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Evaluation of Cultural and Non-Synthetic Methods for Southern Crabgrass (Digitaria ciliaris) Management in St. Augustine...

Permanent Link: http://ufdc.ufl.edu/UFE0043080/00001

Material Information

Title: Evaluation of Cultural and Non-Synthetic Methods for Southern Crabgrass (Digitaria ciliaris) Management in St. Augustinegrass Lawns
Physical Description: 1 online resource (83 p.)
Language: english
Creator: GLENN,BRIAN D
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: ACETIC -- AUGUSTINEGRASS -- BICARBONATE -- BORAX -- CRABGRASS -- CULTURAL -- DIGITARIA -- HERBICIDES -- MOWING -- NONSYNTHETIC -- ORGANIC -- SODIUM -- SOUTHERN -- VINEGAR -- WEED
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: Southern crabgrass (Digitaria ciliaris (Retz.) Koeler) is a common weed problem in turfgrass throughout the United States, particularly in St. Augustinegrass (Stenotaphrum secundatum Walt. Kuntze) lawns in Florida. Due to recent herbicide label changes, and lack of tolerance, no postemergence herbicides are currently available to the homeowner for crabgrass control in St. Augustinegrass (Gale, 2003). Alternative weed control methods such as cultural practices and alternative herbicides have been investigated to a limited extent by others for postemergence crabgrass management (Busey and Johnston, 2006). Experiments were conducted at the West Florida Research and Education Center in Jay, Florida and at the Plant Science Research and Education Unit in Citra, Florida to more extensively evaluate cultural practices for crabgrass management. Three irrigation treatments (no irrigation, irrigation based on evapotranspiration (ET), and daily irrigation), three mowing heights (5, 7.5, 10 cm), and four fertility treatments (0, 98, 146, 195 kg N ha-1) split into three applications throughout the year (April, June, August) were used. Crabgrass counts were significantly higher in plots that received irrigation daily, compared to ET and non-irrigated blocks. Crabgrass density increased as mowing height decreased at Jay, FL. Plots that were not fertilized had the lowest crabgrass counts, while those receiving fertility showed increased counts, usually increasing with increasing nitrogen rate. Treatments that followed IFAS recommendations for irrigation, mowing height, and fertility in St. Augustinegrass had crabgrass counts 77% less than treatments that did not follow recommendations in August of 2010. Alternative herbicides (defined as non-synthetic chemicals that have herbicidal properties) evaluated included acetic acid (vinegar), borax, sodium bicarbonate (baking soda), and Garden Weasel AG Crabgrass Killer (an improved sodium bicarbonate formulation including cinnamon, flour, and cumin). Greenhouse and field trials were conducted at Jay, FL to test product efficacy in controlling crabgrass and turf injury. In the greenhouse, one rate of vinegar (2x 280.6 L ha-1) and two rates of AG Crabgrass Killer (976.6 and 1464.9 kg ha-1) provided ? 70% control for 1-2 leaf crabgrass 7 days after application (DAA). By 21 DAA, only asulam (a synthetic herbicide included for comparison) provided ? 70% control at any weed stage. No alternative herbicide provided ? 70% control weed control at any weed stage longer than 7 DAA. Initial turf injury was very high for most rates of vinegar, sodium bicarbonate, and AG Crabgrass Killer, causing ? 20% St. Augustinegrass damage 7 DAA. By 21 DAA, turf injury levels had fallen to ? 20% for all treatments except higher rates of sodium bicarbonate and AG Crabgrass Killer. Although acceptable levels of control were not consistently seen from any alternative herbicide tested, they may have a future role as a supplement to proper cultural practices for crabgrass suppression in St. Augustinegrass.
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 BRIAN D GLENN.
Thesis: Thesis (M.S.)--University of Florida, 2011.
Local: Adviser: Brecke, Barry J.
Local: Co-adviser: Ferrell, Jason A.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2013-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0043080:00001

Permanent Link: http://ufdc.ufl.edu/UFE0043080/00001

Material Information

Title: Evaluation of Cultural and Non-Synthetic Methods for Southern Crabgrass (Digitaria ciliaris) Management in St. Augustinegrass Lawns
Physical Description: 1 online resource (83 p.)
Language: english
Creator: GLENN,BRIAN D
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: ACETIC -- AUGUSTINEGRASS -- BICARBONATE -- BORAX -- CRABGRASS -- CULTURAL -- DIGITARIA -- HERBICIDES -- MOWING -- NONSYNTHETIC -- ORGANIC -- SODIUM -- SOUTHERN -- VINEGAR -- WEED
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: Southern crabgrass (Digitaria ciliaris (Retz.) Koeler) is a common weed problem in turfgrass throughout the United States, particularly in St. Augustinegrass (Stenotaphrum secundatum Walt. Kuntze) lawns in Florida. Due to recent herbicide label changes, and lack of tolerance, no postemergence herbicides are currently available to the homeowner for crabgrass control in St. Augustinegrass (Gale, 2003). Alternative weed control methods such as cultural practices and alternative herbicides have been investigated to a limited extent by others for postemergence crabgrass management (Busey and Johnston, 2006). Experiments were conducted at the West Florida Research and Education Center in Jay, Florida and at the Plant Science Research and Education Unit in Citra, Florida to more extensively evaluate cultural practices for crabgrass management. Three irrigation treatments (no irrigation, irrigation based on evapotranspiration (ET), and daily irrigation), three mowing heights (5, 7.5, 10 cm), and four fertility treatments (0, 98, 146, 195 kg N ha-1) split into three applications throughout the year (April, June, August) were used. Crabgrass counts were significantly higher in plots that received irrigation daily, compared to ET and non-irrigated blocks. Crabgrass density increased as mowing height decreased at Jay, FL. Plots that were not fertilized had the lowest crabgrass counts, while those receiving fertility showed increased counts, usually increasing with increasing nitrogen rate. Treatments that followed IFAS recommendations for irrigation, mowing height, and fertility in St. Augustinegrass had crabgrass counts 77% less than treatments that did not follow recommendations in August of 2010. Alternative herbicides (defined as non-synthetic chemicals that have herbicidal properties) evaluated included acetic acid (vinegar), borax, sodium bicarbonate (baking soda), and Garden Weasel AG Crabgrass Killer (an improved sodium bicarbonate formulation including cinnamon, flour, and cumin). Greenhouse and field trials were conducted at Jay, FL to test product efficacy in controlling crabgrass and turf injury. In the greenhouse, one rate of vinegar (2x 280.6 L ha-1) and two rates of AG Crabgrass Killer (976.6 and 1464.9 kg ha-1) provided ? 70% control for 1-2 leaf crabgrass 7 days after application (DAA). By 21 DAA, only asulam (a synthetic herbicide included for comparison) provided ? 70% control at any weed stage. No alternative herbicide provided ? 70% control weed control at any weed stage longer than 7 DAA. Initial turf injury was very high for most rates of vinegar, sodium bicarbonate, and AG Crabgrass Killer, causing ? 20% St. Augustinegrass damage 7 DAA. By 21 DAA, turf injury levels had fallen to ? 20% for all treatments except higher rates of sodium bicarbonate and AG Crabgrass Killer. Although acceptable levels of control were not consistently seen from any alternative herbicide tested, they may have a future role as a supplement to proper cultural practices for crabgrass suppression in St. Augustinegrass.
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 BRIAN D GLENN.
Thesis: Thesis (M.S.)--University of Florida, 2011.
Local: Adviser: Brecke, Barry J.
Local: Co-adviser: Ferrell, Jason A.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2013-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0043080:00001


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1 EVALUATION OF CULTURAL AND NON SYNTHETIC METHODS FOR SOUTHERN CRABGRASS ( Digitaria ciliaris ) MANAGEMENT IN ST. AUGUSTINEGRASS LAWNS By BRIAN GLENN A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2011

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2 2011 Brian Glenn

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3 To my wife, Rachel, and my daughter Julia

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4 ACKNOWLEDGMENTS I would like to thank my major advisor, Dr. Barry Brecke, for the opportunity and help he gave me to pursue this degree. I also thank my committee co chair, Dr. Jason Ferrell, for all of the help with presentations and getting a handle on everything. Speci al thanks to Dr. Bryan Unruh for answering many a random question, and Dr. Greg Mac D onald and Dr. Kevin Kenworthy for advice they gave on my project. I thank all the grad students at the weed shop for the encouragement and laughs, especially Neha Rana f or the many statistics questions. A special thanks to everyone at the WFREC, especially Adam White and Vernon Tedder for all the hard work and keeping everything alive. Above all, I would like to thank my family, my wife Rachel and my daughter Julia for their love and support, and sticking with it through the summers at the farm.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TA BLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 9 ABSTRACT ................................ ................................ ................................ ................... 10 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 12 Management Strategies ................................ ................................ .......................... 14 Current Strategies Using Herbicides ................................ ................................ 15 Preemer gence control ................................ ................................ ................ 15 Postemergence control ................................ ................................ .............. 15 Alternative Strategies ................................ ................................ ....................... 16 Cultural practices ................................ ................................ ....................... 16 Alternative herbicides ................................ ................................ ................. 19 Summary ................................ ................................ ................................ ................ 20 2 CULTU RAL PRACTICES ................................ ................................ ....................... 22 Materials and Methods ................................ ................................ ............................ 23 General Procedures ................................ ................................ ......................... 23 Irr igation ................................ ................................ ................................ ..... 24 Mowing height ................................ ................................ ............................ 25 Nitrogen fertility ................................ ................................ .......................... 25 Evaluation ................................ ................................ ................................ ......... 25 Results and Discussion ................................ ................................ ........................... 26 Crabgrass Cover and Count Jay, Florida ................................ ....................... 26 Crabgrass Cover and Count Citra, Florida ................................ ..................... 29 St. Augustinegrass Quality ................................ ................................ ............... 30 Summary ................................ ................................ ................................ ................ 31 3 ALTERNATIVE HERBICIDES ................................ ................................ ................ 47 Materials and Methods ................................ ................................ ............................ 48 Alternative Herbicide Greenhouse Evaluation ................................ .................. 48 Alternative Herbicide Field Evaluation ................................ .............................. 49 AG Crabgrass Killer Ingredient Greenhouse Evaluation ................................ .. 50 Results and Discussion ................................ ................................ ........................... 50 Alternative Herbicide Greenhouse Evaluation ................................ .................. 50 Crabgrass control ................................ ................................ ....................... 50

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6 Shoot dry weights ................................ ................................ ...................... 52 Alternative Herbicide Field Evaluation ................................ .............................. 53 Crabgrass control ................................ ................................ ....................... 53 St. Augustinegrass tolerance ................................ ................................ ..... 55 AG Crabgrass Killer Ingredient Evaluation ................................ ....................... 56 Summary ................................ ................................ ................................ ................ 58 APPENDIX: FIGURES AND TABLES FROM REMOTE SENSING DATA .................... 77 LIST OF REFERENCES ................................ ................................ ............................... 79 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 83

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7 LIST OF TABLES Table page 2 1 Influence of irrigation and fertility on crabgrass cover in S t. Augustinegrass in 2009 at Jay, FL. ................................ ................................ ................................ .. 35 2 2 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass in 2009 at Jay, FL. ................................ ................................ .... 36 2 3 Influence of irrigation and fertility on crabgrass cover in St. Augustinegrass in 2010 at Jay, FL. ................................ ................................ ................................ .. 37 2 4 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass in 2010 at Jay, FL. ................................ ................................ .... 38 2 5 I nfluence of mowing height on crabgrass cover in St. Augustinegrass in 2009 at Jay, FL. ................................ ................................ ................................ ........... 39 2 6 I nfluence of mowing height on crabgrass grid count in St. Augustinegrass in 2009 at Jay, FL. ................................ ................................ ................................ .. 39 2 7 Influence of mowing height on crabgrass cover in St. Augustinegrass in 2010 at Jay, FL ................................ ................................ ................................ ............ 40 2 8 I n fluence of mowing height on crabgrass grid count in St. Augustinegrass in 2010 at Jay, FL ................................ ................................ ................................ ... 40 2 9 Influence of fe rtility on crabgrass cover in St. Augustinegrass in 2009 at Citra, FL ................................ ................................ ................................ .............. 41 2 10 Influence of fertility on crabgrass cover in St. Augustinegrass in 2010 at Citra, FL ................................ ................................ ................................ ....................... 41 2 11 Influence of fertility on crabgrass grid count in St. Augustinegrass in 2009 at Citra, FL ................................ ................................ ................................ .............. 41 2 12 Influence of fertility on crabgrass grid count in S t. Augustinegrass in 2010 at Citra, FL ................................ ................................ ................................ .............. 41 2 13 Response of St. Augustinegrass to fertility in 2009 in Jay, FL. ........................... 42 2 14 Response of St. Augustinegrass to fertility in 2010 in Jay, FL. ........................... 42 2 15 Response of St. Augustinegrass to fertility in 2009 in Citra, FL. ......................... 42 2 16 Response of St. Augustinegrass to fertility in 2010 in Citra, FL. ......................... 43

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8 3 1 Alternative herbicide treatments for greenhouse evaluation ............................... 60 3 2 Alternative herbicide treatments for field evaluation. ................................ .......... 61 3 3 Treatments for AG Crabgrass Killer ingredient evaluation. ................................ 61 3 4 Crabgrass control with alternative herbicides in the greenhouse 7 days after application Trial I ................................ ................................ ............................. 62 3 5 Crabgrass control with alternative herbicides in the greenhouse 7 days afte r application Trial II ................................ ................................ ............................. 63 3 6 Crabgrass control with alternative herbicides in the greenhouse 21 days after application Trial I ................................ ................................ .............................. 6 4 3 7 Crabgrass control with alternative herbicides in the greenhouse 21 days after application Trial II ................................ ................................ ............................. 65 3 8 Crabgrass shoot dry weights Trial I ................................ ................................ .. 66 3 9 Crabgrass shoot dry weights Trial II ................................ ................................ 67 3 10 Crabgrass control in the field with alternative herbicides 7 days after application 2009 ................................ ................................ .............................. 68 3 11 Crabgrass control in the field with alternative herbicides 7 days after application 2010 ................................ ................................ ............................... 69 3 12 Crabgrass control in the field with alternati ve herbicides 21 days after application 2009. ................................ ................................ .............................. 70 3 13 Crabgrass control in the field with alternative herbicides 21 days after application 2010 ................................ ................................ .............................. 71 3 14 St. Augustinegrass injury from alternative herbicides 7 days after application 2009 ................................ ................................ ................................ ................. 72 3 15 St. Augustinegrass injury from alternative herbicides 7 days after appli cation 2010 ................................ ................................ ................................ ................. 73 3 16 St. Augustinegrass injury from alternative herbicides 21 days after application 2009 ................................ ................................ ................................ ................. 74 3 17 St. Augustine grass injury from alternative herbicides 21 days after application 2010 ................................ ................................ ................................ ................. 75 3 18 Postemergence crabgrass control with Crabgrass Killer ingredients 14 days after application. ................................ ................................ ................................ 76

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9 3 19 Shoot dry weights as influenced by AG Crabgrass Killer ingredients. ................ 76 LIST OF FIGURES Figure page 2 1 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with no irrigation in 2009 in Jay, FL. ................................ .......... 44 2 2 Influence of irrigation and fertility on crabgrass grid co unt in St. Augustinegrass with ET irrigation in 2009 in Jay, FL. ................................ ......... 44 2 3 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with daily irrigation in 2009 in Jay, FL. ................................ ...... 44 2 4 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with no irrigation in 2010 in Jay, FL. ................................ .......... 45 2 5 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with ET irrigation in 2010 in Jay, FL. ................................ ......... 45 2 6 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with daily irrigation in 2010 in Jay, FL. ................................ ...... 45 2 7 Total rainfall by month in 2009 and 2010 in Jay, FL. ................................ .......... 46 2 8 Total rainfall by month in 2009 and 2010 in Citra, FL. ................................ ........ 46 4 1 Percent volumetric water content based on irrigation and nitrogen fertility in Jay, FL on July 21, 2010. ................................ ................................ ................... 77 4 2 Chlorophyll count based on mowing height and nitrogen fertility in Jay, FL on July 22, 2009. ................................ ................................ ................................ ..... 77 4 3 Chlorophyll count based on mowing hei ght and nitrogen fertility in Jay, FL on July 21, 2010. ................................ ................................ ................................ ..... 78

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10 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Maste r of Science EVALUATION OF CULTURAL AND NON SYNTHETIC METHODS FOR SOUTHERN CRABGRASS ( Digitaria ciliaris ) MANAGEMENT IN ST. AUGUSTINEGRASS LAWNS By Brian Glenn May 2011 Chair: Barry Brecke Cochair: Jason Ferrell Major: Agronomy Southern crabgrass ( Digit aria ciliaris (Retz.) Koeler) is a common weed problem in turfgrass throughout the U nited States particularly in St. Augustinegrass ( Stenotaphrum secundatum [Walt.] Kuntze) lawns in Florida. Due to recent herbicide label changes, and lack of tolerance, n o postemergen ce herbicides are currently available to the homeowner for crabgrass control in St. Augustinegrass (Gale, 2003) Alternative weed control methods such as cultural practices and alternative herbicides have been investigated to a limited extent by others for postemergence crabgrass management ( Busey and Johnston, 2006 ) Experiments were conducted at the West Florida Research and Education Center in Jay, F lorida and at the Plant Science Research and Education Unit in Citra, F lorida to more exten sively evaluate cultural practices for crabgrass management. Three irrigation treatments (no irrigation irrigation based on evapotranspiration (ET) and daily irrigation), th ree mowing heights (5, 7.5, 10 cm), and four fertilit y treatments (0, 98, 146, 1 95 kg N ha 1 ) split into three applications throughout the year (April, June, August) were used. Crabgrass counts were significantly higher in plots that received irrigation daily, compared to ET and non

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11 irrigated blocks. C rabgrass density increased as m owing height decreased at Jay, FL Plots that were not fertilized had the lowest crabgrass counts, while those receiving fertility showed increased counts, usually increasing with increas ing nitrogen rate Treatments that followed IFAS recommendations fo r irrigation, mowing height, and fertility in St. Augustinegrass had crabgrass counts 77% less than treatments that did not follow recommendations in August of 2010. Alternative herbicides ( defined as non synthetic chemicals that have herbicidal propertie s ) evaluated included acetic acid (vinegar), borax, sodium bicarbonate (baking soda), and Garden Weasel AG Crabgrass Killer (an improved sodium bicarbonate formulation including cinnamon, flour, and cumin ) Greenhouse and field trials were conducted at Ja y, FL to test product efficacy in controlling crabgrass and turf injury. In the greenhouse, one rate of vinegar (2x 280.6 L ha 1 ) and two rates of AG Crabgrass Killer (976.6 and 1464.9 kg ha 1 control for 1 2 leaf crabgrass 7 days after application ( DAA ) By 21 DAA, only asulam (a synthetic herbicide included for comparison) at any weed stage longer than 7 DAA. Initial turf injury was very high for most rates of vinegar, sodium damage 7 ents except higher rates of sodium bicarbonate and AG Crabgrass Killer. Although acceptable levels of control were not consistently seen from any alternative herbicide tested, they may have a future role as a supplement to proper cultural practices for cr abgrass suppression in St. Augustinegrass.

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12 CHAPTER 1 INTRODUCTION Southern crabgrass ( Digitaria ciliaris (Retz.) Koeler ) is a summer annual grass species that is native to the Old World and it infests many tropical and subtropical areas of the world (Cla yton et al. 2006). In the United States, its range is northward along the coastal plains into Connecticut, east of the Appalachians, throughout Florida, extending west into Texas, Nebraska and Kansas (Murphy 2007). Leaf blades measure 3 25 cm in length and 2 10 mm in width ( Anonymous 2008). Southern crabgrass is characterized by dense hairs on both sides of the leaf and sheath surface. The ligule is membraneous and toothed. Seed heads are compromised of 2 to 9 racemes that branch at varying location s. It can be tufted, prostrate or spreading; its stems are branched and it can root at the nodes (Clayton et al. 2006). Reproducing from seed, it is very prolific (several seed crops can be produced every year) and seeds are spread mainly by mechanical m eans (Peters and Dunn 1971) Southern crabgrass can germinate under no light conditions, but germination is higher with light ( Chauhan and Johnson 2008). Seeds germinated at a rate of <40% when daytime/nighttime temperatures were 25/15 C; germination incr eased to >80% when temperatures were 30/20 C ( Chauhan and Johnson 2008). Spreading can also occur by plants rooting at nodes, often forming dense mats. Southern crabgrass is differentiated from large crabgrass ( Digitaria sanguinalis ( L. ) Scop ) by the length of prickle on the abaxial le af surface (Gilani et al, 2002) and the l ength of the second glume (Clayton et al. 2006) Its habitat includes open fields, pastures, disturbed areas, and lawns (Holm et al. 1977 ). rass, and tropical finger grass (Murphy 2007).

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13 St. August inegrass ( Stenotaphrum secundatum [Walt.] Kuntze.) is a warm season perennial turfgrass that is the most widely used species for lawns in Florida where it is grown on 1.2 million home lawns across the state (Hodges et al. 1994). Its origins can be traced to the warm climates of the Old World, but alternative hypotheses state that it could be native to North America, with samples having been found in the Carolinas in Hanson et al. 1969; Busey 2000). St. Augustinegrass is characterized by t hick leaf blades and large running stolons that can produce heavy thatch requiring mechanical thatch removal. The recommended mowing height is 7.6 to 10.2 cm in for Florida and the generalized mean summer evapotranspirati on rate is 4.3 to 6.6 cm 1 week (Unruh and Elliot 1999). St. Augustinegrass also requires a higher mowing height than other common warm season turfgrasses including bermudagrass ( Cynodon dactylon ( L. ) Pers. ) (Trenholm et al. 2000 ; Christians 2004 ). St. Augustinegrass has been in use as a turfgrass since 1880, but did not reach its (Busey 2000). It is usually propagated vegetatively, due to limited or no seed production. Its range includes Florida and the Gul f Coast states, extending west into Texas (Busey 2000) Winter kill limits its use to the southern portion of the transition zone. Colder winters induce dormancy until soil temperatures warm in the spring to above 16 C (Christians and Engelke 1994) St. Augustinegrass has relatively poor cold tolerance, moderate salt tolerance, and is subject to winter desiccation in drier climates (Christians 2004). It is also susceptible to southern chinch bugs ( Blissus insularis ) gray leaf spot ( Pyricularia grisea ) large patch ( Rhizoctonia

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14 solani ) and St. Augustinegrass decl ine (SAD) caused by the p anicum mosaic virus ( PMV ) Advantages include moderate to good shade tolerance depending on the cultivar rapid growth, and thick canopy that compete s well with weeds. Management Strategies Southern crabgrass is a troublesome weed that appears and persists in residential lawns throughout the southeastern United States. Each year in the state of Florida, $90 million dollars are spent on herbicides for weed control in tur fgrass (Hodges et al 1994). Coupled with the high cost of chemicals, new pesticide regulations and environmental protection statutes have caused applicators to begin to look for alternative means by which to control turf pests. Changing public opinion h as also led many homeowners to desire organic weed management programs for their lawns, which is characterized by using non chemical methods such as mowing, mulching, and cultivation as well as non synthetic herbicides (Ferguson and Chase 2004). The origi nal organic movement began in Great tillage (Macilwain 2004 ) In the past ten years the movement has seen resurgence, and has also included increasing biodiversity, reducing erosion, and r educing materials that may be moved to off target sites ( Macilwain 2004). Current research in organic systems is mainly directed toward crop production systems, and there is a need for the evaluation of organic weed control methods for use in turfgrass. Another reason for interest in alternative weed control products is the lack of postemergence herbicides labeled for use in St. Augustinegrass turf. Currently, there are few selective herbicides labeled for residential postemergence control of grassy wee ds in improved St. Augustinegrass cultivars. Preemergen ce options are still

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15 available, but they must be applied before weeds germinate in order to have control activity. Current Strategies Using Herbicides Preemergence control Many herbicide options ar e available to homeowners with established lawns for control of crabgrass preemergence. The h erbicides in the triazine herbicide family are photosystem II inhibitors that are used extensively in St. Augustinegrass (Teuton et al. 2004; Senseman 2007) Mit os i s inhibitors are also used preemergence and include S metolachlor [2 chloro N (2 ethyl 6 methylphenyl) N {(1S) 2 methoxy 1 methyethyl}acetamide], pendimethalin [N (1 ethylpropyl) 3,4 dimethyl 2,6 dinitrobenzenamine], prodiamine [2,4 dinitro N 3 N 3 dipro pyl 6 (trifluoromethyl) 1,3 benzenediamine] and napropamide [N,N diethyl 2 (1 naphthalenyloxy) propanamide] (Senseman 2007). Oxidiazon [3 {2,4 dichloro 5 (1 methylethoxy)phenyl} 5 (1,1 dimethylethyl) 1,3,4 oxadiazol 2 (3H)one] is a protoporphyrinogen oxid ase inhibitor which is also used, and often in conjunction with other herbicides to broaden the spectrum of control (Senseman 2007) Postemergence control Currently, there are few selective herbicides labeled for postemergence control of grassy weeds in improved St. Augustinegrass cultivars in residential settings Asulam [ methyl {(4 aminophenyl) sulfonyl} carbamate], a dihydropteroate synthetase inhibitor used for postemergence control of crabgrass in St. Augustinegrass, is no longer labeled for reside ntial use (Gale 2003). Label changes have made atrazine [6 choro N ethyl N (1 methylethyl) 1,3,5 triazine 2,4 diamine] a restricted use pesticide making it unavailable to the homeowner without a pesticide applicator license. New restrictions

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16 include redu ced use rates and imposed buffer zones around impounded water. Ethofumesate [2 ethoxy 2,3 dihydro 3,3 dimethyl 5 benzofuranyl methanesulfonate] is relatively tolerant in St. Augustinegrass and has been used for bermudagrass suppression (Johnson and Carrow 1995) It has shown to have fair control of crabgrass, and is labeled for residential turf. However, label restrictions require application by a licensed pesticide applicator. Alternative Strategies Cultural practices Cultural control practi ces are often used in integrated pest management programs in conjunction with chemical means as another tool for decreasing weed pressure. Cultural practices used in turf situations can include mowing height, cultivation practices ( i.e., aerification, vert icutting), fer tility, and irrigation scheduling With the right combination of methods, these practices can provide a means of managing weed populations with lower inputs and possibly lessen the potential negative impacts of herbicides such as weed resist ance, le a ching, and drift. Mowing height. Mowing is a common practice in most turfgrass situations. Increasing mowing height is generally accepted to improve turf health. However, many applications such as putting greens and athletic fields can call f or very low heights. When easily done, an increased mowing height may be a means to decrease the germination and growth of crabgrass and other weed seeds by limiting the amount of sunlight that reaches the soil surface. Previous research has provided mix ed results when using mowing height as a means to control crabgrass. Increased mowing heights reduced crabgrass populations in trials with cool season turf such as Kentucky bluegrass ( Poa pratensis L. ) (Dunn et al. 1981), Chewings fescue ( Festuca rubra L. ssp.

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17 fallax (Thuill.) Nyman ) (Jagschitz and Ebdon 1985), and tall fescue ( Festuca arundinacea Schreb. ) (Dernoeden et al. 1993; Voigt et al. 2001). Trials with warm season grasses have been for the most part inconclusive. In bermudagrass, mowing proved to be inconsistent and did not appear to provide any weed control of crabgrass (Callahan and Overton 1978). The effect of mowing on weed growth in St. Augustinegrass was evaluated in south Florida from 2001 to 2003. Dollarweed ( Hydrocotyle umbellate L. ) control was not consistently affected by mowing. Growth of other weeds including Florida pusley ( Richardia scabra L.) southern sida ( Sida acuta Burm. f.) and Carolina dichondra ( Dichondra carolinensis Michx.) was reduced in only one year when the weed in tensity was the greatest and only at the highest mowing height (Busey and Johnston 2006). While the results of increased mowing height in cool season turfgrasses has been documented to decrease crabgrass populations, the same effects have not been reporte d in warm season grasses. Fertility. Depending on the species, turf generally requires a high input of nitrogen for optimal growth. Nitrogen is usually supplemented by applying fertilizer, which is available in many different forms. The same nitrogen t hat is available for the turf is also available for uptake by weeds. Because of the vigor of most turfgrasses, plants that receive adequate levels of nitrogen can often out compete weeds for resources. Using supplemental nitrogen has been shown to reduce weed infestation in both warm and cool season turfgrasses. Higher nitrogen rates ( 196 300 kg N ha 1 yr 1 ) reduced crabgrass populations in tall fescue (Dernoeden et al 1993; Voigt et al. 2001), Chewings fescue (Jagschitz and Ebdon 1985), and Kentucky b luegrass (Dunn et al. 1981; Johnson and Bowyer 1982; Murray et al. 1983).

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18 When fertility level was increased in St. Augustinegrass, weed pressure was reduced for all weed species evaluated in the study except for dollarweed (Busey and Johnston 2006). Th is included a small population of southern crabgrass, but the results were not definitive because of the size of the sample. The data shows that there is a strong relationship for higher rates of nitrogen and decreas ed crabgrass population; however, more information is needed to better describe the relationship between nitrogen fertilization and crabgrass growth in warm season grasses such as St. Augustinegrass. Irrigation. Based on different water requirements, many turfgrasses need supplemental irrigati on to remain healthy. Weed species that are found in lawns and other turf applications can grow under various soil moisture levels which helps them remain competitive during drought conditions. The results of different irrigation regiments are varied am ong weeds growing in warm and cool season turf. Treatments in cool season turf infested with annual bluegrass ( Poa annua L. ) show ed little or no change in weed populations by changing the frequency of watering (Jiang et al. 1998) In perennial ryegrass ( Lolium perenne L. ) a study showed that irrigation treatments had no effect on dandelion ( Taraxacum officinale ) or smooth crabgrass ( Digitaria ischaemum Schreb. ) (Jiang et al. 1998) In St. Augustinegrass dollarweed coverage increased with increas in g irr igation, while density of other weeds including southern crabgrass decreased (Busey and Johnston 2006). Although the previous study included crabgrass, the population density may have been too low to detect changes in level of infestation.

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19 Alternative her bicides Alternative herbicides are those which are not the synthetic chemicals traditionally used to control weeds. These include common household products such as sodium bicarbonate (baking soda), acetic acid (vinegar), sodium chloride, and borax. Litt le information has been published in regards to the use and effectiveness of these products as an herbicide (Chase et al. 2004) The recent demand for organic food production and products has contributed to the exploration of natural products for use in w eed management. Sodium bicarbonate ( baking soda ) has been shown to be antagonistic when used with synthetic herbicides ( Thelen et al. 1995). When sodium bicarbonate was used alone as a postemergence herbicide, some activity was noted A 1994 study con ducted by Dr. Barry Brecke at the University of Florida showed sodium bicarbonate provided between 35 and 45% control of crabgrass at 28 days after application when applied to crabgrass at the 1 3 leaf growth stage. Application rates were between 49 and 9 8 kg ai ha 1 New products that contain sodium bicarbonate, mixed with other natural materials, are being marketed to control crabgrass postemergence. Claims include crabgrass control while being safe for most warm season turfgrasses, including St. August inegrass (Anonymous 2005) Continued research is needed to determine tolerance of St. Augustinegrass to sodium bicarbonate and effectiveness for crabgrass control. Acetic acid, which is the principle ingredient in vinegar, has been researched in the past few years to test its effectiveness in weed management. Organic growers have expressed interest because it is considered a natural product and can be used postemergence. Early research showed effective control of common lambsquarter ( Chenopodium alba L. ), giant foxtail ( Setaria faberi Herrm. ) redroot pigweed

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20 ( Amaranthus retroflexus L. ) and smooth pigweed ( Amaranthus hybridu s L. ) at co ncentrations of acetic acid ranging from 15 to 30 % (Radhakrishnan et al. 2002; Evans et al 200 9 ). Vinegar provided above 80% control of crabgrass 1 day after treatment when applied at the 2 to 3 leaf growth stage, (Evans and Bellinder 2009). However, ti ming was critical in the application of vinegar because it acts as a contact material and it was most effective on smaller weeds. ( Allgaier 1944). The most predominant use of borax as an herbicide is to control ground ivy ( Glechoma hederacea L.). Results have varied, but have shown moderate to good postemergence control of ground iv y in field trials (Rossi et al. 1996; Hatter m an Valenti et al. 1996). Temporary injury to t urfgrass was recorded with all treatments. Because borax is comprised of the micronutrient boron, toxicity problems are a concern with continued applications. Levels of boron required to create toxic levels are still unclear. Research is needed to deter mine the effectiveness of borax for control of crabgrass and the sensitivity of St. Augustinegrass to borax. Summary The lack of postemergence chemical control for crabgrass in St. Augustinegrass has lead to interest in areas other than synthetic chemical control. Cultural practices and alternative herbicides may provide a means to manage southern crabgrass populations. Potential management strategies should be available for use by homeowners without excessive complications. Cultural practices have been used in many turfgrasses to promote plant health and to suppress weed growth. Research is needed to document the effect that these practices, specifically mowing height, irrigation, and nitrogen fertility levels, will have on

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21 St. Augustinegrass quality a nd crabgrass management. Alternative herbicides are used in applications such as organic crop production as a means of weed control. They include common household products such as sodium bicarbonate (baking soda), vinegar, and borax. Research is needed to document the efficacy of crabgrass control at different weed stages, and to determine St. Augustinegrass tolerance. The information gathered from the described research will be used to increase current management options for postemergence crabgrass con trol, in particular those strategies that will augment organ ic weed control strategies.

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22 CHAPTER 2 CULTURAL PRACTICES Southern crabgrass ( Digitaria ciliaris (Retz.) Koeler ) is an annual grass species that is native to the Old World and infests many tropic al and subtropical temperature regions around the world (Clayton et al. 2006). The range of adaptation of southern crabgrass in the United States extends from Texas, across to Florida, and north east of the Appalachians to Connecticut (Murphy 2007). It in fests most open areas including pastures, fields, lawns, golf courses, athletic fields and commercial turf (Holm et al. 1977) Southern crabgrass poses a particular challenge to homeowners, due to the limited control options available in St. Augustinegrass ( Stenotaphrum secundatum [Walt.] Kuntze). Sensitivity to many herbicides, along with label changes to herbicides once used in St. Augustinegrass, have resulted in a situation with no available postemergence herbicides for southern crabgrass control in St Augustinegrass lawns This has required researchers to exploring options other than traditional synthetic chemi cals for crabgrass management. Cultural practices are used by turfgrass managers and homeowners as a way to maintain and improve plant health. These practices include mowing height, irrigation, aerification, vertical mowing and fertilization. Many of these practices have been researched in the past to determine their impact on weed populations. Weed pressure was decreased in St. Augustinegra ss at a mowing height of 11.4 cm, but not significantly at any other height evaluated ( 6 .4 and 8 9 cm ) (Busey and Johnston 2006). Dollarweed coverage increased in St. Augustinegrass with an increase in irrigation, while density of other weeds including cra bgras s decreased (Busey and Johnston

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23 2006). When fertility level was increased, weed pressure was reduced for all weed species evaluated in the study except for dollarweed (Busey and Johnston 2006). However, little research has concentrated on the effect of cultural practices on managing crabgrass in St. Augustinegrass. Because of the extensive amount of St. Augustinegrass grown for home lawns in the state of Florida (Hodges et al. 1994) research is needed to evaluate of crabgrass management using cultur al practices. This information can also be used to create B MP s (Best Management Practices) for homeowners with St. Augustinegrass lawns and crabgrass populations. Therefore the objective of this research was to determine the effect of mowing height, irri gation, and nitrogen fertility on management of crabgrass populations and St. Augustinegrass performance Materials and Methods General Procedures Studies to evaluate the effects of cultural practices for southern crabgrass management were conducted in tw o locations across n orth Florida. The first was established at the West Florida Research and Education Center in Jay, F lorida blocks measuring 9.1 m by 9.1 m were sod ded, separated by 3.0 m alleys. Treatments were arranged as a split split plot design with three replications. Main plots were irrigation, sub plots were mowing height and sub sub plots were fertility treatments. Soil at the Jay, FL location was a Dothan fine sandy loam (fine loamy, siliceous, thermic Plinthic Paleudults) with 77% sand, 14% silt, 9% clay, and 2% organic matter. The second location was the Plant Science Research and Education Unit in Citra, F lorida The study site at the Citra, FL locati on was a preexisting block of

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24 three replications. Main plots were mowing height and sub plots were fertility treatments. Irrigation was not used as a treatment due to li mitations in installing irrigation at the site. Plot size at both locations was 3 m by 1.5 m. Soil characteristics at the Citra, FL location is a Hague series sand (loamy,siliceous, semiactive, hyperthermic Arenic Hapludalfs), with a cation exchange capa city of 6.1, 1.4% organic matter, and pH 5.8 Southern c rabgrass was overseeded on May 15 and Jun e 13 in 2009 and on March 15 and 19 in 2010 at Jay, FL and Citra, FL respectively. outhern crabgrass seed obtained from Elstel Farm and Seeds 1 was overseeded both years at a rate of 98 kg ha 1 applied with a drop spreader. Irrigation Irrigation pipes and sprinklers were installed during April of 2009. An irrigation audit was performed in June of 2009 to ensure irrigation uniformity, distribut ion, and rate of delivery. Irrigation treatments were separated into three frequency regiments: 1) no supplemental irrigation, 2) water replacement based on evapotranspiration (ET) rates for St. Augustinegrass, and 3) irrigation applied daily. The evapot ranspiration rate used was that calculated as described by Unruh and Elliot, ( 1999 ). The crop coefficient value of St. Augustinegrass (0.8) was multiplied by the ET rate added for the previous seven days. The value was then divided by two, and the amount was applied to plots through irrigation. Water need based on the recommended ET was applied twice weekly. Irrigation treatments began as St. Augustinegrass greened up in the spring and continued until the onset of dormancy in the fall. 1 Elstel Farm and Seeds, 2640 Springdale Road, Ardmore, OK 73401 9106

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25 Mowing height Mow ing height treatments were the split plots at Jay, FL and the main plots at Citra, FL. Three different mowing heights were used: 5, 7.5, and 10 cm. The 7.5 and 10 cm heights represent the recommended mowing height s for St. Augustinegrass in Florida while the 5 cm is lower than recommended (Unruh and Elliot 1999 ). Plots were mowed using a walk behind mulching rotary mower. Clipping were not collected. Plots were mowed weekly from the time of St. Augustinegrass green up to fall dormancy Nitrogen f ertilit y Nitrogen was applied at 0, 98 146 and 195 kg N ha 1 yr 1 simulating low to high recommendations of fertilization for St. Augustinegra ss by UF/IFAS (Unruh and Elliot 2009). The four rates of nitrogen fertilizer were divided into three sequential appl ications applied in April, June, and August. A granular fertilizer ( 18 0 18 ) with 35% slow release nitrogen was used and was applied to plots using a shaker can. Evaluation Plots were evaluated with grid counts and visual ratings of crabgrass populations every 2 w ee k s after the first fertilizer application. Crabgrass density was estimated using a 0 .9 m 2 grid that is divided into 36 squares measuring 13 cm 2 each The grid was placed in the plot to be evaluated and the number of squares containing crabgras s w as recorded. In addition crabgrass percent cover was visually estimated using a scale of 0 100%, 0 indicating no crabgrass present and 100 equal to complete crabgrass cover of the plot. Turf quality was visually estimated using a scale of 1 9 in acco rdance to standard evaluation procedures set by the National Turfgrass Evaluation Program (NTEP)

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26 According to NTEP,1 is the poorest quality (dead turf) and 9 is the highest quality possible (NTEP 2010) An acceptable turf q uality rating was 6 or higher. D ata were subject to an analysis of variance using the PROC GLIMMIX of SAS (2008) to determine possible intera ctions and treatment effects. Means were separated using Weed counts and weed cover data were transformed using a square root t ransformation due to non normal distribution. Results and Discussion Crabgrass Cover and Count Jay, F lorida T reatment by year and treatment by evaluation date interactions at the Jay, FL location were detected for all observations. T herefore, data hav e been presented separately by year for crabgrass count, cover, and St. Augustinegrass quality. An interaction was observed between irrigation and nitrogen fertility both years. In 2009, crabgrass cover was significantly higher in plots with no supplement al irrigation with higher rates of nitrogen particularly early in the season ( Table 2 1 ) However in irrigated plots crabgrass density did not differ among nitrogen treatments later in the season regardless of whether plots were irrigated based on ET o r irrigated daily. In 2009 c rabgrass counts showed results similar to those observed with crabgrass cover (Table 2 1 vs. Table 2 2 ). Only treatments with no supplemental irrigation had crabgrass counts >10 throughout the year and counts increased with increasing fertility only in the plots that did not receive supplemental irrigation (Figure 2 1) Nitrogen level had no effect on crabgrass counts whether irrigated based on ET or on a daily schedule (Figure 2 2 and 2 3) In 2010, treatments that were ir rigated daily had the most crabgrass cover consistently throughout the year after June with > 35% cover for plots receiving nitrogen

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27 ( Table 2 3 ) Treatments with no irrigation and ET irrigation did not have crabgrass cover exceeding 30% (Table 2 3 ) nor cr abgrass count >16 (Table 2 4) at any date. All daily irrigation treatments receiving nitrogen had significantly higher crabgrass cover t han any ET irrigated treatment in June (Figure 2 4, 2 5, and 2 6) All daily irrigated plots that were also fertilized at any level had higher crabgrass counts than any other treatment (Table 2 4). All treatments that did not receive nitrogen had low crabgrass cover and had low crabgrass count s The results from nitrogen treatments in this study are not in agreement with previous research using nitrogen fertility for weed management. Busey and Johnston (2006) found that as nitrogen levels increased in St. Augustinegrass, crabgrass populations decreased The difference in results could be attributed to the small populati on size (compared with 21 other weeds in plots) of crabgrass in the Busey and Johnston study. The results in our study showed that the lowest crabgrass densities were obtained in the absence of supplemental nitrogen to St. Augustinegrass. This level of i nput might not be desirable due to the likelihood of reduced turf quality. If nitrogen is used, the amount should be determined based on various site conditions, including availability of irrigation and h istory of crabgrass infestation Results from ir rigation treatments in 2009 were similar to findings of Busey and Johnston study (2006) where crabgrass coverage decreased with increasing irrigation In 2010, results were different as crabgrass population was significantly higher at the highest rate of irrigation. If St. Augustinegrass is newly sodded, it should remain irrigated until established to prevent rapid decline resulting in open areas that could lead to crabgrass encroachment. When St. Augustinegrass is well established, irrigation

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28 should be applied sparingly to maintain turf health. When applied in excess of ET replacement crabgrass growth is encouraged. If turf does not receive any supplemental irrigation, nitrogen levels should be limited to minimize crabgrass growth due to excess nutrien ts. There were no interactions between treatments and mowing height; therefore, data were pooled. In 2009, crabgrass cover was not significantly different at any date ( Table 2 5) Crabgrass counts increased significantly as mowing height was increased on two dates in September (Table 2 6 ) A few rating dates showed that St. Augustinegrass mowed at 10.2 cm had the most crabgrass cover and counts throughout much of the year. In 2010, crabgrass cover and counts increased as mowing height decreased on most dates ( Table 2 7 and Table 2 8) Crabgrass counts were the greatest at the lowest mowing height for each evaluation date. Counts were significantly lower in plots mowed at 10 cm than 5 cm for four dates during the year (Table 2 8). Crabgrass cover appea red to be higher at the lowest mowing height for every date except August 18. The inconsistent results over years observed in this study is similar to previous research describing the effect of mowing height on crabgrass coverage in St. Augustinegrass. B usey and Johnston (2006) observed a significant reduction in crabgrass coverage in only one year of a 3 year study at the highest mowing height (6.4, 8.9, and 11.4 cm) Results in this study differed between years, and the highest mowing height was only e ffective in decreasing crabgrass cover in 2010. The differences in mowing height on crabgrass cover between years at the Jay, FL location could be attributed to both differences in stage of turfgrass establishment and

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29 date o f overseeding of crabgrass. S t. Augustinegrass sod was laid on April 17, 2009. The sod was watered regularly to promote establishment until irrigation treatments began on June 13. The length of establishment before irrigation treatments were applied could have had an effect on crabg rass cover, as higher temperatures and lower levels of rainfall are typical in June in north Florida. Treatments that did not receive irrigation showed higher crabgrass cover than irrigated plots. Lack of irrigation usually adds stress to turfgrass, causi ng leaf firing and eventual thinning of the turf canopy. Weeds can take advantage of open areas in the canopy, leading to increased populations. Crabgrass was also overseeded in June, well beyond the usual date of crabgrass emergence Because southern cra bgrass is a summer annual, and usually begins to emerge as temperatures increase in the spring (Clayton et al. 2006). Average temperatures in Florida during June are well above levels needed for crabgrass germination, and are around those needed for optim um growth. Also, fertility treatments were applied within two weeks of crabgrass overseeding. As the crabgrass began to emerge, nitrogen was supplied earlier than what would be applied normally. Nitrogen is first applied in the spring after St. Augustin egrass has almost completely broken dormancy. Usually this occurs at least one month after crabgrass has begun to germinate. The addition of nitrogen soon after overseeding could have affected crabgrass populations in a way that would not be observed if normal management practices were followed. Crabgrass Cover and Count Citra, F lorida There was an interaction between years at the Citra, FL location; therefore, years are shown separately. Data were pooled by fertility Mowing height for most da tes was not significant but nitrogen was significant for all dates. Crabgrass cover and counts

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30 were the lowest for plots with no nitrogen for each date and highest for plots receiving 195 kg N ha 1 in 2009 and 2010 (Table 2 9; 2 10 ; 2 11; 2 12). The imp act of nitrogen on crabgrass abundance in Citra, FL did not agree with the Busey and Johnston (2006) who observed that crabgrass populations decreased as nitrogen levels increased in St. Augustinegrass. The difference in results could be attributed to th e small amount of crabgrass in the observed population of the earlier study The current experiment had crabgrass densities ranging from 2 35 % cover while Busey and Johnston (2006) reported < 30 % cover for all treatments. The data at the Citra, FL locat ion were similar with the Jay, FL location in that crabgrass populations were lowest on those plots receiving no supplemental nitrogen. However, crabgrass populations on plots that were fertilized varied between Jay, FL and Citra, FL Irrigation was not a treatment factor at the Citra, FL location, but an interaction was seen between irrigation and nitrogen at the Jay, FL location. Plots at the Citra, FL location were irrigated, but did not follow any irrigation regime implemented in Jay, FL The amount of rainfall and temperatures also varied between locations (Figure 2 3 and 2 4) The difference in irrigation frequency, amount, and weather conditions may explain the difference between crabgrass populations at Citra, FL and Jay, FL St. Augustinegr ass Quality There were treatment by year and treatment by date of evaluation interactions for all irrigation, mowing, and fertility treatments at both locations; therefore, data are shown separately by year and location. There were no interac tions betwee n treatment factors (irrigation, mowing and fertility) ; therefore, data were pooled by nitrogen treatments being the only significant factor For all quality ratings the highest quality

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31 was achieved when fertilized at 195 kg N ha 1 and the lowest quali ty at 0 kg N ha 1 (Table 2 13; 2 14; 2 15; 2 16) In Jay and Citra, FL no untreated plot achieved an acceptable quality rating (Table 2 13 and Table 2 14) on any rating date in 2009 and 2010 T reatments fertilized at 98 kg N ha 1 and 146 kg N ha 1 ach ieved acceptable quality rating s, but not for the entire season However, St. Augustine quality was >6 for treatments fertilized at 195 kg N ha 1 for all evaluation dates except early season in June 2010 at Citra at both locations, in 2009 and 2010. Dif ferences between years could be attributed to various environmental factors. In both locations, 2010 had significantly longer periods throughout the summer without rainfall. Because plots that are not irrigated only receive water from rainfall, t hese per iods could have possibly led to water stress beyond the permanent wilting point. Even if rainfall was plentiful after an extended dry period, turf decline would have been irreversible. Also, since plot layout was unchanged between years, St. Augustinegras s plots not receiving nitrogen had more time elapse from the last application of nitrogen (applied at the sod farm before sod was harvested). The extended absen c e of supplemental nitrogen may have caused further decline of quality in 2010 from ratings tak en in t he similar time of year in 2009. Summary Cultural practices are used in turfgrass management to improve plant health but the impact on weed management has not been exhaustively explored. These practices can include altering mowing height, irrigati on, and nitrogen fertility. Due to the lack of postemergence options available to homeowners for southern crabgrass control in St. Augustinegrass, alternative management techniques were evaluated for effectiveness.

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32 Mowing height and nitrogen fertility ra te were jointly tested in two locations for two years; irrigation frequency was tested only at the Jay, FL location for two years. Crabgrass density and St. Augustinegrass quality responded to mowing, irrigation, and fertility at the Jay, FL location. At Citra, only fertility impacted crabgrass density and turf quality. Effect of irrigation frequency on crabgrass populations was not consistent over years. In 2009, plots with no irrigation had the highest crabgrass densities. In 2010, irrigation frequen cy was positively correlated with crabgrass density. The differences between years may have resulted from recently sodded St. Augustinegrass and its establishment in 2009. As irrigation treatments were imposed June 2009, the no irrigation plots to rapidl y decline. This was due to the short period that the turf had to establish as well as the hot and dry conditions when irrigation treatments were implemented. The decline led to increased open areas in non irrigated plots, which led to rapid crabgrass enc roachment. Plots irrigated based on ET tended to have the least increase in crabgrass populations early in the growing season, and lower populations throughout the summer, due to improved turf health. Nitrogen fertility was a significant factor for diff erences in crabgrass populations for both locations. As nitrogen fertility levels increased, crabgrass populations also increased for most treatments. The effect of fertility was more pronounced at the Citra, FL location for both years. Southern crabgra ss appears to be competitive with St. Augustinegrass for nitrogen uptake ( Chauh an and Johnson 2008) In making management recommendations, nitrogen should be limited if crabgrass management is desired.

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33 Mowing height was significant across all dates at Ja y, FL, but not at Citra, FL. Results differed in Jay, FL for 2009 and 2010. The lowest mowing height resulted in the lowest crabgrass populations in 2009, but the highest levels of crabgrass infestation in 2010. These differences were seen throughout th e summer in both years. Possible explanations for this difference could be the result of late crabgrass planting and turf establishment in 2009. Newly sodded turf is more susceptible to decline because of lack of irrigation due to a root system that is s till establishing. As a result, those plots that were not irrigated when turf was still establishing suffered a rapid decline, leading to open areas in which weeds could establish. Planting crabgrass later in the season can expose seedlings to optimal gr owth conditions immediately. This could cause differences in results seen because crabgrass does not follow the normal summer annual life cycle that it is exposed to under normal field conditions. Another factor to be considered is the visual rating pro cess because of the difficulty of rating crabgrass in frequently mowed St. Augustinegrass turf. Crabgrass populations at the lower mowing heights may have been underestimated because of their small size. Another year of data collection would be required accurately assess the effect of mowing height on managing crabgrass coverage. Turfgrass quality was significantly affected only by fertility in both locations. Quality increased for all treatments in correlation to the amount of nitrogen applied to the turf. In general, the absence of nitrogen did not provide acceptable turf quality, especially in 2010. Nitrogen applied at the highest level did provide the highest level of quality, but also encouraged the highest level of crabgrass populations. Nitrog en fertility

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34 should be managed based on the level of expected quality with the knowledge that as quality increases, so does crabgrass incidence. Based on the results, no single management technique appears to be responsible for acceptable management of crabgrass. Turfgrass health should be considered first. Higher mowing heights and a moderate level of both irrigation and fertility are recommended as Best Management Principles (BMPs) for homeowners to follow. Those cultural factors evaluated in these studies that resulted in the best management of crabgrass also seemed to agree with these commonly followed BMPs.

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35 Table 2 1. Influence of irrigation and fertility on crabgrass cover in St. Augustinegrass in 2009 at Jay, FL Treatment % Crabgrass Cover Visual Irrigation Fertility (kg ha 1 ) 8 Jul 22 Jul 5 Aug 19 Aug 2 Sep 16 Sep No Irrigation 0 3.3 a c 10.0 b d 7.0 abd 24.4 ab 19.4 ab 20.6 ab 98 4.4 a c 16.9 a c 13.8 a c 32.2 ab 27.2 ab 23.3 ab 146 11.4 ab 26.6 ab 18.0 ab 37.2 ab 27.4 ab 28.3 ab 195 12.9 a 35.8 a 20.3 a 43.3 a 32.4 a 35.6 a ET Irrigation 0 0 c 0 d 3.3 dc 6.6 b 9.1 b 8.3 b 98 0 c 0.8 dc 2.1 dc 6.9 b 9.4 b 10.0 b 146 0 c 0.4 dc 3.2 dc 7.7 b 11.7 ab 12.2 ab 195 0.2 c 0.4 dc 3.7 dc 6.3 b 9.4 b 8.3 b Daily Irrigation 0 0.2 c 0 d 5.0 b d 5.8 b 7.3 b 8.3 b 98 0.8 c 6.3 dc 7.6 a d 11.3 ab 9.4 b 11.7 ab 146 0.4 c 4.1 dc 3.8 cd 6.6 b 7.8 b 9.7 b 195 1.4 bc 8.3 dc 6.4 a d 6.9 b 13.3 ab 9.4 b

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36 Table 2 2. Influence of irrigation and fertility on crabgrass grid count in St. A ugustinegrass in 2009 at Jay, FL. Treatment Crabgrass Grid Count a Irrigation Fertility (kg ha 1 ) 8 Jul 22 Jul 5 Aug 19 Aug 2 Sep 16 Sep No Irrigation 0 0.7 b 3.0 bc 5.3 a d 8.3 abc 5.7 abc 7.6 ab 98 2.8 ab 6.2 abc 7.3 abc 10.7 ab 8.8 ab 9.4 ab 146 3 .8 ab 9.9 ab 13.9 a 10.6 ab 8.7 ab 10.6 a 195 4.7 ab 15.2 a 13.0 ab 13.2 a 12.1 a 11.3 a ET Irrigation 0 0 b 0 c 0.8 d 4.9 abc 2.0 bc 3.4 ab 98 0 b 0.2 c 0.7 d 3.7 bc 2.7 bc 3.4 ab 146 0 b 0.6 c 0.7 d 4.2 bc 3.0 bc 4.4 ab 195 0 b 0.3 c 1.7 cd 3.8 abc 2.3 bc 2.8 b Daily Irrigation 0 0.1 b 0 c 3.3 cd 2.4 c 1.4 c 5.6 ab 98 0.6 b 1.8 bc 5.3 a d 3.2 bc 2.6 bc 4.8 ab 146 0 b 1.6 bc 3.8 bcd 3.2 bc 2.1 bc 4.1 ab 195 0.3 b 3.1 bc 4.8 a d 3.4 bc 3.7 bc 3.9 ab a Crabgrass presence measured with 36 squ are grid

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37 Table 2 3 Influence of irrigation and fertility on crabgrass cover in St. Augustinegrass in 2010 at Jay, FL. Treatment % Crabgrass Cover Visual Irrigation Fertility (kg ha 1 ) 26 May 8 Jun 23 Jun 7 Jul 21 Jul 3 Aug 18 Aug 3 Sep No Irrigati on 0 1.1 c 1.1 d 5.6 c 2.8 de 5.6 d 3.3 ef 7.2 def 12.2 cd 98 6.1 bc 12.2 bcd 16.1 bc 23.3 bc 18.9 c 23.3 bcd 31.1 bc 26.3 abc 146 7.8 abc 12.2 bcd 14.4 bc 28.9 abc 16.1 c 19.4 bcd 22.2 cd 21.7 bcd 195 3.9 bc 19.4 bcd 16.1 bc 25.6 abc 17.8 c 11.1 def 26.7 bc 16.7 cd ET Irrigation 0 2.8 bc 1.1 d 1.7 c 5.6 de 3.9 d 2.4 f 6.1 ef 5.0 d 98 2.2 bc 1.7 cd 0.6 c 18.3 cd 20.6 c 16.7 b e 15.0 c f 15.6 bcd 146 1.7 bc 2.2 cd 2.2 c 27.8 abc 22.2 bc 16.1 b e 17.8 cde 12.8 cd 195 1.1 c 3.3 cd 1.1 c 15.6 cde 2 0.0 c 14.4 c f 15.0 c f 12.4 cd Daily Irrigation 0 5.0 bc 0 d 3.9 c 1.1 e 0.6 d 3.9 ef 2.2 f 6.7 cd 98 16.1 ab 25.0 ab 30.6 ab 50.6 ab 49.4 ab 41.1 abc 46.7 abc 45.0 ab 146 25.0 a 30.6 ab 29.4 ab 58.9 a 62.2 a 41.7 ab 58.9 ab 52.2 a 195 25.6 a 54.4 a 56.7 a 58.9 a 73.9 a 62.2 a 70.0 a 50.6 a

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38 Table 2 4. Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass in 2010 at Jay, FL. Treatment Crabgrass Grid Count a Irrigation Fertility (kg ha 1 ) 26 May 8 Jun 23 Jun 7 Jul 2 1 Jul 3 Aug 18 Aug 3 Sep No Irrigation 0 1.1 c 1.1 d 5.6 c 2.8 de 5.6 d 3.3 ef 7.2 def 12.2 cd 98 6.1 bc 12.2 bcd 16.1 bc 23.3 bc 18.9 c 23.3 bcd 31.1 bc 26.3 abc 146 7.8 abc 12.2 bcd 14.4 bc 28.9 abc 16.1 c 19.4 bcd 22.2 cd 21.7 bcd 195 3.9 bc 19.4 bcd 16.1 bc 25.6 abc 17.8 c 11.1 def 26.7 bc 16.7 cd ET Irrigation 0 2.8 bc 1.1 d 1.7 c 5.6 de 3.9 d 2.4 f 6.1 ef 5.0 d 98 2.2 bc 1.7 cd 0.6 c 18.3 cd 20.6 c 16.7 b e 15.0 c f 15.6 bcd 146 1.7 bc 2.2 cd 2.2 c 27.8 abc 22.2 bc 16.1 b e 17.8 cde 12.8 c d 195 1.1 c 3.3 cd 1.1 c 15.6 cde 20.0 c 14.4 c f 15.0 c f 12.4 cd Daily Irrigation 0 5.0 bc 0 d 3.9 c 1.1 e 0.6 d 3.9 ef 2.2 f 6.7 cd 98 16.1 ab 25.0 ab 30.6 ab 50.6 ab 49.4 ab 41.1 abc 46.7 abc 45.0 ab 146 25.0 a 30.6 ab 29.4 ab 58.9 a 62.2 a 41.7 ab 58.9 ab 52.2 a 195 25.6 a 54.4 a 56.7 a 58.9 a 73.9 a 62.2 a 70.0 a 50.6 a a Crabgrass presence measured with 36 square grid

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39 Table 2 5. Influence of mowing height on c rabgrass cover in St. Augustinegrass in 2009 at Jay, FL. Treatment % Crabgra ss Cover Visual Mowing Height (cm) 8 Jul 22 Jul 5 Aug 19 Aug 2 Sep 16 Sep 5.1 2.6 a 7.6 a 6.6 a 12.6 a 11.6 a 12.8 a 7.6 3.0 a 10.0 a 8.2 a 16.8 a 16.6 a 15.8 a 10.2 3.2 a 9.8 a 8.7 a 19.3 a 17.8 a 17.8 a Table 2 6. Influence of mowing height on crabgrass grid count in St. Augustinegrass in 2009 at Jay, FL. Treatment Crabgrass Grid Count a Mowing Height (cm) 8 Jul 22 Jul 5 Aug 19 Aug 2 Sep 16 Sep 5.1 1.1 a 3.8 a 4.3 a 4.8 a 3.4 b 4.4 b 7.6 1.4 a 3.4 a 5.1 a 5.7 a 4.5 ab 6.0 ab 10.2 0.7 a 3.3 a 5.8 a 7.4 a 5.9 a 7.4 a a Crabgrass presence measured with 36 square grid

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40 Table 2 7 Influence of mowing height on c rabgrass cover in St. Augustinegrass in 2010 at Jay, FL Treatment % Crabgrass Cover Visual Mowing Height (cm) 26 May 8 Jun 23 Jun 7 Jul 21 Jul 3 Aug 18 Aug 3 Sep 5.1 12.6 a 21.4 a 17.9 a 38.8 a 30.7 a 23.9 a 25.7 a 25.6 a 7.6 6.1 a 8.9 b 12.6 a 25.0 ab 25.3 a 20.8 a 29.3 a 22.3 a 10.2 5.8 a 10.6 ab 14.0 a 15.6 b 21.8 a 19.2 a 24.7 a 21.4 a Table 2 8. Influence of mowing height on crabgrass grid count in St. Augustinegrass in 2010 at Jay, FL Treatment Crabgrass Grid Count a Mowing Height (cm) 26 May 8 Jun 23 Jun 7 Jul 21 Jul 3 Aug 18 Aug 3 Sep 5.1 4.8 a 6.3 a 2.9 a 19.1 a 17.6 a 11.7 a 14.9 a 14.4 a 7.6 2.3 ab 3.6 a 2.2 a 11. 9 ab 13.2 ab 9.4 a 13.5 ab 11.7 a 10.2 1.6 b 3.2 a 2.1 a 7.7 b 9.9 b 8.2 a 9.7 b 10.5 a a Crabgrass presence measured with 36 square grid

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41 Table 2 9. Influence of fertility on crabgrass cover in St. Augustinegrass in 2009 at Citra, FL Treatment % Cra bgrass Cover Visual Fertility (kg ha 1 ) 17 Jul 4 Aug 18 Aug 0 1.4 a 2.6 b 2.8 b 98 2.7 a 9.7 ab 12.8 ab 146 1.8 a 28.6 a 27.8 a 195 6.1 a 35.0 a 36.3 a Table 2 10. Influence of fertility on crabgrass cover in St. Augustinegrass in 2010 at Citra, FL Treatment % Crabgrass Cover Visual Fertility (kg ha 1 ) 10 Jun 23 Jun 5 Jul 23 Jul 30 Aug 0 0.6 b 1.1 c 5.0 b 0 b 0 b 98 9.4 a 13.3 b 35.0 a 32.2 a 5.6 a 146 16.7 a 23.9 ab 27.2 a 35.6 a 4.1 a 195 27.8 a 38.3 a 44.4 a 47.2 a 12.2 a Table 2 11. Influence of fertility on crabgrass grid count in St. Augustinegrass in 2009 at Citra, FL Treatment Crabgrass Grid Count a Fertility (kg ha 1 ) 17 Jul 4 Aug 18 Aug 0 0.6 b 1.0 b 1.8 b 98 4.0 ab 5.4 ab 5.7 ab 146 2.4 ab 10.1 a 9.6 a 195 6.1 a 12.6 a 11 .1 a a Table 2 12. Influence of fertility on crabgrass grid count in St. Augustinegrass in 2010 at Citra, FL Treatment Crabgrass Grid Count a Fertility (kg ha 1 ) 10 Jun 23 Jun 5 Jul 23 Jul 30 Aug 0 0.7 b 0.2 c 1.0 b 0 b 0 b 98 4.0 a 4.8 b 14.1 a 14.2 a 3.2 a 146 5.1 a 8.1 ab 21.1 a 15.8 a 3.3 a 195 10.2 a 11.8 a 24.8 a 21.0 a 7.0 a a

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42 Table 2 13. Response of St. Augustinegrass to fertility in 2009 in Jay, FL. Treatment Turfgrass Quality a Fertility (kg ha 1 ) 8 Jul 22 Jul 5 Aug 19 Aug 2 Sep 16 Sep 0 4.9 c 4.9 c 5.8 d 5.9 c 5.9 c 5.9 c 98 5.7 b 5.7 b 6.2 c 6.3 b 6.2 b 6.4 b 146 6.1 ab 6.1 ab 6.4 b 6.5 b 6.4 b 6.4 b 195 6.4 a 6.4 a 6.7 a 6.9 a 6.8 a 6.9 a a measured using NTEP 1 9 rating scale Table 2 15. Respon se of St. Augustinegrass to fertility in 2009 in Citra, FL. Treatment Turfgrass Quality a Fertility (kg ha 1 ) 17 Jul 4 Aug 18 Aug 12 Sep 0 5.8 c 5.8 c 5.4 c 5.9 b 98 6.7 b 6.6 b 6.1 b 6.5 a 146 6.9 ab 6.7 ab 6.2 b 6.9 a 195 7.3 a 7.1 a 6.6 a 6.9 a a m easured using NTEP 1 9 rating scale Table 2 14. Response of St. Augustinegrass to fertility in 2010 in Jay, FL. Treatment Turfgrass Quality a Fertility (kg ha 1 ) 26 May 8 Jun 23 Jun 7 Jul 21 Jul 3 Aug 18 Aug 3 Sep 0 4.6 c 4.0 d 4. 1 c 3.8 c 3.9 c 4.2 c 4.1 c 4.2 b 98 5.5 b 5.2 c 5.3 b 6.0 b 5.8 b 6.2 b 6.5 b 7.1 a 146 5.9 ab 5.7 b 5.7 b 6.5 a 6.3 ab 6.6 ab 7.1 a 7.4 a 195 6.2 a 6.3 a 6.3 a 6.8 a 6.8 a 6.8 a 7.3 a 7.1 a a measured using NTEP 1 9 rating scale

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43 Table 2 16. Response of St. Augustinegrass to fertility in 2010 in Citra, FL. Treatment Turfgrass Quality Fertility (kg ha 1 ) 10 Jun 23 Jun 5 Jul 23 Jul 30 Aug 0 3.6 c 3.8 c 3.9 b 3.9 c 4.2 b 98 4.7 b 5.1 b 5.6 a 5.9 b 6.1 a 146 5.2 a 5.8 a 5.7 a 6.5 a 6.3 a 195 5.4 a 6.2 a 6.1 a 6.6 a 6.5 a a measured using NTEP 1 9 rating scale

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44 Figure 2 1 Influence of irrigation and fertility on crabgrass grid count in St. Augustineg rass with no irrigation in 2009 in Jay, FL Figure 2 2 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with ET irrigation in 2009 in Jay, FL. Figure 2 3 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with daily irrigation in 2009 in Jay, FL.

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45 Figure 2 4. Influence of irrigation and fertility on crabgrass grid count in S t. Augustinegrass with no irrigation in 2010 in Jay, FL. Figure 2 5 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with ET irrigation in 2010 in Jay, FL. Figure 2 6 Influence of irrigation and fertility on crabgrass grid count in St. Augustinegrass with daily irrigation in 2010 in Jay, FL.

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46 Figure 2 7 Total rainfa ll by month in 2009 and 20 10 in Jay, FL Figure 2 8 Total rainfall by month in 2009 and 20 10 in Citra, FL.

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47 CHAPTER 3 ALTERNATIVE HERBICIDES Southern crabgrass ( Digitaria ciliaris (Retz.) Koeler ) is an annual summer grass species that is found in many o f the tropical and subtropical areas of the world (Clayton et al. 2006). It is native to the Old World, and can be found throughout the s outheast region of the United St ates, including Florida (Murphy 2007). Common names include grass, and tropical finger grass. It commonly invades pastures, lawns, roadsides, and open areas (Holm et al. 1977 ). St Augustinegrass ( Stenotaphrum secundatum [Walt.] Kuntze) is the most widely grown turfgrass for lawns in the state of Florida (Hodge s et al. 1994). It is characterized by coarse leaf blades, aggressive growth habit which forms a dense canopy, and thick stolons (Christians 2004) St. Augustinegrass is also sensitive to many herbicides used to control crabgrass in other turfgrasses (Un ruh 2009) Label changes and restrictions of herbicides previously used for crabgrass control in St. Augustinegrass have eliminated postemergence herbicide options for this weed in residential St. Augustinegrass, leading homeowners to search for new produ cts and met hods for crabgrass management. Alternative herbicides can be generalized as materials that have been used for weed control or suppression that are not traditional synthetic chemicals. Many are products common in household s, including sodium bi carbonate, acetic acid (vinegar), and borax. AG Crabgrass Killer is marketed by Garden Weasel for crabgrass control in turf contains sodium bicarbonate, cinnamon, cumin, and corn and wheat flour (Anonymous 2005) The active ingredient for AG Crabgrass Ki ller is listed as cinnamon, with inert ingredients making up the remainder of the product. Because of the lack of

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48 research on the effectiveness of these products as herbicides, evaluation is needed to determine which ingredients are causing weed control. Current research with alternative herbicides is almost completely related to weed control in organic cropping systems (Chase et al. 2004) The objectives of this research were to 1) evaluate southern crabgrass control provided by selected alternative her bicides 2) measure tolerance of St. A ugustinegrass to these products and 3) to assess the ingredients of AG Crabgrass Killer for effectiveness at controlling southern crabgrass. Materials and Methods Alternative Herbicide Greenhouse Evaluation Southern crabgrass from Elstel Farm and Seeds 1 was overseeded at a rate of 98 kg ha 1 on the soil surface in 58 cm 2 pots filled with potting media Fafard Mix #4 2 After crabgrass emergence, plants were evaluated frequently for stage of growth. Herbicides treatment s were applied at three growth stages; 1 2 leaf, 3 4 leaf, and 1 2 tiller in each of two trials (Trial I and Trial II) A list of products and use rates is outlined in Table 3 1. Sodium bicarbonate and AG Crabgrass Killer were applied to crabgrass using a shaker can. A pplications labeled as dry were applied to dry foliage (Table 3 1) Wet treatments were applied to wet foliage, and lightly misted until all product was adequately moist. Vinegar, borax, and asulam were applied with a boom sprayer using a CO 2 propellant with 11002 flat fan nozzles calibrated to deliver 187 L ha 1 at 159 kPa. Vinegar treatments that required a second application were applied 7 days after initial applications. For Trial II, asulam was added as a comparative control treatme nt to 1 Elstel Farm and Seeds 2640 Springdale R oad, Ardmore, OK 73401 9106 2 Fafard, Inc. PO Box 790 Agawam, MA 0100 0790 (40% peat, 30% bark, 30% vermiculite v/v).

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49 compare crabgrass control between alternative herbicides and a common synthetic herbicide used in Augustinegrass sod production. Visual estimates of crabgrass control were recorded at 1, 3, 7, 14, 21, and 28 days after application (DAA). Control was evaluated using a scale of 0 to 100%, where 0 indicated no crabgrass control and 100 equals crabgrass death At the end of each experiment southern crabgrass shoots were harvested and oven dried at 65 C for 5 days and shoot dry weights (g) were recorded All studies were arranged in a randomized complete block design with four replications and were conducted twice. Data were analyzed using analysis of variance and means were separated using a LSD (0.05). Alternative Herbicide Field Evaluation So uthern crabgras s was overseeded at a rate of 98 kg ha 1 in established in Jay, F lorida in 2009 and 2010 After emergence, crabgrass plants were evaluated frequently for stage of growth. Treatments were applied at 1 2 leaf and 1 2 tiller crabgrass growth stage. A list of treatments is outlined in Table 3 2. Plots measured 1.5 m by 3.0 m and t reatments were arranged in a randomized complete block design with 3 replications and were conducted twice. Sodium bicarbonate and AG Cra bgrass Killer treatments were applied using a shaker can to plots wet from dew or irrigation event. Vinegar and borax were applied with a boom sprayer using a CO 2 propellant with 11002 flat fan nozzles calibrated to deliver 187 L ha 1 at 159 kPa. Subseque nt vinegar applications were applied 7 da ys after initial applications. Turfgrass injury and crabgrass control were visually evaluated at 1, 3, 7, 14, 21, and 28 DAA. Turfgrass injury ratings were based on a scale of 0 to 100%, 0 indicating no turf injur y and 100 equaling completely brown turfgrass.

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50 Crabgrass control was evaluated using a scale of 0 to 100%, where 0 indicated no crabgrass control and 100 equal to complete crabgrass control Data were analyzed using analysis of variance and means were se parated using an LSD value (0.05). AG Crabgrass Killer Ingredient Greenhouse Evaluation Southern c rabgrass was seeded at 98 kg ha 1 in to 58 cm2 pots containing Farfald Mix #4 2 Crabgrass was evaluated after emergence to confirm the correct growth s tage. Treatments were applied to crabgrass at 1 2 leaf and 3 4 leaf stages. A list of treatments is outlined in Table 3 3. All treatments were applied using a shaker can. Crabgrass control was visually evaluated at 3, 7, 14, 21, and 28 DAT. Control wa s evaluated using a scale of 0 to 100%, where 0 indicated no crabgrass control and 100 equal to complete crabgrass control At the end of each experiment crabgrass shoots were harvested and oven dried at 65 C for 5 days and shoot dry weights (g) were reco rded. All studie s were arranged in a randomized complete block design with four replications. Data was analyzed using analysis of variance and means were separated with LSD (0.05). Results and Discussion Alternative Herbicide Greenhouse Evaluation Crabgr ass control There was an interaction between trials and growth stages for the greenhouse experiments ; therefore data were analyzed separately for both trials and all stages of growth. The data presented are the 7 and 21 DAA ratings These data were sele cted to represent control after the product had a short period of time to interact with crabgrass (7 DAA) and control after a longer interval to determine if regrowth would occur (21 DAA).

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51 Alternative herbicides provided an acceptable level of southern c rabgrass control (70%) only when applied to crabgrass at the 1 2 leaf stage and evaluated 7 DAA for both trials (Tables 3 4 and 3 5) Control of southern crabgrass 7 DAA was 70% in both trials with two applications of 300 g rain v inegar at 281 L ha 1 (Table 3 4 and 3 5). Two higher rates of AG Crabgrass Killer ( 977 and 1465 kg ha 1 ) applied to wet foliage provided 70% control 7 DAA (Table 3 4 and 3 5). Borax did not offer 64 % control at any leaf stage in either trial 7 DAA (Table 3 4 and 3 5). For most treatments, southern crabgrass control decreased between 7 DAA and 21 DAA. Asulam was the only treatment that provided 70% control of 1 2 and 3 4 leaf crabgrass at 21 DAA in Trial II (Table 3 7). No treatment achieved 70% control of 1 2 tiller stage crabgrass 21 DAA. Products in these trials are generally not manufactured for use as herbicides. Inconsistent control can result from the inability of products to rema in on leaf surfaces, especially in the case of sodium bicarbonate applied directly to plants in a powder form. Borax and vinegar applied as a spray in a liquid form were not mixed with any surfactants, which may have limited the amount of product that rem ained on the leaf surfaces. The impact of surfactants added to these products has not been evaluated. When applied to the leaf surface, th e products tended to bead up on the cuticle of the crabgrass leaf. Surfactants are added to decrease surface tensio n of water droplets, leading to more material coming into contact to the leaf surface and possibly increasing control (Jansen et al. 1961) When using contact materials, the effectiveness of the product often correlates with the amount that comes in conta ct with the leaf surface.

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52 Differences in control between trials and growth stages may be explained by water droplet properties and contact with the leaf surface. Shoot dry weights There was a trial by treatment and growth stage by treatment interaction; t herefore data are shown separately. Significant shoot weight differenc es were seen in both trials for most treatments applied at the 1 2 leaf stage. Shoot weights were less for t reatments at the 3 4 leaf stage and decreased even more at the 1 2 tiller st age. Vinegar provided significantly lower shoot weights compared to the untreated in both trials when applied at the 1 2 leaf stage (Table 3 8 and 3 9) Increased rates or multiple applications of vinegar at any growth stage did not reduce shoot weights more than single applications at lower rates in both trials with the exception of 281 L ha 1 rate in 2009 (Table 3 8) This is similar to what was observed with visual ratings, where control did not differ between treatments for applications made at later growth stages (Table 3 4). The use of s odium bicarbonate products resulted in significantly lower crabgrass shoot dry weights than untreated plants when applied at the 1 2 leaf stage (Table 3 8 and 3 9) Higher rates ( 977 kg ha 1 ) of AG Crabgrass Killer generally reduced shoot weights the most while lower rates ( 488 kg ha 1 ) of AG Crabgrass Killer and sodium bicarbonate resulted in higher shoot weights than the higher treatments No consistent differences were obser ved whether sodium bicarbonate products were applied to wet versus dry foliage. The shoot weight results were consistent with those obtained from visual ratings, were higher rates of AG Crabgrass Killer provided better crabgrass control (Table 3 4 and 3 5 ). Borax treatments reduced shoot weights only when applied at the 1 2 leaf stage (Table 3 8 and 3 9) There were no consistent differences between rate of borax and shoot dry weight. These results were similar to visual evaluations of

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53 crabgrass control from borax applied in greenhouse trials (Table 3 4 and 3 6). Asulam had the greatest effect on reducing shoot weight at the two smaller growth stages of any treatment in Trial II (Table 3 9). Shoot weight reductions of asulam were comparable to other trea tments when applied to larger crabgrass stages The differences in dry shoot weights between the two studies could be attributed to fluctuations in temperatures. Both trials were conducted in an opaque greenhouse in Jay, FL Temperatures during trial dat es fluctuated from a low of 15 C at night to a high of 35 C during the day. In Trial I, there was a large difference between shoot weights from different growth stages, especially at 1 2 leaf stage. An explanation could be that crabgrass for the larger we ed stages (3 4 leaf and 1 2 tiller) was grown during the months of June and July, when crabgrass growth is optim al Crabgrass used for the 1 2 leaf treatments was planted in August, and treatments extended into September. In Trial II, crabgrass was plant ed in M ay and treatments for each crabgrass growth stage were applied in succession throughout the month. The late planting in August of crabgrass used for the 1 2 leaf treatments in Trial I may have affected crabgrass growth, leading to slower growth and lower shoot weights. Alternative Herbicide Field Evaluation Crabgrass control There was an interaction between treatments and years and treatments and growth stages for field trials; therefore data w ere analyzed separately for both trials and all stages of growth. The data presented w ere collected at either 7 or 21 DAA for comparison to greenhouse trials No treatment provided an acceptable level ( 70 %) crabgrass control at either stage when evaluated 21 DAA for both years.

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54 At the 1 2 leaf stage, sodi um bicarbonate and AG Crabgrass Killer applied at 4 88 and 1465 kg ha 1 provided 45 % control both years when evaluated 7 DAA (Table 3 10 and Table 3 11). By 21 DAA, 50 % control was achieved in both years by AG Crabgrass Killer applied at 488 kg ha 1 (Table 3 12 and Table 3 13). All other tre atments provided < 50% control in at least one of the years observed. When compared to results from greenhouse trial s all vinegar treatments had control levels of >10% lower in the field. A possible explanati on is the height difference between crabgrass and St. Augustinegrass at the different weed stages. St. Augustinegrass used in the study was maintained at approximately 7.5 cm. At the 1 2 leaf stage, crabgrass is approximately 4 5 cm in height. The highe r height of St. Augustinegrass may have prevented even coverage of crabgrass foliage, reducing the effectiveness of the vinegar treatments. Sodium bicarbonate products also showed consistently less control in field trials than greenhouse trials. These pr oducts are applied directly to plant foliage in a powder form and must retain contact with the leaf surface to have activity. Because field conditions have greater environmental variability ( i.e., wind and rainfall), the product was more likely to be blow n or washed off the leaf surface, causing reductions in control. As with vinegar and sodium bicarbonate borax treatments were also not as effective in field trials for crabgrass control. For most ratings, control was <10% for both leaf stages. The decr ease in effectiveness could again be due to different environmental factors Southern crabgrass is a summer annual and begins to senesce as day and night temperatures begin to decrease in the fall (Uva et al. 1997) As temperatures fall, crabgrass popula tions begin to decline as they complete their life cycle. Treatments for

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55 the 1 2 tiller growth stage in 2009 were applied on August 4. Decreasing temperature and crabgrass plants that are completing their life cycle may explain the increase in crabgrass control. This would indicate that the effectiveness of the products is not increasing; rather, increased control is a result of naturally declining weed populations. St. Augustinegrass tolerance There was an interaction between treatments and years and t reatments and growth stages for field trials; therefore data w ere analyzed separately for both trials and all stages of growth. The data presented w ere taken either at 7 or 21 DAA because they represent injury observed after the product ha d a short perio d of time to interact with St. Augustinegrass (7 DAA) and the relative rate of turf recovery over time (21 DAA). For most turfgrass applications, 20% turfgrass injury is considered a maximum acceptable threshold. In this study, any injury > 20% would be considered unacceptable. At 7 DAA borax was the only product that was rated at <15% St. Augustinegrass injury when applied to 1 2 leaf stage crabgrass (Table 3 1 4 and Table 3 15). All vinegar, sodium bicarbonate, and AG Crabgrass Killer treatments cau sed unacceptable levels of injury when applied to 1 2 leaf stage crabgrass. At the 1 2 tiller crabgrass stage, turfgrass injury was 15% for all rates of vinegar, sodium bicarbonate and AG Crabgrass Killer at 1465 kg ha 1 in 2009 Unacceptable levels of injury occurred both years from all treatments of vinegar and sodium bicarbonate. By 21 DAA, turfgrass injury was <15% for all tre atments in both years (Table 3 16 and Table 3 17). Injury levels in 2009 were unacceptable for vinegar applied in multiple applications (> 50%), but injury was 5% in 2010 for the same treatment. When applied at the 1 2 tiller stage of crabgrass growth, both multiple ap plication treatments

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56 of vinegar, sodium bicarbonate and AG Crabgrass Killer at 1465 kg ha 1 caused 15% injury both years. Multiple applications of vinegar caused unacceptable injury in both years, while single applications of vinegar h ad unacceptable injury levels only in 2009 (Table 3 16). All sodium bicarbonate products treatments (including AG Crabgrass Killer) were acceptable in 2009 (Table 3 16) I n 2010 injury was unacceptable only when applied at 1465 kg ha 1 (Table 3 17). Di fferences in turfgrass injury between years may be due to the age of the St. Augustinegrass used for these studies. Turfgrass injury can be prolonged if applied to newly sodded turf (McCarty et al. 1995) The St. Augustinegrass block utilized for these s tudies was sodded in March of 2009 and the 2009 treatments were applied to relatively new established turf. By 2010, the turfgrass was well established. Periods of dry weather and other environmental factors could also delay turf recovery. In 2009, crabg rass overseeding was delayed due to turf establishment; therefore, 1 2 leaf treatments were applied July 9 and 1 2 tiller treatments on August 4. In 2010, 1 2 leaf treatments were applied on May 5, with 1 2 tiller treatments applied on June 8. The differ ence in timings may have impacted the level and duration of St. Augustinegrass injury observed. The month of June in Florida is often characterized by high temperatures and dry conditions. The most prolonged injury was seen from treatments applied in Jun e and July. The environmental conditions during these months including high temperatures may explain higher levels of initial a nd prolonged turfgrass injury. AG Crabgrass Killer Ingredient Evaluation A treatment by growth stage interaction was observed f or crabgrass control; therefore, growth stages are shown separately. At the 1 2 leaf stage, both rates of AG

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57 Crabgrass Killer and the sodium bicarbonate applied at 967 kg ha 1 provided 70% crabgrass control (Table 3 18). For most treatments, control wa s less at the 3 4 leaf stage than the 1 2 leaf stage. AG Crabgrass Killer and sodium bicarbonate did not provided a cceptable control when applied to 3 4 leaf stage crabgrass Cinnamon and cumin did not provide acceptable crabgrass control when applied to either growth stage. There was no interaction between treatments and growth stages for crabgrass dry weight; therefore data were pooled from each growth stage. Shoot dry weights that were different from the untreated control included both rates of AG Crabgrass Killer and sodium bicarbonate, and cinnamon applied at 9.3 kg ha 1 (Table 3 19). Both rates of AG Crabgrass Killer and sodium bicarbonate had lower shoot wei ghts than any other treatment. Cinnamon is labeled as the active ingredient in Crabgras s Killer, with all other materials tested listed as inert ingredients (Anonymous 2005) Only treatments containing sodium bicarbonate provided any crabgrass control at both leaf stages. Cumin and cinnamon showed inconsistent control and generally insigni ficant changes in crabgrass shoot dry weight. The results did show an increase in weed control with a combination of cinnamon, sodium bicarbonate and cumin. Another product on the label is wheat and corn flour, though neither have been reported to have h erbicidal properties for postemergence control (Anonymous 2005). The flour components may have been added to improve handling characteristics and improve efficiency. When sodium bicarbonate was applied separately, it tend ed to clump with moisture and doe s not adhere well to the leaf surface. AG Crabgrass Killer does adhere to the leaf surface well, even when moisture is present. The addition of flour in the formulation appears to

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58 improve the ability of AG Crabgrass Killer to remain on the leaf, which ma y lead to an increase in efficacy of sodium bicarbonate due to increased surface contact. Summary Because of the lack of synthetic postemergence herbicide options available to homeowners for southern crabgrass control in St. Augustinegrass, alternative her bicides are being considered in management strategies. Recent shifts in public opinion have also increased interest and demand for organic options for weed control, particularly in home lawn situations. Sodium bicarbonate, vinegar, and borax were all con sidered due to previous research showing herbicidal activity of these materials. Greenhouse trials showed that crabgrass was controlled by these products when applied to the smallest growth stage tested. Repeat applications of vinegar and AG Crabgrass Ki ller were initially effective, but crabgrass recovered after a few weeks. Asulam, a synthetic herbicide included for comparison, was the only treatment to maintain acceptable levels of crabgrass control over time. In field trials, no alternative herbicide tested provided lasting control of southern crabgrass. Because of recovery patterns in crabgrass, additional trials need to be conducted testing multiple applications of sodium bicarbonate products. Vinegar and sodium bicarbonate were both very injuriou s to St. Augustinegrass. Recovery was rapid for most vinegar applications and turf injured by sodium bicarbonate products was slower to recover. If used, both products would have to be used as spot treatments in highly infested areas due to high injury l evels to turfgrass. If alternative herbicides are used for southern crabgrass management, control used as a means of suppression, and used with other weed management practices. If

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59 utilized they would have to be applied to small crabgrass growth, preferably at or immediately after emergence for control.

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60 Table 3 1. Alternative herbicide treatments for greenhouse evaluation Treatment Rate 1 Untreated 2 300 Grain Vinegar a 187 L ha 1 3 300 Grain Vinegar a 187 L ha 1 + 300 Grain Vinegar + 187 L ha 1 4 300 Grain Vinegar a 28 1 L ha 1 5 300 Grain Vinegar a 28 1 L ha 1 + 300 Grain Vinegar + 28 1 L ha 1 6 300 Grain Vinegar a 374 L ha 1 7 AG Crabgrass Killer cd 244 kg ha 1 8 AG Crabgrass Killer cd 488 kg ha 1 9 AG Crabgrass Killer cd 97 7 kg ha 1 10 AG Crabgrass Killer cd 146 5 kg ha 1 11 Sodium Bicarbonate d 146 5 kg ha 1 12 AG Crabgrass Killer ce 244 kg ha 1 13 AG Crabgrass Killer ce 488 kg ha 1 14 AG Crabgrass Killer ce 97 7 kg ha 1 15 AG Crabgrass Killer ce 146 5 kg h a 1 16 Sodium Bicarbonate e 146 5 kg ha 1 17 Borax b 15 kg ha 1 18 Borax b 30 kg ha 1 19 Borax b 61 kg ha 1 a acetic acid 30% b borax 99.5% c active cinnamon 0.95%, inert sodium bicarbonate, corn and wheat flour, cumin 99.1% d wet e dry

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61 Tab le 3 2. Alternative herbicide treatments for field evaluation. Treatment Rate 1 Untreated 2 300 Grain Vinegar a 187 L ha 1 3 300 Grain Vinegar a 187 L ha 1 + 300 Grain Vinegar + 187 L ha 1 4 300 Grain Vinegar a 28 1 L ha 1 5 300 Grain Vinegar a 28 1 L ha 1 + 300 Grain Vinegar + 28 1 L ha 1 6 300 Grain Vinegar 374 L ha 1 7 AG Crabgrass Killer c 244 kg ha 1 8 AG Crabgrass Killer c 488 kg ha 1 9 AG Crabgrass Killer c 97 7 kg ha 1 10 AG Crabgrass Killer c 146 5 kg ha 1 11 Sodium Bicarbonate 146 5 kg ha 1 12 Borax b 15 kg ha 1 13 Borax b 30 kg ha 1 14 Borax b 61 kg ha 1 a acetic acid 30% b borax 99.5% c active cinnamon 0.95%, inert sodium bicarbonate, corn and wheat flour, cumin 99.1% Table 3 3. Treatments for AG Crabgrass Killer ingredi ent evaluation. Treatment Rate 1 Untreated 2 Cinnamon 4.6 kg ha 1 3 Cinnamon 9.3 kg ha 1 4 Sodium Bicarbonate 484 kg ha 1 5 Sodium Bicarbonate 967 kg ha 1 6 Crabgrass Killer a 488 kg ha 1 7 Crabgrass Killer a 977 kg ha 1 8 Cumin 9.3 kg ha 1 a a ctive cinnamon 0.95%, inert sodium bicarbonate, corn and wheat flour, cumin 99.1%

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62 Table 3 4. Crabgrass control with alternative herbicides in the greenhouse 7 days after application Trial I Crabgrass Growth Stage Treatment Rate 1 2 Leaf 3 4 Leaf 1 2 Tiller ----------% Contro l --------Untreated 0 kg ha 1 0 0 0 300 Grain Vinegar 187 L ha 1 63 5 2 + 300 Grain Vinegar + 187 L ha 1 62 5 10 300 Grain Vinegar 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 57 10 15 300 Grain Vine gar 28 1 L ha 1 87 13 15 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 95 15 15 AG Crabgrass Killer a 244 kg ha 1 23 0 13 AG Crabgrass Killer a 488 kg ha 1 56 5 20 AG Crabgrass Killer a 97 7 kg ha 1 81 31 25 AG Crabgrass Killer a 146 5 kg ha 1 91 66 26 Sodium Bicarbonate a 146 5 kg ha 1 26 16 18 AG Crabgrass Killer b 244 kg ha 1 40 14 6 AG Crabgrass Killer b 488 kg ha 1 68 23 11 AG Crabgrass Killer b 97 7 kg ha 1 89 24 20 AG Crabgrass Killer b 146 5 kg ha 1 73 31 34 Sodium Bicarbonate b 14 6 5 kg ha 1 43 19 19 Borax 15 kg ha 1 11 18 5 Borax 30 kg ha 1 6 13 6 Borax 61 kg ha 1 9 10 19 LSD (0.05) 22 10 6 CV% 30 40 28 a wet b dry

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63 Table 3 5 Crabgrass control with alternative herbicides in the greenhouse 7 days after a pplication Trial II Crabgrass Growth Stage Treatment Rate 1 2 Leaf 3 4 Leaf 1 2 Tiller ----------% Contro l --------Untreated 0 kg ha 1 0 0 0 300 Grain Vinegar 187 L ha 1 38 13 10 + 300 Grain Vinegar + 187 L ha 1 46 28 6 300 Grain Vinegar 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 64 48 15 300 Grain Vinegar 28 1 L ha 1 83 59 20 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 55 24 25 AG Crabgrass Killer a 244 kg ha 1 38 13 9 AG Crabgrass Killer a 488 kg ha 1 50 19 5 AG Crabgrass Killer a 97 7 kg ha 1 75 38 16 AG Crabgrass Killer a 146 5 kg ha 1 85 45 18 Sodium Bicarbonate a 146 5 kg ha 1 49 11 20 AG Crabgrass Killer b 244 kg ha 1 44 10 4 AG Crabgrass Killer b 488 kg ha 1 55 8 10 AG Crabgrass Killer b 97 7 kg ha 1 48 14 8 AG Crabgrass Killer b 146 5 kg ha 1 65 14 6 Sodium Bicarbonate b 146 5 kg ha 1 44 16 11 Borax 15 kg ha 1 11 4 4 Borax 30 kg ha 1 35 14 5 Borax 61 kg ha 1 64 15 6 Asulam 2.3 kg ha 1 39 15 5 LSD (0.05) 14 10 9 CV% 20 36 63 a wet b d ry

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64 Table 3 6. Crabgrass control with alternative herbicides in the greenhouse 21 days after application Trial I Crabgrass Growth Stage Treatment Rate 1 2 Leaf 3 4 Leaf 1 2 Tiller ----------% Contro l --------Untreated 0 kg ha 1 0 0 0 300 Grain Vinegar 187 L ha 1 53 7 5 + 300 Grain Vinegar + 187 L ha 1 55 10 7 300 Grain Vinegar 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 37 18 5 300 Grain Vinegar 28 1 L ha 1 67 23 17 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 95 10 15 AG Crabgrass Killer a 244 kg ha 1 25 10 5 AG Crabgrass Killer a 488 kg ha 1 39 10 9 AG Crabgrass Killer a 97 7 kg ha 1 88 21 14 AG Crabgrass Killer a 146 5 kg ha 1 93 36 18 Sodium Bicarbonate a 146 5 kg ha 1 45 19 9 AG Crabgrass Killer b 244 kg ha 1 39 10 6 AG Crabgrass Killer b 488 kg ha 1 65 21 6 AG Crabgrass Killer b 97 7 kg ha 1 87 19 12 AG Crabgrass Killer b 146 5 kg ha 1 83 18 14 Sodium Bicarbonate b 146 5 kg ha 1 43 8 8 Borax 15 kg ha 1 34 5 5 Borax 30 kg ha 1 25 5 6 Borax 6 1 kg ha 1 33 13 9 LSD (0.05) 27 4 4 CV% 35 21 31 a wet b dry

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65 Table 3 7. Crabgrass control with alternative herbicides in the greenhouse 21 days after application Trial II Crabgrass Growth Stage Treatment Rate 1 2 Leaf 3 4 Leaf 1 2 Tiller ----------% Contro l --------Untreated 0 kg ha 1 0 0 0 300 Grain Vinegar 187 L ha 1 20 3 3 + 300 Grain Vinegar + 187 L ha 1 29 3 3 300 Grain Vinegar 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 44 15 1 300 Grain Vinegar 28 1 L ha 1 45 19 1 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 49 4 4 AG Crabgrass Killer a 244 kg ha 1 15 0 1 AG Crabgrass Killer a 488 kg ha 1 16 0 0 AG Crabgrass Killer a 97 7 kg ha 1 31 6 5 AG Crabgrass Killer a 146 5 kg ha 1 52 8 4 Sodium Bicarbonate a 146 5 kg ha 1 24 0 7 AG Crabgrass Killer b 244 kg ha 1 11 0 0 AG Crabgrass Killer b 488 kg ha 1 10 0 2 AG Crabgrass Killer b 97 7 kg ha 1 18 1 1 AG Crabgrass Killer b 146 5 kg ha 1 20 0 5 Sodium Bicarbonate b 146 5 kg ha 1 10 5 3 Borax 15 kg ha 1 5 0 3 Borax 30 kg ha 1 8 1 3 Borax 61 kg ha 1 19 4 5 Asulam 2.3 kg ha 1 87 74 50 LSD (0.05) 12 6 10 CV% 32 56 146 a wet b dry

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66 Table 3 8 Crabgrass shoot dry weights Trial I Crabgrass Growth Stage Trea tment Rate 1 2 Leaf 3 4 Leaf 1 2 Tiller --------Dry Weight (g) -------Untreated 0 kg ha 1 1.01 40.46 32.48 300 Grain Vinegar 187 L ha 1 0.01 47.97 24.30 + 300 Grain Vinegar + 187 L ha 1 0.02 49.40 20.99 300 Grain Vinegar 187 L ha 1 300 G rain Vinegar 28 1 L ha 1 0.66 52.97 30.13 300 Grain Vinegar 28 1 L ha 1 0.02 41.45 22.78 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 0.04 40.40 28.50 AG Crabgrass Killer a 244 kg ha 1 0.32 33.70 25.98 AG Crabgrass Killer a 488 kg h a 1 0.49 37.65 23.48 AG Crabgrass Killer a 97 7 kg ha 1 0.01 26.95 23.93 AG Crabgrass Killer a 146 5 kg ha 1 0.01 13.53 11.75 Sodium Bicarbonate a 146 5 kg ha 1 0.10 31.21 25.00 AG Crabgrass Killer b 244 kg ha 1 0.02 39.53 23.15 AG Crabgrass Killer b 488 kg h a 1 0.22 28.30 29.50 AG Crabgrass Killer b 97 7 kg ha 1 0.01 31.48 28.28 AG Crabgrass Killer b 146 5 kg ha 1 0.17 20.93 17.60 Sodium Bicarbonate b 146 5 kg ha 1 0.13 35.75 22.43 Borax 15 kg ha 1 0.19 44.55 36.88 Borax 30 kg ha 1 0.14 46.85 38.44 Borax 61 k g ha 1 0.47 39.55 19.50 LSD (0.05) 0.54 12.24 13.34 CV% 168 23 35 a wet b dry

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67 Table 3 9 Crabgrass shoot dry weights Trial II Growth Stage Treatment Rate 1 2 Leaf 3 4 Leaf 1 2 Tiller --------Dry Weight (g) ------Untreated 0 kg ha 1 10.48 15.60 17.00 300 Grain Vinegar 187 L ha 1 6.28 11.30 17.95 + 300 Grain Vinegar 187 L ha 1 6.26 9.05 18.10 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 6.95 7.95 15.60 300 Grain Vinegar 28 1 L ha 1 5.40 7.85 18.58 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 6.90 11.45 18.85 AG Crabgrass Killer a 244 kg ha 1 7.65 10.40 16.53 AG Crabgrass Killer a 488 kg ha 1 5.70 9.50 14.85 AG Crabgrass Killer a 97 7 kg ha 1 4.98 9.03 17.83 AG Crabgrass Killer a 146 5 kg ha 1 6.25 10.78 15.03 Sodium Bicarbonate a 146 5 kg ha 1 8.48 13.93 17.88 AG Crabgrass Killer b 244 kg ha 1 7.65 14.58 19.43 AG Crabgrass Killer b 488 kg ha 1 5.28 12.83 16.93 AG Crabgrass Killer b 9 7 7 kg ha 1 6.01 13.45 17.40 AG Crabgrass Killer b 146 5 kg ha 1 4.53 13.30 18.10 Sodium Bicarbonate b 146 5 kg ha 1 7.33 8.20 16.35 Borax 15 kg ha 1 11.00 17.30 17.30 Borax 30 kg ha 1 6.93 12.33 16.45 Borax 61 kg ha 1 5.65 13.15 15.80 Asulam 2.3 kg ha 1 0.33 1.9 0 15.53 LSD (0.05) 2.14 3.49 ns CV% 23 22 22 a wet b dry

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68 Table 3 10 Crabgrass cont rol in the field with alternative herbicides 7 days after application 2009 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ---% Control ---Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 13 72 Borax 30 kg ha 1 8 73 Borax 61 kg ha 1 10 70 A G Crabgrass Killer 244 kg ha 1 43 55 AG Crabgrass Killer 488 kg ha 1 52 52 AG Crabgrass Killer 97 7 kg ha 1 58 47 AG Crabgrass Killer 146 5 kg ha 1 52 23 Sodium Bicarbonate 146 5 kg ha 1 52 52 300 Grain Vinegar 187 L ha 1 35 48 300 Grain Vinegar 187 L ha 1 30 47 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 38 48 300 Grain Vinegar 28 1 L ha 1 35 43 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 10 48 LSD (0.05) 10 37 CV% 18 19

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69 Table 3 11 Crabgrass control in the field with alternative herbicides 7 days after application 2010 Crabgrass Gr owth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ---% Control ---Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 2 2 Borax 30 kg ha 1 3 5 Borax 61 kg ha 1 7 5 A G Crabgrass Killer 244 kg ha 1 46 20 AG Crabgrass Killer 488 kg ha 1 53 27 AG Crabgrass Ki ller 97 7 kg ha 1 45 42 AG Crabgrass Killer 146 5 kg ha 1 58 50 Sodium Bicarbonate 146 5 kg ha 1 50 41 300 Grain Vinegar 187 L ha 1 42 17 300 Grain Vinegar 187 L ha 1 51 78 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 45 28 300 Gr ain Vinegar 28 1 L ha 1 48 78 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 48 45 LSD (0.05) 13 18 CV% 22 34

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70 Table 3 12 Crabgrass control in the field with alternative herbicides 21 days after application 2009 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ---% Control ---Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 7 72 Borax 30 kg ha 1 0 75 Borax 61 kg ha 1 0 78 A G Crabgrass Killer 244 kg ha 1 18 57 AG Crabgrass Killer 488 kg ha 1 55 62 AG Crabgrass Killer 97 7 kg ha 1 50 53 AG Crabgrass Killer 146 5 kg ha 1 59 74 Sodium Bicarbonate 146 5 kg ha 1 32 65 300 Grain Vinegar 187 L ha 1 35 45 300 Grain Vinegar 187 L ha 1 20 50 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 23 45 300 Grain Vinegar 28 1 L ha 1 27 35 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 32 52 LSD (0.05) 26 20 CV% 61 34

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71 Table 3 13 Crabgrass control in the field with alternative herbicides 21 days after ap plication 2010 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ---% Control ---Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 3 0 Borax 30 kg ha 1 3 2 Borax 61 kg ha 1 5 5 A G Crabgrass Killer 244 kg ha 1 52 15 AG Crabgrass Kill er 488 kg ha 1 53 10 AG Crabgrass Killer 97 7 kg ha 1 50 18 AG Crabgrass Killer 146 5 kg ha 1 57 27 Sodium Bicarbonate 146 5 kg ha 1 55 10 300 Grain Vinegar 187 L ha 1 27 8 300 Grain Vinegar 187 L ha 1 42 20 + 300 Grain Vinegar + 187 L ha 1 300 Gr ain Vinegar 28 1 L ha 1 22 15 300 Grain Vinegar 28 1 L ha 1 43 12 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 35 25 LSD (0.05) 16 14 CV% 29 72

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72 Table 3 14 St. Augustinegrass injury from alternative herbicides 7 day s after application 2009 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ----% Injury ----Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 5 0 Borax 30 kg ha 1 8 0 Borax 61 kg ha 1 10 0 A G Crabgrass Killer 244 kg ha 1 28 7 AG Cra bgrass Killer 488 kg ha 1 40 8 AG Crabgrass Killer 97 7 kg ha 1 50 8 AG Crabgrass Killer 146 5 kg ha 1 47 17 Sodium Bicarbonate 146 5 kg ha 1 53 20 300 Grain Vinegar 187 L ha 1 62 27 300 Grain Vinegar 187 L ha 1 60 18 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 62 23 300 Grain Vinegar 28 1 L ha 1 55 22 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 55 27 LSD (0.05) 14 7 CV% 21 32

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73 Table 3 15 St. Augustinegrass injury from alternative herbicid es 7 days after application 2010 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ----% Injury ----Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 3 2 Borax 30 kg ha 1 5 10 Borax 61 kg ha 1 10 8 A G Crabgrass Killer 244 kg ha 1 18 23 AG Crabgrass Killer 488 kg ha 1 32 32 AG Crabgrass Killer 97 7 kg ha 1 53 53 AG Crabgrass Killer 146 5 kg ha 1 58 65 Sodium Bicarbonate 146 5 kg ha 1 58 72 300 Grain Vinegar 187 L ha 1 42 30 300 Grain Vinegar 187 L ha 1 42 93 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 45 35 300 Grain Vinegar 28 1 L ha 1 47 95 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 45 45 LSD (0.05) 13 12 CV% 23 18

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74 Table 3 16 St. Augustinegrass injury from alternat ive herbicides 21 days after application 2009 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ----% Injury ----Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 2 2 Borax 30 kg ha 1 0 2 Borax 61 kg ha 1 0 3 A G Crabgrass Killer 244 kg ha 1 6 8 AG Crabgrass Killer 488 kg ha 1 14 8 AG Crabgrass Killer 97 7 kg ha 1 13 15 AG Crabgrass Killer 146 5 kg ha 1 11 15 Sodium Bicarbonate 146 5 kg ha 1 13 18 300 Grain Vinegar 187 L ha 1 15 38 300 Grain Vinegar 187 L ha 1 53 43 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 12 20 300 Grain Vinegar 28 1 L ha 1 57 52 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 17 23 LSD (0.05) 10 22 CV% 38 75

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75 Table 3 17 St. Augustinegrass injury from a lternative herbicides 21 days after application 2010 Crabgrass Growth Stage Treatment Rate 1 2 Leaf 1 2 Tiller ----% Injury ----Untreated 0 kg ha 1 0 0 Borax 15 kg ha 1 0 0 Borax 30 kg ha 1 0 0 Borax 61 kg ha 1 0 0 A G Crabgrass Kill er 244 kg ha 1 0 5 AG Crabgrass Killer 488 kg ha 1 0 12 AG Crabgrass Killer 97 7 kg ha 1 0 10 AG Crabgrass Killer 146 5 kg ha 1 3 25 Sodium Bicarbonate 146 5 kg ha 1 0 40 300 Grain Vinegar 187 L ha 1 0 8 300 Grain Vinegar 187 L ha 1 3 33 + 300 Grain Vinegar + 187 L ha 1 300 Grain Vinegar 28 1 L ha 1 0 10 300 Grain Vinegar 28 1 L ha 1 5 42 + 300 Grain Vinegar + 28 1 L ha 1 300 Grain Vinegar 374 L ha 1 0 5 LSD (0.05) 4 11 CV% 181 46

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76 Table 3 18. Poste mergence crabgrass control wit h C rabgrass K iller ingredient s 14 days after application Rate Crabgrass Growth Stage Treatment (kg ha 1 ) 1 2 Leaf 3 4 Leaf ----% Control ----Untreated 0 0 0 Cinnamon 4.6 0 3 Cinnamon 9.3 0 0 Sodium Bicarbonate 484 33 19 Sodium Bicarbonate 9 67 70 11 Crabgrass Killer 488 75 29 Crabgrass Killer 977 84 28 Cumin 9.3 23 0 LSD (0.05) 37 10 CV% 72 64 Table 3 19 S hoot dry weights as influenced by AG C rabgrass K iller ingredients Treatment Rate ( kg ha 1 ) Weight (g) Untreated 0 9.35 Cin namon 4.6 9.63 Cinnamon 9.3 5.46 Sodium Bicarbonate 484 4.96 Sodium Bicarbonate 967 4.84 Crabgrass Killer 488 3.65 Crabgrass Killer 977 4.13 Cumin 9.3 9.14 LSD (0.05) 3.57 CV% 5 6

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77 APPENDIX FIGURES AND TABLES F ROM REMOTE SENSING D ATA Figure 4 1 Percent volumetric water content based on irrigation and nitrogen fertility in Jay, FL on July 21, 2010. Figure 4 2 Chlorophyll count based on mowing height and nitrogen fertility in Jay, FL on July 22, 2009.

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78 Figure 4 3 Chlorophyll count based on mowing height and nitrogen fertility in Jay, FL on July 21, 2010.

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79 LIST OF REFERENCES Allgaier, B. E. 1944. The chemical control of klama th weed. I. A pplication of ecological methods in determining the herbicidal and fertilizing properties of ammonium sulfamate and commercial borax Ecology 25:424 432 Anonymous. 2005. Garden Weasel AG Crabgrass Killer product label. Kansas City, MO. Anonymous. 2008. Flora of Pakistan Vol. 0: 228 http://www.efloras.org/florataxon .aspx?flora_id=5&taxon_id=110153 Accessed Nov 12, 2008. Busey, P. 2000. St Augus tinegrass, Turfgrass Profile. http://www.floridaturf.com /staugust/origins.htm Accessed: October 20, 2010. Busey, P. 2003. Cultural management of weeds in turfgrass: a review. Crop Sci. 43:1899 1911. Busey P. and D. L. Johnston. 2006. Impact of cultural factors on weed populations in St. Augustinegrass turf. Weed Sci. 54:961 967 Callahan, L. M. and J. R. Overton. 1978. Effects of lawn management practi ces on a bermudagrass turf. I n Tennessee Farm and Home Science No. 108. Knoxville, TN. Pp. 37 40 Chauhan B S. and D. E. Johnson 2008. Germination ecology of southern crabgrass ( Digitaria ciliaris ) and India crabgrass ( Digitaria longiflora ): Two important weeds of rice in tropics Weed Sci 56: 722 728. Chase C A. J. M Scholberg a nd G E. Mac D onald. 2004. Preliminary evaluation of nonsynthetic herbicides for weed management in organic orange production. Proc. Fla. State Hort. Soc 117:135 138. Christians, N. 2004. Fundamentals of turfgras s management. 2 nd ed. Hoboken, NJ : John Wiley & Sons. Pp. 63 65 Christians, N. E. and M. C. Engelke. 1994. Choosing the right grass to fit the environment. I n Handbook of Integrated Pest Management for Turfgrass and Ornamantals Boca Raton, FL: Lewis Pu blishers Pp. 99 112. Clayton, W. D., K. T. Harman, and H. Williamson. 2006. GrassBase The Online World Grass Flora: Digitaria ciliaris : Web page http://www.kew.org/data/grasses db/www/im p02931.htm Accessed: October 20, 2010.

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80 Dernoeden, P. H., M. J. Carroll, and J. M. Krouse. 1993. Weed management a nd tall fescue quality as influenced by mowing, nitrogen, WI. and herbicides. Crop Sci. 33:1055 1061. Dunn, J. H., C. J. Nelson, and R. D Winfrey. 1981. Effects of mowing and fertilization on quality of ten Kentucky bluegrass cultivars. I n Proc. 4th Int. Turfgrass Res. Conf., Guelph, ON, Canada. Pp. 293 301 Evans, G. J. and R. R Bellinder. 2009. The potential use of vinegar and a clove oil herbicide for weed control in sweet corn, pota to, and onion. Weed Technol. 23:120 128. Evans, G. J., R. R. Bellinder, and M. C. Goffinet. 20 09 Herbicidal effects of vinegar and a clove oil product on redroot pigweed ( amaranthus retroflexus ) and velvetleaf ( abutilon theophrasti ). Weed Technol. 23: 292 299 Ferguson, J. J. and C. A. Chase. 2004. Status and preliminary research on non synthetic herbicides for organic production. Gainesville, FL: University of Florida. EDIS Factsheet HS1003 Gal e, T. W. 2003. Prohibition of asulam use on residential turf Tallahassee, FL: Florida D epartment of Agriculture and Consumer Services, Memorandum 760 Gilani S. S., M. A. Khan, Z. K. Shinwari and Z. Yousaf. 2002. Leaf epidermal anatomy of selected dig itaria species t ribe Paniceae, family Poaceae of Pakistan. Pak. J. Bot 34:257 273. Hanson, A. A F. V. Juska, and G. W. Burton. 1969. Species and varieties. Turfgrass Science, Agronomy 14:370 409. Hatter m an Valenti, H., M. D. K. Owen, and N. E. Chris tians. 1996. Ground ivy ( Glechoma hederacea L.) control in a Kentucky bluegrass turfgrass with borax Env. Hort. 14 :101 104 Hodges, A. W., J. J. Haydu, P. J. van Blokland, and A. P. Bell. 1994. Contribu tion of the turfgrass industry to econo m y, 1991/92: A Value Added Approach. Gainesvil le, FL: University of Florida Food & Resource Economics Department Economic Report ER 94 1. Holm, L. G., D. L Plucknett, J. V. Pancho and J P. Herberger. 1977. worst weeds: distribution and biology. Honolulu, H I : East West Center/University Press of Hawaii.

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81 Jagschitz, J. A., and J. S. Ebdon. 1985. Influence of mowing, fertili zer and herbicide on crabgrass infest ation in red fescue turf. I n F. Lemaire (ed.) Proc. 5th Int. Turfgrass Res. Conf. Avignon, France. Pp. 699 704. Jansen L. L. W. A. Gentner, and W. C. Shaw 1961. Effects of surfactants on the herbicidal activity of several herbicides in aqueous spray systems Weeds 9 : 381 405 Jiang, H., J. Fry, and N. Tisserat. 1998. Assessing irrigation management for its effects on disease and weed levels in perennial ryegrass. Crop Sci. 38:440 445. Johnson B. J. and R.N. Carr ow. 1995. I nfluence of fenoxaprop and e thofumesate treatments o n suppression of common bermudagrass ( Cynodon dactylon ) in tall fescue ( Festuca arundinacea ) turf Weed Technol 9:789 793. Johnson, B. J., and T. H. Bowyer. 1982. Management of herbicide and fertility levels on weeds and Kentuck y bluegrass turf. Agron. J. 74:845 850. Macilwain, C. 2004. Organic: Is it the future of farming? Nature 428:792 793. McCarty, L. B., D. W. Porter, and D. L. Colvin. 1995. Sod regrowth of St. Augustine grass after preemergence herbicide application. Agron J. 87: 503 507. Murphy, T. R. 2007. Weeds of Southern Turfgrasses. Florida: University of Florida; IFAS Pp. 38. Murray, J. J., D. L. Klingman, R. G. Nash, and E. A. Woolson. 1983. Eight y ears of herbicide and nitrogen fertilizer treatments on Kentuck y bluegrass ( Poa pratensis ) turf. Weed Sci. 31:825 831. [NTEP] National Turfgrass Evaluation Program. 20 10 Web page: http:// www.ntep.org Accessed: September 15, 20 10 Peters, R. A. and S. Dunn. 1971. Life history stu dies as related to weed control in the northeast. 6. Large and small crabgrass. Northeast Regional Weed Control Technical Committee (NE 42). Storrs, CT: Connecticut Agricultural Research Station Radhakrishnan, J., J. R. Te asdale, and C. B. Coffman. 200 2. Vinegar as a non toxic and safer weed control option [Abstract ] USDA BARC Poster Day Beltsville, MD. Rossi, F., A. Sausen, and H. Berg. 1996. Effective timing for postemergence ground ivy control. Wisconsin Turf Research Results of 1995 Studies 9:9 0 93

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82 [SAS] Statistical Analysis Systems. 2008. Software Version 9.2. Cary, NC: Statistical Analysis Systems Institute. Senseman, S. A. 2007. Herbicide Handbook. Lawrence, K S : Weed Sci. Soc. of Am. Pp. 249 250. Teuton T C. J. B Unruh, B J. Breck e, G E. MacDonald, G L. Miller, and J Tredaway 2004. Tropical Signalgrass ( Urochloa subquadripara ) control with preemergence and poste mergence applied herbicides. Weed Tech 18 : 419 425. Thelen, K. D., E. P. Jackson, and D. Penner. 1995. 2,4 D in teractions with glyphosate and sodium bicarbonate Weed Technol 9:301 305 Trenholm, L. E., J. L. Cisar, and J. B. Unruh. 2000. St. Augustinegrass for Florida Lawns. Gainesville, FL: University of Florida, Environmental Horticulture Department Fact Sheet ENH5. Voigt, T. B., T. W. Fermanian, and J. E. Haley. 2001. Influence of mowing and nitrogen fertility on tall fescue turf. Int. Turfgrass Soc. Res. J. 9:953 956. Unruh, J. B. 2009. Pest control guide for turfgrass managers. Gainesville, FL: Uni versity of Florida, Environmental Horticulture Department. Pp. 28 63. Unruh, J. B. and M. J. Elliot. 1999. Best Management Practices for Florida Golf Course Florida: University of Florida; IFAS Pp. 25 35. Uva, R. H., J. C. Neal, and J. M. DiTomaso. 199 7. Weeds of the Northeast. Ithaca, NY: Comstock Publishing Associates, Cornell University Press. Pp. 397.

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83 BIOGRAPHICAL SKETCH Brian Glenn is the son of Robert Glenn and Catherine Christianson He grew up in Texas and southern California. Brian graduat ed from high school in 2001, then enrolled at Brigh am Young University in Provo, Utah He took a two year break from school in 2002 for a service mission for his church to sout hern Chile. After his return he married Rachel Eynon in 2007, and graduated i n 2008 with a B achelor of Science degree in l andscape m anagement. He also earned his CLP (Certified Landscape Professional) while in school. Brian completed his master s at the University of Florida in the spring of 20 11 focusing on weed management in tu rfgrass. He plans to pursue a doctorate from the University of Florida focused on research dealing with improving turf management strategies.