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Integrated Impact of Organic Mulching and Soil Solarization on Soil Surface Arthropods and Weeds

Permanent Link: http://ufdc.ufl.edu/UFE0042015/00001

Material Information

Title: Integrated Impact of Organic Mulching and Soil Solarization on Soil Surface Arthropods and Weeds
Physical Description: 1 online resource (130 p.)
Language: english
Creator: Gill, Harsimran
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: ants, arthropods, bark, borer, collembola, cornstalk, cowpea, grass, hemp, insects, integration, lepidoptera, lesser, mulch, mulches, nutsedge, pine, pitfall, plastic, purslane, pyralidae, rating, soil, solarization, sorghum, sudan, sunn, traps, weeds
Entomology and Nematology -- Dissertations, Academic -- UF
Genre: Entomology and Nematology thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Crop yields are affected by several pests above and below ground. Present use of pesticides has affected the balance between pests and their natural enemies both above and below ground. Moreover, use of insecticides has led to other well known environmental concerns. Environmentally friendly techniques are needed to restore the balance of arthropods in soil. Research work in my PhD is focused toward improving the quality of soil surface habitat needed for restoring the balance between soil pests and their natural enemies and eventually improving the yields of crops. A part of my research is also directed toward reducing the attack of lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae), one of the most serious pests of beans and other crops. This will be achieved by use of various kinds of mulches due to their environmentally friendly nature, easy availability, and low cost. Soil solarization is used commercially in areas with high solar radiation and air temperature during the summer. Clear plastic films were evaluated for weed suppression based on the population density of weeds that emerged through breaks in the plastic, for durability in terms of number and size of breaks in the films, and for the total exposed soil area resulting from breaks. Purple nutsedge (Cyperus rotundus L.) was the major weed problem throughout both years. Although a number of very small ( < 0.75 inch long) breaks were observed in Polydaka circumflex plastic film, they never increased in size, and this plastic film remained intact throughout the experiment and provided excellent weed control. Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing some insect pests and weeds. Several different types of organic mulches were evaluated for effects on soil surface arthropods, weeds, and plant mortality. Numbers of Formicidae, Cicadellidae, Orthoptera, and small plant feeders (aphids, whiteflies, and thrips) were higher in control and cowpea mulch plots than in other mulch types, possibly because weed ratings were higher in control and cowpea plots. Regardless of mulch treatment, caterpillars invaded plots and caused heavy damage to Potomac Pink snapdragon (Antirrhinum majus L.) plants. In other experiments, several different types of organic mulches were evaluated for their effects on soil surface insects and related arthropods. Data were collected on insects and other arthropods using pitfall traps. Results indicate that organic mulches can affect a wide range of different insects. Orthoptera (grasshoppers and crickets) and small plant-feeding insects (aphids, whiteflies, and thrips) were most common in control or cowpea mulch plots on several occasions, possibly due to weed growth in these plots. Numbers of flies were highest in pine bark mulch plots on several occasions. Numbers of spiders were not affected by treatments. The integrated impact of soil solarization and mulching on weeds, nematodes, insect pests, and plant performance was evaluated in field grown snapdragons. Solarization or mulching alone reduced weed numbers but integration of solarization and mulching provided the most effective control of weeds. Plant mortality and plant parameters did not differ among the treatments. Extensive plant damage and mortality due to caterpillars were observed in all plots. Lesser cornstalk borer (LCB), is a serious pest of bean (Phaseolus vulgaris L.) and many other crops. The effect of sunn hemp (Crotalaria juncea L.) mulch was examined as a management method for LCB. LCB attack was less (P ? 0.10) in mulched plots compared with bare ground, considering a number of factors such as location and background of field, season, and amount of precipitation. Greater numbers of surviving plants were found in mulched plots compared with bare ground and weedy plots. In general, fresh weight, height, and total length of bean plants were greater in mulched plots compared with other plots. Treatments did not affect numbers of potential predators of LCB. Evidence suggests that LCB attack is reduced by mulches or weeds around host plants.
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 Harsimran Gill.
Thesis: Thesis (Ph.D.)--University of Florida, 2010.
Local: Adviser: McSorley, Robert.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042015:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042015/00001

Material Information

Title: Integrated Impact of Organic Mulching and Soil Solarization on Soil Surface Arthropods and Weeds
Physical Description: 1 online resource (130 p.)
Language: english
Creator: Gill, Harsimran
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: ants, arthropods, bark, borer, collembola, cornstalk, cowpea, grass, hemp, insects, integration, lepidoptera, lesser, mulch, mulches, nutsedge, pine, pitfall, plastic, purslane, pyralidae, rating, soil, solarization, sorghum, sudan, sunn, traps, weeds
Entomology and Nematology -- Dissertations, Academic -- UF
Genre: Entomology and Nematology thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Crop yields are affected by several pests above and below ground. Present use of pesticides has affected the balance between pests and their natural enemies both above and below ground. Moreover, use of insecticides has led to other well known environmental concerns. Environmentally friendly techniques are needed to restore the balance of arthropods in soil. Research work in my PhD is focused toward improving the quality of soil surface habitat needed for restoring the balance between soil pests and their natural enemies and eventually improving the yields of crops. A part of my research is also directed toward reducing the attack of lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae), one of the most serious pests of beans and other crops. This will be achieved by use of various kinds of mulches due to their environmentally friendly nature, easy availability, and low cost. Soil solarization is used commercially in areas with high solar radiation and air temperature during the summer. Clear plastic films were evaluated for weed suppression based on the population density of weeds that emerged through breaks in the plastic, for durability in terms of number and size of breaks in the films, and for the total exposed soil area resulting from breaks. Purple nutsedge (Cyperus rotundus L.) was the major weed problem throughout both years. Although a number of very small ( < 0.75 inch long) breaks were observed in Polydaka circumflex plastic film, they never increased in size, and this plastic film remained intact throughout the experiment and provided excellent weed control. Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing some insect pests and weeds. Several different types of organic mulches were evaluated for effects on soil surface arthropods, weeds, and plant mortality. Numbers of Formicidae, Cicadellidae, Orthoptera, and small plant feeders (aphids, whiteflies, and thrips) were higher in control and cowpea mulch plots than in other mulch types, possibly because weed ratings were higher in control and cowpea plots. Regardless of mulch treatment, caterpillars invaded plots and caused heavy damage to Potomac Pink snapdragon (Antirrhinum majus L.) plants. In other experiments, several different types of organic mulches were evaluated for their effects on soil surface insects and related arthropods. Data were collected on insects and other arthropods using pitfall traps. Results indicate that organic mulches can affect a wide range of different insects. Orthoptera (grasshoppers and crickets) and small plant-feeding insects (aphids, whiteflies, and thrips) were most common in control or cowpea mulch plots on several occasions, possibly due to weed growth in these plots. Numbers of flies were highest in pine bark mulch plots on several occasions. Numbers of spiders were not affected by treatments. The integrated impact of soil solarization and mulching on weeds, nematodes, insect pests, and plant performance was evaluated in field grown snapdragons. Solarization or mulching alone reduced weed numbers but integration of solarization and mulching provided the most effective control of weeds. Plant mortality and plant parameters did not differ among the treatments. Extensive plant damage and mortality due to caterpillars were observed in all plots. Lesser cornstalk borer (LCB), is a serious pest of bean (Phaseolus vulgaris L.) and many other crops. The effect of sunn hemp (Crotalaria juncea L.) mulch was examined as a management method for LCB. LCB attack was less (P ? 0.10) in mulched plots compared with bare ground, considering a number of factors such as location and background of field, season, and amount of precipitation. Greater numbers of surviving plants were found in mulched plots compared with bare ground and weedy plots. In general, fresh weight, height, and total length of bean plants were greater in mulched plots compared with other plots. Treatments did not affect numbers of potential predators of LCB. Evidence suggests that LCB attack is reduced by mulches or weeds around host plants.
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 Harsimran Gill.
Thesis: Thesis (Ph.D.)--University of Florida, 2010.
Local: Adviser: McSorley, Robert.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042015:00001


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1 INTEG RATED IMPACT OF ORGANIC MULCHING AND SOIL SOLARIZATION ON SOIL SURFACE ARTHROPODS AND WEEDS By HARSIMRAN K AUR GILL A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT O F THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2010

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2 2010 Harsimran Kaur Gill

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3 To my loving and wonderful parents, Mr. Gurdeep S. Gill, and Mrs. Sukhcharan K. Gill for their unconditional support and eve rlasting love

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4 ACKNOWLEDGMENTS I express my sincere appreciation for my mentor and major advisor, Dr. Robert McSorley, for his encouragement, guidance, constructive criticism, intellectual stimulation, and encouragement throughout my tenure at the Universi ty of Florida. His expertise and advice in this endeavor have been indispensable to my success. I would also like to thank the other members of my committee, Dr. Danielle Treadwell, Dr. Marc Branham, and Dr. Susan Webb, for their guidance and valuable sugg estions for the improvement of dissertation project. I would like to thank Dr. Donald Hall, Dr. John Capinera, Debbie Hall, and Dr. Heather J. McAuslane for all of their administrative help and the Department of Entomology for the financial support. I wou ld like to thank the staff and workers at the Plant Science, Research and Education Unit, University of Florida, and in particular Nelson Buck for his constant support and timely help in growing and maintaining plants for my research. I would also thank Dr Gary Steck and Lyle Buss for assisting me with insect identifications Words fail me to convey the depth of my feelin gs and gratitude to my coworkers Heidi, Romy Namga y, Simon, John Frederick, and Jeff Pack for their encouragement, generosity and memora ble association. I would also like to thank my friends Amit, Arshdeep, Bijayita Chandra, Cherry McSorley, Deepak, Divya, Dr. Raminder, Gungeet, Gurminder, Gurpreet, Harsh, JayCee, Jatinder Jeff, Kitty, Megan, Preeti, Rajdeep, Raman, Ruchika, Simmy, Sunil and Teresia for great friendship. During my tenure at the University of Florida, I have had the opportunity to build lasting friendships. The experiences I had will always be cherished. I am eternally indebted to my parents who have been a constant source of encouragement and support throughout this work. I seize the opportunity to express my moral obligations to my sister Dr. Harkamal Gill and brother Gurmatpal Gill for their encouragement and moral support.

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5 I would also like to thank my grandparents and in laws family for their support and encouragement. It would have been impossible for me to complete this strenuous task without the support of my husband Gaurav Goyal No appropriate words could be traced in the presently available lexicon to acknowledge the love, unceasing encouragement, sacrifices, support, and selfless devotion extended by him. Above all, I tha nk God for his guidance, grace and unending blessings.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................9 LIST OF FIGURES .......................................................................................................................11 ABSTRACT ...................................................................................................................................12 CHAPTER 1 REVIEW OF LITERATURE .................................................................................................15 Introduction .............................................................................................................................15 Soil Solarization ......................................................................................................................15 Effect of Soil Solarization on Weeds ..............................................................................16 Effect of Soil Solarization on Chemical Properties of Soil .............................................17 Effect of Soil Solarization on Plant Diseases ..................................................................17 Effect of Soil Solarization on Insect Community ............................................................19 Effect of Soil Solarization on Nematodes .......................................................................20 Effects of Soil Solarization on Crop Yield ......................................................................21 Organic Mulches .....................................................................................................................21 Types of Mulches ............................................................................................................22 Effect of Organic Mulches on Insects .............................................................................22 Effect of Organic Mulches on Soi l Temperature and Moisture ......................................24 Effect of Organic Mulches on Yield ...............................................................................25 Effect of Organic Mulches on Weeds .............................................................................25 Effect of Organic Mulches on Plant Diseases .................................................................26 Advantages of Organic Mulches .....................................................................................26 Drawba cks of Organic Mulches ......................................................................................27 Lesser Cornstalk Borer ...........................................................................................................27 Distribution ......................................................................................................................27 Life Cycle ........................................................................................................................28 Eggs ..........................................................................................................................28 Larvae .......................................................................................................................28 Pupae ........................................................................................................................29 Adults .......................................................................................................................29 Hibernation ...............................................................................................................30 Weather Conditions .........................................................................................................30 Host Plants .......................................................................................................................31 Damage ............................................................................................................................31 Management Options .......................................................................................................32 Sampling ...................................................................................................................32 Insecticides ...............................................................................................................32

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7 Cultural practices ......................................................................................................33 Nat ural enemies ........................................................................................................34 Research Objectives ........................................................................................................34 2 COMPARATIVE PERFORMANCE OF DIFFERENT PLASTIC FILMS FOR SOIL SOLARIZATION AND WEED SUPPRESSION ..................................................................36 Introduction .............................................................................................................................36 Materials and Methods ...........................................................................................................37 2007 Experime nt .............................................................................................................38 2008 Experiment .............................................................................................................38 Data Collection ................................................................................................................39 Data Analysis. ..................................................................................................................39 Results and Discussion ...........................................................................................................40 Plastic Durability .............................................................................................................40 Weed Population De nsities ..............................................................................................41 3 IMPACT OF DIFFERENT ORGANIC MULCHES ON THE SOIL SURFACE ARTHROPOD COMMUNITY AND WEEDS IN SNAPDRAGON ....................................56 Materials an d Methods ...........................................................................................................57 Fall 2007 ..........................................................................................................................58 Fall 2008 ..........................................................................................................................58 Data Collection ................................................................................................................59 Data Analysis ...................................................................................................................60 Results .....................................................................................................................................60 Fall 2007 ..........................................................................................................................60 Fall 2008 ..........................................................................................................................61 Discussion ...............................................................................................................................62 4 EFFECT OF ORGANIC MULCHES ON SOIL SURFACE INSECTS AND OTHER ARTH ROPODS ......................................................................................................................73 Introduction .............................................................................................................................73 Methods ...........................................................................................................................75 Fall 2007 ..........................................................................................................................75 Fall 2008 ..........................................................................................................................76 Data Collection ................................................................................................................76 Data Analysis ...................................................................................................................77 Results .....................................................................................................................................77 Fall 2007 ..........................................................................................................................77 Fall 2008 ..........................................................................................................................78 Discussion ...............................................................................................................................78 5 EFFECT OF INTEGRATING SOIL SOLARIZATION AND ORGANIC MULCHING ON THE SOIL SURFACE INSECT COMMUNITY ............................................................83 Int roduction .............................................................................................................................83

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8 Materials and Methods ...........................................................................................................83 Results and Discussion ...........................................................................................................85 6 INTEGRATED IMPACT OF SOIL SOLARIZATION AND ORGANIC MULCHING ON WEEDS, INSECTS, NEMATODES, AND PLANT PERFORMANCE ........................88 Introduction .............................................................................................................................88 Materials and Methods ...........................................................................................................89 Results and Discussion ...........................................................................................................91 7 MULCH AS A POTENTIAL MANAGEMENT STRATEGY FOR LESSER CORNSTALK BORER, E LASMOPALPUS LIGNOSELLUS (INSECTA: LEPIDOPTERA: PYRALIDAE), IN BUSH BEAN ( PHASEOLUS VULGARIS ) ..............100 Introduction ...........................................................................................................................100 Materials and Methods .........................................................................................................101 Experiment A .................................................................................................................102 Summer 2007 .........................................................................................................102 Fall 2007 .................................................................................................................103 Data Collection ..............................................................................................................103 Experiment B .................................................................................................................104 Summer 2007 .........................................................................................................104 Fall 2007 .................................................................................................................104 Data Collection ..............................................................................................................105 Data Analysis .................................................................................................................105 Results ...................................................................................................................................105 Experiment A .................................................................................................................105 Summer 2007 .........................................................................................................105 Fall 2007 .................................................................................................................106 Experiment B .................................................................................................................106 Summer 2007 .........................................................................................................106 Fall 2007 .................................................................................................................107 Discussion .............................................................................................................................107 8 SUMMARY ..........................................................................................................................114 LIST OF REFERENCES .............................................................................................................118 BIOGRAPHICAL SKETCH .......................................................................................................129

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9 LIST OF TABLES Table page 21 Number of breaks in plastic films over time (weeks after treatment applied) in 2007. .....44 22 Cumulative exposed area on bedsz from extra large breaks in plastic films over time (weeks after treatment applied) in 2007. ............................................................................45 23 Number of very small and small breaks in plastic films over time (weeks after treatment applied) in 2008. ................................................................................................46 24 Number of large and extra large breaks in plastic films over time (weeks after treatment applied) in 2008. ................................................................................................47 25 Cumulative exposed area on bedsz from extra large breaks in plastic films over time (weeks af ter treatment applied) in 2008. ............................................................................48 26 Cumulative density of purple nutsedge over time (weeks after treatment applied) in 2007....................................................................................................................................49 27 Density of common weeds at 10 weeks after treatment applied in 2007. ..........................50 28 Density of common weeds over time (weeks after treatment applied) in 2008. ................51 31 Effect of treatments on arthropod taxa (numbers/pitfall trap) on selected sampling dates 2007 .......................................................................................................................66 32 Effect of treatments on arthropod taxa (numbers/board tra p) on selected sampling dates 2007 .......................................................................................................................67 33 Weed coverage on beds rated among treatments using Horsfall and Barrett (1945)a rating scale on different sampling dates, 2007 ...................................................................68 34 Buckeye caterpillars counts and plant mortality, 20072008 .............................................69 35 Effect of treatments on arthropod taxa (numbers/pitfall trap) on selected sampling dates 2008 .......................................................................................................................70 36 Effect of treatments on arthropod taxa (numbers/board trap) on 3 Nov. 2008 ..................71 37 Weed coverage on beds ra ted among treatments using Horsfall and Barrett (1945)a rating scale on different sampling dates, 2008 ...................................................................72 41 Effect of treatments on arthropod taxa (numbers/pitfall trap) on selected dates 2007 .....81 42 Effect of treatments on arthropod taxa (numbers/pitfall trap) on selected dates 2008 .....82

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10 51 Effect of treatments on insect taxa (numbers/pitfall trap) on selected sampling dates 2008....................................................................................................................................87 61 Weed coverage on beds rated among treatments using Horsfall and Barrett (1945) rating scalez on different sampling dates 2008. .................................................................96 62 Nematode population levels in soil samples among treatments on different sampling dates, 200809. ...................................................................................................................97 63 Visual ins ect counts among treatments on different sampling dates, 2008. ......................98 64 Numbers of dead plants among treatments on different sampling dates, 200809. ...........99 65 Average weight and number of blooms on last harvest, 31Mar 2009. .............................99 71 Number of dead bean plants/plot collected on selected sampling dates for experiment A summer ......................................................................................................................110 72 Weight, height, and length of surviving plants in experiments A and B summer and fall ....................................................................................................................................111 73 Number of dead bean plants/pl ot collected on selected sampling dates for experiment A fall ...............................................................................................................................112 74 Number of dead bean plants/plot collected on selected sampling dates for experiment B summer ........................................................................................................................112 75 Number of dead bean plants/plot collected on selected sampling dates for experiment B fall ...............................................................................................................................113

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11 LIST OF FIGURES Figure page 11 Soil temperatures (C) during solarization at 5 cm (2.0 inches) soil depth in 2007 [(1.8 C) + 32 = F] .........................................................................................................52 12 Soil temperatures (C) during solarization at 15 cm (5.9 inches) soil depth in 2008 [(1.8 C) + 32 = F] .........................................................................................................53 21 Soil temperatures (C) during solarization at 5 cm (2.0 inches) soil depth in 2008 [(1.8 C) + 32 = F] .........................................................................................................54 22 Soil temperatures (C) during solarization at 15 cm (5.9 inches) soil depth in 2008 [(1.8 C) + 32 = F] .........................................................................................................55

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12 Abstract of Dissertation Presented to the Graduate School of the University of Fl orida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy INTEG RATED IMPACT OF ORGANIC MULCHING AND SOIL SOLARIZATION ON SOIL SURFACE ARTHROPODS AND WEEDS By Harsimran K aur Gill August 2010 Chair: Robert Mc Sorley Major: Entomology and Nematology Crop yields are affected by several pests above and below ground. Present use of pesticides has affected the balance between pests and t heir natural enemies both above and below ground. Moreover, use of insecticides has led to other well known environmental concerns. Environment ally friendly techniques are need ed to restore the balance of arthropods in soil. Research w ork in my PhD is focused toward improving the quality of soil surface habitat needed for restoring the balance between soil pests and their natural enemies and eventually improving the yields of crops. A part of my research is also directed toward reducing the att ack of lesser cornstalk borer, Elasmopalpus lignosellus (Z eller) (Lepidoptera: Pyralidae), one of the most serious pests of beans and other crops This will be achieved by use of various kinds of mulches due to their environment ally friendly nature, easy availability and low cost. Soil solarization is used commercially in areas with high solar radiation and air temperature during the summer. Clear plastic films were evaluated for weed suppression based on the population density of weeds that emerged through breaks in the plastic, for durability in terms of number and size of breaks in the films, and for the total exposed soil area resulting from breaks. Purple nutsedge ( Cyperus rotundus L. ) was the major weed problem throughout both years. Although a number of very small (< 0.75 inch long) breaks were observed in Polydak

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13 plastic film, they never increased in size, and this plastic film remained intact throughout the experiment and provided excellent weed control. Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing some insect pe sts and weeds. Several different types of organic mulches were evaluated for effects on soil surface arthropods, weeds, and plant mortality. Numbers of Formicidae, Cicadellidae, Orthoptera, and small plant feeders (aphids, whiteflies, and thrips) were high er in control and cowpea mulch plots than in other mulch types possibly because weed ratings were higher in control and cowpea plots. Regardless of mulch treatment, caterpillars invaded plots and caused heavy damage to Potomac Pink snapdragon ( Antirrhin um majus L.) plants. In other experiments, s everal different types of organic mulches were evaluated for their effects on soil surface insects and related arthropods. Data were collected on insects and other arthropods using pitfall traps. Results indicat e that organic mulches can affect a wide range of different insects. Orthoptera (grasshoppers and crickets) and small plantfeeding insects (aphids, whiteflies, a nd thrips) were most common in control or cowpea mulch plots on several occasions, possibly due to weed growth in these plots Numbers of flies were highest in pine bark mulch plots on several occasions. Numbers of spiders were not affected by treatments. The integrated impact of soil solarization and mulching on weeds, nematodes, insect pests, an d plant performance was evaluated in field grown snapdragons Solarization or mulching alone reduced weed numbers but integration of solarization and mulching provided the most effective control of weeds. Plant mortality and plant parameters did not differ among the treatments. Extensive plant damage and mortality due to caterpillars were observed in all plots.

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14 Lesser cornstalk borer (LCB), is a serious pest of bean ( Phaseolus vulgaris L.) and many other crops. The effect of sunn hemp ( Crotalaria juncea L .) mulch was examined as a management method for LCB. LCB attack was less ( P 0.10) in mulched plots compared with bare ground, considering a number of factors such as location and background of field, season, and amount of precipitation. Greater numbers of surviving plants were found in mulched plots compared with bare ground and weedy plots. In general, fresh weight, height, and total length of bean plants were greater in mulched plots compared with other plots. Treatments did not affect numbers of potential predators of LCB. Evidence suggests that LCB attack is reduced by mulche s or weeds around host plants.

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15 CHAPTER 1 REVIEW OF LITERATURE Introduction Many insects are active at the soil surface, including both pests and beneficial species. Mulches applied to the soil surface may disrupt this insect community, and can be used f or managing key insect pests. Much of the work done in the past examined the effect of organic mulches on specific insects, especially flying insects. I n the present study, different organic and inorganic (polyethylene sheets) mulches were compared in term s of their effects on the entire soil surface community including insects, other arthropods, weeds, and nematodes as well as plant performance. Effects of mulch for managing a key pest (lesser cornstalk borer, Elasmopalpus lignosellus (Zeller)) are examined as well. Soil S olarization Soil stea ming and fumigation were developed by the end of 19th century, as the main approaches for soil disinfestations. Today, soil solarization provides a third approach f or controlling soil borne pests Soil solarization, also referred to as solar heating or solar pasteurization, is accomplished by passive heating of moist soil covered with transparent polyethylene plastic sheeting for more than 6 weeks ( Dahlquist et al. 2007, McGovern and McSorley 1997). Solarization is a us eful nonchemical technique for controlling weeds, nematodes, and several soil borne diseases (Katan 1987 Katan and Gamliel 2010, McGovern and McSorley 1997, Stapleton 2000). The increased temperature (45 55 C) at a 5 cm soil depth under clear plastic sh eets causes mortality of a variety of plant pathogens (Katan 1981). Solarization has been shown to be most effective in regions that are cloudless and have hot weather (Heald and Robinson 1987, Katan 1981, Stapleton and Devay 1983). However, this technique has also been applied in regions with humid climates, such as Florida (Chase 2007,

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16 Chellemi et al. 1993, 1997, McGovern et al. 2004, McSorley and Parrado 1986), except when a prolonged period of rain occurred (Wang et al. 2006). Solarization was found to be a cost effective (Chellemi et al. 1997 Katan 1981) and low risk management practice for small farmers and has the potential to increase crop yield (Culman et al. 2006) Soil solarization can be made more effective in raising soil temperature during the summer period using a double layer of plastic mulch as compared with single layer (McGovern et al. 2002) S oil solarization could be combined with other management practices such as fumigants, hot water, organic amendments, host plant resistance, and biocontrol (McGovern and McSorley 1997). Integration of soil solarization and mulching influenced Collembola population levels and occasionally affected other insect groups, depending on their behavior (Gill and McSorley 2010). Solarization is an effective way of controlling weeds (Chase et al. 1998, Daelemans 1989 Horowitz et al. 1983) as well as nematodes (Chellemi et al. 1997 McGovern et al. 2002, McGovern and McSorley 1997, Stapleton and Heald 1991). Solarization has been helpful in managing a variety of pests and diseases and increasing crop yield as a result Soil solarization have a couple of advantages including high benefit/cost ration, ease of use by growers, adaptability to different cropping systems, and integration with other management tools makes this methods perfectly compatible with principles of integrated pest management required by sustainable agriculture ( D Addabbo et al. 2010). Effect of S oil S olarization on Weeds In Turkey, solarization in combination with other treatments provided effe ctive control of different annual weeds such as annual bluegrass ( Poa annua L. ), common purslane ( Portulaca oleracea L. ), redroot pigweed ( Amaranthus retroflexus L. ) and barnyardgrass ( Echinochloa crus galli (L.) Beauv.) but not horseweed ( Conyza Canadens is (L.) Cron q.) (Benlloglu et al. 2005).

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17 In Syria, yield of faba bean ( Vicia faba L. ), lentils (Lens culinaris Medic. ), and peas ( Pisum sativum L. ) increased by 331%, 441%, and 92%, respectively, after managing bean broomrape, Orobanche crenata Forssk. usi ng solarization (Linke et al. 1991). Weed incidence was reduced by up to 98.5% in some corn ( Zea mays L.) cultivars (Ahmad et al. 1996). S oil solarization controlled annual we eds better than perennial weeds due to the resprouting capacity of weeds from dee ply buried underground vegetative structures (Elmore et al. 1997). I n the West Cameroonian highlands, weeds such as cogongrass ( Imperata cylindrical (L.) Beauv.), Amaranthus spp., Portulaca spp., Setaria spp., Digitaria spp., and Ageratum spp. w ere control led by soil solarization ( Daelemans 1989) Effect of Soil S olarization on C hemi cal Properties of S oil In West Cameroonian highlands, soil solarization did not affect chemical properties of soil (Daelemans 1989). Soil solarization enhanced the availability of essential elements in more simpler and soluble forms that led to increase pest resistance and reduced the stalk breakage in corn cultivars (Ahmad et al. 1996) Soil solarization enhanced the growth and development of plants by changing the physical and chemical features of soil through increased breakdown of organic material. Th is resulted in release of soluble nutrients like nitrogen, calcium, magnesium, potassium, and fulvic acid (Elmore et al. 1997). In okra ( Abelmoschus esculentus (L.) Moench) leaf tissue concentrations of potassium, nitrogen, magnesium, and manganese were higher in solarized plots as compared with non solarized plots, while the concentrations of phosphorous and zinc were lower in solarized plots (Seman Varner et al. 2007). Effect o f Soil S olarization on Plant D iseases In Italy solarization was used to manage lettuce drop caused by the fungus Sclerotinia minor and reductions in disease incidence ranged from 51 % to 84% leading to 37% to 86% increases in production of lettuce ( Lactuc a sativa L.) (Scannavini et al. 1993). In Florida, a

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18 co mbination of fumigation and solarization with virtually impermeable film ( VIF) under low density polyethylene films reduced the survival of the fungus Fusarium oxysporum f. sp. lycopersici (Chellemi an d Mirusso 2006). In corn ( Zea mays L.) cultivars, soil solarization reduced symptoms of Fusarium moniliforme and Macrophomina phaseolina by 64% and 78% respectively, and also helped to reduce stalk rot disease by 69% (Ahmad et al. 1996). In Turkey, soil so larization controlled soil borne diseases caused by Rhizoctonia spp. and Phytophthora cactorum (Benlloglu et al. 2005). Most soil borne plant pathogens are inactivated from exposure to 70C for at least 30 min (McGovern and McSorley 1997). Row solarization reduced growth of some soil borne pathogens such as Pyrenochaeta terrestris, Rhizoctonia solani Fusarium spp., Phytophthora cactorum and Verticillium dahliae ( Abu Gharbieh et al. 1991, Hartz et al. 1985, Hartz et al. 1993, Hartz and Bogle 1989, Katan et al. 1980, Keinath 1995, McGovern and Harper 1996, Sivakumar and Marimuthu 1987). Soil solarization is an effective method to control fungal ( Pythium myriotylum Pytopathora nicotianae var. nicotianae and Sclerotium rolfsii ) growth in potting media (Duff and Barnaart 1992). Elmore et al (1997) suggested that soil solarization can help in managing soil borne fungal and bacterial pathogens such as Verticillium dahliae Fusarium spp., Phytophthora cinnamomi Agrobacterium tumefaciens Clavibacter michiganens is and Streptomyces scabies. Soil solarization alone or in combination with organic amendments can be an excellent approach for managing soil borne plant pathogens (Antonio et al. 2005, Antonio and Giovanni 2006 Gamliel and Stapleton 1997). In southeaste rn United States, soil solarization method should be applied each season as preplanting treatment, because beneficial effects of reducing microbial populations do not persist in the following years ( Njoroge et al. 2010). Six weeks of solarization reduced the population density of Verticillium dahliae Kleb. from 1,600 CFU /g/soil to 300 in the pistachio ( Pistacia vera L.) and olive ( Olea

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19 europaea L.) orchards soils in Iran and disease incidence was decreased up to 70% in the orchards (Saremi et al. 2010). Effect of Soil S olarization on Insect C ommunity The e xposure period of solar radiation was a key factor to determine the effectiveness of soil solarization for the control of stored product pests (McFarlane 1989) Reflective plastic mulch suppressed arthr opods populations associated with tomatocanopy in early season compared with conventional and bare beds. The biological bed mulch results suggest that cover crop residues, as well as reflective plastic mulch may be useful in integrated pest management program for fresh market tomato ( Solanum lyc opersicum L.) production (Summers et al. 2010). In the Nigerian savanna suppression of Callosobruchus maculates (F.) was observed in bambara groundnut ( Vigna unguiculata (L.) Walp .) seeds after exposure to sunlight Complete control of bruchid eggs, first and second instar larvae in seeds was observed after the exposure of 7, 14, or 28 h i n metal tins, clay pots, or polypropylene sacks respectively, as compared with seeds that were not exposed to sunlight (Lale an d Ajayi 2001) S oil solarization was observed to change soil chemistry which may weaken or kill some kinds of soil organisms (Elmore et al. 1997) Although not used as frequently against insect pests, seven weeks of soil solarization was found to reduce incidence of stalk borer ( Papaipema spp.) in corn cultivars by 8.9% (Ahmad et al. 1996). In Spain, a f ield experiment was conducted to examine the effect of different ground cover management systems (pinebark, plastic, and straw mulch, tillage, herbicide, a nd natural soil) on the occurrence of ground beetles (Coleoptera: Carabidae) in ciderapple ( Malus domestica Borkh.) orchard Plastic mulch reduced the ground beetle populations compared to tillage and herbicide treatments (Minarro and Dapena 2003).

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20 Effe ct of Soil Solarization on N ematodes Solarization decreased population levels of different species of nematodes ( Chellemi et al. 1997, McGovern and McSorley 1997, McGovern et al. 2002, Stapleton and Heald 1991). A single soil solarization treatment was fo und effective for longterm management of weeds, while on the other side long term effectiveness against nematodes can be achieved by two or three years of soil solarization treatments (Candido et al. 2008) In Syria, populations of several nematodes speci es were decreased in solarized plots (Linke et al. 1991). Ring nematodes ( Mesocriconema spp.) were less prevalent in raised bed solarization as compared with control treatment, while a combination of a cowpea ( Vigna unguiculata L. ) cover crop and raised se ed bed solarization was as effective as soil fumigation for suppression of root knot nematodes ( Meloidogyne spp.) (Saha et al. 2007). In Egypt soil solarization controlled root knot nematodes in tomatoes and also effectively managed reniform nematodes ( Ro tylenchulus reniformis Linford and Oliveira ) (Abdel R ahim et al. 1988). Solarization was also effective for managing reniform nematodes in Florida (McSorley and Parrado 1986) and Texas (Heald and Robinson 1987). Soil solarization is a method for managing a wide range of nematodes like lesion nematode ( Pratylenchus spp.) root knot nematode, reniform nematode, cyst nematode ( Heterodera glycines Ichinohe ) sting nematode ( Belonolaimus spp.) ring nematodes, stubby root nematode ( Paratrichodorus minor ( Colbran) Siddiqi ) and dagger nematodes ( Xiphinema spp.) (Hagan and Gazaway 2000). Soil solarization is not as effective for managing nematodes as for fungal diseases and weeds because nematodes can recolonize in soil quite rapidly. But still soil solarization w as effective for managing nematodes such as ring nematode ( Criconemella xenoplax Raski ), stem and bulb nematode ( Ditylenchus dipsaci Kuhn), potato cyst nematode ( Globodera rostochiensis Woll. ), spiral nematode ( Helicotylenchus digonicus Perry ), dagger nem atodes lesion nematode ( Pratylenchus spp.) northern root knot nematode ( Mel oi dogyne

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21 hapla Chitwood), pin nematode ( P aratylenchus hamatus Thorne and Allen ), and sugar beet cyst nematode ( Heterodera schachtii Schmidt ) (Elmore et al. 1997). Effects of Soil Solarization on Crop Yield Soil beds covered with polyethylene sheets increased marketable yield of pepper ( Capsicum spp.) crop as compared with untreated plots (Chellemi and Mirusso 2006). In Spain soil solarization alone and in combination with Trichoderma increased the strawberry ( Fragaria ananassa Duchesne) yield 7 8 % and 78% in the 2nd year and 11% and 43% in the 3rd year, respectively (Porras et al. 2007). In general, soil solarization enhances the growth of plant yield and quality (Elmore at al. 1997). Soil disinfestation treatments provided protection and stimulation of root growth and crop yield through drastic qualitative and quantitative changes in the soil environment (Chen et al. 1991). Organic Mulches Mulching is the process of spreading or ganic matter around plants to prevent the evaporation of moisture, freez ing of roots, and growth of weeds (Hatwig and Ammon 2002, Hatwig and Hoffman 1975) As organic mulches and amendments decompose, they also lead to improvement of soil chemical and phys ical properties, and can act as a slow release source of nutrients for plant growth ( Gruda 2008, Klett 2010, Lehmann et al. 2000, Mulvaney et al. 2008, Powers and McSorley 2000, Theriault et al. 2009, Wang et al. 2008, Westerman and Bicudo 2005). The Metro Mix MM360 (Scotts, Marysville, OH) at rates of 20% and 40% commercial vermicomposts suppressed the populations of aphids (Aphididae) and mealy bugs ( Pseudococcus spp.) on peppers ( Capsicum annum L.) and mealy bugs on tomatoes ( Lycopersicon esculentum Mill.) (Arancon et al. 2005). It is an effective way to provide shelter for predatory insects and to control weeds (Brown and Tworkoski 2004, Johnson et al. 2004, Teasdale et al. 2004 Wang et al. 2008). Mulches help to maintain soil moisture required for

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22 plant vigor and to promote plant tolerance to the attack of insect pests (Johnson et al. 2004). Organic mulches can be derived from hay, sawdust, compost, straw, crop residues, pine needles, shredded bark, or other plant material that is readily available. Org anic mulches such as bark, wood chips, leaves, pine needles, and grass es or inorganic mulches gravel, pebbles and polyethylene sheets are frequently applied surrounding the plants to improve crop stand (Black et al. 2003). An ideal mulch should be weedfr ee, having uniform color, attractive, and should not be blown away with wind from the application site ( Klett 2010 ). Types of M ulches There are mainly two types of mulches, or ganic and inorganic (Klett 2010). Organic mulches are derived from any kind of or ganic material such as hay, straw, pine needles, shredded bark, and sawdust etc. In cooler locations, organic mulches should be applied late in the spring since early application of mulches can delay soil warming seed germination or seedling emergence, an d crop development. The most commonly used inorganic mulches are polyethylene plastic films. These mulches are relatively inexpensive made from petroleum based products and can be applied mechanically under field conditions. These mulches have the ability to manage a number of weeds, but still nutsedges can poke through the plastic and pose problems to growers. Effect of O rganic Mulches on I nsects Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing specific insect pests. Lepidopteran eggs and larval densities were significantly higher in broccoli (Brassica oleracea L. var. botrytis) monoculture when compared to broccoli with undersown mulches like strawberry clover ( Tribolium fragiferum L. ), white clover ( Tribolium repens L.), and yellow sweetclover ( Melilotus officinalis L.) (Hooks and Johnson 2004). Spiders were found more frequently on bare unmulched plots in

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23 the early stages of crop growth, but later in the season, spider counts were hi gher on broccoli with living mulches. Alfalfa (Medicago sativa L.) living mulch increased the aphidophagous community to manage the outbreaks of the invasive soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae) (Schmidt et al. 2007). Alfalfa and kura clover ( Trifolium ambiguum M. Bieb) mulches increased the predator populations to manage European corn borer ( Ostrinia nubilalis Hbner) (Prasifka et al. 2006). Oat crimson clover killed cover crop mulch reduced the damage caused by soil insect pests to sweetpotato ( Ipomoea batatas (L.) Lam. ) roots. Also, more predators including fire ants, rove beetles, and carabid beetles were captured by pitfall traps in killed cover crop mulch plots compared with conventional tillage plots (Jackson and Harrison 2008). Although living mulches may offer resources to support predators, nonliving mulches derived from killed cover crops or hay from cover crops may offer some benefits as well. A review of manipulative studies showed that in ca. 75% of cases, generalist predators reduced the significant number of pest populations (Symondson et al. 2002). Winter cover crops like wheat ( Triticum aestivu m L.), rye ( Secala cereale L.), oat ( Avena sativa L.), lupine ( Lupinus augustifolius L.), hairy vetch ( Vicia villosa Roth.), and crimson clover ( Trifolium incarnatum L.) affected a variety of insects including aphids (Aphididae), leafhoppers (Cicadellidae), plant bugs (Miridae), and thrips (Thysanoptera) (Tremelling et al. 2002). Predation of beet armyworm, Spodoptera exigua (H bner) pupae was 33% greater in killed cover crop mulch as compared with conventional production plots (Pullaro et al. 2006). Poultry compost reduced the populations of spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.) and migrating woolly a phid, Eriosoma lanigerum (Hausmann) nymphs, while increasing the predator populations (Brown and Tworkoski 2004).

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24 L iving and dead plant vegetation as mulch can suppress the establishment of soil inhibiting herbivores including Colorado potato beetles ( Lept inotarsa decemlineata Say ) by hindering their emergence and migration behavior (Teasdale et al. 2004 ). Living mulches in reduced the populations of crucifer flea beetle ( Phyllotreta cruciferae Goeze) and cabbage aphid ( Brevicoryne brassicae (L.) ) in cabba ge ( Brassica oleracea L.) production system (Andow et al. 1986). Experiments were performed in Colorado to evaluate the effect of different colored mulches on the colonization of western black flea beetle (WBFB), Phyllotreta pusilla Horn. Lower numbers of WBFB were found in black mulch in 3 years of sampling, while aluminum mulch had the highest number of WBFB (Demirel and Cranshaw 2005). Fresh m ulches obtained from white leadtree ( Leucaena leucocephala (Lam.) de Wit) and false tamarind ( L ysiloma l atisiliq uum (L.) Benth.) r educed the density and biomass of snails ( Bautista Ziga et al. 2008) Much of the work done in the past used mulches for the management of flying insect pests (Brown and Tworkoski 2004, Hooks and Johnson 2004, Prasifka et al. 2006, Pull aro et al. 2006 Reeleder et al. 2004 Schmidt et al. 2007, Staley et al. 2010, Tremelling et al. 2002). Effect of O rganic Mulches on Soil Temperature and Moisture In India, field experiments were conducted using five mulches (wheat straw, green twigs, fa rmyard manure (FYM), piltu (dry leaves of Pinus roxburghii ), and forest litter) on potatoes ( Solanum tuberosum L.) cv. Kufri Jyoti Mulching with FYM was most efficient in increasing soil moisture and soil temperature, followed by forest litter (Uniyal and Mishra 2003). In Delaware, field studies conducted on melon ( Cucumis spp.) and potatoes showed that straw mulch helped to reduce soil temperature and increase soil moisture more than the control (weedy, no straw) plots (Johnson et al. 2004). W heat ( Tritic um aestivum L.) straw mulch or FYM mulch can improve soybean ( Glycine max (L.) Merr. ) emergence both in norma l and

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25 crusted soils, may be due to decrease in soil temperature and conservation of soil moisture (Singh and Jolly 2008) Effect of O rganic Mulches on Y ield Application of red clover ( Trifolium pratense L.) and alfalfa ( Medicago sativa L.) green manures led to increase in broccoli ( Brassica oleracea var. italica Pl enk) yield, and available soil nitrogen (N) uptake (Theriault et al. 2009). The percent age of clean pumpkin ( Cucurbita pepo L.) fruit at harvest was higher in leaf mulch production systems compared with bare soil ( Wyenandt et al. 2008) Farmyard manure as mulch was found to be most sufficient in increasing plant height, fresh shoot weight, t uber weight, and tuber yield followed by the forest litter. Higher yield was reported in FYM mulched plots because mulches conserved soil moisture and reduced the soil temperature favoring the plant growth and tuber bulking, respectively (Uniyal and Mishr a 2003). L iving and dead plant vegetation as mulch increased the crop yield by suppressing weeds, populations of Colorado potato beetles, and foliar diseases (Teasdale et al. 2004) Application of sunn hemp mulch or compost can increase the yield and quali ty of winter fresh market tomato (Wang et al. 2009). Effect of O rganic Mulches on W eeds Mulches can control weeds by shading effects on weeds or forming a barrier to the emergence of weeds. Pine bark mulch was reported to improve weed and disease control (Reeleder et al. 2004). Poultry compost manure was observed effective to control weeds for one year after the application of manure (Brown and Tworkoski 2004). In another instance, application of straw mulch at the time of planting suppressed the weed po pulations, but application of straw mulch 4 weeks after planting had less effect on weeds (Johnson et al. 2004). Some of the annual weeds were very susceptible to mulch containing living or dead plant material (Teasdale et al. 2004) Two layers of cattail ( Cyprus articulatus L.) or rice ( Oryza sativa

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26 L.) straw mulch could be effectively used to control weed s population in citrus ( Citrus spp.) groves (Abouziena et al. 2008). The strip placement of h airy vetch ( Vicia villosa Roth.) residue was found to be eff ective method for weed suppres sion and high yield in a tomato production system (Campiglia et al. 2010). Mulch derived from rye ( Secala cereale L.) cover crop was found to be an effective weed control technique in conventional, as well as organic deciduous tree orchards (Ormeo Nez et al. 2008) Effect of O rganic Mulches on Plant D iseases Growth of brown rot fungus ( Monilinia fructicola ) was significantly lower in poultry composted substrate than a sterilized compost substrate (Brown and Tworkoski 2004). F oliar diseases can be suppressed using living and dead plant vegetation as mulch by preventing dispersion of pathogen propagules through windborne processes and splashing (Teasdale et al. 2004). Advantages of O rganic M ulches There are a number of advantages of mulches such as reduction in soil erosion, reduced evaporation, and improved infiltration of water (Powers and McSorley 2000, Snapp et al. 2005) Sunn hemp mulch was observed effective in controlling weeds and led to increase crop yield compared w ith sunn hemp as a cover crop (Wang et al. 2008). Mulches also reduced weed germination, led to improvement of soil texture and tilth, acted as insulator for maintenance of soil temperature, and resulted in stronger root systems (Black et al. 2003 ). Earthw orms usually hide in organic mulches and help in enrichment of soil with their castings and also aerate the soil with their burrows. Some organic mulches like grasses and compost act as a slow release source s of nutrients for plant growth (Dickerson 2001).

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27 Drawback s of O rganic M ulches Organic mulches such as hay and grass clippings sometimes can also serve as a source to introduce weed seeds into the mulched field. Use of mulches leads to an increase in the number of slugs ( Limax spp.) in fields and espe cially in gardens where they may feed on young and succulent plants and cause damage. Some mulch es like dry pine needles can cause fire hazards while others like grass clippings and peat (sphagnum) can be easily bl own by air currents (Klett 2010). Mulches also encourage development of some insect relatives like snails (mollusk), slugs (mollusk), and sow bugs (crustacean) that cause hindrance to plant growth. Thick layers of organic mulches around the base of fruit trees provide hiding places for rodents. In some cases, moist organic mulches can encourage the seedling disease damping off (Dickerson 2001). Lesser Cornstalk Borer Lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), is a polyphagous pest with a wide range of host plants that inclu des weeds, vegetable crops, and field crops (Funderburk et al. 1985). L arvae burrow into the stalk base near the soil surface, damaging vascular tissues resulting in dead heart symptoms and allowing pathogens to enter the plant (Smith and Ota 2002). The l arval stage tunnels within stems and roots. Wilting is the first sign of an infestation in affected plants, followed by stunting, plant deformities and a thin crop stand ( Gill et al. 2009 a ) Distribution LCB was described by Zeller in 1848, but it was not considered of economic importance until 1881 (Riley 1882). LCB occurs widely in the western hemisphere and is known from much of the southern United States. Despite its wide distribution, damage is limited principally to sandy soil ( Metcalf 1962), so i t tends to cause injury in the coastal plain of the southeastern

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28 states from South Carolina to Texas. While more often observed in the southeastern United States, this pest species is sporadic in nature and distributed from Maine to southern California. I t was first discovered outside the continental U.S. in July 1986 infesting sugarcane ( Saccharum officinarum L .) in Kauai (Hawaii) (Chang and Ota 1987). This species is also found in Mexico, Central America, and South America (Genung and Green 1965, Heinric h 1956, Luginbill and Ainslie 1917). Life Cycle Lesser cornstalk borer is a holometabolous insect having distinct life stages that comprise egg, larva, pupa, and adult. There are three to four generations annually in the southeast, but in the southwest t here are only three generations annually. Activity extends from June to November, with the generations overlapping considerably and little evidence of breaks between generations. Overwintering apparently occurs in the larval and pupal stage, and diapause i s not present. A complete life cycle usually requires 30 to 60 days. Eggs The eggs are oval, measuring about 0.6 mm in length and 0.4 mm in width. When first deposited, they are greenish, soon turning pinkish, and eventually reddish. The female deposits nearly all her eggs below the soil surface adjacent to plants. A few, however, are placed on the surface or on leaves and stems. Duration of the egg stage is two to three days. A single female can oviposit about 200 eggs (Capinera 2001), with a report of up to 420 eggs (Biddle et al. 1992). Female moths oviposit eggs in late summer and fall in Kentucky (Bessin 2004), while in Florida, we observed heavy oviposition in spring and early summer. Larvae Larvae are strong and active when disturbed and wiggle vio lently so that in some countries it is called the jumping borer (Schaaf 1974). Larvae live in the soil, constructing

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29 tunnels from soil and excrement tightly woven together with silk. They leave the tunnel to feed in the basal stalk area or just beneath the soil surface, returning and constructing new tunnels as they mature. Thus, tunnels often radiate out from the stem of the food source, just below the soil surface. Normally there are six instars, but the number of instars can range from five to nine depending on environmental conditions (Biddle et al. 1992). During the early instars, larvae are yellowish green, with reddish pigmentation dorsally, tending to form transverse bands. As the larvae mature, whitish longitudinal stripes develop, so that by the fifth instar they are pronounced. The mature larvae are bluish green, but tend toward reddish brown with fairly distinct yellowish white stripes dorsally. Head capsules are dark in color, and measure about 0.23, 0.30, 0.44, 0.63, 0.89, and 1.2 mm in width, r espectively, for instars one through six. Larval lengths are about 1.7, 2.7, 5.7, 6.9, 8.8, and 16.2 mm, respectively. Mean development time is estimated at 4.2, 2.9, 1.4, 3.1, 2.9, and 8.8 days for instars one through six, respectively. Total larval devel opment time varies widely, but normally averages about 20 days. Pupae At larval maturity, caterpillars construct pupal cells of sand and silk at the end of the tunnels. Cocoons measure about 16 mm in length and 6 mm in width. The pupae are yellowish init ially turning brown and then almost black just before adults emerge. Pupae are about 8 mm long and 2 mm wide. The tip of the abdomen is marked by a row of six hooked spines. Pupal development time averages about nine to 10 days, with a range of seven to13 days ( Gill et al. 2009 a ) Adults Moths are fairly small, measuring 17 to 22 mm in wingspan. Sexual dimorphism is pronounced. Variability in color of wings and wing patterns were reported both in male and female moths, depending on climatic and regional conditions (Biddle et al. 1992, Chapin 1999).

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30 In general, the forewing of the male moth is yellowish centrally, bordered by a broad dark band bearing purplish scales ( Gill et al. 2009 a ) In females, however, the entire forewing is dark, sometimes almost b lack, but also bearing reddish or purplish scales. At rest, the female moth is often charcoal colored (Biddle et al. 1992) with wings held straight back along the body, while the male moth is tan colored with charcoal wing strips (Chapin 1999). The thorax is light in males, but dark in females. The hind wings of both sexes are t ransparent with a silvery tint. Adults are most active at night when the temperature exceeds 27 C, and there is little air movement. Such conditions are optimal for mating and oviposition. Adult longevity under field conditions is estimated at about 10 days (Nuessly and Webb 200 4) Hibernation Bessin (2004) concluded that LCB overwinters in the egg stage. Hibernation can also take place in the soil in larval or pupal form (Chapin 1999). Biddle et al. (1992) reported that LCB hibernate as fully grown larvae or pupae. Weather C onditions LCB seem to be adapted for hot, xeric conditions, and therefore tend to be more abundant and damaging following unusually warm, dry weather. On peanut s, this species mostly occurs in noneconomic densities, but sporadic outbreaks are associated with hot and dry climatic conditions (Smith and Barfield 1982). Weather factors, mainly temperature, contribute to the buildup of LCB populations because the eggs are oviposited at a faster rate in hot weather (Mack and Backman 1984). Mack et al. (1993) used data from Alabama and Georgia to develop a predictive equation that forecasts the potential for crop injury and the need to monitor crops. It is based on the c oncept of "borer days." Borer days is calculated as the sum of days during the growing season in which the temperature equals or exceeds 35 C and the precipitation is less than 2.5 mm, less the number of days in which the temperature is less than 35 C an d the

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31 precipitation equals or exceeds 2.5 mm. Thus, it is the sum of the number of hot, dry days less the number cooler, wetter days. If the number of borer days equals or exceeds 10, damage is likely. If a borer day equals 5 to 9, then damage is possible and fields should be scouted. The relationship between borer days and larval abundance is nonlinear and small increases in borer days beyond 10 results in large increases in larval abundance. Host P lants Lesser cornstalk borer is a polyphagous pest that o ften attacks several crops throughout the southeastern United States. Legume and grass crops are most often damaged. In Georgia, Leuck (1966) reported that due to the semi subterranean nature of LCB, it fed on and damaged seedlings and mature soybean plant s above and below the soil surface. Crops that are grown in late spring and early fall in northern Florida [ soybeans ( Glycine max L. ) peanuts ( Arachis hypogaea L. ) and grain sorghum ( Sorghum bicolor L. ) ] are candidates for damage by LCB, due to their fav orable host status and exposure to high populations of LCB (Tippins 1982). LCB also has a number of weed hosts, such as nutsedges ( Cyperus rotundus L. ), watergrass ( Hydrochloa caroliniensis Beauv.), j ohnsongrass ( Sorghum halepense (L.) Pers. ), crabgrass ( Digitaria sanguinalis (L.) Scop.), wild oats (Avena fatua L. ), Bermudagrass ( Cynodon dactylon L. ), wiregrass ( Aristida stricta Michx.), and goosegrass ( Eleusine indica L. ) (Isely and Miner 1994, Gardner and All 1982). Damage The larval stage causes damag e when it feeds upon, and tunnels within, the stems of plants. Normally the tunneling is restricted to the basal region of stalks, including the belowground portion, and girdling may occur. Wilting is one of the first signs of attack in affected plants, but buds may wither, and stunting and plant deformities are common ( Gill et al. 2009 a ) Plant death is not uncommon, and infested areas of fields often have a very thin stand.

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32 Sweet corn plants that did not die after the damage of LCB produced several bushy and stunted suckers with no marketable ears (Nuessly and Webb 200 4). Bessin (2004) reported that the growing point of the plant was killed, leading to "dead hearts" symptoms that are similar to the attack of wireworms. "Dead hearts" symptoms are caused by the larva boring into the stalk at the soil level and tunneling upward. Silken webbing forming a small tube in the soil at the base of the stalk is evidence of the attack of LCB. The larvae bore into the stalk base near the soil surface causing damage to vascular tissues that result in these "dead hearts" symptoms and also allow pathogens to enter into the plant (Smith and Ota 2002). Management O ptions Sampling The egg stage is difficult to sample because eggs are small and resemble sand grains. However, eggs can be separated by flotation. Larval populations are aggregated, and can be separated from soil by sieving or flotation (Mack et al. 1991). To scout for LCB, uproot small plants in 10 locations in a field. If live larvae and pupae are found in 10% of plants, then treatment is recommended (Chapin 1999). Adults are attracted to light traps, but are difficult to monitor with this technique because LCB moths are difficult to distinguish from many other species. This is especially true of the females, which are less distinctive than the males. Pheromone traps have been used successfully to monitor adult populations, and adults can be flushed from fields by beating the vegetation. Adult pheromone trap catches and flush counts are correlated (Funderburk et al 1985). Adult and larval counts are often highly correlated, indicating that flush counts can be used to predict the abundance of larvae in subsequent weeks. Insecticides Insecticides applied for suppression of lesser cornstalk borer are usually applied in a granular formulation in the seed furrow or in a band over the seed bed, using restricted pesticides

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33 according to label recommendations Liquid formulations can also be applied, but it is important that they be directed to the root zone. Cultural p rac tices Modified planting practices have long been used to minimize crop loss. Populations tend to increase over the course of a season, so some damage can be avoided by early planting. Tillage and destruction of weeds are recommended prior to planting beca use this helps to destroy larvae that may be present in the soil and might damage seedlings, the stage most susceptible to destruction. However, crop culture that uses conservation tillage (i.e., retention of crop residue at the soil surface) experiences l ess injury from lesser cornstalk borer feeding because the larvae feed freely on crop residue and other organic matter, sparing the young crop plants (All et al. 1979). Smith and Ota (2002) observed that the LCB damage on sugarcane in Hawaii can be avoided by following agronomic practices that enhance the plant vigor to tolerate damage caused by LCB. Frequent irrigation is also an important agronomic practice for the management of LCB because moist soils discourage female moths from laying eggs and also sup press larval populations in the soil. Previous experiments showed that early planting in Alabama effectively reduced LCB populations in both conventionally and reduced tillage peanuts ( Arachis hypogaea L. ), but the tillage systems did not affect population levels of LCB and predators including carabids, elaterids, and labidurids in pitfall traps (Mack and Backman 1990). In Alabama, a diverse fauna of predatory arthropods was captured in pitfall traps and numbers of arthropods increased throughout the peanut growing season (Kharboutli and Mack 1991). Fungi, predators, and other factors affected LCB mortality in a commercial peanut experiment in Texas (Smith and Johnson 1989). Mortalitydensity relationships revealed that mortality of LCB was density independe nt, in terms of initial egg density (Smith and Johnson 1989).

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34 Natural e nemies While several natural enemies of LCB are known, they are not thought to be major determinants of population trends. Smith and Johnson (1989) constructed life tables for populati ons in Texas, and identified survival of large LCB larvae as the key element in generation survival, but the causative factor remains unidentified. The predominant parasitoids through most of the range of lesser cornstalk borer are Orgilus elasmopalpi Mues ebeck and Chelonus elasmopalpi McComb (both Hymenoptera: Braconidae), Pristomerus spinator (Fabricius) (Hymenoptera: Ichneumonidae), and Stomatomyia floridensis Townsend (Diptera: Tachinidae) (Funderburk et al. 1984). Other parasitoids sometimes present include Bracon gelechiae Ashmead (Hymenoptera: Braconidae), Geron aridus Painter (Diptera: Bombyliidae), and Invreia spp. (Hymenoptera: Chalcididae). Parasitoids rarely cause d more than 10% mortality. Among the predators thought to be important mortality fac tors are a ground beetle, Plilophuga viridicolis LeConte (Coleoptera: Carabidae), bigeyed bugs, Geocoris spp. (Hemiptera: Lygaeidae), and larval stiletto flies (Diptera: Therevidae). Pathogens are commonly present in lesser cornstalk borer populations. The most important pathogen appears to be a granulosis virus, but a Beauveria sp p. fungus, microsporidia, and mermithid nematodes also have been found (Funderburk et al. 1984). Natural enemies generally did not greatly affect population levels of LCB, due to its subterranean habits, silken webbing, and sporadic nature. Research Objectives 1. Comparative performance of different polyethylene f ilms for s oil s olarization and w eed s uppression 2. Impact of different organic mulches on the soil surface arthropod community and weeds in snapdragon 3. Effect of organic mulches on soil surface insects and other arthropods

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35 4. Effect of integrating soil solarization and organic mulching on the soil surface insect community 5. Integrated impact of soil solarization and organic mulchi ng on weeds, insects, nematodes, and plant performance 6. Mulch as a potential management strategy for l esser cornstalk borer, Elasmopalpus lignosellus (Insecta: Lepidoptera: Pyralidae) in bush bean ( Phaseolus vulgaris )

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36 CHAPTER 2 COMPARATIVE PERFORMA NCE OF DIFFERENT PLASTIC FI LMS FOR SOIL SOLARIZATION AND WEE D SUPPRESSION Introduction Soil solarization, also referred to as solar heating or solar pasteurization, is accomplished by passive heating of moist soil covered with transparent plastic film for more than six weeks (McGo vern and McSorley 1997). Solarization is a useful nonchemical technique for controlling weeds, nematodes, and sev eral soil borne diseases (Katan 1987, McGovern and McSorley 1997, Stapleton 2000). The increased temperature (45 55 C) at a 5 cm soil depth under clear plastic films caused mortality of a variety of plant pathogens (Katan 1981). Solarization has been shown to be most effective in regions that are cloudless and have hot weather (Heald and Robinson 1987, Katan 1981, Stapleton a nd Devay 1983). This technique has also been applied in regions with humid climates, such as Florida (Chase 2007, Chellemi et al. 1993, 1997, McGovern et al. 2004, McSorley and Parrado 1986), except when a prolonged period of rain occurred (Wang et al. 2006). Solarization was found to be a cost effective (Chellemi et al. 1997, Katan 1981) and low risk management practice for small farmers and has the potential to increase crop yield (Culman et al. 2006) Solarization has been helpful in managing a variety of pests and diseases and as a result increasing crop yield. Solarization decreased population levels of different specie s of nematodes (Chellemi et al. 1997, McGovern et al. 2002, McGovern and McSorley 1997, Stapleton and Heald 1991). In Italy, solarizati on was used to manage lettuce drop caused by the fungus Sclerotinia minor and reduced the disease from 51 % to 84% leading to 37% to 86% inc rease in production of lettuce ( Lactuca sativa L. ) (Scannavini et al. 1993). In Florida, a combination of solarizati on followed by fumigation under virtually impermeable film ( VIF) reduced the survival of the fungus Fusarium oxysporum f. sp. lycopersici (Chellemi and Mirusso 2006).

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37 Solarization is also very effective in controlling weeds (Chase et al. 1998, Daelemans, 1989, Elmore et al. 1997, Horowitz et al. 1983). In Turkey, solarization in combination with other treatments provided effective control of different annual weeds such as annual bluegrass ( Poa annua L. ), common purslane ( Portulaca oleracea L. ), redroot pigweed ( Amaranthus retroflexus L. ) and barnyardgrass ( Echinochloa crus galli (L.) Beauv.) but not horseweed ( Conyza Canadensis Less. ) (Benlloglu et al. 2005). In Syria, yield of faba bean ( Vicia faba L. ), lentil (Lens culinaris Medikus ), and pea ( Pisum sativ um L. ) increased by 331%, 441%, and 92%, respectively, after managing crenate broomrape ( Orobanche crenata Forssk.) u sing solarization (Linke et al. 1991). Solarization reduced weed incidence up to 99% in some corn ( Zea mays L. ) cultivars (Ahmad et al. 1996). Previous research comparing various thicknesses (25 or 50 m vs. 100 m, and 75 vs. 150 m) of plastic films found that thin plastic films were more effective for trapping solar radiation, thereby leading to increased soil heating (McGovern and McSorl ey 1997). Transparent mulches were found to be more effective than opaque mulches for pathogen suppression (McGovern and McSorley 1997). Several recent solarization studies in Florida were conducted using ISO plastic film (ISO Poly Films, Gray Court, SC ) (McGovern et al. 2004, Saha et al. 2007, W ang et al. 2006). The objective of the present study was to evaluate soil solarization by comparing plastic films from different manufacturers in terms of their durability and their effectiveness in suppressing weed s. Materials and M ethods Field experiments were conducted in the summer of 2007 and 2008 at the University of Florida Plant Science Research and Education Unit (lat. 29o24N, long. 82o9W), located near

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38 Citra, FL. The soil at the experimental site was Arredondo sand (95% sand, 2% silt, 3% clay) with 1.5% organic matter. 2007 Experiment The experime ntal field was rototilled on 15 June to prepare soil and to improve heat conduction through the soil for solarization. On 9 July soil was thoroughly irrigated because moist soils are better conduct ors of heat (Katan 1981). Soil moisture content (measured gravimetrically) prior to be d formation averaged 9.6%. On 10 July, beds were prepared that were 35 f t long with 8 ft centers. On 11 July, five treatments were applied manually by covering the beds with one of four types of transparent plastic films: ISO (1mil thick, ultraviolet light (UV)stabilized; ISO Poly Films, Gray Court, SC) ; VeriPack (2 mil thick; VeriPack Framingham, MA) ; Poly Pak (2 mil thick; Poly Pak Plastics, Medford, MN) ; Bromostop (1.4 mil thick; Bruno Rimini, London, UK) ; or a semi opaque white plastic film (2 mil thick; Rodeo Plastic Bag and Film, Mesquite, TX ). These films were supplied in long rolls with width varying from 6 ft to 8.3 ft, and we re cut into 40 ft lengths. After covering the beds, edges of plastic were sealed by placing soil at the base and ends of each bed. Treatments were arranged in a randomized complete block design with five replications. Each plot was 35 ft long with a raised bed top of 30 inches wide, 8 inches high, and the total bed surface area was 87.5 ft2. Soil thermocouples attached to automatic data loggers (WatchDog Spectrum Technologies, Plainfield, IL) were placed in the field on 11 July, 2007. In a given bed, one soil temperature sensor was placed at 5 cm depth and one at 15 cm depth, with temperatures monitored hourly throughout the season. The experiment was terminated after ten weeks. 2008 E xperiment The experiment was repeated in the same field as the 2 007 experiment. Experimental procedure was similar to that described for 2007, with minor changes as specified below. The

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39 experime ntal field was rototilled on 13 June and beds were prepared on 24 June. Soil moisture content prior to bed formation average d 6.4%. Plastic films as well as soil thermocouples and data loggers wer e applied in the field on 25 June 2008. During the 2008 season, treatments remained the same except that ISO and VeriPack plastic films were no longer manufactured, so a different pl astic film was substituted: Polydak (1.3 mil thick, ultraviolet light (UV)stabilized; transparent film, Ginegar Plastics Products, Ginegar, Israel). Treatments were arranged in a randomized complete block design with five replications. Data C ollection W eed density was recorded for each weed present in plots from 3 to 12 weeks after treatment application. Weeds were counted as they broke through plastic (occasionally occurred with nutsedges, Cyperus spp.) or more commonly as they emerged in open areas whe re plastic had been torn. However, very small (< 0.4 inch) weed seedlings were classified simply as broadleaf, nutsedges, or grasses. In both years, as plastic films deteriorated, they typically split open perpendicular to the length of the bed, causing a break, or tear across the width of the bed. Durability was assessed every two weeks by counting the number of breaks in the plastic films. Breaks were graded into four size classes: very small = < 0.75 inch long; small = < 30 inches long (less than the bed width); large = 30 inches long (across the entire bed width), and extra large. Extra large breaks extended across the entire bed width but opened up along the bed length as well. The area of each large break was calculated by multiplying the length and wi dth of the break, and the total exposed area for each bed was determined by adding the areas of all extra large breaks on each bed. Data A nalysis

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40 Data were analyzed using a oneway analysis of variance (ANOVA) with SAS (version 9.1; SAS Institute, Cary, N C). When analysis of variance showed a significant treatment effect ( P 0.05), treatment means were separated using the least significant difference test (LSD). R esults and D iscussion Soil temperature was higher at the 5 cm soil depth than at15 cm throughout both seasons (Figs. 11, 1 2, 21 and 2 2). During 2007, the highest temperatures recorded were 56 C under ISO film (12 d at temperatures above 50 C) and 54.7 C under Poly Pak (11 d at temperatures above 50 C), at 5 cm soil depth (Fig. 11 and 12 ). In the 2008 season, soil temperatures near 50 C at 5 cm soil depth were often recorded under fairly durable plastic films such as Polydak and Poly Pak (Fig. 21 and 22). Plastic D urability In 2007, Bromostop developed more small breaks than other clear plastic films in week six (Table 21). A greater number of large and extra large breaks were found in Bromostop, VeriPack, and white plastic films as small sized breaks progressed into large breaks over time. At the end of the experiment, a greater number of extra large breaks were found in Bromostop, VeriPack, and white plastic films compared with other plastic films. No difference was found in exposed area among different plastic films initially, but as time progressed, Bromostop developed more e xposed area from breaks than white plastic film, while no difference was observed among ISO, VeriPack, and Poly Pak plastic films (Table 22). At the end of season, white plastic and Bromostop plastic films had more exposed area than ISO, VeriPack, and Po ly Pak films. In 2008, e arly in the season, no difference was observed among treatments in number of small, large, and extra large breaks, but as the season progressed, white plastic and Bromostop

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41 plastic films showed more breaks in comparison to Poly Pak and Polydak films. The thin Polydak plastic film developed a number of very small (< 0.75 inch) breaks due to large birds (sandhill crane, Grus c anadensis ) walking on the film, but these did not develop into large breaks (Table 23). These very small br eaks were observed in 2008 (mainly on Polydak film) but not in 2007. Numbers of extra large breaks increased toward the end of season because small and large breaks were torn further and led to extra large breaks (Table 2 4). Exposed area from extra large breaks was calculated on four different sampling dates. No exposed areas were found in Polydak plastic film throughout the experiment and it remained intact in the field for seven months. Ten weeks after the treatments were applied in the field, all of t he Bromostop and white plastic films were destroyed, and the total exposed area was the same as that of the bed surface (87.50 ft2). Poly Pak had 75% less exposed area (21.19 ft2) at 10 weeks compared with white plastic and Bromostop films by the end of experiment (Table 25). Poly Pak and Polydak plastic films were more durable when exposed to sunlight, compared with white plastic and Bromostop plastic films. Weed Population Densities In 2007, the density of purple nutsedge was greatest in raised beds covered with white plastic film on all sampling dates (Table 26), which may be due to lower penetration of solar radiation through white plastic film. On 20 September cudweed ( Gnaphalium spp.), hairy indigo ( Indigofera hirsute L. ), total grasses, and to tal broadleaf weeds were generally found to be significantly less under Poly Pak, VeriPack, and ISO plastic films than with white plastic and Bromostop plastic films (Table 2 7). Bromostop plastic film was not persistent under prolonged sunlight and was more prone to tearing, which led to the emergence of weeds from open areas on raised beds. Purple nutsedge was the major weed present throughout the season.

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42 Generally, ISO and Poly Pak plastic films were found to be more effective for managing purple nutse dge compared with white plastic and Bromostop films. The differential penetration of opaque and clear plastic mulches might be explained by a light dependent morphological change from rhizome elongation to leaf expansion (Chase et al. 1998). In 2008, purple nutsedge was present early in the season and density increased as the season progressed. Significantly greater density of purple nutsedge was found in Bromostop and white plastic films than in Poly Pak and Polydak plastic films. No difference among treatments was found in density of broadleaf weeds at the start of season; but at the end of season, broadleaf weed density was significantly greater in Bromostop and white plastic compared with Poly Pak and Polydak films (Table 28). In previous studies soil solarization controlled annual weeds better than perennial weeds because some perennial weeds resprout from deeply buried underground vegeta tive structures (Elmore et al. 1997). Among the perennials, the seeds of bermudagrass ( Cynodon dactylon L. Per s. ), johnsongrass ( Sorghum halepense L. Pers. ), and field bindweed ( Convolvulus arvensis L. ) were controlled, but purslane, crabgrass ( Digitaria sanguinalis L. Scop.), and yellow nutsedge ( Cyperus esculentus L. ) were only partially managed by soil solariza tion. Destruction of weeds such as cogongrass ( Imperata cylindrical (L.) Beauv.) pigweed ( Amaranthus spp.), purslane, foxtail (Se taria spp.) and crabgrass was visually observed after removal of plastic films used for a soil solarization study in highlands of the West Province of Cameroon (Daelemans 1989). In the current study, purple nutsedge was controlled using more durable plastic films such as Polydak, Poly Pak, and ISO compared to Bromostop and white plastic films. Purple nutsedge was the dominant weed during 2007 and 2008, and although it is known to cause punctures and breaks in plastic films (Chase et al. 1998), it was controlled under several of the

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43 solarization films used in the current study. Much of the high nutsedge populations in the curr ent study likely resulted from emergence in areas exposed due to breaks in the films. Many of the small breaks recorded during both years resulted from breakdown of the plastic films and did not contain nutsedge plants. Nutsedge populations increased great ly in these exposed areas as plants emerged. Some puncturing of plastic by nutsedge was observed, particularly with the white plastic. However, the white plastic was not very durable, and developed many additional breaks as the plastic deteriorated. The si milar high populations of nutsedge later in the season under the semi opaque white plastic (more likely to be punctured by nutsedge) and the clear Bromostop (less likely to be punctured due to solar heating) suggest that a similar mechanism led to nutsedge population buildup. In this case, that mechanism could be the breakdown of both plastic types. Solarization times of six weeks or longer are needed for consistent weed man agement (McGovern and McSorley 1997), and this was achieved by some of the plastics used here. However, if plastic breaks down prematurely, the temperatures in the exposed areas cool, and weeds such as nutsedge are better able to survive and emerge. UV stabilized films (Polydak and ISO) were durable, while the durability of plastic film s that were not UV stabilized was variable. Poly Pak and VeriPack were stable under field conditions, but Bromostop and white plastic deteriorated rapidly and did not provide seasonlong control of nutsedges. Polydak remained intact throughout the season, even though the film is very thin.

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44 Table 2 1. Number of breaks in plastic films over time (weeks after treatment applied) in 2007. Time after treatment application (weeks) a Small breaks (no.) b Large breaks (no.) b Extra large breaks (no.) b Treatments c 5 6 7 8 6 7 8 6 7 8 ISO film 0.6 a d 0.0 b 0.0 b 0.0 c 0.8 ab 0.0 c 0 .0 b 0.0 b 0.0 b 0.0 b Bromostop 0.6a 13.2 a 17.0 a 14.8 bc 2.0 ab 1.8 b 0.6 b 1.2 a 3.6 a 2.0 a VeriPack 0.4 a 0.6 b 13.8 a 31.0 ab 0.2 ab 3.8 a 4.6 a 0.0 b 0.0 b 2.4 a Poly Pak 0.0 a 0.0 b 0. 0 b 7.6 bc 0.0 b 0.0 c 0.6 b 0.0 b 0.4 b 0.2 b White Plastic 0.2 a 0.6 b 9.4 ab 45.6 a 7.6 a 3.2 ab 0.8 b 0.4 ab 2.4 a 2.6 a aTime after treatment application (weeks) = number of weeks after treatment applied in field. bSmall breaks = < 30 inches (76.2 cm) (less than t he bed width); Large breaks= 30 inches (76.2 cm) (across the entire bed width); Extra large breaks = Extra large breaks extend across the entire bed width but open up along the bed length as well. cTreatments =ISO film (ISO Poly Films, Gray Court, SC) ; B romostop ( Bruno Rimini, London, UK) ; VeriPack (VeriPack ,, Framingham, MA) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; White plastic (Rodeo Plastic Bag and Film Mesquite, TX ). dMean values within the same column followed by same letter are not significantly different according to least significant difference test at P 0.05. Number of breaks present in given week. Number can increase from week to week if more breaks occur. Number can decrease if smaller breaks expand in size and therefore become larger breaks.

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45 Table 2 2. Cumulative exposed area on bedsa from extra large breaks in plastic films over time (weeks after treatment applied) in 2007. Time after treatment application (weeks) b Treatments c 6 7 8 Cumulative exposed area (ft 2 ) ISO film 0.00 a d 0.00 c 0.00 b Bromostop 2.04a 35.29 a 67.47 a VeriPack 0.00a 0.00 c 10 .11 b Poly Pak 0.00 a 0.11 c 3.34 b White Plastic 3.55 a 14.85 b 56.92 a aTotal b ed area = 87.50 ft2 = 8.129 m2;1 ft2 = 0.0929 m2 bTime after treatment application (weeks)= number of weeks after treatment applied in field. cTreatments =ISO film (ISO Poly Film s, Gray Court, SC) ; Bromostop ( Bruno Rimini, London, UK) ; VeriPack (VeriPack, Framingham, MA) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; White plastic (Rodeo Plastic Bag and Film Mesquite, TX ). dMean values within the same column followed by same let ter are not significantly different according to least significant difference test at P 0.05.

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46 Table 2 3. Number of very small and small breaks in plastic films over time (weeks after treatment applied) in 2008. Time after treatment application (weeks) a Very small breaks (no.) b Small breaks (no.) b Treatments c 2 4 6 8 10 12 4 6 8 10 12 White plastic 0.0 b d 0.0 b 0.0 b 0.0 b 0.0 b 0.0 b 0.0 a 6.0 ab 33.4 a 0.0 b 0.0 b Bromostop 0.0 b 0.0 b 0.0 b 0.0 b 0.0 b 0.0 b 0.8 a 15.0 a 13.6 b 0.0 b 0.0 b Poly Pak 0.6 b 0.8 b 0.8 b 1.0 b 1.0 b 1.0 b 0.0 a 0.0 b 3.2 b 11.8 a 13.2 a Polydak 3.6 a 3.6 a 3.6 a 11.6 a 12.6 a 12.6 a 0.0 a 0.0 b 0.4 b 0.0 b 0.0 b aTime after treatment application (weeks)= number of weeks after treatment applied in field. bVery small breaks = < 0.75 inch (1.905 cm); Small breaks= < 30 inches (76.2 cm) (less than the bed width). cTreatment s = White plastic (Rodeo Plastic Bag and Film Mesquite, TX ); Bromostop ( Bruno Rimini, London, UK) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; Polydak (Ginegar Plastics Products, Ginegar, Israel). dMean values within the same column followed by same let ter are not significantly different according to least significant difference test at P 0.05. Number of breaks present in given week. Number can increase from week to week if more breaks occur. Number can decrease if smaller breaks expand in size and therefore become larger breaks.

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47 Table 24. Number of large and extra large breaks in plast ic films over time (weeks after treatment applied) in 2008. Time after treatment application (weeks) a Large breaks (no.) b Extra large breaks (no.) b Treatments c 6 8 10 12 6 8 10 12 White plastic 3.2a d 0 .0 a 0 .0 b 0 .0 b 0.2a 3.8a 1 .0 b 0 .0 b Bromostop 3 .0 a 0 .0 a 0 .0 b 0 .0 b 0.8a 2.8a 1 .0 b 0 .0 b Poly Pak 0 .0 b 0.6a 4.4a 3.8a 0 .0 a 0 .0 b 2.6a 4.4a Polydak 0 .0 b 0 .0 a 0 .0 b 0 .0 b 0 .0 a 0 .0 b 0 .0 b 0 .0 b aTime after treatment application (weeks) = number of weeks after treatment ap plied in field. bLarge breaks= 30 inches (76.2 cm) (across the entire bed width); Extra large breaks= Extra large breaks extend across the entire bed width but open up along the bed length as well. cTreatments = White plastic (Rodeo Plastic Bag and Film Mesquite, TX ); Bromostop ( Bruno Rimini, London, UK) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; Polydak (Ginegar Plastics Products, Ginegar, Israel). dMean values within the same column followed by same letter are not significantly different according t o least significant difference test at P 0.05. Number of breaks present in given week. Number can increase from week to week if more breaks occur. Number can decrease if smaller breaks expand in size and therefore become larger breaks.

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48 Table 25. Cumula tive exposed area on bedsa from extra large breaks in plastic films over time (weeks after treatment applied) in 2008. Time after treatment application (weeks) b Treatments c 6 8 10 12 Cumulative exposed area (ft 2 ) White plastic 0. 49 a d 5 9.82 a 8 7.50 a 8 7.5 0 a Bromostop 0. 30 a 5 4.55 a 8 7.50 a 8 7.50 a Poly Pak 0 .00 a 0 .00 b 6.99 b 21.19 b Polydak 0 .00 a 0 .00 b 0 .00 c 0 .00 c aTotal b ed area = 87.50 ft2 = 8.129 m2;1 ft2 = 0.0929 m2 bTime after treatment application (weeks) = number of weeks after treatment ap plied in field. cTreatments = White plastic (Rodeo Plastic Bag and Film Mesquite, TX ); Bromostop ( Bruno Rimini, London, UK) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; Polydak (Ginegar Plastics Products, Ginegar, Israel). dMean values within the same column followed by same letter are not significantly different according to least significant difference test at P 0.05.

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49 Table 26. Cumulative density of purple nutsedge over time (weeks after treatment applied) in 2007. Time after treatment application (weeks) a Treatments b 3 5 8 10 12 Cumulative density (stems/bed) c ISO film 0.2c d 0.4b 6.4b 23 .0 c 64 .0 bc Bro mostop 5.0ab 11.2a 66 .0 b 142.6ab 267.2ab VeriPack 2.0abc 1.4b 16.6b 57.6bc 140 .0 bc Poly Pak 0.4bc 1.0b 8.4b 18.6c 42.6c W hite Plastic 5.8a 13.0a 136 .0 a 197.2a 425 .0 a aTime after treatment application (weeks) = number of weeks after tr eatment applied in field. bTreatments = ISO film ( ISO Poly Films, Gray Court, SC) ; Bromostop ( Bruno Rimini London, UK) ; VeriPack (VeriPack, Framingham, MA) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; White plastic (Rodeo Plastic Bag and Film, Mesquite TX ). cTotal b ed area = 87.50 ft2 = 8.129 m2; 1 ft2 = 0.0929 m2, so 1 weed/bed = 0.103 weed/yard2 1 stem/87.50ft2 (8.129 m2) bed = 0.1230 stem/m2 dMean values within the same column followed by same letter are not significantly different according to least significant difference test at P 0.05.

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50 Table 27. Density of common weeds at 10 weeks after treatment applied in 2007. Treatments a Purslane Cudweed Hairy Indigo Grasses b Broadleaf (weeds/bed) c ISO film 0.0 a d 0.0 b 0.0 b 0.0 b 0.0 b Bromostop 1.2 a 1.8 ab 2.0 a 9.8 ab 8.8 a VeriPack 0.0 a 0.4 b 0.0 b 1.8 b 0.4 b Poly Pak 0.0a 0.0b 0.6ab 1.4b 0.0b W hite Plastic 3.4a 5.2a 1.4ab 27.6a 11.2a aTreatments = ISO film ( ISO Poly Films, Gray Court, SC) ; Bromostop ( Bruno Rimini, London, UK) ; VeriPack (VeriPack, Framingham, MA) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; White plastic (Rodeo Plastic Bag and Film Mesquite, TX ). bGrasses = predominantly crabgrass and bermudagrass. cTotal b ed area = 87.50 ft2 = 8.129 m2; 1 ft2 = 0.0929 m2 so 1 weed/bed = 0.103 weed/yard2 1 weed/87.50f t2 (8.129 m2) bed = 0.1230 weed/m2 dMean values within the same column followed by same letter are not significantly different according to least significant difference test at P 0.05.

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51 Table 2 8. Density of common weeds over time (weeks after treatment applied) in 2008. Time after treatment application (weeks) a Nutsedges Broadleaf Treatments b 2 4 6 8 10 6 8 10 (weeds/bed) c White plastic 10.6ab d 12.8ab 48.4a 173.2a 363.2a 0 .0 a 0 .0 b 3 .0 ab Bromostop 16.8a 21.2a 59.6a 211 .0 a 380.4a 0.2a 0.6a 4.4a Poly Pak 0.2c 2.6b 1.8b 3.6b 20.8b 0 .0 a 0 .0 b 0.2bc Polydak 5.6bc 6.4b 12.4b 16 .0 b 19.4b 0 .0 a 0 .0 b 0 .0 c aTime after treatment application (weeks) = number of weeks after treatm ent applied in field. bTreatments = White plastic (Rodeo Plastic Bag and Film Mesquite, TX ); Bromostop ( Bruno Rimini, London, UK) ; Poly Pak ( Poly Pak Plastics, Medford, MN) ; Polydak (Ginegar Plastics Products, Ginegar, Israel). cTotal b ed area = 87.50 ft2 = 8.129 m2; 1ft2 = 0.0929 m2, so 1 weed/bed = 0.103 weed/yard2 1 weed/87.50ft2 (8.129 m2) bed = 0.1230 weed/m2 dMean values within the same column followed by same letter are not significantly different according to least significant difference test at P 0.05.

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52 20 30 40 50 60 13Jul 15Jul 17Jul 19Jul 21Jul 23Jul 25Jul 27Jul 29Jul 31Jul 02Aug 04Aug 06Aug Date Temperature (oC) WP BS PP ISO VP Fig ure 11. Soil temperatures (C) dur ing solarization at 5 cm (2.0 i nches ) soil depth in 2007 [(1.8 C) + 32 = F]. WP = White plastic; BS = Bromostop (Bruno Rimini, London, UK) =; PP = Poly Pak; ISO = ISO Poly Films; VP = VeriPack 2007 5 cm

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53 WP BS PP ISO VP 20 30 40 50 60 13Jul 15Jul 17Jul 19Jul 21Jul 23Jul 25Jul 27Jul 29Jul 31Jul 02Aug 04Aug 06Aug Date Temperature (oC) Figure 12. Soil temperatures (C) during solarization at 15 cm (5.9 inches) soil depth in 2008 [(1.8 C) + 32 = F]. WP = White plastic; BS = Bromostop (Bruno Rimini, London, UK) ; PP = Poly Pak ; P D = Poly dak (Ginegar Plastics Products, Ginegar, Israel) 2007 15 cm

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54 20 30 40 50 60 27Jun 02Jul 07Jul 12Jul 17Jul 22Jul 27Jul 01Aug 06Aug 11Aug 16Aug Date Temperature (oC) WP BS PP ISO Fig ure 21. Soil temperatures (C) during solarization at 5 cm (2.0 inches) soil depth in 2008 [(1.8 C) + 32 = F]. WP = White plastic; BS = Bromostop (Bruno Rimini, London, UK) ; PP = Poly Pak ; P D = Poly dak (Ginegar Plastics Products, G inegar, Israel) 2008 5 cm

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55 WP BS PP ISO 20 30 40 50 60 27Jun 02Jul 07Jul 12Jul 17Jul 22Jul 27Jul 01Aug 06Aug 11Aug 16Aug Date Temperature (oC) Fig ure 22. Soil temperatures (C) during solarization at 15 cm (5.9 inches) soil depth in 2008 [(1.8 C) + 32 = F]. WP = White plastic; BS = Bromostop (Bruno Rimini, London, UK) ; PP = Poly Pak ; P D = Poly dak (Ginegar Plastics P roducts, Ginegar, Israel) 2008 15 cm

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56 CHAPTER 3 IMPACT OF DIFFERENT ORGANIC MULCHES ON T HE SOIL SURFACE ARTHROPOD COMMUNITY AND WEEDS IN SNAPDRAGON Mulching is the process of spreading organic matter around plants to prev ent the evaporation of moisture and growth of weeds as well as provide frost protection to roots. It is an effective way to provide shelter for predatory insects and to control weeds (Brown and Tworkoski 2004, Johnson et al. 2004, Teasdale et al. 2004). Pine bark mulch was reported to improve weed and disease control (Reeleder et al. 2004). Mulches may even help to promote plant tolerance to the attack of insect pests (Johnson et al. 2004). Organic mulches can be derived from hay, straw, crop residues, pine needles, shredded bark, or other plant material that is readily available (Campiglia et al. 2010, Mulvaney et al. 2008, Wang et al. 2008, Westerman and Bicudo 2005) Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing specific inse ct pests. Compared to broccoli ( Brassica oleracea L. var. botrytis ) monoculture, living mulches reduced the densities of Lepidopteran eggs and larvae, and increased number of spiders (Hooks and Johnson 2004). Alfalfa ( Medicago sativa L.) living mulch incre ased the aphidophagous community to manage the outbreaks of the invasive soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae) (Schmidt et al. 2007). Alfalfa and kura clover ( Trifolium ambiguum M. Bieb) mulches increased the predator populations t o manage European corn borer ( Ostrinia nubilalis Hbner) (Prasifka et al. 2006). Although living mulches may offer resources to support predators, mulches derived from killed cover crops or hay from cover crops offer some benefits as well. Winter cover cr ops like wheat ( Triticum aestivu m L. ) reduced the population of insects

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57 including aphids (Aphididae), leafhoppers (Cicadellidae), plant bugs (Miridae), and thrips (Thysanoptera) (Tremelling et al. 2002). Predation by natural enemies on beet armyworm, Spodoptera exigua (Hbner) pupae was 33% greater in killed cover crop mulch than in conventional production plots (Pullaro et al. 2006). Mulch made from a sunn hemp ( Crotalaria juncea L.) cover crop reduced incidence of lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Gill et al. 2010). Poultry compost reduced pest population levels o n apple ( Malus domestica Borkh.) orchards while increasing the predator populations (Brown and Tworkoski 2004). Much of the work done in the past examined mulches for man aging flying insect pests (Brown and Tworkoski 2004, Gill et al. 2010, Hooks and Johnson 2004, Prasifka et al. 2006, Pullaro et al. 2006, Reeleder et al. 2004, Schmidt et al. 2007, Tremelling et al. 2002). On the other hand, management of soil surface arth ropods using mulches is less explored. The objectives of the current study were: (1) To determine the impact of mulches on the soil surface insect community using pitfall traps and board traps; (2) To determine the impact of mulches on weeds; and (3) To de termine the impact of mulches on potential plant pests of snapdragon ( Antirrhinum majus L. ) Materials and Methods Field experiments were conducted at the University of Florida Plant Science Research and Education Unit (29o24N, 82o9W), near Citra, FL in fall 2007 and 2008. The soil type was Arredondo sand (95% sand, 2% silt, 3% clay) with 1.5% organic matter (Thomas et al. 1979).

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58 Fall 2007 The site was sprayed with glyphosate ( Roundup, Monsanto, St Louis, MO) to kill weeds in late September followed by rototilling on 3 October. Individual plots for each treatment were 3.0 m long and 2.4 m wide. Average soil moisture before planti ng was 6.1 % Five treatments were compared: cowpea ( Vigna unguiculata (L.) Walp.) (C) mulch, sunn hemp (SH) mulch, sorghum s udangrass ( Sorghum bicolor Moench S. sudanense (Piper) Stapf) (SO) mulch, pine bark mulch nuggets (PB) (HTC Hood Timber Co., Adel, GA) and unmulched control (C). Cover crop mulches were obtained from crops of Iron and Clay cowpea, Tropic Sun sunn hem p, and Growers Choice sorghum sudangrass. Treatments were arranged in a randomized complete block design with 5 replications (total of 25 plots). All plots were planted with 2 3 cm tall Potomac Pink snapdragon seedlings (Speedling Inc., Sun City, FL) on 4 October, spaced 10 cm apart at a rate of 30 transplants per row. Mulches were obtained on 11 October from cover crops planted near the experimental site. A bove ground biomass was harvested by clipping plants at the base. The resulting mulches (3 5 cm d eep) were a mixture of leaves and stems and were applied manually surrounding the snapdragon plants on the same day they were harvested. Fresh c owpea (18.1kg/plot), sunn hemp (15.9 kg/plot), and sorghum sudangrass (17.7 kg/plot) mulches were obtained from cover crops and pine bark nuggets (29.8 kg/plot) were purchased locally. Plots were irrigated as needed using drip irrigation. Fall 2008 The field experiment was repeated at the same location in fall 2008, with all the same treatments and procedure s remained the same except for a few minor changes. The

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59 experimental field was sprayed with glyphosate to kill weeds in the first week of Septembe r followed by rototilling on 16 September. S oil moisture at planting averaged 6.9 % Snapdragon s eedlings were plant ed on 7 October. Fresh c owpea (12.7 kg/plot), sunn hemp (15.9 kg/plot), sorghum sudangrass (13.6 kg/plot), and pine bark nuggets ( 29.8 kg/plot) were applied on 9 October. Data C ollection Insects were collected using pitfall traps (Borror et al. 1989) on fo ur different sampling dates in both seasons. A plastic sandwich container (14 cm 14 cm 4 cm) was used as a pitfall trap. One pitfall trap was placed in the middle of the plot, and buried so that the upper edge was flush with soil surface. The traps wer e filled three quarters with water, along with 3 to 4 drops of dish detergent (Ultra Joy, Procter and Gamble, Cincinnati, OH) to break surface tension, ensuring that the insects would remain in the trap. Pitfall traps were set out in the morning and colle cted before noon the next day (which was recorded as sampling date). The traps were brought to the laboratory, kept in a cold room at 10C, and contents transferred and stored in 70% ethanol in vials. Insects were identified to order and family levels usin g a dissecting microscope. Wooden board traps (Cole 1946) were used to provide hiding places for sampling cryptic arthropods. One board trap (15cm 15 cm 2.5 cm thick) was placed on soil surface at the end of each plot. Board traps were sampled twice in 2007 and once in 2008. Boards were tilted to one side, and insects were counted and identified to order and family level, followed by replacement of traps on the same spot until the next sampling date. Weeds were grouped as grasses [primarily bahiagrass ( Paspalum notatum L.), bermudagrass ( Cynodon dactylon L.), and some crabgrass ( Digitaria spp.)] nutsedges

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60 ( Cyperus rotundus L.) and broadleaf weeds [ primarily Florida pusley (Richardia scabra L.), eveningprimrose ( Oenothera laciniata Hill), and cudweed ( Gnaphalium spp.) ] and evaluated on five sampling dates in 2007 and four dates in 2008. Each plot was rated for the percentage of surface area covered with weeds using the 1 to 12 Horsfall and Barrett rating scale (Horsfall and Barrett 1945), where 1 = 0%, 2 = 0 3%, 3 = 36%, 4 = 612%, 5 = 1225%, 6 = 2550% of ground covered with weeds, whereas 7 = 2550%, 8 = 1225%, 9 = 612%, 10 = 3 6%, 11 = 03%, and 12 = 0% of ground not covered with weeds. Snapdragon plant mortality was recorded at 2 sampling dates i n both seasons by counting numbers of dead snapdragon plants/plot. The plants were also examined for presence of leaf feeding caterpillars and numbers were counted/plot. Data A nalysis Data from each season were subjected to oneway analysis of variance (A NOVA) using the Statistical Analysis System (version 9.1; SAS Institute, Cary, NC). Treatment means were separated using the least significant difference (LSD) range test, when analysis of variance showed a significant treatment effect ( P 0.05). Results Fall 2007 The numbers of Collembola, Araneae, Coleoptera, and Diptera collected from pitfall traps did not differ among treatments on all sampling dates (Table 31). Coleoptera collected consisted of the families Staphylinidae, Carabidae, Elateridae, and Chrysomelidae; while Dipetra included Muscidae, Dolichopodidae, and other microdipterans. On the last sampling date, Formicidae numbers were higher in CP than in SH and SO plots. On the same date, Orthoptera (Gryllidae and Acrididae) numbers were

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61 greater in CP than in several other treatments, but other plant feeders (mainly aphids, thrips, and whiteflies) were most abundant in C treatment. Treatment effects on Cicadellidae varied during the season, but they generally reached their highest levels in CP or C plots. Board traps were used to sample cryptic insects on two sampling dates but results were variable (Table 3 2). Gryllidae and Labiduridae did not differ among treatments. Numbers of Araneae were highest in SO plots on 14 November but spiders were often absent under boards. Coleoptera (Staphylinidae, Carabidae, Elateridae, and Chrysomelidae) numbers were higher in CP than in SO or PB in November Other insects (small Hemiptera and Noctuidae) were greatest in CP on one date and in SO on the other. On all sampling dates, weed coverage ratings of nutsedges and broadleaf weeds did not differ among treatments (Table 33). Grasses were affected slightly by treatment on one sampling date. At the end of the season, the weed coverage rating of broadleaf weeds was highest in C plots. Buckeye caterpillars ( Junonia coenia Hbner) were often observed feeding on leaves as well as stems of snapdragon plants, but counts did not differ a mong treatments. On 26 November higher snapdragon mortality was observed in SO plots than in C and PB plots (Table 34). Fall 2008 Numbers of Collembola, Cicadellidae, Orthoptera, and Coleoptera did not differ among treatments (Table 35). On the last two sampling dates, Formicidae numbers were higher in CP than in SH. On 18 November Diptera (mainly Muscidae, Dolichopodidae, and other microdipterans) numbers were greater in CP, SH, and PB plots compared with

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62 SO. On the last sampling date, other plant feeders (aphids, thrips, and whiteflies) were highest in C plots. Numbers of insect s found under board traps were very low and generally not affected by treatments (Table 36). However, Labiduridae numbers were highest in PB plots (Table 36). Rating of ground coverage by nutsedges did not differ among treatments throughout the season (Table 37). On 23 November coverage by grasses was very high (rating of 7 indicates > 50% of ground covered) in C plots, significantly greater than several other treatments. Broadleaf weed ratings were highest in C plots but not different from CP toward the middle of the season. Buckeye caterpillar counts did not differ among treatments, as in the previous season. Plant mortality did not differ among treatments (Table 34). Discussion In general, higher weed ratings of grasses and broadleaf weeds were ob served in CP and C plots in both seasons. In C plots, absence of any mulch allowed weeds to grow without any obstacle, leading to greater weed ratings. The greater weed rating in CP plots is due to the low C: N ratio (14:1) of cowpea hay that led to the degradation of the mulch, allowing the emergence of weeds through open spaces. These results are consistent with other studies in which mulches reduced the weed populations (Brown and Tworkoski 2004, Johnson et al. 2004, Teasdale et al. 2004, Wilke and Snapp 2008). Generally, Cicadellidae, Orthoptera (Gryllidae and Acrididae), other plant feeders, and Formicidae were found to be higher in CP and C plots. The preference of Cicadellidae, Orthoptera, and other plant feeders to feed on plant materials such as we eds

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63 in C and CP plots may have led to their higher numbers in these plots. The group of other plant feeders was mainly small sucking insects that feed on plant sap and included aphids, thrips, and whiteflies. Although these insects are typically sampled by other methods such as sticky cards rather than pitfall traps (Southwood and Henderson 2000), small numbers of them will fall from vegetation into pitfall traps as well (Tremelling et al. 2002). In north central Florida, winter cover crops affected a varie ty of insects including aphids (Aphididae), leafhoppers (Cicadellidae), plant bugs (Miridae), and thrips (Thysanoptera) (Tremelling et al. 2002). In the literature, Formicidae have been observed to feed on or tend sucking insects (Borror et al. 1989). Thus their higher numbers in the C and CP plots may be related to increased levels of plant feeding insects. Pullaro et al. (2006) found higher number of fire ants in plots with cover crop mulch compared with conventional plots. The pitfall trap is one of the most commonly used methods to sample arthropods (Southwood and Henderson 2000). Wooden board traps were used to sample soil surface cryptic arthropods by Cole (1946). In our study, more taxa and greater numbers of insect groups were found in pitfall traps compared with board traps. Counts of some taxa found in board traps were too low to be useful. However, board traps were found useful for sampling of earwigs, and in one instance for predators like spiders and coleopteran s. Cole (1946) reported Dermaptera and Coleoptera (Staphylinidae, Carabidae, and Histeridae) to be common under board traps. Earwig populations were higher in PB mulch plots, possibly because PB was the only much that did not degrade (C: N ratio = 208:1) fast, unlike the other mulches used and allowed hiding place for earwigs.

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64 In 2007 under board traps, Coleoptera were greatest in CP plots, but in general, effects of mulches on predators were limited and inconsistent. Araneae as generalist predators were occasionally found higher in SO mulches. Sturdy stems and leaves of SO mulch may have allowed free movements of these generalist predators. Hooks and Johnson (2004) reported that spider counts were significantly higher on broccoli with living mulches compared with unmulched plots. Little effect of treatments was found on predators, while no effect was found on the key plant pest, buckeye caterpillars. Numbers of buckeye caterpillars did not differ among treatments, and they caused heavy damage resulting in high plant mortality. Plant morta lity was observed to be higher in SO plots compared with other plots. Allelopathic potential of sorghum and its effectiveness to control weeds has been well documented in the literature (Weston et al. 1989). Roth et al. (2000) reported that tilled sorghum residue often delayed the deve lopment of the following wheat ( Triticum aestivum L.) crop which was grown in rotation, but grain yield was not affected because allelopathic compounds degraded in soil. In the current study, arthropods varied in their respons es to different mulches. Several groups were affected indirectly due to the effects of mulches on weed growth. Higher weed coverage was found in C and CP plots, and that may have led to increased populations of plant feeding insects such as Cicadellidae, O rthoptera, and small sap feedin g insects, as all as other groups associated with them, such as Formicidae and Araneae. Some groups such as Collembola were unaffected by mulches, while others such as Coleoptera and Diptera, showed only minimal response. Mul ches did not

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65 consistently affect predators of herbivores insects. Buckeye caterpillars were not affected by treatments and caused high plant mortality.

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66 Table 31. Effect of treatments on arthropod taxa (numbers/pitfall tra p) on selected sampling dates, 2007 Trt a Formicidae Collembola Araneae Cicadellidae Diptera Orthoptera Coleoptera OPF b 30 October CP 0.6 0.40a 299 200a 0.0 0.00a 1.8 0.49a 4.6 2.99a 0.4 0.24a 0.2 0.20a 0.2 0.20a SH 1.2 0.49a 233 116a 0.2 0.20a 0.0 0.00b 3.8 1.62a 0.4 0.24a 0.0 0.00a 0.2 0.20a SO 0.6 0.40a 77 38a 2.4 1.91a 0.2 0.20b 1.8 0.97a 0.2 0.20a 0.0 0.00a 0.2 0.20a PB 0.4 0.24a 291 94a 0.2 0.20a 0.4 0.24b 6.6 2.93a 1.0 0.77a 0.4 0.40a 0.8 0.80a C 0.6 0.4 0a 291 135a 0.0 0.00a 0.2 0.20b 6.6 3.06a 0.2 0.20a 0.2 0.20a 0.4 0.24a 14 Nov ember CP 4.2 1.50a 56 19a 1.2 0.58a 1.8 0.37a 15.6 3.70a 2.0 0.95a 1.6 0.75a 2.6 0.68a SH 2.8 1.59a 75 23a 0.6 0.40a 1.2 0.37ab 1 0.8 2.13a 1.6 0.93a 2.0 0.55a 1.8 1.07a SO 3.0 1.52a 51 18a 5.2 5.20a 0.8 0.37ab 6.2 2.01a 1.2 0.49a 0.2 0.20a 0.8 0.49a PB 2.2 1.11a 33 9a 0.2 0.20a 0.2 0.20b 6.0 1.79a 0.8 0.37a 1.8 0.73a 0.4 0.24a C 4.0 1.38a 50 33a 0.4 0.24a 1.4 0.51a 10.8 4.64a 1.6 0.40a 1.4 0.51a 1.2 0.73a 27 November CP 3.4 1.78a 122 76a 0.8 0.49a 1.6 0.68ab 16.0 2.07a 4.2 1.20a 9.8 6.68a 1.0 0.45a SH 3.6 1.12a 50 15a 0.4 0.24a 1.4 0.51b 10. 4 3.39a 3.8 0.49a 2.4 0.93a 0.8 0.37a SO 11.4 8.81a 50 9a 0.2 0.20a 0.6 0.24b 14.2 5.10a 2.6 0.87a 2.4 0.93a 1.8 0.80a PB 1.2 0.49a 48 20a 0.2 0.20a 0.8 0.20b 6.4 2.01a 1.6 0.60a 1.4 0.51a 1.6 0.60a C 6.0 3.46a 35 10a 1.0 0.77a 3.2 1.02a 8.2 2.54a 2.2 0.80a 11.2 8.95a 2.4 0.51a 11 December CP 6.6 1.21a 101 56a 1.8 0.58a 1.4 0.93abc 10.8 2.35a 5.0 1.10a 3.8 3.31a 2.2 1.50b SH 2.4 1.12b 127 85a 1.0 0.55a 0.6 0.40c 6. 4 2.16a 2.2 0.80bc 1.0 0.55a 1.2 0.37b SO 2.0 0.71b 38 8a 3.6 2.62a 0.2 0.20c 6.4 0.81a 1.0 0.45c 0.4 0.24a 2.2 1.32b PB 3.2 1.46ab 30 5a 1.6 1.60a 2.0 0.71ab 8.0 1.95a 3.8 0.37ab 1.6 0.93a 2.0 1.05b C 4.0 1.30ab 35 10a 0.8 0.20a 2.6 0.51a 10.0 2.59a 1.8 0.37bc 1.0 0.55a 6.4 1.83a aCP = cowpea, SH = sunn he mp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control bOther plant feeders include whiteflies (Aleurodidae) aphids (Aphididae) a nd thrips (Thysanoptera) Data are means standard error of 5 replications. Means in columns for each sampling date followed by the same letters do no t differ significantly based on LSD test ( P 0.05)

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67 Table 32. Effect of treatments on arthropod taxa (numbers/board tra p) on selected sampling dates, 2007 Treatment a Araneae Gryllidae Labiduridae Coleoptera OI b 14 November CP 0.4 0.24ab 1.0 1.0 0 a 0.0 0.0 0 a 2.6 1.47a 3.2 1.46a SH 0.0 0.0 0 b 0.8 0.58a 0.0 0.0 0 a 0.6 0.4 0 ab 0.4 0.4 0 b SO 0.8 0.2 0 a 0.4 0.24a 0.0 0.0 0 a 0.0 0.0 0 b 1.6 0.68ab PB 0.2 0.2 0 b 0.2 0.2 0 a 0.0 0.0 0 a 0.0 0.0 0 b 0.2 0.2 0 b C 0.0 0.0 0 b 1.0 0.32a 0.0 0.0 0 a 1.8 0.37ab 1.0 0.32ab 4 De c ember CP 0.0 0.0 0 a 4.4 0.68a 0.4 0.24a 1.8 0.73a 0.0 0.0 0 b SH 0.0 0.0 0 a 1.8 0.80a 0.0 0.0 0 a 3.8 2.42a 0.0 0.0 0 b SO 0.0 0.0 0 a 1.2 0.73a 0.2 0.2 0 a 1.2 0.58a 0.8 0.49a PB 0.0 0.0 0 a 1.6 0.81a 0.4 0.24a 0.2 0.2 0 a 0.2 0.2 0 b C 0.0 0.0 0 a 2.8 1.16a 0.8 0.49a 1.2 0.49a 0.0 0.0 0 b aCP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control bOther insects include small Hemiptera, and Noctuidae Data are means standard error of 5 replications. Means in columns for each sampling date followed by the same letters do not differ significantly based on LSD test ( P 0.05)

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68 Table 33. Weed coverage on beds rated among treatments using Horsfall and Barrett (1945)a rating sca le on different sampling dates, 2007 Sampling date Treatment b 30 October 5 November 19 November 3 December 17 December Grasses CP 1.6 0.24 a 1.6 0.24ab 2.0 0.45a 2.4 0.51a 3.0 0.89a SH 1.2 0.20a 1.2 0.20b 1.6 0.24a 2.0 0.32a 2.6 0.68a SO 1.6 0.24a 1.2 0.20b 1.4 0.24a 1.8 0.37a 1.8 0.37a PB 1.8 0.20a 1.8 0.2 0 ab 1.6 0.24a 2.0 0.45a 2.2 0.37a C 2.0 0.3 2a 2.2 0.20a 2.4 0.40a 2.2 0.37a 2.6 0.68a Nutsedges CP 2.2 0.37a 2.0 0.32a 2.4 0.24a 3.0 0.32a 3.4 0.81a SH 2.0 0.32a 2.2 0.37a 2.0 0.00a 2.4 0.24a 2.6 0.24a SO 2.2 0.49a 1.8 0.37a 1.8 0.37a 2.2 0.20a 2.2 0.37a PB 2.2 0.37a 2.4 0.40a 2.2 0.20a 3.0 0.45a 2.2 0.37a C 2.0 0.32a 2.0 0.32a 2.0 0.00a 3.2 0.58a 3.6 0.87a Broadleaf weeds CP 1.4 0.24a 2.8 0.37a 2.2 0.37a 4.0 0.45a 3.8 0.37ab SH 1.2 0.20a 1.6 0.24a 2.2 0.20a 2.4 0.40a 3.2 0.49b SO 1.8 0.20a 1.8 0.20a 2.2 0.20a 3.0 0.71a 3.6 0.51ab PB 1.4 0.24a 1.8 0.20a 2.4 0.24a 3.6 0.24a 3.0 0.32b C 1.4 0.24a 1.8 0.20a 2.4 0.40a 3.0 0.55a 4.6 0.24a aHorsfall and Barret t (1945) rating scale where 1 = 0%, 2 = 03%, 3 = 36%, 4 = 612%, 5 = 1225%, 6 = 2550% of ground covered with weeds, whereas 7 = 2550%, 8 = 1225%, 9 = 612%, 10 = 3 6%, 11 = 03%, and 12 = 0% of ground not covered with weeds. bCP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control Data are means standard error of 5 replications. Means in columns for each weed type followed by the same letters do not differ significantly based on LSD test ( P 0.05)

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69 Table 34. Buckeye caterpill ars counts and plant mortality, 20072008 Numbers per plot b Treatment a Buckeye caterpillars Dead plants 6 November 2007 CP 0.6 0.24a 7.4 3.14a SH 1.0 0.63a 7.4 3.50a SO 2.0 1.26a 10.0 2.81a PB 1.0 0.45a 3.0 2.28a C 0.8 0.49a 1.6 0.51a 26 November 2007 CP 1.0 0.00a 9.8 2.92ab SH 0.6 0.24a 10.0 3.08ab SO 0.4 0.24a 14.6 3.98a PB 0.6 0.40a 4.4 2.56b C 0.4 0.24a 3.4 0.51c 4 November 2008 CP 2.4 0.51a 3.4 1. 91a SH 5.4 2.66a 6.6 2.11a SO 5.4 1.60a 5.8 2.08a PB 3.2 1.53a 5.0 1.55a C 3.6 1.21a 3.2 1.20a 25 November 2008 CP 3.2 1.24a 7.6 2.98a SH 2.2 1.07a 12.8 3.54a SO 2.0 1.30a 10.4 3.91a PB 5.8 2.52a 6.2 2.31a C 2. 8 0.86a 3.8 1.32a aCP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control bBased on 30 plants per plot Data are means standard error of 5 replications. Means in columns for each sampling date followed by the sa me letters do not differ significantly based on LSD test ( P 0.05)

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70 Table 35. Effect of treatments on arthropod taxa (numbers/pitfall tra p) on selected sampling dates, 2008 Treat a Formicidae Collembola Araneae Cicadellidae Diptera Orthoptera Coleoptera OPF b 21 Oct CP 27.8 14.32a 13.0 2.59a 0.4 0.2 4ab 0.4 0.40a 6.8 1.11a 1.0 0.45a 3.4 1.89a 7.2 1.46a SH 11.4 4.60a 16.4 4.99a 0.2 0.20b 0.8 0.58a 10.8 5.13a 0.6 0.24a 3.8 0.97a 3.2 1.43a SO 6.8 3.17a 19.2 6.61a 1.2 0.58a 1.6 0.51a 8.0 2.19a 0.8 0.20a 5.8 2.03a 2.0 1.14a PB 3.8 1.36a 17.4 3.31a 0.2 0.20b 1.8 0.97a 7.2 1.02a 0.2 0.20a 2.2 0.73a 4.0 1.30a C 6.6 1.96a 26.4 4.62a 0.0 0.00b 1.6 0.68a 9.0 2.02a 0.6 0.40a 4.2 0.73a 5.2 1.36a 4 Nov CP 13.4 4.76a 25.4 6.0 2a 0.0 0.00a 2.2 0.49a 8.8 2.37a 1.8 0.73a 3.6 2.04a 5.6 2.68a SH 20.2 15.06a 68.6 39.25a 0.0 0.00a 1.4 0.51a 19.4 5.35a 1.0 0.55a 3.6 1.08a 2.4 0.93a SO 2.0 0.71a 30.4 4.28a 0.8 0.37a 0.2 0.20a 12.4 4.01a 1.4 0.75 a 1.4 0.51a 3.4 0.40a PB 5.6 1.72a 94.2 26.16a 0.4 0.24a 2.0 0.32a 16.2 3.46a 1.6 0.60a 1.6 0.68a 3.6 1.69a C 6.0 1.58a 97.4 38.27a 0.4 0.24a 1.8 0.92a 26.2 9.60a 1.6 0.93a 3.0 1.26a 6.2 1.46a 18 Nov CP 11.8 1.39a 21.8 8.12a 0.8 0.20a 1.4 0.93a 8.0 1.30ab 1.2 0.73a 1.2 0.73a 4.0 1.38a SH 2.2 0.80b 11.2 4.19a 0.2 0.20a 0.6 0.40a 7.6 1.50ab 1.8 0.86a 0.4 0.40a 1.8 0.97a SO 5.0 2.45ab 9.4 2.29a 26.2 25.7a 0.6 0.24a 2.8 1.50c 1.4 0.24a 0.4 0.40a 2.8 0.58a PB 9.8 4.14a 11.2 3.68a 0.6 0.24a 1.0 0.32a 9.8 1.80a 1.0 0.32a 1.0 0.63a 2.2 0.66a C 4.8 2.62ab 4.6 1.17a 0.4 0.24a 0.4 0.24a 5.2 1.39bc 1.6 0.51a 0.8 0.58a 2.8 0.86a 8 Dec. CP 25.0 13.05a 16.8 2.44a 0.2 0.20a 4.6 1.40a 8.6 2.56a 1.4 0.51a 3.6 1.47a 2.2 1.20b SH 4.0 2.12b 15.4 4.6a 0.6 0.40a 2.6 0.40a 6 .2 1.07a 0.6 0.40a 8.2 5.25a 3.6 1.21b SO 3.4 1.12b 7.8 1.93a 0.0 0.00a 2.6 1.21a 15.2 8.25a 0.2 0.20a 6.6 3.63a 3.2 1.24b PB 2.8 1.16b 13.2 1.62a 0.2 0.20a 2.4 0.93a 14.8 2.56a 1.0 0.55a 8.0 1.30a 4.2 1.96b C 7.4 2.75ab 8.4 2.58a 0.0 0.00a 4.2 0.37a 10.8 0.92a 0.8 0.58a 8.8 2.62a 17.2 8.2 7a aCP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control bOther plant feeders include whiteflies (Aleurodidae) aphids (Aphididae) and thrips (Thysanoptera) Data are means standard error of 5 replications. Means in columns for each sampling date followed by the same letters do not differ significantly based on LSD test ( P 0.05)

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71 Table 36. Effect of treatments on arthropod taxa (numbers/board trap) on 3 November, 2008 Treatment a Araneae Gryllidae Labiduridae Coleoptera OI b CP 0.0 0.0 0 a 0.2 0.2 0 a 0.0 0.0 0 b 0.2 0.20a 0.4 0.24a SH 0.2 0.2 0 a 0.0 0.0 0 a 0.0 0.0 0 b 0.4 0.24a 0.6 0.24a SO 0.0 0.0 0 a 0.0 0.0 0 a 0.0 0.0 0 b 0.4 0.40a 0.4 0.24a PB 0.2 0.2 0 a 0.2 0.2 0 a 0.4 0.24a 0.2 0.20a 0.2 0.2 0 a C 0.0 0.0 0 a 0.2 0.2 0 a 0.0 0.0 0 b 1.0 0.32a 0.0 0.0 0 a aCP = cowpea, SH = sunn hemp, SO = sor ghum sudangrass, PB = pine bark, C = unmulched control bOther insects include small Hemiptera, and Noctuidae Data are means standard error of 5 replications. Means in columns for each sampling date followed by the same letters do not differ signifi cantly based on LSD test ( P 0.05)

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72 Table 37. Weed coverage on beds rated among treatments using Horsfall and Barrett (1945)a rating scale on different sampling dates, 2008 Sampling date Treatment b 16 Oct. 27 Oct. 9 Nov. 23 Nov. Grasses CP 1.6 0.40a 1.8 0.37a 2.2 0.73a 5.6 0.51ab SH 1.4 0.24a 1.2 0.20a 1.6 0.24a 4.0 0.32b SO 1.4 0.24a 1.2 0.20a 1.2 0.20a 4.0 0.32b PB 1.4 0.24a 2.0 0.32a 1.6 0.40a 4.2 0.58b C 1.6 0.40a 2.2 0.49a 2.0 0.77a 7.2 1.07a Nu tsedges CP 2.0 0.00a 2.0 0.00a 2.4 0.51a 2.0 0.45a SH 2.0 0.32a 2.2 0.20a 2.0 0.32a 1.6 0.24a SO 2.2 0.20a 2.2 0.20a 1.8 0.20a 1.2 0.20a PB 2.0 0.55a 2.6 0.60a 2.4 0.51a 2.0 0.45a C 2.4 0.40a 2.6 0.68a 3.2 0.58 a 2.2 0.37a Broad leaf weeds CP 2.0 0.55a 4.0 0.32ab 5.2 0.86ab 2.2 0.58a SH 1.8 0.37a 3.6 0.51b 3.6 0.24b 2.0 0.32a SO 2.2 0.20a 3.0 0.32b 4.0 0.55b 1.4 0.24a PB 2.0 0.32a 2.8 0.49b 3.2 0.49b 1.6 0.24a C 1.8 0.2 0a 5.2 0.86a 6.6 0.98a 2.2 0.58a aHorsfall and Barrett (1945) rating scale where 1 = 0%, 2 = 0 3%, 3 = 36%, 4 = 612%, 5 = 1225%, 6 = 25 50% of ground covered with weeds, whereas 7 = 2550%, 8 = 1225%, 9 = 612%, 10 = 36%, 11 = 03%, and 12 = 0% of ground not covered with weeds. bCP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control Data are means standard error of 5 replications. Means in columns for each weed type followed by the same letters do not dif fer significantly based on LSD test ( P 0.05)

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73 CHAPTER 4 EFFECT OF ORGANIC MULCHES ON SOIL SURFAC E INSECTS AND OTHER ARTHROPODS Introduction Organic mulches can be derived from hay, straw, crop residues, pine needles, tree bark, or other readily available plant material. Using cover crop r esidues as organic mulches has a number of advantages to the farming system such as reducing soil erosion, conserving soil moisture, moderating soil temperatu re, improving infiltratio n of water and providing a slow release source of nutrients (Powers and McSorley 2000, Snapp et al. 2005, Westerman and Bicudo 2005). Plant mulches can be an effective way to provide shelter for predatory insects (Brown and Tworkoski 2004, Johnson et al. 2004) and to cont rol weeds (Reeleder et al. 2004, Teasdale et al. 2004 ). Mulches can help to maintain soil moisture required for plant vigor and to promote plant tolerance to the attack of insect pests (Johnson et al. 2004). Cover crops and other organic mulches are useful methods for managing some insect pests. Alfalfa ( Medic ago sativa L.) and kura clover ( Trifolium ambiguum M. Bieb) mulches increased predator populations to manage European corn borer ( Ostrinia nubilalis Hbner) (Prasifka et al. 2006). Lepidopteran eggs and larval densities were significantly higher in broccol i (Brassica oleracea L. var. botrytis) monoculture when compared to broccoli with undersown mulches like strawberry clover ( Tribolium fragiferum L.), white clover ( Tribolium repens L.), and yellow sweet clover ( Melilotus officinalis L.) (Hooks and Johnson 2004). Spiders were found more frequently on bare unmulched plots in the early stages of crop growth, but later in the season, spider numbers were higher on broccoli with living mulches. Alfalfa living mulch increased predators to manage outbreaks of the i nvasive soybean aphid, Aphis glycines Matsumura (Schmidt et al. 2007).

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74 These examples suggest that living mulches may offer resources to support predators, however nonliving mulches derived from killed cover crops, hay from cover crops, or composted was te products may offer benefits as well. Poultry compost reduced the populations of spotted tentiform leafminer (Phyllonorycter blancardella (Fabr.)) and migrating woolly apple aphid ( Eriosoma lanigerum (Hausmann)) nymphs, while increasing predator populati ons (Brown and Tworkoski 2004). The MetroMix 360 (MM360) (Scotts, Marysville, OH) at rates of 20% and 40% commercial vermicomposts suppressed the populations of aphids (Aphididae), a nd mealybugs ( Pseudococcus spp.) on peppers ( Capsicum annum L.) and mealy bugs on tomatoes ( Lycopersicon esculentum Mill.) (Arancon et al. 2005). Winter cover crops including wheat ( Triticum aestivu m L.), rye ( Secala cereale L.), oat ( Avena sativa L.), lupine ( Lupinus augustifolius L.), hairy vetch ( Vicia villosa Roth.), and cri mson clover ( Trifolium incarnatum L.) affected a variety of insects including aphids leafhoppers (Cicadellidae), plant bugs (Miridae), and thrips (T hysanoptera) (Tremelling et al. 2002). Predation of beet armyworm, Spodoptera exigua (Hbner) pupae was 33% greater in cover crop mulch as compared with conventional production plots (Pullaro et al. 2006). Mulch from sunn hemp ( Crotalaria juncea L.) hay was effective in reducing incidence of lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) on bean ( Pha seolus vulgaris L.) (Gill et al. 2010). Changes in cropping systems affect insect pests and their natural enemies (Hummel et al. 2002). Organic mulches might provide hiding place to harbor populations of natural enemies. In about 75% of cases, generalist p redators either single species or species assemblages significantly reduced the pest numbers (Symondson et al. 2002). Most of the previous work used mulches for the management of insect pests, particularly flyi ng insects (Brown and Tworkoski 2004, Gill et al. 2010, Hooks and Johnson 2004, Prasifka et al. 2006, Pullaro et al. 2006,

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75 Reeleder et al. 2004, Schmidt et al. 2007, Tremelling et al. 2002). The effects of mulches on insects and other soil arthropods living on the soil surface is a less explored area. The objective of the present study was to determine the impact of mulches on the community of arthropods that live and move on the soil surface. Mulches were readily available or easily supplied by cover crop residues. Methods Field experiments were co nducted in fall 2007 and 2008 at the University of Florida Plant Science Research and Education Unit (29o24N, 82o9W), Citra, FL. The soil at the experimental site was Arredondo sand (95% sand, 2% silt, 3% clay) with 1.5% organic matter (Thomas et al. 1979). Fall 2007 The experimental field was sprayed with glyphosate ( Roundup, Monsanto, St. Louis, MO) to kill weeds on 26 September fol lowed by rototilling on 3 October. Average soil moisture measured gravimetrically before plant ing was 6.1% Five treatme nts compared were: cowpea ( Vigna unguiculata (L.) Walp.) (C) mulch; sunn hemp (SH) mulch; sorghum sudangrass ( Sorghum bicolor Moench S. sudanense [Piper] Stapf) (SO) mulch; pine bark mulch nuggets (PB) (HTC Hood Timber Co., Adel, GA); and unmulched contr ol (C). Cover crops mulches were obtained from crops of Iron and Clay cowpea, Tropic Sun sunn hemp, and Growers Choice sorghum sudangrass, respectively. Treatments were arranged in a randomized complete block design with five replications (total of 25 plots). Individual plots for each treatment were 3.0 m long and 2.4 m wide. In order to assess effects of mulches during the vegetable growing season in Florida, all plots were planted with Roma II bush beans ( Phaseolus vulgaris L. ) on 4 October. Seeds were spaced 10 cm apart at a rate of 30 seeds per row, in two rows per plot.

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76 Mulches were obtained from cover crops planted near the experimental site and aboveground biomass was cut on the same day it was applied to the plots. Cover crops were harvested on 11 October by clipping plants at the base. The resulting mulches (35 cm deep) were a composite of leaves and stems and were applied manually surrou nding the rows of bean plants. Cowpea (18.1kg fresh wt /plot), sunn hemp (15.9 kg fresh wt /plot), and sorghum sudangrass (17.7 kg fresh wt /plot) were obtained from cover crops and pine bark nuggets (29.8 kg/plot) were purchased locally. Plots were irrigated as needed using drip irrigation. Fall 2008 The experiment was repeated at the same site in fall 2008, with the same treatments. Experimental procedures remained the same with a few minor changes. The experimental field was sprayed with glyphosate to kill weeds in the first week of September followed by rototilling on 16 September. Average soil moisture mea sured gravimetrically at planting was 6.9%. Beans were planted on 7 October. Cowpea (12.7 kg fresh wt /plot), sunn hemp (15.9 kg fresh wt /plot), sorghum sudangrass (13.6 kg fresh wt /plot), and pine bark nuggets (29.8 kg/plot) were applied on 9 October. Data C ollection Insects were collected on several sampling dates in both seasons using pitfall traps, which are typically used for capturing insects that run or move on the soil surface (Borror et al. 1989). A plastic sandwich container (14 cm 14 cm 4 cm) was used as a pitfall trap. One pitfall trap was placed in the middle of each plot, and buried so that the upper edge was flush with the soil surface. The traps were filled three quarters with water, along with 3 to 4 drops of dish detergent (Ultra Joy, P rocter and Gamble, Cincinnati, OH) to break surface tension, ensuring that the insects would remain in the trap. Pitfall traps were set out in the morning and collected before noon the next day (which was recorded as sampling date). The traps were brought to the

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77 laboratory, kept in a cold room at 10 C, and contents transferred and stored in 70% ethanol in vials. Insects and related arthropods were identified to order and family levels using a dissecting microscope. Data A nalysis Data from each season were subjected to one way analysis of variance (ANOVA) using the Statistical Analysis System (version 9.1; SAS Institute, Cary, NC). Treatment means were separated using the least significant difference (LSD) range test, when analysis of variance showed a significant treatment effect (P 0.05). Results Fall 2007 The numbers of leafhoppers and spiders collected from pitfall traps did not differ among treatments on all sampling dates (Table 41). In addition, the few micro Hymenoptera (mainly small parasitoid and wasps) were not affected by treatments (data not shown). On the first sampling date, numbers of ants and beetles were higher in CP than in PB and C plots. Beetles collected were from the families Staphylinidae, Carabidae, Elateridae, and Chrysomelidae, but none of these individual families were significantly (P 0.05) affected by treatments. Other small plant feeding insects (whiteflies, aphids, and thrips grouped together) were most abundant in CP plots on several sampling dates (Table 41). However, the individual insect families that comprise these groups wer e not affected by treatment. Highest numbers of Orthoptera (grasshoppers and crickets) and flies were found in PB on one sampling date. On the last sampling date, Collembola numbers were higher in SH plots than SO plots. A variety of other plant feeding insects were occasionally recovered at low levels in pitfall traps. These other insects consisted of cutworms (24.2%), planthoppers (36.0%), spittlebugs (12.3%), and stink bugs (12.1%). Their total numbers in CP plots of 4.2/plot on 6 November and 3.8/plot on 20

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78 November were greater ( P 0.05) than the 0.8/plot found in SH plots on these dates (data not shown). Fall 2008 Numbers of spiders (Table 2) and small parastoids (data not shown) did not differ among treatments. On the first three sampling dates, an t numbers were higher in CP plots than in other plots. Orthoptera (grasshoppers and crickets), beetles, and small plant feeders (aphids, whiteflies, thrips) were most abundant in C or CP plots on at least one sampling date (Table 4 2). Collembola (springta ils) were most abundant in C plots on the first sampling date, but least abundant in C plots in early November. Leafhopper numbers were highest in SO plots in one instance. On the last two sampling dates, numbers of flies were highest in PB plots. Most of the other insects found (75% of total) were Negro bugs (Cydnidae), which were higher ( P 0 .05) in CP plots (11.6/plot) and C plots (9.2/plot) than in other plots (avg. 1.6/plot) on 28 October (data not shown). Discussion Effects of treatments on insect gr oups varied during the growing season, but some trends were evident. Many insect groups, including ants, beetles, grasshoppers and crickets, and small plant feeding insects (aphid s whiteflies, and thrips), were highest in C or CP plots on several occasion s. With the exception of ants and some beetles, these insects are plant feeders, and weeds (nutsedges, grasses, and broadleaf weeds) in C and CP plots may have led to their higher numbers in these plots. CP mulch degraded quickly due to low C: N ratio (14: 1), and allowed the emergence of weeds after 3 4 weeks The pitfall trap is the one of the most commonly used methods to sample insects and other arthropods on the soil surface (Southwood and Henderson 2000). Although small plant feeders such as aphids, whiteflies, and thrips are typically sampled by other methods such as sticky cards rather than pitfall traps (Southwood and Henderson 2000),

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79 small numbers of them will fall from vegetation into pitfall traps as well (Tremelling et al. 2002). In north central Florida, winter cover crops affected a variety of insects including aphids, leafhoppers, plant bugs, and thrips as measured by pitfall traps (Tremelling et al. 2002). Ants have been observed to feed on or tend sucking insects such as aphids and whiteflie s (Borror et al. 1989), so their increased numbers may be related to the other insects in C and CP plots. This e ffect was also observed by Pullaro et al. (2006) who recorded a greater number of fire ants in plots with cover crop mulch compared with convent ional plots. Beetles are the largest and most diverse group of insects, and varied in their response to treatment over the two seasons, reaching highest numbers in CP plots on the first sampling date in 2007 and in C plots on the last sampling date in 2008. In 2007, Coleoptera families found were Chrysomelidae (48.4%), Staphylinidae (23.4 %), Carabidae (12.2 %), and Elateridae (14.2 %). The majority of leaf feeding chrysomelid beetles present in CP plots was similar to other plant feeding insects. During 2008, Coleoptera consisted of families Chrysomelidae (3.4 %), Staphylinidae (71.7 %), Carabidae (21.6 %), and Elateridae (3.2 %). Many Staphylinidae and Carabidae are predators, and the increased abundance of prey insects in C plots may have stimulated these predatory beetles. Plant feeding beetles (Chrysomelidae) respond ed to early season weed growth, while predatory beetles (Staphylinidae, and Carabidae) likely require d time fo r plant feeding prey to increase in number hence the response later in the season. The occurrence of higher Colle mbola numbers in SH plots may have been due to a continuous supply of organic matter by degradation of mulch. Generally, Collembola are cryptozoic and feed on fungi associated decaying organic matter (Coleman et al. 1996, Powers and McSorley 2000). Flies were most common in PB plots, possibly because PB was the only mulch that did not degrade as fast as others (C: N ratio = 208:1), and may have served as shelter for insects. This

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80 mulch may have provided favorable ha bitat f or longlegged flies (Dolichopodidae) that typically inhabit organic debris (Borror et al. 1989, Triplehorn and Johnson 2005) .

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81 Table 4 -1 Effect of treatments on arthropod taxa (numbers/pitfall trap) on selected dates in Citra, FL, 2007 Trt a Formicidae (An ts) Collembola (Springtails) Cicadellidae (Leafhoppers) Diptera (Flies) Orthoptera b Araneae (Spiders) Coleoptera (Beetles) OPF c 24 Oct ober CP 14.8 3.4 a 70.8 21.9a 1.0 0.8 a 7.4 1.7 a 1.6 0.9 a 0.6 0.4 a 4.2 1.4 a 2.0 0.6 a SH 10.2 3.6 ab 30 4.8 161.4a 1. 0 0.6 a 6.2 2.2 a 0.4 0.2 a 0.8 0.2 a 2.8 0.6 ab 0.4 0.2 a SO 8.4 2.6 ab 124.8 39.7a 1.2 0.7 a 4.0 0.5 a 0.6 0.6 a 1.0 0.3 a 2.4 0.9 ab 1.0 0.6 a PB 3.8 1.2 b 273.0 128.3a 0.8 0.4 a 8.6 2.1 a 0.6 0.4 a 0.2 0.2 a 0.8 0.6 b 2.0 1.3 a C 2.8 0.9 b 247.6 106.4a 2.2 0.8 a 5.4 1.2 a 0.4 0.2 a 0.8 0.4 a 0.8 0.4 b 2.2 0.9 a 6 Nov ember CP 10.8 3.5 a 57.0 13.0a 2.4 0.9 a 6.4 1.0 b 1.2 0.2 a 0.6 0.2 a 1.4 0.2 a 2.2 1.5a SH 9.6 5.2 a 78.0 16.6a 1.6 0.7 a 4.6 0.4 b 0.6 0.4 a 1.6 0.5 a 2.0 1.0 a 0.2 0.2a SO 4.4 0.9 a 63.4 21.0a 1.8 1.1 a 6.2 1.1 b 0.8 0.4 a 1.2 0.5 a 2.2 0.4 a 0.2 0 .2 a PB 5.0 1.4 a 35.2 9.4a 0.6 0.4 a 10 .0 1.4 a 1.6 0.6 a 0.8 0.6 a 1.4 0.2 a 1.4 0.7 a C 6.0 1. 2 a 47.2 15.8a 1.8 0.7 a 3.8 0.9b 1.2 0.9 a 0.8 0.4 a 1.6 0.6 a 0.6 0.2a 20 Nov ember CP 5.0 1.8 a 83.2 30.2a 1.8 0.5 a 6.2 1.5 a 0.6 0.2 b 0.0 0.0 a 1.2 0.5 a 3.0 0.9 a SH 2.6 0.7 a 209.0 117.8 a 1.0 0.8 a 3.6 1.7a 1.0 0.5 ab 0.2 0.2 a 1.0 0.3 a 0.4 0.2b SO 2.0 1.1 a 70.4 9.5 a 2.2 0.3 a 4.0 1.1 a 0.6 0.2 b 0.2 0.2 a 1.2 0.3 a 0.8 0.6 b PB 4.2 2.0 a 69.4 16.6a 1.4 0.5 a 8.0 2.5 a 2.2 0.6 a 3.4 2.7 a 0.8 0.3 a 1.0 0.8 b C 2.0 0.2 a 89.6 51.6a 6.4 5.0 a 6 .8 2.4 a 0.4 0.4 b 0.2 0.2 a 1.8 0.5 a 0.8 0.4 b 3 Dec ember CP 0.2 0.2 a 63.0 11.8ab 1.4 0.5 a 7.2 1.0 a 3.0 1.3 a 0.8 0.2 a 3.8 1.5 a 1.6 0.8 a SH 1.6 0.4 a 80.2 12.3a 1.6 0.9 a 5.8 0.5 a 0.8 0.4 a 1.0 0.4 a 1.4 0.7 a 2.0 0.8 a SO 1.6 0.5 a 74.8 19.5ab 1.0 0.4 a 6.6 2.4 a 2.0 0.6 a 0.6 0.2 a 2.4 1.0 a 2.8 1.5 a PB 1.6 0.9 a 32.0 5.9c 1.4 0.8 a 9.8 0.8 a 1.4 0.7 a 1.0 0.6 a 1.6 0.5 a 2.0 0.9 a C 0.6 0.2 a 40.4 8.9bc 3.2 1.1 a 9.4 1.9 a 2.6 1.9 a 0.8 0.2 a 3.2 1.4 a 3.2 0.8 a 17 Dec ember CP 1.6 1.4 a 18.6 2.6a 0.8 0.5 a 0.6 0.2 a 0.0 0.0 a 0.6 0.4 a 0.2 0.2 a 1.4 0 .7 a SH 1.4 0.9 a 19.0 5.4a 0.0 0 .0 a 0.4 0.2 a 0.2 0.2 a 0.2 0.2 a 0.2 0.2 a 0.8 0.4 ab SO 18.4 15.9 a 16.6 5.2a 0.4 0.4 a 0.8 0.4 a 0.2 0.2 a 0.4 0.2 a 0.8 0. 6 a 0.2 0.2 ab PB 0.4 0.4 a 12.2 3.0a 0.2 0.2 a 0.8 0.5 a 0.4 0.2 a 0.0 0.0 a 0.2 0.2 a 0.0 0.0 b C 1.2 0.5 a 9.2 3.7a 0.4 0.4 a 1.0 0.6 a 0.4 0.4 a 0.0 0.0 a 0.2 0.2 a 0.8 0.3 ab aTreat ments CP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control bAcrididae (grasshoppers) and Gryllidae (crickets) cOther plant feeders include whiteflies (Aleurodidae), aphids (Aphididae), and thrips (Thysanoptera) Dat a are means standard error of 5 replications. Means in columns for each sampling date followed by the same letters do not differ significantly based on LSD test ( P 0.05)

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82 Table 42. Effect of treatments on arthropod taxa (numbers/pitfall trap) on sele cted dates in Citra, FL, 2008 T rt a Formicidae (Ants) Collembola (Springtails) Cicadellidae (Leafhoppers) Diptera (Flies) Orthoptera b Araneae (Spiders) Coleoptera (Beetles) OPF c 13 Oct ober CP 20.2 1.9 a 28.6 9.7 b 1.8 0.8 b 21.8 3.8 a 0.0 0.0 a 0.2 0.2 a 1.0 0.6 a 3.6 0.9 a SH 9.2 1.4 b 41.8 24.2 ab 2.2 0.9 b 13.4 2.2 a 0.0 0.0a 0.2 0.2 a 0.0 0.0 a 6.2 2.4 a SO 8.0 2.4 b 24.0 9.2 b 5.6 1.9 a 19.8 5.0 a 0.0 0.0a 0.2 0.2 a 0.2 0.2 a 3.6 1.8 a PB 6.0 0.9 b 35.2 10.1 b 0.8 0.4 b 24.0 2.8 a 0.2 0.2a 0.2 0.2 a 0.2 0.2 a 3.2 0.7 a C 8.4 2.7 b 86.0 17.9 a 1.2 0.9 b 16.4 2.2 a 0.2 0.2 a 0.6 0.2 a 0.8 0.6 a 2.8 1.3 a 28 October CP 15.0 3.2 a 20.0 6.0 a 6.8 3.3 a 5.0 1.5 a 0.8 0.6 a 0.8 0.4 a 1 .4 1.2 a 1 1.6 2. 4 a SH 5.2 2.2 b 24.6 6.6 a 1.4 0.9 a 4.6 2.1 a 1.6 0.8 a 0.2 0.2 a 1.6 0.6 a 1.0 0.8 b SO 3.0 1.7 b 47.2 13.1 a 2.4 0.7 a 6.0 0 .7 a 0.6 0.2 a 0.6 0.4 a 1.6 2.7 a 2.6 0.7 b PB 4.6 1.7 b 37.4 8.1 a 1.8 0.9 a 5.4 1.4 a 0.4 0.2 a 0.6 0 .4 a 1.0 0.5 a 1.2 0.4 b C 5.4 0.8 b 46.2 10.9 a 6.0 2.3 a 4.6 1.1 a 0.8 0.5 a 0.2 0.2 a 3.2 1.2 a 9.2 1.8 a 9 November CP 9.0 2.9 a 22.8 0.9 a 3.0 1.3 a 8.2 1.8 b 1.0 0.6 a 0.0 0.0 a 5.2 2.1 a 2.4 1.3 a SH 2.2 0.7 b 22.8 4.8 a 1.0 0.8 a 6.0 0.3 b 1.2 0.7 a 0.6 0.2 a 1.4 0.4 a 2.4 0.9 a SO 1.6 1.1 b 22.6 3.8 a 2.6 1.1 a 9.2 1.8 b 1.6 0.7 a 0.0 0.0 a 1.4 0.5 a 4.4 2.2 a PB 2.4 1.4 b 22.0 4.3 ab 2.0 0.6 a 16. 4 3.5 a 0.8 0.6 a 0.6 0.4 a 3.4 1.2 a 0.8 0.2 a C 4.0 0.7 b 12.0 2.4 b 3.4 0.8 a 6.4 0.9 b 2.0 1.0 a 0.2 0.2 a 2.6 1.3 a 2.0 1.0 a 24 November CP 3.8 1.1 a 17.4 2.9 a 4.0 1.3 a 4.4 1.3 b 1.6 0.6 a 0.4 0.2 a 2.0 0.8 ab 1.0 0.5 ab SH 1.0 0.6 a 18.8 4.3 a 3.6 1.4 a 3.2 1.3 b 0.6 0.2 ab 3. 0 3.0 a 1.8 0.7 b 0.6 0.4 b SO 2.4 1.1 a 18.2 3.6 a 1.8 0.4 a 5.4 0.8 b 0.6 0.4 ab 1.8 1.1 a 1.6 0.7 b 2.0 0.8 ab PB 2.2 1.2 a 19.8 3.0 a 2.4 0.7 a 11.4 3.7 a 0.4 0.4 b 0.2 0.2 a 0.8 0.4 b 0.8 0.4 ab C 2.6 0.8 a 10.6 2.7 a 5.0 3.0 a 3.2 0.7 b 0.4 0.2 b 0.0 0.0 a 4.0 0. 8 a 2.8 1.2 a aTreatments CP = cowpea, SH = sunn hemp, SO = sorghum sudangrass, PB = pine bark, C = unmulched control bAcrididae (grasshoppers) and Gryllidae (crickets) cOther plant feeders include whiteflies ( Aleurodidae) aphids (Aphididae) and thrips (Thysanoptera) Data are means standard error of 5 replications. Means in columns for each sampling date followed by the same letters do not differ significantly based on LSD test ( P 0.05)

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83 CHAPTER 5 EFFECT OF INTEGRATIN G SOIL SOLARIZATION AND ORGANIC MULCHING ON THE SOIL SURFACE INSECT COMMUNITY Introduction Mulching by spreading organic matter around plants is an effective method to manage some pest i nsects as well as weeds (Brown and Tworkoski 200, Johnson et al. 2004). Mulches also provide shelter for predatory insects (Pullaro et al. 2006). Soil solarization, a hydrothermal method of managing nematodes, diseases, insects, and weeds, is accomplished by passive heating of moist soi l covered with transpar ent plastic sheeting (McGovern and McSorley 1997). Because of the lethal effects from high soil temperature, solarization must be conducted before crops are planted. The objective of the present study was to evaluate the integrated e ffects of solarization and organic mulch ing on the soil surface insect community, including non target and beneficial insects. Field experiments were conducted in fall 2008 at the University of Florida Plant Science Research and Education Unit (lat. 29o24 N, long. 82o9W), near Citra, FL. The soil was Arredondo sand (95% sand, 2% silt, 3% clay) with 1.5% organic matter. The field was rototilled in Jul y, and beds were formed (20 cm high, 76 cm wide, with 1.8 m between bed centers). Individual plots were sing le beds, 9.14 m in length. Average soil moisture measured gravimetrically before bed formation was 8.7%. Materials and Methods Four treatments were arranged in a randomized complete block design with 5 replications. The treatments co mpared were: solarizat ion (S) = plastic pre plant, nothing post plant; mulch (M) = mulch pre plant, mulch post plant; mulch + solar (MS) = plastic pre plant, mulch post plant; control (C) = nothing pre plant, mulch post plant. For the

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84 mulch treatment, a pre plant mulch of sunn hemp ( Crotalaria juncea L.), 3 cm thick (8.16 kg total weight/plot), was applied over the bed surface on 13 Aug ust In the solarization treatment, beds were covered with Polydak (1.3 mil thick, UV stabilized, transparent film, Ginegar Plastics Products, Ginegar, Israel) plastic film for 6 weeks beginning on 12 Aug ust as described by Gill et al. (2009 b). After 6 weeks, plastic was removed, and all beds were planted with Potomac Pink snapdragons ( Antirrhinum majus L. ) Mulch was again applied on 2 Oct obe r as a main mulch application, to M, C, and MS treatments. Note that is not possible to have mulch and solarization plastic present on one plot at the same time. Soil surface insects were sampled with plastic sandwich containers (14 cm 14 cm 4 cm deep ) used as pitfall traps as described by Borror et al. (1989). Each pitfall trap was placed in the center of the plot and buried so that the upper edge was flush with the soil surface. Traps were filled threequarters full with tap water, and 3 to 4 drops o f dish detergent (Ultra Joy, Procter and Gamble, Cincinnati, OH) added to break surface tension, and ensure that the insects remain in the trap. Traps were set out in the morning and collected before noon the next day (recorded as the sampling date). Traps were placed in cold storage (10 C), contents transferred and stored in 70% ethanol, and insects were identified to order and family and counted. Data were subjected to oneway analysis of variance (ANOVA) with the Statistical Analysis System (version 9. 1; SAS Institute, Cary, NC). Treatment means were separated based on the least significant difference (LSD) range test, at P 0.05.

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85 Results and Discussion Preplant mulching or solarization was useful in reducing weeds in the plots. The main weeds were nu tsedges ( Cyperus spp.), grasses, Florida pusley ( Richardia scabra L.) purslane ( Portulaca oleracea L.), and hairy indigo ( Indigofera hirsuta L .). The percentage of the plot surface area occupied by weeds averaged 3 to 5% in MS, ca 90% in C, 20 to 25% in S and 35 to 40% in M plots, respectively. On most sampling dates, Collembola populations were higher in the M treatment than in the S treatment (Table 51). Collembola are associated with decom posing organic matter (Colemen and Crossley 1996), which was provided by sunn hemp in the M treatment. Collembola were not as abundant in S plots, possibly because mulch was absent. In addition, the solarization process itself may have reduced populations that were present in soil. Many groups of arthropods, includ ing spiders, ants, grasshoppers, crickets, elaterids, and staphylinids were unaffected by the treatments (data not shown), but interesting trends were observed in some others. Cicadellids were more abundant ( P 0.10) in C plots (12.0 2.59/ trap) than in MS plots (5.8 2.42/trap) on November 9. On Oct ober 28, highest numbers ( P 0.10) of carabids (0.8 0.37/ trap) and flea beetles (0.4 0.24/trap) were observed in S plots. Highest numbers ( P 0.10) of dol ichopodids (8.0 2.43/trap) were observed in S plots on 8 Dec ember Solarized plots were free of mulch and had relatively low weed levels, both of which might influence insect movement. Environmental heterogeneity is known to interfere with movement and host finding of flea beetl es and other insects (Root 1973, Smith and McSorley 2000). On 28 Oct ober and 9 Nov ember other plant feeders (whiteflies, thrips, and aphids) were significantly great er ( P 0.05) in the C treatment compared with the other 3

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86 treatments (Table 51). It is possible that whiteflies, thrips, aphids, and maybe leafhoppers were present and fed on the abundant weeds in the control treatment. Treatments that limit weeds may be helpf ul in limiting these plant feeding insects as well. Integrating solarization and mulching did not have much overall impact on the insect community, compared to solarization alone, but it did lead to recovery of Collembola populations later in the season to similar levels found in mulched plots.

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87 Table 51. Effect of treatments on insect taxa (numbers/pitfall trap) on selected sampling dates 2008 Treatment a Collembola Other plant feeders b 13 October MS 10.2b 3.34 1.6a 0.51 C 21.8ab 5.46 4.4a 1.54 S 14.6b 5.33 3.8a 0.97 M 32.2a 6.63 6.8a 3.34 ANOVA c F value 3.26 1.24 P value 0.0492 0.3268 28 Oct ober MS 13.8b 4.93 1.0b 0.45 C 15.0b 1.76 7.6a 2.87 S 12.0b 1.52 2.4b 1.03 M 32.8a 3.51 0.6b 0.40 ANOVA F val ue 8.9 4.3 P value 0.0011 0.0209 9 November MS 46.6a 8.25 0.8b 0.37 C 34.4a 6.45 6.4a 2.38 S 14.0b 3.73 1.6b 0.81 M 32.6a 5.35 1.6b 0.51 ANOVA F value 4.76 3.9 P value 0.0148 0.0287 8 December MS 21.8ab d 3.80 3.0a 0.7 1 C 34.4a 7.56 1.6a 0.93 S 16.0b 2.61 2.6a 0.75 M 24.2ab 2.24 2.0a 0.84 ANOVA F value 2.83 0.59 P value 0.0717 0.6302 aSolarization (S) = plastic pre -plant, nothing post plant; mulch (M) = mulch pre -plant, mulch post -plant; mulch + so lar (MS) = plastic pre -plant, mulch post -plant; and control (C) = nothing pre -plant, mulch post -plant. bOther plant feeders include whiteflies, aphids, and thrips cStatistics from analysis of variance (ANOVA). Data are means standard error of 5 replicati ons. Means followed by the same letters do not differ significantly based on LSD test (P 0.05) dMean separation at P 0.10

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88 CHAPTER 6 INTEGRATED IMPACT OF SOIL SOLARIZATION AN D ORGANIC MULCHING O N WEEDS, INSECTS, NEMA TODES, AND PLANT PER FORMANCE Introduction Soil solarization is a hydrothermal method that involves passive heating of moist soil covered with plastic sheeting (transparent polyethylene) for the disinfestation of soil borne pests (Katan et al. 1976, Stapleton 2000). This is an effective way of controlling weeds (Chase et al. 1998, Daelemans 1989, Horowitz et al. 1983) as wel l as nematodes (Chellemi et al. 1997, McGovern et al. 2002, McGovern and McSorley 1997, Stapleton and Heald 1991). Although not used as frequently against insect pests, seven weeks of soil solarization was found to reduce incidence of stalk borer ( Papaipema spp.) in corn cultivars by 8.9% (Ahmad et al. 1996). Work has been done using variety of mulches to manage different insect pests (Prasifka et al. 2006, Schmidt et al. 2007, Tremelling et al. 2002) as wel l as weeds (Brown and Tworkoski 2004, Johnson et al. 2004, Teasdale et al. 2004). Combination of organic mulch with plastic mulch can improve the yield and quality of bell pepper s ( Capsicum annuum L.) due to the improveme nt of soil fertility (Wang et al. 2010). In the past, soil solarization has been combined with other management practices like fumigants, hot water, organic amendments, host plant resistance, and biocontrol to manage soil borne plant pathogens (Antonio et al. 2005, Antonio and Giovanni 2006, Gamliel and Stapleton 1997, McGovern and McSorley 1997). Although results differed depending on the type of pathogens involved. Both soil solarization and mulching techniques have been used alone to manage soil borne pe sts as mentioned above, but no work has been done by integrating both solarization

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89 and mulching techniques. The objective of this research was to examine the integrated effect of soil solarization and mulching on plant performance and pests including insec ts, weeds, and nematodes. Materials and Methods A field experiment was conducted in 2008 at the University of Florida Plant Science Research and Education Unit (29o24N, 82o9W), Citra, FL. The soil at the experimental site was Arredondo sand (95% sand, 2 % silt, 3% clay) with 1.5 % organic matter (Thomas et al. 1979). The experimental field was rototilled in the last week of July to prepare the soil and to allow thorough heat conduction for soil solarization. Individual plots for each treatment were single beds 20 cm (0.65 feet) high, 76 cm (2.5 feet) wide, and 914 cm (30 ft) long with 180 cm (5.9 feet) between bed centers. Average soil moisture measured gravimetrically before bed formation was moderately moist (8.7%). Four treatments were arranged in a ran domized complete block design with five replications (20 plots). The treatments compared were solarization (S), mulch (M), integration of mulch and solarization (MS), and control (C). In the mulch treatment, a pre plant mulch of sunn hemp ( Crotalaria junce a L.) hay, 3 cm thick (8.16 kg total weight/plot, C: N = 15.5:1), was applied over the bed surface on 13 Aug ust Sunn hemp was used as mulch because it was readily available and has potential as a summer legume cover crop in Florida (Treadwell and Alligood 2008). In treatments receiving solarization, beds were covered with Polydak (1.3mil thick, UV stabilized, transparent film, Ginegar Plastics Products, Ginegar, Israel) plastic film for 6 weeks beginning on 12 Aug ust (Gill et al. 2009 b). After 6 weeks the plastic was removed, and all beds were planted with Potomac Pink snapdragon ( Antirrhinum majus L.) seedlings (Speedling Inc., Sun City, FL) at a spacing of

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90 10 cm (4 inches) apart to provide 90 seedlings per plot. Mulch was again applied on 2 Oct obe r as a main mulch application, to mulch, control, and mulch + solar treatments. Therefore, the condition of all treatments pre planting and post planting was as follows: solarization = plastic pre plant, nothing post plant; mulch = mulch pre plant, mulch post plant; mulch + solar = plastic pre plant, mulch post plant; control = nothing pre plant, mulch post plant. It is not possible to have mulch and solarization plastic present at exactly the same time on the bed. Soil temperature sensors (WatchDog Spe ctrum Technologies, Inc., Plainfield, IL) were placed in the field at the same time when beds were covered with plastic. Soil temperatures were monitored hourly at depths of 5 cm (2 inches) and 15 cm (6 inches) throughout the solarization period. Weeds, both grasses and broa d leaves were assessed on 2 October 16 October 28 October 8 November and 23 Nov ember Each plot was rated for the percentage of surface area covered with weeds using the 1 to 12 Horsfall and Barrett rating scale (Horsfall and Barret t, 1945), where 1 = 0%, 2 = 03%, 3 = 36%, 4 = 612%, 5 = 1225%, 6 = 2550% of ground covered with weeds, whereas 7 = 2550%, 8 = 1225%, 9 = 612%, 10 = 36%, 11 = 03%, and 12 = 0% of ground not covered with weeds. Soil samples for nematode analysis were collected from each plot at four times during the season until the end of the experiment. Four soil cores (2.5 cm diameter 20 cm deep) were collected and combined into one composite representative sample from each plot. Nematodes were extracted from a 100cm3 subsample using a modified sieving and centri fugal flotation method (Jenkins 1964). After extraction, nematodes were identified and counted using an inverted microscope.

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91 Insects, especially buckeye caterpillars ( Junonia coenia Hbner, Lepidopt era: Nymphalidae) and saltmarsh caterpillars ( Estigmene acrea (Drury), Lepidoptera: Arctiidae), were visually counted on snapdragon plants. Buckeye caterpillars were further enumerated as small (< 1 cm) and large (> 1 cm). Dead plants were counted on four different sampling dates. At the end of the experiment, snapdragon blooms were harvested by cutting stems about 35 cm above ground. The number of cut blooms was counted and the average weight per plot was determined. All data were subjected to one way an alysis of variance (ANOVA) using the Statistical Analysis System (version 9.1; SAS Institute, Cary, NC). Treatment means were separated using the least significant difference (LSD) test, when the analysis of variance showed a significant treatment effect ( P 0.05). Results and Discussion Soil temperature was higher at a depth of 5 cm than at 15 cm throughout the solarization period. The highest temperature recorded at 5 cm was 51.2C. At 5 cm, maximum soil temperature were > 50 C on 2 days, 4550 C for 25 days, and 4045 C for 16 days. A 15 cm soil depth, maximum soil temperatures recorded were 4045 C for 12 day and never reached 45 C. Weed densities were generally reduced in plots receiving solarization treatments. The rating of coverage by gras ses especially bermudagrass ( Cynodon dactylon (L.) ), goosegrass ( Eleusine indica (L.) Pers.), and crabgrass ( Digitaria spp.) was significantly higher in control plots compared with mulch, solarized, and MS plots on all sampling dates (Table 6 1). Ratings of broadleaf weed cover were significantly higher in control and mulched plots compared with MS and solarized plots. The major broadleaf weed found was Florida pusley

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92 ( Richardia scabra L.), along with traces of eveningprimrose ( Oenothera laciniata Hill) and cudweed ( Gnaphalium spp.) The rating for total area covered by weeds was found to be much greater in the control treatment than in the other treatments. In most cases, solarization, mulching, as well as the integration of solarization and mulching did not differ in terms of controlling grasses. However, mulching alone was inferior for managing broadleaf weeds and total weed coverage. Integration of solarization and mulching was effective in controlling the weed coverage area throughout the season. This ma y be because solarization helped to keep weeds under control during the first half of the experiment, while mulching with sunn hemp during the second half helped manage weeds to an additional extent. Plant parasitic nematodes were sampled on 2 October 20 Jan uary 19 March and 23 April. Root knot ( Meloidogyne spp.) and stubbyroot ( Paratrichodorus spp.) nematode populations were highest in control plots on one sampling date (Table 6 2). Initially, solarization and integration of solarization and mulching controlled root knot nematodes, presumably by killing them with high temperature. In previous studies, solarization and cowpea mulch were useful for root knot nematode suppression (Saha et al. 2005). Prior to planting, control plots were free of any kind of management attempt such as plastic or organic mulch and therefore found to have the highest root knot nematode numbers. However, root knot nematodes recovered from solarization effects by the 20 January sampling, about 3.5 months after the experiment began. Ring nematode ( Mesocriconema spp.) populations were low and did not differ among treatments. Buckeye an d saltmarsh caterpillars attacked the snapdragon plants during the course of experiment. The number of saltmarsh and small buckeye caterpillars di d not differ among treatments (Table 63). On 4 November the number of large buckeye caterpillars was

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93 observed to be much higher in the MS treatment compared with the other treatments. On 25 November large buckeye counts were found to be higher in MS com pared to control and mulch treatments. The number of saltmarsh and buckeye caterpillars declined ( 1.2/plot) on the last sampling date in January (data not shown) due to increased plant mortality and cold weather. Snapdragon was observed to be an excellen t host plant for buckeye caterpillars. The number of snapdragon plants was generally lower in control and mulch treatments compared with MS and solarization treatments, and, likely led to lower buckeye caterpillar counts in these treatments. Buckeye females oviposit on snapdragon plants, and more plants were present in the MS and solarization treatments (Table 64). As buckeye caterpillars grow and consume the host plants, they will relocate to other plants. However, the saltmarsh caterpillar is larger and more mobile than the buckeye, causes heavier plant damage, and will move quickly to find and consume new food plants. This may be first observation of damage to snapdragons by these caterpillars. Snapdragon mortality was assessed throughout the season on 16 October 4 November 25 November and 6 January (Table 64). Higher plant mortality was found in the mulch treatment on the first sampling date, while on 4 November the number of dead plants was greater both in control and mulch plots compared with res t of the treatments, some of which may have resulted from heavy weed competition. A di fferent trend was observed on 6 January with higher numbers of dead plants in MS and mulch treatments. At the earlier stages of the experiment, snapdragon plants were ea ten by caterpillars, which led to higher plant mortality in the mulch treatment initially, and soon after in the control plots as well. It is likely that most of this early season mortality was due to saltmarsh caterpillars, since buckeye caterpillars were not observed on plants in October. Saltmarsh caterpillars do not

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94 remain long on small seedling plants, but consume or damage an entire plant and move on to another plant. Saltmarsh caterpillars were common in weedy areas adjacent to the field and moved ar ound freely in the plots that had high levels of weeds (control and mulch treatments). In contrast, buckeye females locate host plants where eggs and larvae will develop. Because there was no physical hindrance such as mulch or weeds in some plots, it may become easy for insects to locate host plants and lay eggs on them. The resource concentration hypothesis argues that the presence of diverse flora negatively affects the ability of insect pests to fin d and utilize host plants (Root 1973, Dent 2000, Sm ith and McSorley 2000). The solarization and MS treatments helped to keep weed populations low. After taking off the plastic from beds, it became easier for buckeye females or saltmarsh caterpillars to locate host plants. Later on, the same beds were covered w ith sunn hemp mulch which also provided hiding places for caterpillars and other insects. These factors may have caused the dead plant count to be significantly higher in MS than in solarization on the last two sampling dates. Due to the extensive plant da mage and death, number of blooms and average weight did not differ among treatments (Table 65). Solarization was effective in controlling weeds, and i ntegration of solarization and mulching was more effective than solarization alone in controlling total weed coverage, on two sampling dates. Root knot nematodes were managed initially to some extent by the integration of solarization and mulching, while stubbyroot and ring nematode populations were not affected by the treatments used in the experiment. An important mortality factor in this experiment was feeding damage from saltmarsh and buckeye caterpillars, neither of which were directly affected by the soil treatments because these insects were observed to move freely among plants over the surface of soi l. However, there was some suggestion that

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95 population levels of large buckeye caterpillars were favored by the integration treatment because solarization as a pretreatment helped to reduce plant mortality (leaving more plants available for attack) and mul ch as post treatment increased populations of large buckeye caterpillars. Dead plant counts were sporadic among treatments, and the average weight and number of blooms did not differ among treatments. The data illustrate the extensive damage that can be done by these caterpillars to a good host plant such as snapdragon. The adult buckeye is a colorful and attractive butterfly therefore snapdragon may be a useful food plant to include in butterfly gardens to encourage this species.

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96 Table 61. Weed coverage on beds rated among treatments using Horsfall and Barrett (1945) rating scalea on different sampling dates, 2008. Sampling date Treatment 2 October 16 October 28 October 8 November 23 November Grasses MS b 1.2 b c 3.0 b 2.8 b 3.8 b 3.0 c Control 6.4 a 7 .4 a 8.0 a 9.0 a 8.8 a Solarization 1.8 b 3.0 b 3.4 b 3.8 b 4.6 b Mulch 2.4 b 4.0 b 4.0 b 4.2 b 4.0 bc Broadlea f weeds MS 1.0 b 1.6 b 1.8 b 1.4 b 2.0 c Control 4.0 a 5.0 a 5.2 a 4.8 a 5.2 a Solarization 1.4 b 1.6 b 2.0 b 1.6 b 3.2 b Mulch 3.4 a 4.0 a 4.8 a 4.6 a 4.8 a Total weed c overed a rea MS 1.6 c 3.6 c 3.0 c 4.0 c 3.2 d Control 7.0 a 8.2 a 9.2 a 10.2 a 9.4 a Solarization 2.6 c 4.0 c 5.2 b 4.8 c 4.6 c Mulch 5.0 b 5.8 b 6.4 b 6.4 b 6.0 b aHorsfall and Barrett (1945) rating scale where 1 = 0%, 2 = 03%, 3 = 36%, 4 = 612%, 5 = 1225%, 6 = 2550% of ground covered with weeds, whereas 7 = 2550%, 8 = 1225%, 9 = 612%, 10 = 36%, 11 = 03%, and 12 = 0% of ground not covered with weeds. bMS = Mulch + solarized cData are means of 5 replications. For each weed category, means in columns followed by the same letter do not differ significantly based on LSD test ( P 0.05)

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97 Table 62. Nematode population levels in soil samples among treatments on different sampling dates, 200809. Nematodes per 100 cm 3 soil Treatment 2 October 08 20 January 09 19 March 09 23 April 09 Root k not MS a 1.2 b b 4.4 a 3.8 a 37.6 a C ontrol 6.8 a 7.4 a 6.6 a 10.0 a Solarization 0.4 b 8.8 a 17.4 a 37.6 a Mulch 1.6 ab 4.8 a 8.2 a 19.2 a Stubby r oot MS 4.8 a 0.8 a 4.4 b 0.8 a Control 2.8 a 5.0 a 25.2 a 0.0 a Solarization 2.2 a 1.4 a 6.0 ab 1.0 a Mulch 4.8 a 3.2 a 22.0 ab 0.4 a Ring MS 0.8 a 4.4 a 1.4 a 0.2 a Control 2.2 a 3.0 a 0.8 a 1.0 a Solarization 1.0 a 10.0 a 1.6 a 0.6 a Mulch 1.4 a 1.8 a 1.2 a 1.0 a aMS = Mulch + solarized bData are means of 5 replications. For each nematode, means in columns followed by the sam e letter do not differ significantly based on LSD test (P 0.05)

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98 Table 63. Visual insect counts among treatments on different sampling dates, 2008. Number of caterpillars per plot Treatment Small buckeye a Large b uckeye a Saltmarsh 4 Nov ember MS b 18.4 a c 8.4 a 1.0 a Control 1.2 a 0.2 b 0.8 a Solarization 4.6 a 3.4 b 0.6 a Mulch 2.2 a 0.2 b 0.2 a 25 November MS 1.8 a 2.8 a 0.0 a Control 0.4 a 0.4 b 0.2 a Solarization 2.2 a 1.6 ab 0.2 a Mulch 0.2 a 0.2 b 0.0 a aSmall buckeye = < 1 cm length; large buckeye = > 1 cm length. bMS = Mulch + solarized cData are means of 5 replications. On each sampling date, means in columns followed by the same letter do not differ significantly based on LSD test ( P 0.05)

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99 Table 64. Numbers of dead plants among treatments on different sampling dates, 200809. Dead plants per plot Treatment 16 October 08 4 November 08 25 November 08 6 January 09 MS a 8.6 bc b 14.6 b 34.2 a 41.0 a Control 9.8 b 30.6 a 35.4 a 32.4 b Solarization 2.8 c 4.6 b 14.2 b 17.8 b Mulch 20.6 a 43.2 a 46.0 a 46.6 a aMS = Mulch + solarized bData are means of 5 replications. Means in columns followed by the same letter do not differ significantly based on LSD test ( P 0.05) Table 65. Ave rage weight and number of blooms on last harvest, 31March 2009. Treatment Average weight (kg/plot) Number of blooms/plot MS a 0.47 a b 22.4 a Control 0.45 a 28.6 a Solarization 1.13 a 59.0 a Mulch 0.31 a 16.6 a aMS = Mulch + solarized bData are means of 5 replications. Means in columns followed by the same letter do not differ significantly based on LSD test ( P 0.05)

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100 C HAPTER 7 MULCH AS A POTENTIAL MANAGEMENT STRATEGY FOR L ESSER CORNSTALK BORER, ELASMOPALPUS LIGNOSELLUS (INSECTA: LEPIDOPTER A: PYRALIDAE) IN BUSH BEAN ( PHASEOLUS VULGARIS ) Introduction Lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zelle r), is a polyphagous pest with a wide range of host plants that includes weeds, vegetable crops, and field crops (Funderburk et al. 1985). L arvae burrow into the stalk base near the soil surface, damaging vascular tissues resulting in dead heart symptoms and allowing pathogens to enter the plant (Smith and Ota 2002). The l arval stage tunnels within stems and roots. Wilting is the first sign of an infestation in affected plants, followed by stunting, plant deformities and a thin crop stand (Gill et al. 20 09 a ) Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing some specific ins ect pests (Prasifka et al. 2006, Schmidt et al. 2007, Teasdale et al. 2004, Tremelling et al. 2002), and may be applicable against LCB. Organic mulches may be derived from hay, straw, crop residues, pine needles, shredded bark, or other plant material that is readily available. Mulching is an effective way to provide shelter for predatory insects and to control weeds (B rown and Tworkoski 2004). Mulches also help to maintain soil moisture required for plant vigor and to promote tolerance in plants to attack of insect pests (Johnson et al. 2004). Previous experiments showed that early planting in Alabama effectively r educed LCB populations in both conventionally and reduced tillage peanuts ( Arachis hypogaea L.), but the tillage systems did not affect population levels of LCB and predators including carabids, elaterids, and lab idurids in pitfall traps (Mack and Backman 1984). In Alabama, a diverse

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101 fauna of predatory arthropods was captured in pitfall traps and numbers of arthropods increased throughout the pea nut growing season (Kharboutli and Mack 1991). Fungi, predators, and other factors affected LCB mortality in a co mmercial peanut experiment in Texas (Smith and Johnson 1989). Mortality density relationships revealed that mortality of LCB was density independent, in terms of initial egg density (Smith and Johnson 1989). The objectives of the current study were to: (1 ) evaluate the effect of mulch on LCB incidence, (2) examine the effect of mulch on plant mortality and plant growth parameters including fresh weight, plant height, and total length, and (3) determine the effect of mulch on nontarget organisms Mulch was obtained from a cover crop of sunn hemp ( Crotalaria juncea L.) that was cut and then dried before application. Sunn hemp is a tropical legume that is being grown as a nitrogenrich cover crop. It is an excellent choice as a summer cover crop in Florida (T readwell and Alligood 2008) and was readily available for this study. M aterials and Methods Field experiments were conducted in small plots at two different locations, the Experimental Design Field Teaching Laboratories (Experiment A) and Plant and Soil Sciences Field Teaching Laboratories (Experiment B), both on the University of Florida, campus in Gainesville, FL (lat. 2939N and long. 8222). Experiments were conducted in the summer and repeated in the fall, 2007 (4 tests total). The soil was Millhopper sand (loamy, siliceous, hyperthermic, Grossarenic Paleudult, with 92% sand, 3% silt, and 5% clay, and low (< 2%) organic matter). Vegetable crops were planted during the previous year in these sites, which had a history of LCB problems.

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102 Experiment A S ummer 2007 The experiment area was 44 m 19 m. Plots of 1m2 area (1m 1m) were demarcated within this total field area. Prior to treatment establishment, the field was relatively weedy in early summer 2007. The most abundant weeds present were eveningpri mrose ( Oenothera laciniata Hill), Florida pusley (Richardia scabra L.), and purple nutsedge ( Cyperus rotundus L.). Other less common weeds were clover ( Trifolium spp.), crabgrass ( Digitaria sanguinalis (L.) Scop.), cudweed ( Gnaphalium purpureum L.), goosegrass ( El e usine indica Gaertn), nightshade ( Solanum spp.), purslane ( Portulaca oleracea L.) and toadflax ( Linaria c anadensis (L.) Dumont). Plots were prepared on 10 June by removing weeds, hoeing to break soil clods and debris, and irrigating to have optim al soil moisture for planting. Three treatments were compared: bare ground (with all weeds removed), mulch (plot area was first cleaned by removing weeds), and weeds (original weed cover maintained). Treatments were arranged in a randomized complete block design with five replications (total of 15 plots). Roma II bush beans ( Phaseolus vulgaris L.) were planted on 12 June in three rows 15 cm apart and 70 cm long at a rate of 20 seeds per row and at a soil depth of 2 cm. Bean emergence was observed on 19 Ju ne A mulch of sunn hemp hay, 3 cm thick (2.8 kg total weight/plot), was applied manually (on the same day that plants emerged) in between rows of beans and surrounding bean plants in the mulch plots only. The mulch was obtained from a crop of Tropic Sun sunn hemp planted at another location on 8 May and harvested on 12 June by clipping plants at the base, and air drying the clippings for one week. Mulch was a composite of leaves and stems. Plots were irrigated as needed, and weeds were removed from time to time to maintain bare ground and mulch treatment plots free of weeds.

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103 Fall 2007 The test was repeated at the same site in the following fall season, with all the same treatments. Experimental procedure remained the same as that of the summer season, wit h a few minor changes. Beans were planted 1 m2 in plots on 10 Sep tember in three rows 15 cm apart at a rate of 35 seeds per row (higher seedling rate than summer test) with row length of 70 cm. Sunn hemp mulch was harvested on 13 September and bean emergen ce started on 14 September Sunn hemp hay was applied 3 cm thick (2.8 kg total weight/plot) on the same day of plant emergence. Data C ollection Bean mortality was recorded throughout both the seasons by counting numbers of dead bean plants/plot due to de ad heart symptoms. Dead bean plants were removed and then brought back to the laboratory and stems dissected. The plants were examined for presence or symptoms of LCB larvae as well as the presence of pathogens. At the end of both seasons, five of the rem aining surviving plants were removed, and average fresh weight, above ground plant height, and total length (height of plant plus root length) were measured. Bean yields were not recorded due to the high percentage of dead plants. Insects were collected us ing pitfall traps on 25 June for the summer season and 18 September for the fall season. A plastic sandwich container (14 cm 14 cm 4 cm) was used as a pitfall trap (Borror et al. 1989, Triplehorn and Johnson 2005). One pitfall trap was placed in the mi ddle of the plot, and buried so that the upper edge was flush with soil surface. The traps were filled three quarters with water, along with 3 to 4 drops of dish detergent (Ultra Joy, Procter and Gamble, Cincinnati, OH) to break surface tension, ensuring that the insects would remain in the trap. Pitfall traps were set out in the morning and collected before noon the next day

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104 (which was recorded as sampling date). The traps were brought to the laboratory, kept in a cold room at 10 C, and contents transfer red and stored in 70% ethanol in vials. Insects were identified to order and family levels using a dissecting microscope. Experiment B Summer 2007 Unlike experiment A, this site had been rototilled in early Jun e 2007 and was free of weeds. Plots of 1m2 a rea (1m 1m) were established on 20 Jun e and soil was prepared for planting by hand with a hoe and irrigated to have optimal soil moisture for seed germination. Two treatments were compared: bare ground and mulch. The treatments were arranged in a random ized complete block design with five replications (total of 10 plots). Roma II bush beans were planted on 22 June in three rows 15 cm apart at a rate of 40 seeds per row at a soil depth of 2 cm. Bean emergence was observed on 26 June Sunn hemp harvested on June 12 was air dried and applied on 29 Jun e to form a mulch 3 cm deep (2.0 kg total weight/plot) using similar protocol as described for experiment A. Hay was placed between rows of beans plants and surrounding the beans plants in mulch plots only. We eds were removed as needed to maintain bare ground and mulch treatments free of weeds. Fall 2007 The test was repeated at the same site in the following fall season, with the same two treatments. The experimental procedure remained the same as in summer, with some minor changes. Beans were planted on 19 September in three rows 15 cm apart at a rate of 35 seeds per row with row length of 70 cm. Sunn hemp mulch was harvested on 13 September and bean emergence was observed on 23 September A layer of sunn hem p hay 3 cm deep (2.0 kg total weight/plot) was applied on the same day of bean emergence in the mulch plots.

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105 Data C ollection I nsects were collected on 19 July for summer and 16 October for the fall season. Procedures for insect trapping and for data colle ction on plant mortality and plant parameters remained the same as in Experiment A. Data A nalysis For each data set, data were subjected to oneway analysis of variance (ANOVA) using the Statistical Analysis System (version 9.1; SAS Institute, Cary, NC). For Experiment A, treatment means were separated using the least significant difference (LSD) range test, when analysis of variance showed a significant treatment effect ( P 0.10). R esults Experiment A Summer 2007 Plant mortality did not differ betwee n bare ground and mulched plots (Table 71). Dead plants in this experiment showed typical symptoms caused by LCB which included dead heart, silken webbing, and plant wilting. Dead plants were removed and examined for the presence of LCB and other pathogens. Of the plants removed and examined in the laboratory, all showed these typical symptoms and most had feeding damage to the stems from LCB. Many contained LCB within the stem. At the end of the experiment, more plants survived in mulched plots than in weedy plots (Table 71). No significant difference was observed in plant weight among treatments, although plant height and length (height + root length) were significantly greater in mulched and weedy treatments compared with the bare ground (Table 72).

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106 Major groups of predatory arthropods found in pitfall traps in both summer and fall of 2007 in this experiment were Carabidae (1.93 0.6/plot), Formicidae (21.6 13.7/plot), Araneae (1.26 0.5/plot), and Staphylinidae (0.1 0.1/plot) but all were unaf fected by treatment. The most common nonpredators were Dolichopodidae, Collembola, and Cicadellidae (data not shown). No significant differences with treatment were observed in numbers of these different kinds of insects. Fall 2007 Plant mortality was higher in the bare ground treatment compared with other treatments toward the middle of the experiment, but at the end of the experiment, total mortality and number of surviving plants remained the same in all treatments (Table 73). Unlike in the summer, de ad plants had rotten roots and therefore were examined in the laboratory for the presence of pathogens. In most cases, plant mortality was caused by Rhizoctonia fungus. Plant weight and plant length were greatest in the mulched treatment (Table 7 2). As in the summer experiment, no differences among treatments were found in any of the arthropod groups caught in pitfall traps (data not shown). Experiment B Summer 2007 Greater plant mortality in the bare ground treatment than in the mulch treatment ( P 0.10) was observed on every sampling date (Table 74). The main cause of mortality was LCB, and plants showing symptoms of LCB attack were isolated from all plots. At the end of the experiment, higher numbers of surviving plants were present in mulched plots than in the bare ground. Among these surviving plants, no significant differences were found in weight or height, but a slight increase in length was observed in mulched plots (Table 72).

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107 Major groups of predatory arthropods found in pitfall traps in both summer and fall of 2007 were Carabidae (0.6 0.4/pl ot) and Formicidae (65.6 12.5/plot). The most common nonpredators were Dolichopodidae, Collembola, and Cicadellidae (data not shown). The only significant differences between treatments were obse rved am ong Dolichopodidae (42.8 12.9 in bare and 15.6 5.8 in mulch plots) in summer and Collembola in both summer (55.2 16.5 in bare and 299 156 in mulch plots) and fall (32.4 11.8 in bare and 126 30.2 in mulch plots) seasons. Fall 2007 No di fference in plant mortality was found between treatments except that higher plant mortality was observed in bare ground plots on the last sampling date (Table 7 5). Total mortality and number of surviving plants remained same in both treatments. In fall, p lant mortality was mainly caused by attack from fungal pathogens rather than from LCB as in the summer season. Plant weight, height, and length were significantly higher in the mulched treatment compared with the bare ground treatment (Table 72). D iscussi on During the fall season, the major cause of plant mortality was the fungal pathogen Rhizoctonia spp. in both experiments A and B. The amount of rainfall was higher in the fall season compared with the summer season. Total rainfall in June between planti ng and emergence was 0.69 cm in experiment A and 1.65 cm in experiment B, while corresponding levels in September were 2.49 cm in experiment A and 5.72 cm in experiment B (Anonymous 2010). The higher rainfall in fall may have led to higher soil moisture an d the increased growth of fungi, resulting in root rot and ultimately bean plant mortality. LCB attack has been reported to be less severe under moist conditions (Biddle et al. 1992, Nuessly

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108 and Webb 2006). During the summer season in both experiments, pla nt mortality was due to attack of LCB. This insect has been considered a dryland insect, and typically survives well in dry, hot conditions and in sandy soils (Luginbill and Ainslie 1917). In experiment B, consistently greater plant mortality due to LCB w as observed in bare ground plots than in mulch plots throughout the season. Many predators of LCB found in other studies (Kharboulti and Mack 1991, Mack and Backman 1990, Smith and Johnson 1989) including carabids, ants, spiders, and staphylinids, were al so recovered in the current experiments. However, there was no evidence that LCB was reduced by predation in the mulch plots because similar numbers of predatory insects were collected in both treatments. Differences may have resulted from the ability of L CB adults to find and oviposit on host plants in areas with differing crop backgrounds (mulch vs. bare). The resource concentration hypothesis argues that the presence of diverse flora negatively affects the ability of insect pests to find and utilize host pl ants (Root 1973, Dent 2000, Smith and McSorley 2000). Incidence of LCB attack was higher in the bare ground treatment than in the mulched treatment, possibly because insects may have difficulty in recognizing host plants as compared with easy recognition of host plants in bare plots. Smith (1976) reported increased attraction of the cabbage aphid, Brevicoryne brassicae (L.), by visual recognition of a sparsely planted crop that stood out against bare ground. In contrast, no difference was found between mulch and bare plots in experiment A. The differences in effect of mulch on LCB attack at these two experiment locations may be due to the different location and background of the experiments. Experiment A had a high, dense background population level of w eeds, especially Florida pusley and eveningprimrose while experiment B was free from weeds. In fact, the small plots in experiment A were

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109 established by removing these weeds from the plots themselves, but weeds remained on the borders of all plots. Because of the small size of the plots, the border area and landscape around the plots may have had a major influence on an actively mobile pest like LCB. It is possible that weeds could serve as alternate hosts and divert LCB from attack on the bean plants. However, Florida pusley and eveningprimrose are not known hosts of LCB ( Gardner and All 1982, Gill et al. 2009 a Isely and Miner 1994). Furthermore, incidence of attack by LCB on bean plants was very high at both locations, although differences among treatm ents were not noted in experiment A. The weedy background of experiment A may have affected the ability of insects to recognize host plants within the small plots at this site. In contrast, the small plots at experiment B stood out easily in a bare landscape, except when young plants were obscured with mulch, which may have led to higher attack of LCB in experiment B during the summer season. This observation of differential LCB attack in experiments A and B may be additional evidence for the ability of this insect to locate host plants when host resources are concentrated. While visual cues may be involved, the presence of weeds may offer olfactory interference as well. Further research is needed to determine the cues used by female moths to find and oviposit on host plants. In the current study, sunn hemp mulch was found to be effective in managing LCB populations while considering a number of factors such as background of field, treatment, and season. Mulch was helpful in managing LCB when plots stood out against a bare background, but was ineffective when weeds surrounded the plots. Incidence of LCB attack on host plants was severe in experiments starting in June, but was absent in experiments beginning in September, when Rhizoctonia fungus was the majo r mortality factor.

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110 Table 71. Number of dead bean plants/plot collected on selected sampling dates for experiment A summer Days after bean emergence a Treatment 10 21 24 30 Total Mortality Surviving Plants Bare 10.00 0.71 a 6.20 3.65 a 5.60 2.25 a 3.20 1.39 b 28.00 7.78 a 11.00 2.59 ab Mulch 7.00 0.84 ab 2.80 1.50 a 4.80 0.80 a 8.20 1.77 a 24.00 1.64 a 18.80 3.65 a Weed 6.20 1.50 b 5.80 2.13 a 5.80 1.91 a 6.40 0.93 ab 26.00 4.05 a 4.80 1.39 b ANOVA b : F value 3.50 0.51 0.0 9 3.24 0.15 6.72 Df 2,12 2,12 2,12 2,12 2,12 2,12 P value 0.0635 0.6102 0.9146 0.0750 0.8618 0.011 aDays after bean emergence = number of days after bean plants emerged. Surviving plants measured at end of experiment. bStatistics from analysis of varian ce (ANOVA). Data are means standard error of 5 replications. Means followed by the same letters do not differ significantly based on LSD test ( P 0.10)

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111 Table 72. Weight, height, and length of surviving plants in experiments A and B summer an d fall Plant parameters Treatment Weight (g/plant) Height (cm) Length (cm) Experiment A, summer Bare 3.73 1.30 a 12.08 3.85 b 20.96 4.97 b Mulch 6.84 1.02 a 30.76 2.73 a 40.20 3.26 a Weed 3.51 0.97 a 26.92 4.37 a 36.72 3.86 a ANOVA a : F v alue 2.82 7.05 6.28 Df 2,12 2,12 2,12 P value 0.0989 0.0094 0.0136 Experiment A, fall Bare 8.44 0.63 b 10.91 0.50 a 45.97 1.86 b Mulch 11.63 1.12 a 11.51 0.55 a 56.57 1.77 a Weed 8.58 1.10 b 9.59 1.13 a 50.66 2.61 ab ANOVA a : F value 3.4 1 1.58 6.32 Df 2,12 2,12 2,12 P value 0.0670 0.2467 0.0134 Experiment B, summer Bare 5.47 1.06 18.81 1.75 30.38 1.40 Mulch 10.78 2.97 27.39 5.14 40.87 5.08 ANOVA a : F value 2.84 2.49 3.97 Df 1,8 1,8 1,8 P value 0.1304 0.1529 0.0815 Experiment B, fall Bare 5.75 0.43 9.29 0.56 31.69 1.26 Mulch 10.42 0.97 11.62 0.74 44.08 1.35 ANOVA a : F value 19.45 6.27 45.01 Df 1,8 1,8 1,8 P value 0.0023 0.0367 0.0002 aStatistics from analysis of variance (ANOVA). Data are means standard error of 5 replications. Means followed by the same letters do not differ significantly based on LSD test ( P 0.10)

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112 Table 73. Number of dead bean plants/plot collected on selected sampling dates for experiment A fall Days after bean emer gence a Treatment 11 18 22 32 Total Mortality Surviving Plants Bare 2.60 0.93 a 6.40 1.03 a 3.60 0.68 a 4.80 0.97 a 32.80 8.84 a 48.00 8.38 a Mulch 1.20 0.80 a 3.20 0.66 b 1.20 0.37 b 3.80 2.24 a 17.40 5.04 a 62.40 4.48 a Weed 4.00 0.89 a 2 .00 0.84 b 1.20 0.58 b 2.00 0.84 a 16.00 2.30 a 55.60 5.82 a ANOVA b : F value 2.56 7.05 6.13 0.89 2.40 1.25 Df 2,12 2,12 2,12 2,12 2,12 2,12 P value 0.1189 0.0094 0.0147 0.4358 0.1332 0.3201 aDays after bean emergence = number of days after bean plants emerged. Surviving plants measured at end of experiment. bStatistics from analysis of variance (ANOVA). Data are means standard error of 5 replications. Means followed by the same letters do not differ significantly based on LSD test ( P 0.05) Table 74. Number of dead bean plants/plot collected on selected sampling dates for experiment B summer Days after bean emergence a Treatment 15 18 23 31 Total Mortality Surviving Plants Bare 19.40 2.62 10.40 2.27 6.20 0.73 11.20 4.15 63. 20 6.76 6.20 2.20 Mulch 11.60 2.98 4.00 0.84 2.20 0.86 2.40 1.50 41.80 6.79 23.60 6.46 ANOVA b : F value 3.87 6.99 12.50 3.97 4.99 6.50 Df 1,8 1,8 1,8 1,8 1,8 1,8 P value 0.0847 0.0295 0.0077 0.0814 0.0560 0.0342 aDays after bean emergence = number of days after bean plants emerged. Surviving plants measured at end of experiment. bStatistics from analysis of variance (ANOVA). Data are means standard error of 5 replications.

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113 Table 75. Number of dead bean plants/plot collected on selected sampling dates for experiment B fall Days after bean emergence a Treatment 13 18 23 31 Total Mortality Surviving Plants Bare 1.40 0.51 1.80 1.36 0.20 0.2 2.80 1.16 18.20 2.67 29.60 9.54 Mulch 1.80 0.92 1.20 0.49 0.00 0.0 0.00 0.0 14.60 2.29 27.20 7.00 ANOVA b : F value 0.15 0.17 1.00 5.85 1.05 0.04 Df 1,8 1,8 1,8 1,8 1,8 1,8 P value 0.7128 0.6883 0.3466 0.0419 0.3365 0.8443 aDays after bean emergence = number of days after bean plants emerged. Surviving plan ts measured at end of experiment. bStatistics from analysis of variance (ANOVA). Data are means standard error of 5 replications.

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114 CHAPTER 8 SUMM A RY Soil solarization is an important practice for small acreage farmers and home gardeners and is used comme rcially in areas with high solar radiation and air temperature during the summer. In this technique clear plastic films are used to increase soil temperature to manage soilborne plant pests such as insects, diseases, nemat odes, fungi, and weeds. Several different ki nds of plastic films were evaluated in 2007 and 2008 for durability, weather tolerance, and w eed suppression. Treatments were arranged in a randomized complete block design with five replications. In 2007, treatments were four clear plastic film s including: ISO, VeriPack, Poly Pak, Bromostop, and a white plastic control. In 2008, treatments were Polydak, Poly Pak, Bromostop, and white plastic. Films were evaluated for weed suppression based on the population density of weeds that emerged through breaks in the plastic, for durability in terms of number and size of breaks in the films, and for the total exposed soil area resulting from breaks. Purple nutsedge ( Cyperus rotundus L. ) was the major weed problem throughout both years. In both years, t otal exposed area was greater with white plastic and Bromostop (81.5 ft2/bed) compared to other plastic films (< 21.5 ft2/bed). Due to their durability, Poly Pak, ISO, and VeriPack suppressed nutsedge more than Bromostop and white plastic. Although a number of very small (< 0.75 inch long) breaks were observed in Polydak plastic film, they never increased in size, and this plastic film remained intact throughout the experiment and provided excellent weed control. Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing some insect pests and weeds. Several different types of organic mulches were evaluated for effects on soil surface arthropods, weeds, and plant mortality. Field experiments were conducted in fall 2007 and 2008 near Citra, FL. In both

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115 seasons, five treatments were compared: cowpea ( Vigna unguiculata (L.) Walp.) mulch, sunn hemp ( Crotalaria juncea L.) mulch, sorghum sudangrass ( Sorghum bicolor Moench S. sudanense (Piper) Stapf) mulch, pine bark nuggets, and unmulched control. Mulches were applied around snapdragon ( Antirrhinum majus L.) plants in small plots, and treatments arranged in a randomized complete block design with five replications. Data collected included arthropod co unts using pitfall traps and board traps, weed ratings, direct counts of buckeye, ( Junonia coenia Hbner) (Lepidoptera: Nymphalidae) caterpillars, and snapdragon plant mortality. Arthropod groups sampled using pitfall and board traps varied in their responses to treatments. Numbers of Formicidae, Cicadellidae, Orthoptera, and small plant feeders (aphids, whiteflies, and thrips) were higher in control and cowpea plots, possibly because weed ratings were higher in control and cowpea plots. Buckeye caterpillar s were not affected by the treatments and caused high mortality of snapdragon plants in all plots. Several different types of organic mulches were evaluated for their effects on soil surface insects and related arthropods. Field experiments were conducted in fall 2007 and 2008 near Citra, FL. In both seasons, five tr eatments were compared: cowpea (CP) mulch, sunn hemp (SH) mulch, sorghum sudangrass (SO) mulch, pine bark nuggets (PB) and unmulched control (C). Mulches were applied to small plots, and treat ments arranged in randomized complete block design with five replications. Data were collected on insects and other arthropods using pitfall traps. Results indicate that organic mulches can affect a wide range of different insects. Orthoptera (grasshoppers and crickets) and small plant feeding insects (aphids, whiteflies, and thrips) were most common in C or CP plots on several occasions, possibly due to weed growth in these plots. Numbers of ants, which often tend or feed on small plant feeders, were obser ved to be higher in CP and C plots. Responses of beetles varied, depending on which families of beetles

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116 were present. Numbers of flies were higher in PB plots on several occasions. Numbers of spiders were not affected by treatments. Soil solarization is a hydrothermal method to increase soil temperature for managing soil borne plant pests that include insects, weeds, nematodes, and fungi, while mulching is an effective way to control weeds along with providing shelter for predatory insects. The integrated impact of soil solarization and mulching on wee ds, nematodes, insect pests and plant performance was evaluated in field grown Potomac Pink snapdragon ( Antirrhinum majus L.) in fall 2008 at the University of Florida Plant Science Research and Education U nit, Citra, FL. Four treatments were compared: solarization (S), mulch (M), integration of mulch and solarization (MS), and an untreated control (C). Treatments were arranged in a randomized complete block design with five replications. For the mulch treat ment, a pre plant mulch of sunn hemp hay was applied over the bed surface. In the solarization treatment, beds were covered with Polydak plastic film for 6 weeks. After 6 weeks, the plastic was removed, and all beds were planted with snapdragons For MS tr eatment, plastic was applied as preplant, and sunn hemp mulch as post plant application. Data were collected on the mortality of snapdragon plants, weed ratings, nematode counts in soil, plant parameters (plant weight and number of blooms), and visual count of insects, especially buckeye caterpillar and saltmarsh caterpillar ( Estigmene acrea (Drury), Lepidoptera: Arctiidae). Solarization or mulching alone reduced weed numbers but integration of solarization and mulching provided the most effective control of weeds. Population levels of large buckeye caterpillars were highest in the MS treatment. Plant mortality and plant parameters did not differ among the treatments. Extensive plant damage and mortality due to caterpillars were observed in all plots.

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117 Les ser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), is a serious pest of bean ( Phaseolus vulgaris L. ) and many other crops. The effect of mulching as a management method for LCB was examined in two field experiments conducted in small plots (1 m2) at two different locations (experiments A and B) in Alachua Co., FL. Both experiments were conducted in the summer and repeated in the fall, 2007. The treatments were arranged in a randomized complete block design with five replications at both locations In experiment A, treatments were bare ground, plots with mulch, and plots with weeds (original weed cover); while in experiment B, treatments were bare ground and mulched plots. The mulch was obtained from a crop of sunn hemp planted at another location. Data were collected on bean plant mortality, plant growth parameters (fresh weight, height, and length including roots of surviving plants), and population levels of potential predators. LCB attack was less ( P 0.10) in mulched plots compared with bare g round, considering a number of factors such as location and background of field, season, and amount of precipitation. Greater numbers of surviving plants were found in mulched plots compared with bare ground and weedy plots. In general, fresh weight, height, and total length of bean plants were greater in mulched plots compared with other plots. Treatments did not affect numbers of potential predators of LCB. Evidence suggests that LCB attack is reduced by mulches or weeds around host plants.

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118 LIST OF REFER ENCES Abdel Rahim, M. F., M. M. Satour, K. Y. Mickail, S. A. El Erakis, A. Grinstein, and J. Katan. 1988. Effectiveness of soil solarization in furrow irrig ated Egyptian soils. Plant Dis. 72: 143 145. Abouziena, H. F., O. M. Hafez, I. M. El Metwally, S. D Sharma, and M. Singh. 2008. Comparison of weed suppression and mandarin fruit yield and quality obtained with organic mulches, synthetic mulches, cultivati on, and glyphosate. HortScience 43: 795 799. Abu Gharbieh, W. I., W. I. H. Saleh, and L. Al Banna. 1991. Application of solar heated water for soil solarization. In J. E. DeVay, J. J. Stapleton, and C. L. Elmore (e ds. ) Soil Solarization. FAO Plant Production and Protection Paper 109, Food and Agriculture A rganization of the United Nations Rome. Ahmad, Y., A. Hameed, and M. Aslam. 1996. Effect of soil solarization on corn stalk rot. Plant Soil 179: 17 24. All, J. N., R. N. Gallaher, and M. D. Jellum. 1979. Influence of planting date, preplanting weed control, irrigation, and conservation tillage practic es on efficacy of planting time insecticide applications for control of lesser cornstalk borer in field corn. J. Econ. Entomol. 72: 265268. Andow, D. A., A. G. Nicholson, H. C. Wien, and H. R. Willson. 1986. Insect populations on cabbage grown with lining mulches. Environ. Entomol. 15: 293299. Anonymous. 2010. Florida Automated Weather Network. University of Florida, Gainesville, FL. http://fawn.ifas .ufl.edu Antonio, G., B. Luigi, L. Loretta, and C. Giovanni. 2005. Soil carbon, nitrogen and phosphorus dynamics as affected by solarization alone and combined with organic amendment. Plant Soil 279: 307325. Antonio, G., and C. Giovanni. 2006. Compositional shifts of bacterial groups in a solarized and amended soil as determined by denaturing gradient gel electrophoresis. Soil Biol. Biochem. 38: 91102. Arancon, N. Q., P. A. Galvis, and C. A. Edwards 2005. Suppression of insect pest populations and damage to plants by vermicomposts. Bioresource Technol. 96: 11371142. Bautista Ziga, F., C. DelgadoCarranza, and H. Estrada Medina. 2008. Effect of legume mulches and cover crops earthworms and snails. Trop. Subtrop. Agroecosystems 8: 4560.

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119 Benlloglu, S., O. Boz, A. Yildiz, G. Kaskavalci, and K. Benlioglu. 2005. Alternative soil solarization treatments for the control of soilborne diseases and weeds of strawberry in the Western Anatolia of Turkey. J. Phytopathology 153: 423430. Bessin, R. 2004. The common stalk borer in corn University of Kentucky, Entomology. Unive rsity of Kentucky, Lexington, KY. www.uky.edu/Ag/Entomology/entfacts/fldcrops/ef129.htm Biddle, A. J., S. H. Hutchins, and J. A. Wightman. 1992. Pest living below ground Elasmopalpus lignosellus : Lesser cornstalk borer, pp. 202203. In R. G. McKinley ( eds. ) Vegetable crop pest s. CRC P ress, I nc., Boca Raton FL. Black, R. J., E. F. Gilman, G. W. Knox, and K. C. Ruppert. 2003. Mulches for the landscape. ENH 103, EENY 155, Featur ed Creatures, Entomology and Nematology Department, Universit y of Florida, Gainesville, FL. http://edis.ifas.ufl.edu.MG/25 Borror, D. J., C. A. Triplehorn, and N. F. Johnson. 1989. An introduct ion to the study of insects, pp. 751753. 6th (ed.), Saunders College Publishing, Chicago, IL. Brown, M. W., and T. Tworkoski. 2004. Pest management benefits of compost mulch in apple orchards. Agric. Ecosyst. Environ. 103: 465472. Campiglia, E ., F. Caporali, E. Radicetti, and R. Mancinelli. 2010. Hairy vetch ( Vicia villosa Roth.) cover crop residue management for improving weed control and yield in no tillage tomato ( Lycopersicon esculentum Mill.) production. Europ. J. A gronomy. 33: 94102. Candido, V., T DAddabbo, M. Basile, D. Castronuovo, and V. Miccolis. 2008. Greenhouse soil solarization: effect on weeds, nematodes and yield of tomato and melon. Agron. Sustain. Dev. 28: 221230. Capinera, J. L. 2001. Handbook of Ve getable Pests, pp. 729. Academic Press, San Diego CA. Chang, V., and A. K. Ota. 1987. The lesser cornstalk borer: a new important pest of young sugarcane, pp. 2730. I n Annual Report, 1986. Experiment station. Hawaiian Sugar Planters Association, Pahala H I Chapin, J. W. 1999. Lesser cornstalk borer on peanut. Entomology Insect I nformation Series, Clemson University. Clemson, SC. http://entweb.clemson.edu/eiis/pdfs/a g21.pdf Chase, C. A. 2007. Soilborne plant pathogens and pest management with soil solarization. University of Florida, Gainesville, Florida. www.imok.ufl.edu/LIV/groups/cultural /pests/solar.htm Chase, C. A., T. R. Sinclair, D. G. Shilling, J. P. Gilreath, and S. J. Locascio. 1998. Light effects on rhizome morphogenesis in nutsedges ( Cyperus spp.): Implications for control by soil solarization. Weed Sci. 46: 575 580.

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120 Chellemi, D. O., and J. Mirusso. 2006. Optimizing soil disinfection producers for fresh market tomato and pepper production. Plant Dis. 90: 668674. Chellemi, D. O., S. M. Olson, J. W. Scott, and D. J. Mitchell. 1993. Reduction of phytoparasitic nematodes on tomato by soil solarization and ge notype. J. Nematol. 25: 800805. Chellemi, D. O., S. M. Olson, D. J. Mitchell, I. Secker, and R. McSorley. 1997. Adaptation of soil solarization to the integrated management of soilborne pests of tomato under humid conditions. Phyt opathology 87: 250258. Chen, Y., A. Gamliel, J. Stapleton, and T. Aviad. 1991. Chemical, physical, and microbial changes related to plant growth in disinfested soils, pp. 103129. In J. Katan, J. E. DeVay ( e ds.) Soil solarization. CRC Press, Inc. Boca Rat on, FL. Cole, L. C. 1946. A study of the cryptozoa of an Illinois woodland. Ecol Monogr. 16: 4986. Coleman, D. C., and D. A. Jr. Crossley. 1996. Secondary production: Activities of heterotrophic organisms the soil fauna, pp. 51106. In Fundamentals of soil ecology. Academic Press, San Diego, CA. Culman, S. W., J. M. Duxbury, J. G. Lauren, and J. E. Thies. 2006. Microbial community response to soil solarization in Nepals ricewheat cropping system. Soil Biol. Biochem. 38: 33593371. D Addabbo, T., V. Miccolis, M. Basile, and V. Candido. 2010. Soil solarization and sustainable agriculture pp. 217274. In E. Lichtfocus ( e d.) Sociology, organic farming, climate change, and soil science. Springer, NL Daelemans, A. 1989. Soil solarization in West Cameroo n: Effect on weed control, some chemical properties and pathogens of the soil. Acta Hort. 255: 169175. Dahlquist, R. M., T. S. Prather, and J. J. Stapleton. 2007. Time and temperature requirements for weed seed thermal death. Weed Sci. 55: 619 625. Demire l, N., and W. Cranshaw. 2005. Colonization of cabbage by the western black flea beetle ( Phyllotreta pusilla ) as affected by mulch and time of day. Phytoparasitica 33: 309313. Dent, D. 2000. Cultural and interference methods, pp. 235266. In Insect Pest Management 2nd edition. CABI publishing, Cambridge, MA. Dickerson, G. W. 2001. Mulches for garden and landscapes. College of Agriculture and Home Economics, New Mexico State University, Las Cruces, NM. www.e extension.net/pubs/_h/h121.html Duff, J. D., and A. Barnaart. 1992. Solarization controls soilborne fungal pathogens in nursery potting mixes. Aust. Plant Pathol. 21:20.

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121 Elmore, C. L., J. J. Stapleton, C. E Bell, and J. E. DeVay. 1997. Soil solarization a nonpesticidal method for controlling diseases, nematodes and weeds. Division of Agricultural and Natural Resources, University of California, Oakland, CA. http://vric.ucdavis.edu/pdf/soil_solarization.pdf Funderburk, J. E., D. C. Herzog, T. P. Mack, and R. E. Lynch 1985. Sampling lesser cornstalk borer (Lepidoptera: Pyralidae) adults in several crops with reference to adult dispersion patterns. Environ. Entomol. 14: 452458. Funderburk, J. E., D. G. Boucias, D. C. Herzog, R. K. Sprenkel, and R. E. Lynch. 1984. Parasitoids and pathogens of larval lesser cornstalk borers (Lepidoptera: Pyralidae) in northern Florida. Environ. Entomol. 13: 13191323. Gamliel, A., and J. J. Stapleton. 1997. Improvement of soil solarization with volatiles compounds generated from organic amendments. Phytoparasitica 25: 31S 38S. Gardner, W. A., and J. N. All. 1982. Chemical control of the lesser cornstalk borer in g rain sorghum. J. Ga. Ent Soc. 17: 167171. Genung, W. G., and V. E. Green. 1965. Some stem boring insects associated with soybeans in Florida. Coop. Econ. Ins. Rep. 5:304. Gill, H. K., J. L. Capinera, and R. McSorley. 2009 a. Lesser cornstalk borer, Elasm opalpus lignosellus (Zeller) (Insecta: Lepidoptera: Pyralidae). EENY 155, Entomology and Nematology Department, University of Florida, Gainesville, FL. http://edis.ifas.ufl.edu/IN312 Gill, H. K., R. McSorley, and D. D. Tredwell. 2009 b Comparative p erfo rmance of different plastic films for soil s olarization and weed suppression. HortTech. 19: 769 774. Gill, H. K., and R. McSorley. 2010. Effect of integrating soil solarization and organic mulching on the soil surface insect community Fla. Entomol. 93: 308309. Gill, H. K., R. McSorley, G. Goyal, and S. E. Webb. 2010. Mulch as a potential management strategy for l esser cornstalk borer, Elasmopalpus lignosellus (Insecta: Lepidoptera: Pyralidae), in bush bean ( Ph aseolus vulgaris ). Fla. Entomol. 93: 183190. Gruda, N. 2008. The effect of wood fiber mulch on water retention, soil temperature and growth of vegetable plants. J. Sustain. Agric. 32: 629643. Hagan, A. K., and W. S. Gazaway. 2000. Soil solarization for the control of nematodes and soilborne diseases. Auburn University, Auburn, AL http://www.aces.edu/pubs/docs/A/ANR 0713/ Hartz, T. K., and C. R. Bogle. 1989. Response of tomato and watermelon to row solarization. Appl. Agric. Res. 4: 15.

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122 Hartz, T. K., C. R. Bogle, and B. Villalon. 1985. Response of pepper and muskmelon to row solarization. HortScience 20: 699. Hartz, T. K., J. E. DeVay, and C. L. Elmore. 1993. Solarization is an effective soil disinf estation technique for strawberry production. HortSci ence 28: 104. Hatwig, N.L., H. Ammon. 2002. Cover crops and living mulches. Weed Sci. 50: 688 699. Hartwig, N. L., and L. D. Hoffman 1975. Suppression of perennial legume and grass cover crops for no t illage corn. Proc. Northeast. Weed Sci. Soc 29: 8288. Heald, C. M., and A. F. Robinson. 1987. Effects of soil solarization on Rotylenchulus reniformis in the lower Rio Grande Valley of Texas. J. Nematol. 19: 93 103. Heinrich, C 1956. American moths of the family subfamily Phycitinae. U. S. Nat. Mus. Bull. 207:1581. Hooks, C. R. R., and M. W. Johnson. 2004. Using undersown clovers as living mulches: effects on yields, lepidopterous pest infestation, and spider densities in a Hawaiian broccoli agroecosyste m. Int. J. Pest Manag. 50: 115120. Horowitz, M., Y. Regev, and G. Herzlinger. 1983. Solarization for weed control. Weed Sci. 31:170179. Horsfall, J. G., and R. W. Barratt. 1945. An improved grading system for measuring plant diseases. Phytopathology 35: 655. Hummel, R L., J. F. Walgenbach, G. D. Hoyt, and G. G. Kennedy. 2002. Effects of production systems on vegetable arthropods and their natural enemies. Agric. Ecosys. Environ. 93: 165176. Isely, D., and F. D. Miner. 1994. The lesser cornstalk borer, a pest of fall beans. J. Kansas Ent. Soc. 17: 5157. Jackson, D. M., and H. F. Harrison. 2008. Effects of killed cover crop mulching systems on sweetpotato production, soil pests, and insect predators in South Carolina J. Econ. Entomol. 101: 18711880. Je nkins, W. R. 1964. A rapid centrifugal flotation technique for separating nematodes from soil. Plant Dis. Reptr. 48:692. Johnson, J. M., J. A. Hough Goldstein, and M. J. Vangessel. 2004. Effects of straw mulch on pest insects, predators, and weeds in water melons and potatoes. Environ. Entomol. 33: 16321643. Katan, J. 1981. Solar heating (solarization) of soil for control of soilborne pests. Ann. Rev. Phytopathology 19: 211236.

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123 Katan, J. 1987. Soil solarization, pp. 77105. In I. Chet (ed.), Innovative approaches to plant disease control. Wiley, NY. Katan, J., and A. Gamliel. 2010. Soil solarization 30 years on: What lessons have been learned?, pp. 265283. In U. Gisi, I. Chet, and M. L. Gullino ( e ds.) Recent developments in management of plant diseases Springer, NL Katan, J. A., A. H. Greenberger, H. Alon, and A. Grinstein. 1976. Solar heating by polyethylene mulching for the control of diseases caused by soil borne pathogens. Phytopathology 66:683688. Katan, J., I. Rotem, Y. Finkel, and J. Daniel. 1980. Solar heating of the soil for the control of pink root and other soilborne diseases in onion. Phytoparasitica 8: 39. Keinath, A. P. 1995. Reductions in inoculum densities of Rhizoctonia solani and control of belly rot on pickling cucumbers with solariza tion. Plant Dis. 79: 1213. Kharboulti, M. S., and T. P. Mack. 1991. Relative and seasonal abundance of predaceous arthropods in Alabama peanut fields as indexed by pitfall traps. J. Econ. Entomol. 84: 10151023. Klett, J. E 2010. Mulches for home grounds. Colorado State University Extension Horticulture, Colorado State University, Fort. Collins, CO. www.ext.colostate.edu/pubs/garden/07214.html Lale, N. E. S., and F. A. Ajayi. 2001. Su ppression of development of Callosobruchus maculatus (F.) (Col.: Bruchidae) in bambara groundnut seeds exposed to solar heat in the Nigerian savanna. J. Pest Sci. 74: 133 137. Lehmann, J., J. P. da Silva, Jr. L. Trujillo, K. Uguen. 2000. Legume cover crops and nutrient cycling in tropical fruit tree production. Acta Hort. 531: 35 72. Leuck, D. B. 1966. Biology of the lesser cornstalk borer in South Georgia. J. Econ. Entomol. 59: 797801. Linke, K. H., M. C. Saxena, J. Sauerborn, and H. Masri. 1991. Effect of soil solarization on the yield of food legumes and on pest control, pp. 139154. In J. E. DeVay, J. J. Stapleton, and C. L. Elmore (eds.) Soil solarization. FAO P lant P roduction and P rotection P aper 109. Food and Agriculture O rganization of the United Nations, Rome. Luginbill, P., and G. F. Ainslie. 1917. The lesser cornstalk borer. U. S. Dep. Agric. Entomol. Bull. No. 529: 127. Mack, T. P., and C. B. Backman. 1984. Effects of temperature and adult age on the oviposition rate of Elasmopalpus lignosel lus (Zeller), the lesser cornstalk borer. Environ. Entomol. 13: 966969.

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124 Mack, T. P., and C. B. Backman. 1990. Effect of two planting dates and three tillage systems on the abundance of Lesser cornstalk borer (Lepidoptera: Pyralidae), other selected insect s, and yield in peanut fields. J. Econ. Entomol. 83: 10341041. Mack, T. P., D. P. Davis, and C. B. Backman. 1991. Predicting lesser cornstalk borer (Lepidoptera: Pyralidae) larval density from estimates of adult abundance in peanut fields. J. Entomol. Sci 26: 223230. Mack, T. P D. P. Davis, and R. E. Lynch. 1993. Development of a system to time scouting for the lesser cornstalk borer (Lepidoptera: Pyralidae) attacking peanuts in the southeastern United States. J. Econ. Entomol. 86: 164173. McFarlane, J. A. 1989. Guidelines for pest management research to reduce stored food losses caused by insects and mites. Bulletin No. 22. Overseas Development Natural Resources Institute, Chatham, Kent, UK. McGovern, R. J., and F. Harper. 1996. Suppression of Rhizoctonia solani and Fusarium spp. in Brassica oleracea L. var. acephala by bed solarization and metam sodium in Bermuda. Phytopathology ( s uppl .) 86: 115. McGovern, R. J., and R. McSorley. 1997. Physical methods of soil sterilization for disease manageme nt including soil solarization, pp. 283313. In N. A. Rechcigl and J. E. Rechcigl (e ds. ) Environmentally Safe Approaches to Crop Disease Control CRC Press, Inc. Boca Raton, FL. McGovern, R. J., R. McSorley, and K.H. Wang. 2004. Optimizing bed orientation and number of plastic layers for soil solarization in Florida. Soil Crop Sci. Soc. Fla. Proc. 36:133139. McGovern, R. J., R. McSorley, and M. L. Bell. 2002. Reduction of landscape pathogens in Florida by soil solarization. Plant Dis. 86: 13881395. McS orley, R., and J. L. Parrado. 1986. Application of soil solarization to Rockdale soils in a subtropical environment. Nematropica 16:125140. Metcalf, R. L. 1962. Lesser cornstalk borer, pp. 497498. In Destructive and useful insects. McGraw Hill Book Compa ny, San Francisco, CA. Minarro, M., and E. Dapena. 2003. Effects of groundcover management on ground beetles (Coleoptera: Carabidae) in an apple orchard. Appl. Soil Eco l 23: 11111 7. Mulvaney, M J., C. W. Wood, and B. Wood. 2008. Nutrient release rates f rom organic mulches and cover crops. In D.M. Endale (ed.) Proc. 30th So. Conserv. Agric. Syst. Conf. and 8th Ann. GA Conserv. Prod. Syst. Trng. Conf., Tifton, Georgia, July 2931, 2008. http://w ww.ag.auburn.edu/auxiliary/nsdl/scasc

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129 BIOGRAPHICAL SKETCH Harsimran K Gill (Rosie) wa s born in Moga (Punjab) in India. She received her bachelors degree in agriculture with honors in plant protection from the Department of Entomology, Punjab Agricultural University, Ludhiana, India in 1999. She took a general entomology course in her bachelors and found that insects were fascinating creatures to work with and she decided to pursue graduate education in entomology. She obtained her masters degree in entomology from the same institute in 2005. Her masters research focused on monitoring a nd management of insecticide resistance in American bollworm, Helicoverpa armigera (Hbner) on cotton. She was awarded university merit certificate for academic achievements during her m asters. She worked as a research fellow in the same department for one year after her masters. In January 2007, she enrolled at the University of Florida to pursue a Doctor of Philosophy degree under the supervision of Dr. Robert McSorley in the Department of Entomology and Nematology. Her research was focused on the integr ated management of soil surface arthropods and weeds using soil solarization and organic mulching. She received research (4) and travel grants (20 ) from the department, university and also from various scientific societies. She presented many talks and pos ters at the Florida Entomological Society, Southeastern B ranch of Entomological Society of America, Entomological Society of America, Florida State Horticultural Society, Caribbean Food Crops Society, Graduate Student Council Interdisciplinary Research Con ference Forum, National Science Foundation Research day, and is also a member of the Gamma Sigma Delta honor society of agriculture. She won various scholarships and awards (15 ) at state, regional and national scientific meetings as well as in college and at university. She served as historian and secretary for the Entomology and Nematology Student Organization, secretary for Gator Citrus Club, department representative

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130 and social chair for Graduate Student Council. She also served as coordinator of the Sem inar Committee for three years. This committee was responsible for organizing the weekly departmental seminars with local and national speakers. She was awarded the best i nternational graduate s tudent in the college of Agriculture (International Student Outstanding Achievement A ward) as well as the best i nternational student in the Univers ity of Florida (Alec Courtelis A ward).