The effect of aminocyclopyrachlor soil concentration on percent mortality of selected revegetation species 10 weeks after planting. Experiment 2. P 60 values reflect the predicted aminocyclopyrachlor concentration that would result in less than 60% morta lity. Plant Species Regression equation R 2 P 60 values (kg ai ha 1 ) Pinus palustris y= 34000+10860*(1 exp( 0.004*x)) 0.45 1 Quercus laevis y= 0.2503+36.81*(1 exp( 4.609*x)) 0.04 1 Quercus virginiana y= 36.81*(1 exp( 4.609*x)) 0.28 1 Andropogon virginic us var. glauca 2 1 Aristida stricta y= 35.26*(1 exp( 5.981*x)) 0.33 1 Eragrostis spectabilis y= 1.931+418.2*(1 exp( 0.2448*x)) 0.24 1 Panicum anceps y= 16.67+ 13.89*(1 exp( 6620*x)) 0.15 1 Liatris spicata y= 4.949+243700*(1 exp( 0.0007*x)) 0.47 1 Solidago fistulosa 1 1 Species exhibits less than 60% mortality at all rates of aminocyclopyrachlor in soil. 2 Data not regressed

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61 Figure 3 1 Pinus palustris ( Longleaf pine ) response to aminocyclopyrachlor conce ntration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error. y= 132.6+(( 133.17)/(1+((x/0.1340) 0.7713 ))) R 2 = 0.52

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62 Figure 3 2 Quercus laevis ( Turkey oak ) respo nse to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error.

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63 Figure 3 3 Quercus virginiana ( Live oak ) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error. y= 2.626+((94)/(1+((x/0.036 3) 1.6217 ))) R 2 = 0.68

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64 Figure 3 4 Liatris spicata ( Blazing star ) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with s tandard error.

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65 Figure 3 5 Solidago fistulosa ( Goldenrod ) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Me ans of 4 replications present with standard error. y= 9.3893+((111.41)/(1+((x/0.0224) 0.7203 ))) R 2 = 0.51

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66 Figure 3 6 Andropogon virginicus var. glauca ( Chalky bluestem ) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately af ter aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error. y= 3.2214+((39.42)/(1+((x/0.285) 2.61 ))) R 2 = 0.10

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67 Figure 3 7 Aristida stricta var. beyrichiana ( Wiregrass ) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error.

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68 Figure 3 8 Eragrostis spectabilis ( Purple lovegrass ) re sponse to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error.

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69 Figure 3 9 Panicum anceps ( Spreading panicum ) response to aminocyclopyrachlor concentration in soil 14 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 1. Means of 4 replications present with standard error. y= 5.2432+((66.21)/(1+((x/0.0792) 3.9694 ))) R 2 = 0.42

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70 Figure 3 1 0 Pinus palustris ( Longleaf pine ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 2. Means of 4 replications pre sent with standard error. y= 65.4696 +(( 54.6711)/(1+((x/0.1356) 5.1174 ))) R 2 = 0.50

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71 Figure 3 1 1 Quercus laevis ( Turkey oak ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experimen t 2. Means of 4 replications present with standard error. y= 78.3222+( ( 47.3068)/(1+((x/0.0732) 2.6756 ))) R 2 = 0.25

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72 Figure 3 1 2 Quercus virginiana ( Live oak ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclop yrachlor application for experiment 2. Means of 4 replications present with standard error. y= 116.4+(( 103.3399)/(1+((x/0.1357) 1.1045 ))) R 2 = 0.39

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73 Figure 3 1 3 Liatris spicata ( Blazing star ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after pla nting) immediately after aminocyclopyrachlor application for experiment 2. Means of 4 replications present with standard error.

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74 Figure 3 1 4 Solidago fistulosa ( Goldenrod ) response to aminocyclopyrachlor concentrat ion in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 2. Means of 4 replications present with standard error.

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75 Figure 3 1 5 Andropogon virginicus var. glauca ( Ch alky bluestem ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 2. Means of 4 replications present with standard error.

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76 Figure 3 1 6 Aristida stricta var. beyrichiana ( Wiregrass ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 2. Means of 4 replications present with standard error.

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77 Figure 3 1 7 Eragrostis spectabilis ( Purple lovegrass ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for expe riment 2. Means of 4 replications present with standard error. y= 32.9165+(( 30.9165)/(1+((x/0.1398) 53.8695 ))) R 2 = 0.19

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78 Figure 3 1 8 Panicum anceps ( Spreading panicum ) response to aminocyclopyrachlor concentration in soil 10 WAP (weeks after planting) immediately after aminocyclopyrachlor application for experiment 2. Means of 4 replications present with standard error. y= 55.6525+(( 48.0156)/(1+((x/0.2937) 3.2998 ))) R 2 = 0.16

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79 CHAPTER 4 HERBICIDE EVALUATIONS FOR COGONGRASS CONTROL UNDER FIELD CONDITIONS Background Information Cogongrass ( Imperata cylindrica ) is considered one of the top ten worst weeds in the world (Lowe et al. 2004) This aggressive, rhizomatous perennial grass is listed as a noxious weed federally, as well as by 7 southern states including Florida (Plant Protection and Quarantine 2010) It has invaded m any areas in Florida ranging from pine plantations to reclaimed phosphate mining sites and other disturbed natural areas (Hubbard 1944; MacDonald 2009) Cogongrass originated in the US as an escape from a Satsuma orange crate around Grand Bay, Alabama in 1912 (Hubbard 1944) It was also intentionally introduced i nto Mississippi in 1921 as potential forage (Dickens and Moore 1974), and was brought into Florida in the 1930s and 1940s as potential forage and for soil stabilization (Hubbard 1944). I nitial rese arch indicated potential as a pest and u nfortunately, it continued to spread from illegal plantings and by accidental means. Cogongrass is now estimated to cover over 500,000 ha in the US and over 500 million ha worldwide (Holm et al 1977; MacDonald 2007; Holzmueller and Jose 2010) Cogongrass can spread by wind blown seeds and rhizomes (MacDonald 2009) Established stands can produce over 40 tons of rhizomes per acre (Terry et al 1997) It has been reported that cogongrass rhizomes may exude allelopathi c substances that inhibit the growth of other plants ( Eussen 1979; Bryson and Carter 1993; Casini et al. 1998 ) As cogongrass invades an area, all other vegetation is generally excluded forming a dense monoculture The difficul ty in managing cogongrass is that all rhizomes must be completely killed to eliminate cogongrass from an area.

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80 Cogongrass is also a detriment to the fire dependent ecosystems of the southeastern US Cogongrass is a fire adapted species and retains dead leaf blades throughout the ye ar providing a large amount of fuel (Holm et al. 1977). Cogongrass fires are extremely hot and fast moving often destroy ing surrounding trees and native vegetation (Eussen and Wirjahardja 1973; Seavoy 1975; Eussen 1980 ). In addition, these fires are a sa fety hazard for fir efighters and prescribed burn managers In the past ten years there has been a greater effort to educate the public about this grass, find adequate control measures, and prevent the spread of cogongrass to other states in the US. Curre ntly the recommended herbicide treatments for cogongrass are 1.64 kg ai ha 1 imazapyr or 3.28 kg ai ha 1 glyphosate (Shilling et al. 1997; Willard et al. 1997) Both of these chemicals are non selective products used to control a wide range of species. I mazapyr generally provides control for a longer period of time due to its soil persistence, however off target damage limits its use to certain areas. Herbicides that are selective and are least harmful to the environment are important for natural area man agers. Aminocyclopyrachlor is a synthetic auxin herbicide that has been shown to be highly effective on a wide range of plants and has a much lower use rate than typical natural area herbicides. In Mississippi cogongrass control with aminocyclopyrachlor treatments have been reported, but little work has been conducted under conditions in Florida (Wright and Byrd 2009) This new herbicide also promises greater selectivi ty potential for native plants compared to non selective herbicides such as glyphosate and imazapyr.

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81 In addition to aminocyclopyrachlor, several herbicide combinations (either glyphosate or imazapyr mixtures) have been anecdotally tested for cogongrass control (Willard et al. 1997; Faircloth et al. 2005 ). Other trials suggest specific additi ves will enhance activity of glyphosate or imazapyr (Bennett 2007; Demers et al. 2008; Williams nutrients that claim to promote deeper, denser roots and temporarily increase photosynthesis (Ramsey et al. 2006). Previous studies on this additive have had mixed results when combined with standard rates of glyphosate and imazapyr (Ramsey et al. comb ination with a lower rate of imazapyr, which might also serve as a potential treatment to gain cogongrass control and native plant tolerance. Therefore, the objectives of this research were to: 1) evaluate aminocyclopyrachlor alone and in combination for cogongrass control; 2) evaluate surfactants in combination with glyphosate or imazapyr for cogongrass control; and 3) evaluate alternative herbicides for cogongrass control. Materials and Methods Field studies were conducted at Chito Branch Reserve in Hill sborough County, Florida. Chito Branch is a 2,232 ha reserve purchased in 2001 by the Southwest Florida Water Management District in cooperation with Tampa Bay Water The goal of this purchase was to provide a reservoir for collecting and storing drinking water for the Hillsborough County area. This unique property consists of a variety of habitats with a diversity of wildlife and native plant species. An 81 ha tract of Chito Branch, consisting of abandoned agricultural land, has now become a heavily infe sted monoculture of

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82 cogongrass. The entire area was burned in August of 2009 and all three studies described here were initiated in October 2009. All herbicides were applied using an ATV fitted with a CO 2 pressurized sprayer calibrated to deliver 187 L ha 1 Unless otherwise stated, a non ionic surfactant ( 0 .25% v/v) was added to each herbicide treatment. Herbicides were evaluated in three separate studies. The first study evaluated aminocyclopyrachlor alone and in combination with glyphosate and imazapyr Treatments included aminocyclopyrachlor at 0.28 kg ai ha 1 aminocyclopyrachlor at 0.28 kg ai ha 1 plus imazapyr at 0.32 kg ai ha 1 or 0.64 kg ai ha 1 and aminocyclopyrachlor at 0.28 kg ai ha 1 plus glyphosate at 1.64 kg ai ha 1 or 3.28 kg ai ha 1 Trea tments also included imazapyr at 0.64 kg ai ha 1 and glyphosate at 3.28 kg ai ha 1 to represent standard application rates. The second study evaluated imazapic, imazamox, and combinations of glyphosate with imazapic and imazapyr. Treatments included imazap ic at 0.1 kg ai ha 1 and 0.2 kg ai ha 1 imazamox at 0.27 kg ai ha 1 and 0.54 kg ai ha 1 glyphosate at 0.25 kg ai ha 1 plus imazapic at 0.09 kg ai ha 1 glyphosate at 1.29 kg ai ha 1 plus imazapic at 0.1 kg ai ha 1 and glyphosate at 1.29 kg ai ha 1 plus imazapyr at 0.64 kg ai ha 1 Treatments also included imazapyr at 0 .64 kg ai ha 1 and glyphosate at 3.28 kg ai ha 1 as standards. The third study evaluated Cogon X 1 combinations of Cogon X with glyphosate and imazapyr, and imazapyr with three types of adj uvants. Treatments included Cogon X at 0.64 kg ai ha 1 alone, Cogon X at 0.64 kg ai ha 1 plus glyphosate at 0.64 kg ai ha 1 1 Stimupro, LLC, Robertsdale, AL 2 Induce, Helena Chemical Company, Collierville, TN 3 Helena Chemical Company, Collierville, TN

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83 and 3.28 kg ai ha 1 Cogon X at 0.64 kg ai ha 1 plus imazapyr at 0.32 kg ai ha 1 imazapyr at 0 .64 kg ai ha 1 plus a non ionic surfactant 2 and 1% or 2% methylated seed oil 3 Treatments also included glyphosate alone at 3.28 kg ai ha 1 and 0.64 kg ai ha 1 Treatments for all three experiments were arranged in a randomized complete block design with four replications for each treatment. Plot size was 7.25 x 15 meters. Visual evaluations were take n every three months based on the following scale: 0 = no co ntrol; 100 = complete control. Rhizomes were collected every six months and used for a growth study and dry weight data for the aminocyclopyrachlor experiment (Study 1) Three soil cores (10cm 2 diameter x 15 cm deep) per plot were collected for rhizome b iomass data. The rhizomes were sorted, dried, and weighed. For the growth study, three 15 cm rhizomes from each plot were plan ted in pots in the greenhouse. Shoot emergence data was collected over a period of 6 weeks. The data was analyzed using proc GLM program in SAS 9.2. Analysis of variance (ANOVA) was used to test for treatment by experiment interactions. Means of 4 replications for studies 1 and 2 and 3 replications for study 3 (because of space constraints) were separated using Fishers Protected Le ast Significant Difference Procedure at p < 0.05. Results and Discussion Aminocyclopyrachlor provided 10% 92% less cogongrass control when compared to glyphosate and imazapyr treatments ( Table 4.1). At 24 WAT there was little difference between all treated p lots with injury ranging from 88% to 98% At 31 WAT, control of cogongrass wa s significantly less for the aminocy clopyrachlor alone treatment (69 %) compared to those treatments containing imazapyr. By 58 WAT aminocyclopyrachlor provided no control and on ly the imazapyr alone treatment

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84 provided greater than 90% control. Glyphosate alone and aminocyclopyrachlor plus the high rate of imazapyr still showed acceptable (> 75%) control, but all other combinations trol from all treatments declined to unacceptable levels 92 WAT, emphasizing the need for follow up control measures to eradicate cogongrass from an area (Holzmueller and Jose 2010; Willard et al. 1996). The addition of aminocyclopyrachlor to both imazapyr and glyphosate did not provide increased cogongrass control compared to imazapyr or glyphosate applied alone. Interestingly, at 58 WAT there was a significant decrease in cogongrass control in the aminocyclopyrachlor plus 3.28 kg ai ha 1 glyphosate compar ed to 3.28 kg ai ha 1 glyphosate alone (51 % and 79 %, respectively). This phenomenon of reduced cogongrass control with the addition of auxin type herbicides to glyphosate and imazapyr has been previously documented (Shaw and Arnold 2002; Koger et al. 2007; Kammler et al. 2010). Rhizome biomass was also measured over time in this study ( Table 4.2). At 36 WAT, all treated plots showed reduced rhizome biomass compared to the control plots. By 66 WAT all imazapyr and glyphosate treatments, regardless of combina tions, showed a decrease in rhizome biomass by at least 50%. All treated areas showed a reduction in rhizome biomass over time from 36 to 82 WAT. Imazapyr alone, glyphosate alone, and aminocyclopyrachlor plus imazapyr at 0.64 kg ai ha 1 had significantly l ess rhizome biomass at 82 WAT (2.9 g, 2.75 g, and 0. 90 g, respectively) compared to the untreated control (13.2 g) The aminocyclopyrachlor alone treatment displayed no significant decrease in rhizome biomass compared to the untreated area s (9.75 g and 13 .2 g).

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85 Overall, 0.64 kg ai ha 1 imazapyr provided the greatest control of cogongrass over time while also providing a significant reduction in rhizome biomass. A minocyclopyrachlor plus 0.64 kg ai ha 1 imazapyr also provided extended cogongrass control and reduced rhizome biomass. Conversely, the aminocyclopyrachlor alone treatment did not provide extended cogongrass control and did not significantly reduce rhizome biomass. Though aminocyclopyrachlor was shown to suppress cogongrass (Wright and Byrd 2009) and reduced shoot regrowth in the greenhouse study, it failed to provide acceptable control in Florida field trials. Differences between the Mississippi and Florida field studies may be due to genetic variability within the cogongrass populations, or envir onmental and edaphic factors (Bryson et al. 2010). The effect of tank mix additives with imazapyr or glyphosate herbicide for cogongrass control was also evaluated. On all evaluation dates, Cogon X did not provide significant control of cogongrass when app lied alone, and did not significantly increase cogongrass control when combined with either rate of glyphosate (Table 4.3) However, Cogon X combined with a lower rate of imazapyr (0.32 kg ai ha 1 ) maintained greater than 90% control of cogongrass at 92 we eks after treatment. In previous studies, imazapyr alone at rates lower than 0.5 kg ai ha 1 showed cogongrass control at approximately 82% (Faircloth 2007; Johnson et al. 1999 ; Shilling and Gaffney 1995 ). The ability to reduce the application rate of a br oad spectrum herbicide like imazapyr with the addition of Cogon X may increase selectivity and allow for faster recolonization with native species. At 24 and 31 WAT, significant cogongrass control (>80%) was seen with all treatments of glyphosate and imaza pyr regardless of rate or adjuvant used. By

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86 58 WAT, only the treatments with the highest rates of glyphosate and imazapyr treatments provided greater than 70% control of cogongrass. Though previous research has indicated methylated seed oils can decrease s urface tension and increase herbicidal activity ( Miller and Westra 1996), there was no difference between the non ionic surfactant and 1% and 2% methylated seed oil for cogongrass control 92 WAT (98%, 95%, and 94% control, respectively). Overall, the great All glyphosate treatments failed to provide acceptable control 92 WAT, regardless of rate or the addition of Cogon X. The effect of selected imidazolinone herbicides for cogongrass control i s shown in Table 4.4 Significant control (> 75%) of cogongrass was seen at 24 and 31 WAT for imazapyr plus glyphosate, imazapic plus the high rate of glyphosate, imazamox at the high rate, and glyphosate and imazapyr alone treatments. By 58 WAT control o f cogongrass for the imazamox at the high rate had dropped below the 75% acceptable level to 49%. At 92 WAT, t he 0 .1 kg ai ha 1 imazapic plus 1.3 kg ai ha 1 glyphosate treatment showed significantly greater cogongrass control (80%) compared to all other im azapic or imazamox treatments ( 3% 48 %) Imazapyr plus glyphosate (84%), glyphosate alone (71%) and imazapy r alone (97 %) treatments also provided significant control of cogongrass though not signi ficantly different from the 0.1 kg ai ha 1 imazapic plus 1 .3 kg ai ha 1 glyphosate treatment. The use of imazapic plus a lower rate of glyphosate (1.286 kg ai ha 1 compared to 3.28 kg ai ha 1 ) may provide land managers with an opportunity to increase selectivity with less damage on certain native grasses

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87 which i n turn could increase native species recruitment and competition for future cogongrass regrowth (Faircloth et al. 2005) The goal of these three separate studies was to evaluate herbicide treatments to increase selectivity for cogongrass control. Selectiv ity can be achieved through the use of new herbicides such as aminocyclopyrachlor (experiment one), herbicide combinations with reduced rates of imazapyr and glyphosate (experiment two), and the addition of adjuvants to tank mixes (experiment three). Comb ining the results from all three studies, it was found that imazapyr still provided the only long term acceptable control of cogongrass. However, study of the use of Cogon X combined with a low rate of imazapyr for cogongrass control should be repeated, a s this product combination may allow for reduced rates of imazapyr and increase the selectivity for native species.

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88 Table 4.1 The effect of aminocyclopyrachlor treatments on cogongrass control over time in Hillsborough county, Florida Weeks After Treat ment 24 31 58 92 Herbicide Treatment kg ai ha 1 ------% cogongrass control 1 ------Aminocyclopyrachlor 0.28 88 69 0 0 Imazapyr 0.64 98 98 92 61 Glyphosate 3.28 98 89 77 35 Aminocyclopyrachlor + Imazapyr 0.28 + 0.64 98 96 79 58 Aminocyclopyrachlor + Imazapyr 0.28 + 0.32 97 95 54 34 Aminocyclopyrachlor + Glyphosate 0.28 + 3.28 97 86 51 28 Aminocyclopyrachlor + Glyphosate 0.28 + 1.64 95 79 18 10 LSD 0.05 2 8 24 33 36 1 Percent visual data based on the following scale: 0= no control; 100= complete d eath 2 Means of 4 replications separated using Fishers Protected Least Signific ant Difference Procedure at p < 0 .05

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89 Table 4.2 The effect of aminocyclopyrachlor treatment on cogongrass rhizome biomass over time in Hillsborough County, Florida. Weeks After Treatment 36 66 82 Herbicide Treatment kg ai ha 1 Average rhizome biomass (g) Untreated 27.8 30.8 13.2 Aminocyclopyrachlor 0.28 27.1 25.3 9.7 Imazapyr 0.64 18.3 6.5 2.9 Glyphosate 3.28 12.6 6.4 2.7 Aminocyclopyrachlor + Imazapyr 0.28 + 0.64 16.4 6.5 0.9 Aminocyclopyrachlor + Imazapyr 0.28 + 0.32 15.8 10.0 4.1 Aminocyclopyrachlor + Glyphosate 0.28 + 3.28 15.8 9.0 5.2 Aminocyclopyrachlor + Glyphosate 0.28 + 1.64 14.5 14.2 6.0 LSD 0.05 1 7.9 6.6 7.7 1 Means of 4 replications separated using Fishers Protected Least Significant Difference Procedure at p < 0.05.

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90 Table 4.3 The effect of surfactants or additives on the activity of glyphosate or imazapyr treatments on cogongrass control over time in Hillsborough County, Florida. Weeks After Tr eatment 24 31 58 92 Herbicide Treatment kg ai ha 1 ------% cogongrass control 4 ------Cogon X 0.64 0 0 3 0 Glyphosate 0.64 87 75 38 7 Glyphosate 3.28 98 99 92 78 Glyphosate + Cogon X 1 0.64 + 0.64 83 82 52 23 Glyphosate + Cogon X 3.28 + 0.64 98 96 93 67 Imazapyr + Cogon X 0.32 + 0.64 97 99 98 93 Imazapyr + NIS 2 1.64 98 99 100 98 Imazapyr + MSO 1% 3 1.64 98 99 70 95 Imazapyr + MSO 2% 3 1.64 98 99 100 94 LSD 0.05 5 15 18 18 20 1 Stimupro, LLC, Robertsdale, AL 2 Induce, Helena Chemical Company, Col lierville, TN 3 Helena Chemical Company, Collierville, TN 4 Percent visual data based on the following scale: 0= no control; 100= complete death 5 Means of 3 replications separated using Fishers Protected Least Significant Difference Procedure at p < 0.05

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91 Table 4.4 The effect of selected imidazolinone herbicides on cogongrass control over time in Hillsborough County, Florida. Weeks After Treatment 24 31 58 92 Herbicide Treatment kg ai ha 1 ------% cogongrass control 1 ------Imazapic + glyphosate 0.0 9 + 0.25 40 40 8 26 Imazapic 0.1 15 0 3 3 Imazapic 0.2 45 45 21 48 Imazapic + glyphosate 0.1 + 1.29 89 91 81 80 Imazapyr + glyphosate 0.64 + 1.29 98 99 96 84 Imazamox 0.27 61 36 16 5 Imazamox 0.54 93 90 49 30 Glyphosate 3.28 97 86 85 71 Imazapyr 1. 64 98 99 99 97 LSD 0.05 2 31 22 28 32 1 Percent visual data based on the following scale: 0= no control; 100= complete death 2 Means of 4 replications separated using Fishers Protected Least Significant D ifference Procedure at p < 0.05

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92 CHAPTER 5 CONCLUSIO NS Aminocyclopyrachlor is a synthetic auxin herbicide proposed for invasive species management and native species restoration ( DuPont Crop Protection 2010 ). It is both foliar and soil active and is effective on a range of broadleaf and brush weedy species as well as possible selectivity for invasive grass control ( Bukun et al. 2008; Claus et al. 2008 ; Armel e t al. 2009; Blair and Lowe 2009 ; Evans et al. 2009; Gannon et al. 2009; Montgomery et al. 2009; Roten et al. 2009; Turner et al. 2009; Westra et al. 20 09; Wilson et al. 2009 ; Rupp et al. 2011 ). Unlike other herbicides commonly used in natural areas such as glyphosate and imazapyr, the selectivity of aminocyclopyrachlor provides the potential for inva sive plant control with less damage to desired native s pecies. The natural ecosystems in Florida are home to over 4000 native plants with 300 endemic to Florida (Whitney et al. 2010). The mild climate and range of soil types throughout the state provide for this diverse range of habitats, however these factor s are also conducive to invasive plants (Brown et al. 1990; Anonymous 1999 ). Over 900 escaped exotic species exist in the state currently, displacing native plant ecosystems, disrupting ecosystem functions, and hybridizing with na tive species (Whitney et al. 2010 ; FLEPPC 2011). When developing a new herbicide for invasive plant control, it is important to consider its effects on native species and soil residual effects for restoration scenarios Three studies were established to evaluate the effectiveness of aminocyclopyrachlor for invasive grass control and native plant tolerance. Greenhouse studies evaluated the post emergence effects of aminocyclopyrachlor on a variety of native grasses and broadleaf species as well as five invasive grasses ; West Indian marshgrass ( Hymenachne amplexicaulis ), cogongrass ( Imperata cylindrica ), natalgrass

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93 ( Melinis repens ), torpedograss ( Panicum repens ), and paragrass ( Urochloa mutica ). All five invasive grasses initial growth was not reduced at any rate of aminocyclopyrach lor, however I mperata cylindrica and Urochloa mutica shoot regrowth was reduced by 50% at 0.09 and 0 .15 kg ai ha 1 respectively. Of the native species evaluated, Eragrostis elliottii was the most tolerant and Aristida stricta and Eragrostis spectabilis were the most sensitive grasses All broadleaves evaluated except Garberia heterophylla were highly sensitive to a ll rates of aminocyclopyrachlor These results indicate that aminocyclopyrachlor is selective to both invasive and native grasses evaluated. Therefore if it is applied to an area that is a mixture of invasives and native species, the native grasses will tolerate the application while the broadleaves will be highly injured. In order to determine optimal plant back times for native plant species restoration, t olerance of several of these native species to soil residual levels of aminocyclopyrachlor was evaluated Utilizing plant species injury, optimal plant back times were determined for these species based on the half life of aminocyclopyrachlo r in a given soil type. Seedlings of several native forbs, grasses, and trees were transplanted into field plots treated with vary ing rates of aminocyclopyrachlor The two broadleaf species, Liatris spicata and Solidago fistulosa showed greater than 50% i njury at all rates. Pinus palustris was tolerant to rates below 0.16 kg ai ha 1 and Andropogon virginicus var glauca showed no injury to aminocyclopyrachlor. Aminocyclopyrachlor caused significant injury (>80%) to all other species. Based on these fin dings, Andropogon virginicus var glauca could be planted immediately after herbicide application. Broadleaf species Liatris spicata and Solidago fistulosa, showed injury at all rates regardless o f plant back interval. With the exception

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94 of Aristida str icta grasses had the shortest plant back interval ranging from 0 to 194 days The plant back interval for trees ranged from 73 to 200 days and over a year for both broadleaf species. Because c ogongrass severely impacts many ecosystems in Florida, a field study was conducted to investigate the potential for cogongrass control with aminocyclopyrachlor (Hubbard 1944; Lowe et al. 2004; MacDonald 2009). Aminocyclo pyrachlor was evaluated alone and in combination with imazapyr or glyphosate and compared to standa rd treatments Aminocyclopyrachlor alone provided good initial control (31 weeks after treatment) but no long term control (92 WAT) of cogongrass. There was also no advantage of combining aminocyclopyrachlor with imazapyr or glyphosate. Two additional ex periments indicated that neither imazapic nor imazamox were eff ective for cogongrass control. Cogon X different surfactant type s did not influ ence the efficacy of gly phosate for cogongrass control, however when Cogon X was combined with a low rate of imazapyr, greater than 90% control was observed. Additional studies of the use of Cogon X with lower rates of imazapyr are warranted. Aminocyclopyrachlor can be useful in natural area restoration, as it provides effective control of numerous invasive plant species ( Bukun et al. 2008; Claus et al. 2008 ; Armel e t al. 2009; Blair and Lowe 2009 ; Evans et al. 2009; Gannon et al. 2009; Montgomery et al. 2009; Roten et al. 2009; Turner et al. 2009; Westra et al. 2009; Wilson et al. 2009 ; Rupp et al. 2011 ). However it does not appear to offer a unique role

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95 LIST OF REFERENCES [Anonymous]. 1999. South Florida Multi Species Recovery Plan. Bethesda, MD: Fish & Wildli fe Service Abrahamson W. G. and D. C. Harnett. 1990. Pine flatwoods and dry prairies. Pages 103 150 in R. L. Myers and J. J. Ewel eds. Ecosystems of Florida. Orlando, FL: University of Central Florida Press. Armel G. R., W. E. Klingeman, P. C. Flanagan, G. K. Bree den, and M. Halcomb. 2009. Comparisons of the experimental herbicide DPX KJM44 with aminopyralid for co ntrol of key invasive weeds in T ennessee. Proceedings of the 49th Annual WSSA Meeting in Orlando, FL. Barron M. C. 2005. Residual Herbicide Impact on Na tive Plant Restoration as an Integrated Approach to Cogongrass Management. Thesis dissertation. Gainesville, FL: University of Florida. Bell J. L., I. C. Burke, and T. S. Prather. 2011. Uptake, translocation and metabolism of aminocyclopyrachlor in prickl y lettuce, rush skeletonweed and yellow starthistle. Pest Manag. Sci. 67:1338 1348. Bennett D. 2007. Delta Farm Press Blair M. and Z. Lowe. 2009. Evalu ation of KJM 44 for marestail ( Conyza canadensis ) and total vegetation con trol. Proceedings of the 49th Annual WSSA Meeting in Orlando, FL Boonitte A. and P. Ritdhit. 1984. Allelopathic effects of some weeds on mungbean plants ( Vigna radiata ). Proc. 1st Tropical Weed Conf 2:401 406. Brecke, B.J., J.B. Unruh, and D.E. Partrid ge Telenko. 2010. Aminocyclopyrachlor for weed management in warm season turfgrass. Proc. Southern Weed Science Society. 63:193. Brockway D. G., K. W. Outcalt, and R. N. Wilkins. 1998. Restoring longleaf pine wiregrass ecosystems: Plant cover, diversity an d biomass following low rate hexazinone application on F lorida sandhills. For. Ecol. Manage. 103:159 175. Brown R. B., E. L. Stone, and V. W. Carlisle. 1990. Soils. Pages 35 69 in R. L. Myers and J. J. Ewel eds. Ecosystems of Florida. Orlando, FL: Unive rsity of Central Florida Press. Bryson C. T. and R. Carter. 1993. Cogongrass, I mperata cylindrica, in the U nited S tates. Weed Technol. 7:1005 1009.

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96 Bryson C. T., J. L. Krutz, G. N. Ervin, K. N. Reddy, and J. D. Byrd. 2010. Ecotype variability and edaphic characteristics for cogongrass ( I mperata cylindrica ) populations in M ississippi. Invasive Plant Science and Management 3:199 207. Bukun B., R. B. Lindenmayer, S. J. Nissen, P. Westra, D. L. Shaner, and G. Brunk. 2010. Absorption and translocation of amin ocyclopyrachlor and aminocyclopyrachlor methyl es ter in C anada thistle ( Cirsium arvense ). Weed Sci. 58:96 102. Bukun B., S. J. Nissen, P. Westra, G. Brunk, D. Shaner, and T. Gaines. 2008. Absorption and translocation of 14C DPX KJM44 an d DPX MAT28 in Cirs ium arvense (C anada thistle). Proceedings of the 5th International Weed Science Congress Carriker R. R. and T. Borisova. 2008. Public Policy and Water in Florida. Gainesville, FL: Food and Resource Economics Department, Florida Cooperative Extension Ser vice, Institute of Food and Agricultural Sciences, University of Florida FE757. Casini P., V. Vecchio, and I. Tamantiti. 1998. Allelopathic interference of itchgrass and cogongrass: Germination and early development of rice. Trop. Agr. 75:445 451. Claus J., R. Turner, G. Armel, and M. Holliday. 2008. DuPont aminocyclopyrachlor (proposed common name)(DPX MAT28/KJM44) herbicide for use in turf, IWC, bare ground and brush markets. Proceedings of the 5th International Weed Science Congress 277. Clewell A. F. 2003. Strategy for Restoring Wiregrass Ecosystems. in 30th Annual Conference on Ecosystems Restoration and Creation. Tampa, FL. Coile N. C. and D. G. Shilling. 1993. Cogongrass, Imperata c ylindrica (L.) Beauv.: A Good Grass Gone Bad! Tallahassee, FL: Flo rida Department of Agriculture and Consumer Services, Division of Plant Industry 28. revisited: An experimental test using cogongrass. Biol Invasions 9:433 443. Cornish P. S ., A. A. Khurshid, and N. Agarwa. 1996. Glyphosate: A Re Appraisal of the Threat to Crop Plants. in Proceedings of the 8th Australian Agronomy Conference. Toowoomba, Queensland: The University of Southern Queensland. Cornish P. S. and S. Burgin. 2005. Res idual effects of glyphosate herbicide in ecological restoration. Restor. Ecol. 13:695 702. Crafts S. A. 1946. Selectivity of herbicides. Plant Physiol. 21:345 261. Daneshgar P. and S. Jose. 2008. Mechanisms of invasion: A review. in R. K. Kohli, S. Jose, H. P. Singh and D. R. Batish eds. Invasive Plants and Forest Ecosystems. : CRC Press.

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97 Daneshgar P., S. Jose, A. Collins, and C L. Ramsey. 2008. Cogongrass ( Imperata cylindrica ), an alien invasive grass, reduces survival and productivity of an establishi ng pine forest. Forest Science 54:579 587. Davis J. H. 1967. General Map of Natural Vegetation of Florida. Gainesville, FL: IFAS S 178. Demers C., A. Long, and R. Williams. 2008. Controlling Invasive Exotic Plants in North Florida Forests. Gainesville, F L: University of Florida IFAS Extension SS FOR19. Dickens R. and G. M. Moore. 1974. Effects of light, temperature, KNO3, and storage on germination of cogongrass. Agron. J. 66:187 188. DiTomaso J. M., G. B. Kyser, J. R. Miller, S. Garcia, R. F. Smith, G. Nader, J. M. Connor, and S. B. Orloff. 2006. Integrating prescribed burning and clopyralid for the management of yellow starthistle ( Centaurea solstitialis ). Weed Sci. 54:pp. 757 767. Dozier H., J. F. Gaffney, S. K. McDonald, E. R. R. L. Johnson, and D. G. Shilling. 1998. Cogongrass in the United S tates: History, ecology, impacts, and management. Weed Technol. 12:pp. 737 743. DuPont Crop Protection. 2010. Aminocyclopyrachlor Herbicide (MAT28) Technical Information Bulletin: An Overview (as of April 19, 2 010). EDDSMaps. 2012. Cogongrass Distribution. Available at http://www.eddmaps.org/ Accessed February 9, 2012. Edmisten J. A. 1963. The Ecology of the Florida Pine Flatwoods. Ph.D. dissertation. Gaines ville, FL: University of Florida. Eussen J. H. 1980. Biological and ecological aspects of alang alang [ Imperata cylindrica (L.) Beauv.]. Pages 15 22 in Proceedings of BIOTROP Workshop on Alang Alang in Bogor. Bogor, Indonesia: Biotropica Special Pub. Eus sen J. H. 1979. Some competition experiments with alang alang [ Imperata cylindrica (L.) beauv.] in replacement series. Oecologia 40:351 356. Eussen J. H. and S. Wirjahardja. 19 73. Studies of an alang alang [ Imperata cylindrica (L.) beauv.] vegetation. Bio trop. Bull. 6:1 24. Evans C. C., D. P. Montgomery, and D. L. Martin. 2009. Musk thistle control on O klahoma highway rights of way with DPX KJM44. Proceedings of the 49th Ann ual WSSA Meeting in Orlando, FL Ewel J. J. 1986. Invasibility: lessons from sout h Florida. Pages 214 230 in H. A. Mooney and J. A. Drake eds. Ecology of Biological Invasions of North America and Hawaii. New York, NY: Springer Verlag.

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98 Faircloth W. 2007. Managing Cogongrass on Rights of Way: a challenge to prevent further spread. in Proceedings of the Regional Cogongrass Conference: A Cogongrass Management Guide. Mobile, AL. Faircloth W. H., M. G. Patterson, J. H. Miller, and D. H. Teem. 2005. Wanted Dead Not Alive: Cogongrass. : Alabama Cooperative Extension ANR 1241. FLEPPC. 2011. List of invasive plant species. Wildland Weeds 14:11 14. Florida Native Plant Society. 2004. Ecosystems of Florida. Available at http://www.fnps.org/pages/plants/vegtypes.php Acce ssed February 9, 2012. Florida Natural Areas Inventory (FNAI). 2010. Guide to the natural communities of Florida: 2010 edition. Florida Natural Areas Inventory Frank J. H., E. D. McCoy, H. G. Hall, G. F. O'Meara, and W. R. Tschinkey. 1997. Immigration and Introduction of Insects. Pages 75 in D. Simberloff, D. C. Schmitz and T. C. Brown eds. Strangers in Paradise. Washington DC: Island Press. Gannon T. W., F. H. Yelverton, L. S. Warren, and C. A. Silcox. 2009. Broadleaf weed control with aminocyclopyrac hlor (DPX KJM44) in fine turf. Proceedings of the 49th Annual WSSA Meeting in Orlando, FL. Glitzenstein J. S. and D. R. Streng. 2003. Effects of Fire Regime and Habitat on Survival and Growth of Outplanted Wiregrass and Toothache Grass Plugs in the Franci s Marion National Forest, SC. in 30th Annual Conference on Ecosystems Restoration and Creation. Tampa, FL. Gordon D. R. 1998. Effects of invasive, non indigenous plant species on eco system processes: Lessons from F lorida. Ecol. Appl. 8:pp. 975 989. Grele n H. E. and R. H. Hughes. 1984. Common Herbaceous Plants of Southern Forest Range. SO 210 ed. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest and Range Experiment Station. Pp. 147. Henderson S., T. P. Dawson, and R. J. W hittaker. 2006. Progress in invasive plants research. Prog. Phys. Geogr. 30:25 46. Weeds: Distribution and Biology. Honolulu, HI: Univ. Press of Hawaii. Pp. 609. Hol zmueller E. and S. Jose. 2010. Response of cogongrass to imazapyr herbicides on a reclaimed phosphate mine site in central F lorida, USA. Ecol. Restor. 28:300 303. Hubbard C. E. 1944. Imperata Cylindrica Taxonomy, Distribution, Economic Significance, and Control. Aberstwyth, Wales: Imperial Bureau Pastures and Forage Crops. Pp. 53.

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99 Johnson E. R. R. L., J. F. Gaffney, and D. G. Shilling. 1999. The influence of discing on the effica cy of imazapyr for cogongrass [ Imperata cylindrica (L.) beauv.] control. P roc. South. Weed Sci. Soc 52:165. Jose S., S. Ranasinghe, and C. L Ramsey. 2010. Longleaf pine ( Pinus palustris P. mill.) restoration using herbicides: Overstory and understory vegetation responses on a c oastal plain flatwoods site in F lorida, U.S.A. Res tor. Ecol. 18:244 251. Kammler K. J., S. A. Walters, and B. G. Young. 2010. Effects of adjuvants, halosulfuron, and grass herbicides on cucurbita spp. injury and grass control. Weed Technol. 24:147 152. Kluson R. A., S. G. Richardson, D. B. Shibles, and D. B. Corley. 2000. Responses of Two Native and Two Nonnative Grasses to Imazapic Herbicide on Phosphate Mined Lands in Florida. in 17th Annual Meeting of the American Society for Surface Mining and Reclamation. Tampa, FL. Koger C. H., I. C. Burke, D. K. Miller, J. A. Kendig, K. N. Reddy, and J. W. Wilcut. 2007. MSMA antagonizes glyphosate and glufosinate efficacy on broadleaf and grass weeds. Weed Technol. 21:pp. 159 165. Invasive Alien Species a Selection from the Global Invasive Species Database. : Invasive Species Specialist Group (ISSG) Lym R. G. and D. R. Kirby. 1991. Effect of glyphosate on introduced and native grasses. Weed Technol. 5:421 425. MacDonald G. E. 200 Southeastern US. Pages 10 in Proceedings of the Regional Cogongrass Conference: A Cogongrass Management Guide. Mobile, AL: Alabama Cooperative Extension System. MacDonald G. E., B. Selle rs, K. Langeland, T. Dupperon Bond, and E. Ketterer. 2008. Invasive Species Management Plans for Florida. Gainesville, FL: University of Florida, IFAS Extension 1529. MacDonald G. E. 2009. Cogongrass ( Imperata cylindrica ) A Comprehensive Review of an In vasive Grass. Pages 286 in R. K. Kohli, S. Jose, H. P. Singh and D. R. Batish eds. Invasive Plants and Forest Ecosystems. Boca Raton, FL: CRC Press. Mauchamp A., I. Aldaz, E. Ortiz, and H. Valdebenito. 1998. Threatened species, a re evaluation of the st atus of eight endemic plants of the G alapagos. Biodiversity and Conservation 7:97 107.

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100 Miller D., G. E. MacDonald, D. Shilling, and B. Brecke. 2002. Integrated Management of Invasive Weeds as a Component of Native Plant Restoration. Bartow, FL: Florida In stitute of Phosphate Research Final Report. Miller P. and P. Westra. 1996. Herbicide Surfactants and Adjuvants. : Colorado State University Cooperative Extension, Production Crop Series 0.559. Montgomery D., C. Evans, and D. Martin. 2009. Control of koch ia with DPXKJM44 along O klahoma highway rights of way. Proceedings of the 49th Annual WSSA Meeting in Orlando, FL Myers R. L. 1990. Scrub and high pine. Pages 150 193 in R. L. Myers and J. J. Ewel eds. Ecosystems of Florida. M yers R. L. and J. J. Ewel. 1990. Ecosystems of Florida. 1st ed. Orlando, FL: University of Central Florida Press. Pp. 765. Norcini J. G., T. N. Chakravarty, R. S. Kalmbacher, and W. Chen. 2003. Microp ropagation of Wiregrass and Creeping Bluestem, and Propagation of Gopher Apple F inal Report. in 30th Annual Conference on Ecosystems Restoration and Creation. Tampa, FL. Pfaff S. C. Maura, and M. Gonter. 2002 Development of Seed Sources and Establishment Methods for Native Upland Reclamation Final Report. Pimentel D., L. Larch, R. Zuniga, and D. Morrison. 2000. Environmental and economic costs of non in digenous species in the United S tates. BioScience 50:53 65. Plant Protection and Quarantine. 2010. Federal Noxious Weed List (1 may 2010). : USDA Animal and Plant Health Inspection S ervice Platt W. J. and M. W. Schwartz. 1990. Temperate hardwood forests. Pages 194 229 in R. L. Myers and J. J. Ewel eds. Ecosystems of Florida. Orlando, FL: University of Central Florida Press. Ramsey C. L., S. Jose, D. Zamora, and P. Daneshgar. 200 6. Cogongrass control with chopper and GlyPro plus when combined with silwet L 77 and MSO concentrate. 59th Annual Meeting of Southern Weed Science Society Richardson S. G., N. Bissett, C. Knott, and K. Himel. 2003. Weed Control and Upland Native Pla nt Establishment on Phosphate Mi ned Lands in Florida. in 30th Annual Conference on Ecosystems Restoration and Creation. Tampa, FL. Rinella M. J., M. R. Haferkamp, R. A. Masters, J. M. Muscha, S. E. Bellows, and L. T. Vermeire. 2010. Growth regulator herbicid es prevent invasive annual grass seed production. Invasive Plant Science and Management 3:12 16.

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101 Roten R. L., R. J. Richardson, and A. P. Gardner. 2009. Responses of selected woody plants to DPX KJM44. Proceedings of the 49th Annual WSSA Meeting in Orland o, FL Rupp, R. N., M. Edwards, J. Harbour, J. H. Meredith, and S. K. Rick. 2011. Weed control with aminocyclopyrachlor in pastures and rangeland. WSSA Seavoy R. E. 1975. The origin of trop ical grasslands in Kalimantan, I ndonesia. J. Trop. Geo. 40:48 52. Seefeldt S. S., J. E. Jensen, and E. P. Fuerst. 1995. Log logistic analysis of herbicide dose response relationships. Weed Technol. 9:pp. 218 227. Segal D. S., V. D. Nair, D. A. Graetz, K. M. Portier, N. J. Bissett, and R. A. Garren. 2001. Post Mine Reclamation of Native Upland Communities. Bartow, FL: Florida Institute of Phosphate Research Final Report. Senseman S. A. 200 7. Herbicide Handbook. 9th ed. Lawrence, KS: Weed Science Society of America. Shaw D. R. and J. C. Arnold. 2002. Weed control fr om herbicide combinations with glyphosate. Weed Technol. 16:pp. 1 6. Shilling D. G. 2003. Integrated Management of Cogongrass for Native Habitat Restoration ( Imperata cylindrica ). in 30th Annual Conference on Ecosystems Restoration and Creation. Tampa, FL Shilling D. G., T. A. Bewick, J. F. Gaffney, S. K. McDonald, C. A. Chase, and E. R. R. L. Johnson. 1997. Ecology, Physiology, and Management of Cogongrass ( Imperata cylindrica ) : Florida Institute of Phosphate Research Final Report. 128 p. Shilling D. G. and J. F. Gaffney. 1995. Cogongrass control requires integrated approach Rest. Manage. Notes 13:227. Shinn S. L. and D. C. Thill. 2002. Tolerance of several perennial grasses to imazapic Weed Technol. 18:60 65. Simberloff D., D. C. Schmitz, and T. C. Brown. 1997. Strangers in Paradise. Washington DC: Island Press. Soil Survey Staff. 2004. Official Soil Series Descriptions. Available at http://soils.usda.gov/t echnical/classification/osd/index.html Accessed January 30, 2012. Terry P. J., G. Adjers, I. O. Akobundu, A. U. Anoka, M. E. Drilling, S. Tjitrosemito, and M. Utomo. 1997. Herbicides and mechanical control of Imperata cylindrica as a first step in grass land rehabilitation. Agroforest. Syst. 36:151 179.

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102 Turner R. G., J. S. Claus, E. Hidalgo, M. J. Holliday, and G. R. Armel. 2009. Technical introduction of the new DuPont vegetation management herbicide aminocyclopyrachlor. Proceedings of the 49th Annual W SSA Meeting in Orlando, FL US FWS. 2012. Endangered Species: Florida. Available at http://www.fws.gov/endangered/ Accessed February 5, 2012. Viswanath V., C. Ma, E. Etherington, P. Dharmawardh ana, D. W. Pearce, B. S. Rood, V. B. Busov, and S. H. Strauss. 2011. Greenhouse and field evaluation of transgenic poplars with modified gibberellin metabolism and signaling genes BMC Proc. 5:O22:. Wallace J. and T. S. Prather. 2010. Tolerance of perenni al pasture grass seedlings to aminocyclopyrachlor In 2010 Idaho Weed Control Report. Wallace J. and T. S. Prather. 2011. Spotted knapweed control with aminocyclopyrachlor and sulfonylurea combinations. In 2011 R esearch Progress R eport Spokane, WA: WSWS. Weber E. 1. 2003. Inva sive Plant Species of the World : A Reference Guide to Environmental Weeds / Ewald Weber. Wallingford, Oxon, UK ; Cambridge, MA, USA: CABI Pub. Westbrooks R. G. 1998. Invasive Plants. Changing the Landscape of America: Fact Book. Washington, D.C.: Federal Interagency Committee for the Management of Noxious and Exotic Weeds. Westra P., S. Nissen, D. Shaner, B. Lindenmayer, and G. Brunk. 2009. Invasive weed management with aminocyclopyrachlor in the central great plains. Proceeding s of the 49th Ann ual WSSA Meeting in Orlando, FL Whitney E. D., D. B. Means, and A. Rudloe. 2010 Priceless Florida: Natural Ecosystems and Native Species. Sarasota, FL: Pineapple Press, Inc. Pp. 423. Willard T. R., J. F. Gaffney, and D. G. Shilling. 1997. Influence of herbicide combinations and application technology on cogongrass ( I mperata cylindrica ) control. Weed Technol. 11:76 80. Williams R. and P. J. Minogue. 2008. Biology and Management of Cogongrass. Gainesville, FL: University of Florida IFA S Extension FOR191. Wilson M. J., J. K. Norsworthy, S. Bangarwa, G. Griffith, J. Still, and R. Scott. 2009. Effect of rate and timing on broadleaf weed control in rice with DPXKJM44. Proceedings of the 49th Annual WSSA Meeting in O rlando, FL Wright R. S. and J. D. Byrd. 2009. Potential new herbicides to add to M ississippi

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103 BIOGRAPHICAL SKETCH Anna Lin Greis was born to Linda and John Greis of Tallahassee, Florida. She grew up in Snellville, Ge orgia and moved back to Tallahassee her sophomore year of high school. She graduated from Leon High School in 2005 and began her undergraduate studies at the University of Florida, Gainesville. In 2009 she graduated with a Bachelor of Science degree in bu siness with a major in marketing and minors in landscape architecture and environmental horticulture. Her love for plants and the degree in weed science. During her studies she has worked for the UF libraries, as a graduate assistant in weed science, and as a SCEP student for the USDA Forest Service Southern Regional Office. After completing her Master of Science degree in agronomy with a minor in forestry, she plans to work for the US Forest Service and pursue a career in weed science.