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Comparison of Methodologies in Determining Host Plant Resistance to Southern Chinch Bug in St. Augustinegrass and Invest...

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Title:
Comparison of Methodologies in Determining Host Plant Resistance to Southern Chinch Bug in St. Augustinegrass and Investigation on Seed Set Rate of Carpetgrass
Physical Description:
1 online resource (53 p.)
Language:
english
Creator:
Ma, Long
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Horticultural Sciences
Committee Chair:
Lu, Huangjun
Committee Co-Chair:
Cherry, Ronald H
Committee Members:
Mcauslane, Heather J
Zhao, Xin
Kenworthy, Kevin E

Subjects

Subjects / Keywords:
blissus -- carpetgrass -- resistance -- seed -- stenotaphrum
Horticultural Sciences -- Dissertations, Academic -- UF
Genre:
Horticultural Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
St. Augustinegrass is used as lawn grass throughout the southern United States for its wide adaptation to varying environmental conditions. The southern chinch bug, Blissus insularis Barber, is the plant’s most damaging insect pest. Host plant resistance of St. Augustinegrass has been determined in numerous studies using various techniques. However, efficacy of these various procedures in determining St. Augustinegrass resistance to southern chinch bug has not been compared. The objective of this study was to determine the effect of time and methodologies in determining St.Augustinegrass resistance to southern chinch bugs. Four varieties were tested for resistance using four different methods (bag, jar, box, tube) and different time intervals to measure chinch bug mortality. Overall, survival was greater in whole plant methods (box and tube) than excised stolon methods (bag and jar). The bag test gave the most erratic results of the four methods. The effect of time in determining resistance was also very evident. In our tests, it was clear that shorter time intervals in measuring mortality may result in not measuring resistance in a variety. In summary, researchers should carefully consider method, time and temperature as important variables in determining St. Augustinegrass resistance to southern chinch bugs. Seed set rate of common carpetgrass was investigated in a greenhouse study. The preliminary results showed that seed set rates ranged from 0.25 to 0.79 when selfed, while open-pollinated flowers had 0.27– 0.70 of seed-set rates. The differences of seed set rates between selfed and open-pollinated flowers varied among genotypes.
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 Long Ma.
Thesis:
Thesis (M.S.)--University of Florida, 2013.
Local:
Adviser: Lu, Huangjun.
Local:
Co-adviser: Cherry, Ronald H.

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2013
System ID:
UFE0045976:00001

MISSING IMAGE

Material Information

Title:
Comparison of Methodologies in Determining Host Plant Resistance to Southern Chinch Bug in St. Augustinegrass and Investigation on Seed Set Rate of Carpetgrass
Physical Description:
1 online resource (53 p.)
Language:
english
Creator:
Ma, Long
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Horticultural Sciences
Committee Chair:
Lu, Huangjun
Committee Co-Chair:
Cherry, Ronald H
Committee Members:
Mcauslane, Heather J
Zhao, Xin
Kenworthy, Kevin E

Subjects

Subjects / Keywords:
blissus -- carpetgrass -- resistance -- seed -- stenotaphrum
Horticultural Sciences -- Dissertations, Academic -- UF
Genre:
Horticultural Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
St. Augustinegrass is used as lawn grass throughout the southern United States for its wide adaptation to varying environmental conditions. The southern chinch bug, Blissus insularis Barber, is the plant’s most damaging insect pest. Host plant resistance of St. Augustinegrass has been determined in numerous studies using various techniques. However, efficacy of these various procedures in determining St. Augustinegrass resistance to southern chinch bug has not been compared. The objective of this study was to determine the effect of time and methodologies in determining St.Augustinegrass resistance to southern chinch bugs. Four varieties were tested for resistance using four different methods (bag, jar, box, tube) and different time intervals to measure chinch bug mortality. Overall, survival was greater in whole plant methods (box and tube) than excised stolon methods (bag and jar). The bag test gave the most erratic results of the four methods. The effect of time in determining resistance was also very evident. In our tests, it was clear that shorter time intervals in measuring mortality may result in not measuring resistance in a variety. In summary, researchers should carefully consider method, time and temperature as important variables in determining St. Augustinegrass resistance to southern chinch bugs. Seed set rate of common carpetgrass was investigated in a greenhouse study. The preliminary results showed that seed set rates ranged from 0.25 to 0.79 when selfed, while open-pollinated flowers had 0.27– 0.70 of seed-set rates. The differences of seed set rates between selfed and open-pollinated flowers varied among genotypes.
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 Long Ma.
Thesis:
Thesis (M.S.)--University of Florida, 2013.
Local:
Adviser: Lu, Huangjun.
Local:
Co-adviser: Cherry, Ronald H.

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2013
System ID:
UFE0045976:00001


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1 COMPARISON OF METHODOLOGIES IN DETERMINING HOST PLANT RES ISTANCE TO SOUTHERN CHINCH BUG IN ST. AUGUSTINEGRASS AND INVESTIGATION ON SEED SET RATE OF CARPETGRASS By LONG MA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR TH E DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2013

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2 2013 Long Ma

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3 To my parents

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4 ACKNOWLEDGMENTS Many people have helped me with my graduate study and the completion of this thesis. I especially appreciate study. I also want to express my gratitude to Dr. Ron Cherry, Dr. Kevin Kenworthy and Dr. Heather McAuslane for their great help with my projects and paper writing I am thank ful I thank other people who have provide d help for my study and research e specially Lucy Skelley in the E ntomology & Nematology Department and Alvin Wilson in the Everglade Research and Education C enter I am also grate help with zoysia grass crossing. They have greatly inspi red me to overcome difficulties in my life.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 ABSTRACT ................................ ................................ ................................ ..................... 9 CHAPTER 1 LITERATURE REVIEW ................................ ................................ .......................... 11 Economic Importance of St. Augustinegrass in Florida ................................ .......... 11 Distribution, Cytotaxonomy, and Genetics of St. Augustinegrass ........................... 11 Origin and Related Species ................................ ................................ .............. 11 Taxonomy and Geography ................................ ................................ ............... 12 Polyploidy and Importance in Sod Production ................................ .................. 13 St. Augustinegrass Biology ................................ ................................ ..................... 15 Plant Characteristics ................................ ................................ ........................ 15 Reproduction ................................ ................................ ................................ .... 16 Environmental Adaptation ................................ ................................ ................ 16 Biotic Stress ................................ ................................ ................................ ..... 18 Chinch Bugs ................................ ................................ ................................ ........... 18 Taxonomy of Southern Chinch Bugs ................................ ................................ 18 Biology and Feeding Habit ................................ ................................ ............... 18 Host Plants ................................ ................................ ................................ ....... 19 Management and C ontrol ................................ ................................ ................. 20 Host Plant Resistance ................................ ................................ ............................. 21 Lab Screening Techniques ................................ ................................ ..................... 22 Common Carpetgrass ................................ ................................ ............................. 23 Use and Distribution ................................ ................................ ......................... 23 General Biology ................................ ................................ ................................ 23 Reproduction and Ploidy Level ................................ ................................ ......... 24 2 EFFECT OF TIME AND METHODOLOGIES IN DETERMING ST. AUGUSTINEGRASS RESISTANCE TO SOUTHERN CHINCH BUGS .................. 25 Introduction ................................ ................................ ................................ ............. 25 Materials and Methods ................................ ................................ ............................ 26 Bag Test ................................ ................................ ................................ ........... 26 Jar Test ................................ ................................ ................................ ............ 27 Box Test ................................ ................................ ................................ ........... 27 Tube Test ................................ ................................ ................................ ......... 28 Statistical Analysis ................................ ................................ ............................ 28

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6 Results and Discussion ................................ ................................ ........................... 28 Conclusions ................................ ................................ ................................ ............ 30 3 TEST ON SEED SET RATE OF COMMON CA RPET GRASS ............................... 39 Introduction ................................ ................................ ................................ ............. 39 Materials and Me thods ................................ ................................ ............................ 40 Plants Materials ................................ ................................ ................................ 40 Seed Set Rate Evaluation ................................ ................................ ................ 41 Statistical Analysis ................................ ................................ ............................ 41 Results and Discussion ................................ ................................ ........................... 42 Conclusions ................................ ................................ ................................ ............ 44 LIST OF REFERENCES ................................ ................................ ............................... 46 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 53

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7 LIST OF TABLES Table page 2 1 No. of adult southern chinch bugs surviving (out of 10) at different intervals (days) on four varieties using four different methods. ................................ ......... 31 2 2 No. of adult southern chinch bugs surviving (out of 10) at different intervals (days) using whole plants ................................ ................................ ................... 32 2 3 No. of adult southern chinch bugs surviving (out of 10) at different intervals (days) using excised stolons ................................ ................................ ............... 33 3 1 Minimum, maximum and mean values for number of branches, spikelets per branch and seed set rate unde r self and open pollination ................................ .. 45 3 2 Estimate of variance components and broad sense heritabilities for number of branches, spikelets per branch and seed set rate under self and open pollination ................................ ................................ ................................ ........... 45 3 3 Seed set rates under different pollination methods a nd comparison of mean values within each genotype ................................ ................................ .............. 45

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8 LIST OF FIGURES Figure page 2 1 Southern chinch bugs. From left to right a re nymph, short wing adult and long wing adult ................................ ................................ ................................ ........... 34 2 2 Bag test ................................ ................................ ................................ .............. 35 2 3 Jar test ................................ ................................ ................................ ................ 36 2 4 Box test ................................ ................................ ................................ .............. 37 2 5 Tube test ................................ ................................ ................................ ............ 38

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9 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science COMPARISON OF METHODOLOGIES IN DETERMINING HOST PLANT RES ISTANCE TO SOUTHERN CHINCH BUG IN ST. AUGUSTINEGRASS AND INVESTIGATION O N SEED SET RATE OF CARPETGRASS By Long Ma August 2013 Chair: Huangjun Lu Cochair: Ronald Cherry Major: Horticultural Science s St. Augustinegrass is used as lawn grass throughout the southern United States for its wide adaptation to varying environmental conditions The southern chinch bug, Blissus insularis Host plant resistance of St. Augustinegrass has been determined in numerous studies using various techniques. However, efficacy of these various procedures in determining St. Augustinegrass resistance to s outhern chinch bug has not been compared. The objective of this study was to determine the effect of time and methodologies in determining St. Augustinegrass resistance to southern chinch bugs. Four varieties were tested for resistance using four different methods (bag, jar, box, tube) and different time intervals to measure chinch bug mortality. Overall, survival was greater in whole plant methods (box and tube) than excised stolon methods (bag and jar). The bag test gave the most erratic results of the fo ur methods. The effect of time in determining resistance was also very evident. In our tests, it was clear that shorter time intervals in measuring mortality may result in not measuring resistance in a variety. In summary, researchers

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10 should carefully cons ider method, time and temperature as important variables in determining St. Augustinegrass resistance to southern chinch bugs. Seed set rate of common carpetgrass was investigated in a greenhouse study. The preliminary results showed that seed set rate s ra nged from 0.25 to 0.79 when selfed while open pollinated flowers had 0. 2 7 0.70 of seed set rate s. The differences of seed set rates between selfed and open pollinated flowers varied among genotypes.

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11 C HAPTER 1 LITERATURE REVIEW Economic Importance o f St. Augustinegrass i n Florida St. Augustinegrass [ Stenotaphrum secundatum (Walt.) Kuntz e] was the first turfgrass planted in Florida in 1880 with the e arliest commercial sod production recorded in the 1920s It is the most popular turfgrass in Florida due to its competitive characters such as high density, less weed invasion and wide environmental adaptation (Busey and White, 1993). By 1987, about 1 billion square feet of turfgrass was produced annually in Florida producing about $100 million in annual sale s with St. Augustinegrass bei ng the predominant species (White and Busey, 1987). R ecent data show s that annual sod production has increased to an estimated 103 923 acres and has created more than $1 billion economic impact, $ 514 million in field value and 5 633 jobs St. Augustinegrass is still the predominant turfgrass in sod production having 51% of total acreage compared to b ahiagras s (ranked second) at 32 % The Floratam variety occupied 81% of total St. Augustinegrass acreage Both bermudagrass and z oysiagrass accounted for less than 10% ( Satterthwaite et al. 2009 ). Distribution, Cytotaxonomy, a nd Genetics o f St. Augustinegrass O rigin and Related S pecies The genus Stenotaphrum o riginates from tropical climates belongs to the tribe Paniceae of the Panicoideae subfamily. It consists of seven species six out of seven being re stricted to the Old W orld. S tenotaphrum secundatum (i.e. St. Augustinegrass ) is the only widely distributed species found in both the Old World and New W orld (Sauer, 1972 ). This fact strongly suggest s th e Old W orld origin of Stenotaphrum But t he origin of S. secundatum is not clear Milla Lewis et al. (2013) suggest ed a possible dual origin

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12 of St. Augustinegrass based on genetic analysis of existing St. Augustinegrass cultivars and its p lant introduction s in both the Old world and N ew world Sauer (1972) reported possible hybridization of S. secund atum with S. dimidiatum but had no chromosome information. Milla Lewis et al (2011 ) discovered resistance to Magnaporthe grisea (grey leaf spot disease transmission agent) on some members in the Lon gicaudatus race (Busey, 1995) which was previously only reported in S. dimidiatum A recent molecular analysis investigated the gene tic relationships amo ng diploid and polyploid cultivars, plant introductions and p embagrass ( S. dimidiatum ) which will benefit the determination of polyploid and aneuploid formation (Milla Lewis et al. 2013 ). Taxonomy a nd Geography Busey (1982 ) clustered St. Augustinegrass into five grou ps based on 26 characteristic evaluated using 96 genotypes. L ater reassignment into races or groups was based on previous classification. Assignments include the Floratam group, Bitterblue group Bre vi florus race, and Longicaudatus race (Buse y, 1986). The Floratam group is distinguished by long spikelet (>5.2mm) containing genotypes such as Floratam and Floralawn The Breviflorus race is identified with spikelet s less than 5.2mm and short inflorescence branch es ( 15mm ) including Dwarf Group and Gulf Coast G roup which contain the cultivars Seville, Raleigh and Texas Common Subsequently, the Long icaudatus race is separated by long internodes (80mm on average) containing cultivars Roselawn and Florida common Lastly, the Bitterblue group contai cultivars Bitterblue and Floratine (Busey, 1986). Milla Lewis et al (2013 ) reported consistent results for previous classification based on principle coordinate analysis (PCO) and cluster analysis.

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13 T he Gulf Coast G roup, endemic to the southeast ern United State s is homogeneous with Raleigh (Busey 2003 ). T he Dwarf G roup is homogeneous with a reddish stolon, purple stigma and dark green leaves (Busey, 1982) Seville (Riordan et al 1980) an artificial hybrid between Gulf Coast Group and Dwarf Group, was the first St. Augustinegrass released w ith a known pedigree (Busey, 200 3 ). FX 10 St. Augustinegrass was released by Busey (1993) and does not belong to any races or groups mentioned above. It was selected from second generation progenies from African plant introductio ns (PIs) and clustered by Milla Lewis et al (2013 ) into t he same group as those PIs. Polyploidy a nd Importance i n Sod Production Chromosome numbers of St. Augustinegrass have been investigated to understand the genetic relationships among the cultivars. The diploid St. Augustinegrass contains 18 chromosomes (n=9). Polyploid St. Augustinegrass was first reported by Long and Bashaw (1 961) including both sterile triploid s (2n=27) and sterile tetraploid s which was first collected in 1791 at the Cape of Good Hope (Sauer, 1972). The se sterile triploid s were generall y established via vegetative propagation. Bitterblue, one triploid genotype, was the foundation cultiva r for the Florida sod industry and the only suitable cultivar fro m 1934 to 1973 (Busey and White, 1993). A historically important sterile polyploid cult ivar i s Floratam which is an a neuploid having 32 chromosomes. This cultivar was release d by Ho rn et al (1973) for its combined resistance to southern chinch bug and the St. Augustinegrass Decline s train of Panicum Mosaic Virus (PMV SAD). However, the chinch bug resistance in Floratam

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14 was later overco me by a polyploid damaging populati on of the bugs (PDP) (Busey and Center, 1987), which was confirmed by Cherry and Nagata (1997). Floratam has been widely used in the sod industry since its release and continues to be popular despite the loss of resistance to southern chinch bugs Busey (1986) reported that Floratam occupi ed 77 percent of the total sod production. Satterthwaite et al (2009) reported that 81 percent of St. Augustinegrass sod production was planted in Floratam FX 10 an other aneuploid (2n=30) cultivar, was released in 1993 for its resistance to PDP southern chinch bugs with other good characters (Busey 1993). It was selected from the second generation progeny of controlled pollination among African polyploid St. Augustinegrass germplasm with bivalent pairing and regular disjunction b earing normal seeds (Busey 1990; Busey 1993). Milla Lewis et al (2013 ) investigated the use of flow cytometry to determine the ploidy levels of St. Au gustinegrass, using chromosome counts from existing cultivars and PIs including Bitterblue, PI300129, PI291594, Flo ratine, PI290888, PI300130, FX 10, Floratam and Floralawn It was determined that flow cytometry is a useful tool for ploidy analysis in St. Augustinegrass. Different ploidy levels in St. Augustinegrass lead to adaptive polymorphism. Polyploid St. Augustinegrass normally have longer, wider, and hicker leaf blade s with brighter green color compared with diploid genotypes Diploid s, however, are more highly branched with a stronger rapid cover ability leading to early maturity and harvest (Busey et al 1982; Busey 1986 ; Busey 2003 ). Different ploidy level s also account for the majority of the variation s in resistance to biotic stress. Polyploids are mo re resistant to both PDP and standard southern chinch

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15 bug (Busey 1990 ; Busey and Zaenker, 1992; Reinert et al 1986) b ut they are more susceptible to grey leaf spot disease than diploids (Atilano and Busey 1983). But one diploid variety Captiva was developed resistant to southern chinch bugs (Nagata and Cherry 2003). The resistant mechanisms also differ in diploid and polyploid varieties. Rangasamy (2006) reported that Captiva showed both antibiosis and antixenosis whereas FX 10 only showed anti xenosis. As most variation is between ploidy levels, variations may not be useful u ntil successful hybridization between different ploidy levels can be achieved (Busey 2003). Genovesi et al (2009) applied embryo rescue techniques and achieved 10.88% cros sability among eight polyploid and six diploid genotypes indicati ng a possible better use of genetic variation within St. Augustinegrass in the future. St. Augustinegrass Biology Plant C haracteristics Leaf blades of S t. Augustinegrass are 5 14mm wide and round tipped with conspicuous midr ib. They are normally glabrous and sparsely pubescent in genotypes with suggested introgression with S. dimidiatum (Busey 1986). The leaves arranged strictly distichously along the slightly flattened stolons and their bas es attenuated and subsequently delimited by a constricted collar St. Augustinegra ss has a membranous ligule, a laterally compressed leaf sheath and no auricles (Busey 2003). The St. Augustinegrass inflorescence is a spike with branches contracted into the rachis and generally reduced to single spikelet s A d isarticulated inflorescence rachis can float for 7 10 days which may account for local disp ersals (Sauer 1972). Spike length is free of environmental influences which can be used for cultivar identi fication (Busey 1993). The awnles s spikelets, 3 6mm long, consist of dissimilar glumes on the

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16 outside and two differently positioned florets inside. The lower glume is scale like and nerveless while the upper one is similar to nerved lemmas. The lower fl oret is generally imperfect (staminate or neuter) while the upper perfect floret is perfect wit h three anthers and two stigmas (Busey 2003). The stigma color is white, purple or bicolor and the anther color ranges from creamy white to burgundy (Busey et a l 1982). St. Augustinegrass spread s by branching above ground stolons. It has relative poor wear tolerance with slow recovery from defoliation (Busey 2003). Stolon pigmentation ranges from almost green to intense red (Busey et al 1982). Reproduction St. Augustinegrass is generally vegetatively propagated via cutting stolons, plugs or sod. Effort on development of seeded cultivars has not been successful Some heavily seeded cultivars, for instance, are esthetically unacceptable (Busey 2003). Environmental A daptation St. Augustinegrass is adapted to wide range of soil conditions with different pH values, and different organic matter content. It is more salt tolerant than other warm season grasses. The species also has various levels of resista nce to drought and shade (Horn et al 1973). Different level s of s alt tolerance have been noted for some cultivars Flo ratam and Floralawn are highly tolerant compared to other cultivars (Dudeck et al 1993). Seville is more saline tolerant than Floratam (Meyer et al 1989). Floratine and Ha waii Sel St. Augustinegrass were reported with salt tolerance as well (Marcum and Murdoch 1990). St. Augustinegrass is reported to have medium to good drought resistance with a great diversity among cultivars (Beard 1989) However, it is not as resistant as other C4

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17 grasses like bermudagrass ( Cynodon spp .) and Zoysiagrass ( Zoysia spp ) (Busey 1996). Floratam and Floralawn were reported to be drought tolerant by Beard ( 1989) and further confirmed by Sifers and Beard (1 999 ) FX 10 St. Augustinegrass has a significantly better drought tolerance than floratam and other cultivars for its deep rooting ability (Miller and McCarty 2001 ). St. Augustinegrass can tolerate partial tree shade have better shade tolerance than Floratam (Busey and Davis 1991). Partial shade tolerance is desired in residential landscape s (Busey 2003). Smith and Whiteman (1983) reported that St. Augustinegrass had the best response among eight tropical gr ass species ( Axonopus compressus, Brachiaria decumbens, B. humidicola, B. miliiformis, Dicanthium caricosum, Ischaemum aristatum, Paspalum conjugatum and Stenotaphrum secundatum ) under 80% coconut canopy shade The e ffect s of nutrients on the growth of St. Augustinegrass have been studied Cherry et al (2012) found that n utritio n content of leaf tissues varied among varieties indicating that Floratam has a less nutrition requirement for the leaves than Raleigh and Captiva Proper fertilization is a big conc ern in turf production. Trenholm et al (2012) reported that the turf quality of Floratam decreases under extremely low nitrogen application rate (49kgN/ha 1 applied in ~60d intervals). Cherry et al (2011) found that increased fertilization le d to signif icantly greater gray leaf spot dise ase in Captiva St. Augustinegrass but did not affect southern chinch bug resistance. Nitrogen leaching and runoff is a common problem related to turfgrass fertilization However, St. Augustinegrass has significantly less nitrogen leaching than mixed species landscape

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18 (Erickson et al 2001). Trenholm et al (2012) also reported that little nitrate nitrogen leaching occurred in Floratam St. Augustin egrass. B iotic S tress St. Augustinegras s has fewer nematode and disease problems compared with other warm season grasses (Horn et al 1973). The southern chinch bug, Blissus insularis Barber, Genotypic variation among cultivars and breeding accessions e xists for southern chinch bug resistance (Reinert and Dudeck 1974 ; Lu and Cherry 2012 ) and other traits such as grey leaf spot disease resistance (Busey et al 1993 Atilano and Busey 1983 ) and PMV SAD resistance (Horn et al 1973). Chinch Bug s Taxonomy of Southern C hinch B ugs There are three species of chinch bugs with major economic importance in the United States. They a re the western chinch bug, Blissus occiduus Barber, the hairy chinch bug, Blissus leucopterus hirtus Montandon; and the south ern chinch bug, Blissus insularis Barber (Vittum et al 1999). The primary c hinch bug in Florida and pest of St. Augustinegrass is the southern chinch bug (Reinert and Kerr, 1973) B iology a nd Feeding Habit The s outhern chinch bug is a piercing sucking i nsect that drain s sap from St. Augustinegrass leaf tissue (Wilson 1929). The egg period was reported to vary from 7 d to 14d T he nym ph stage lasts for 28 to 30 d containing five to six instars T he a dult chinch bug live s from 45 to 56 d Damage to tissue can occur from both nymph and adult stages ( Wilson, 1929 ; Kuitert and Nutter 1952 ; Eden and Self 1960 ; Komblas,

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19 1962 ; Ke rr, 1966). T wo typ es of s outhern chinch bugs ( l ong wings and short wings) exist showing seasonal wing polymorphism ( Van Duzee, 1886 ; Webster 1907 ; Wilson 1929 ) Chinch bugs prefer to reside along the edges of the close fitting leaves of St. Augustinegrass. Their feeding greatly influences the growing cond ition of the whole plant (Beyer 1924). The infested turf will turn brown in p atches and cause yellowing along the margins of damaged areas and may even completely die out (Watson 1925). Southern chinch bug infestation also faciliate weed establishment on St. Augus tinegrass lawns (Rainbolt et al. 2006). Lawns under drought stres s i sandy soils were more susceptible to southern chinch bug infestation (Wilson 1929). In neighborhood, chinch bugs can move from lawn to lawn easily cover ing a long distance in a short time period. In a specific lawn, they tend to be distributed in scattered patches rather than uniformly across the entire lawn (Kerr, 1966) Reinert (1978) found the highest southern chinch bugs population density along the periphery of damaged grass samples. Cherry (2001) concluded that southern chinch bugs were highly concentrated in small areas within ligh t to moderate infestations lawns Host Plants B. leucopterous caused serious damage to St. Augustinegrass in the southeastern United States according to Wils on (1929). Hamilton (1935) observed damage of B. leu copterous to lawns and golf courses in the eastern United States. Barber (1918) reported that the most common chinch bug in Florida was a variation of B. leucopterous Kerr (1966) mentioned that D.E.Leonard identified the common chinch bug in Florida as a separate species B. insularis Kerr (1966) considered B. insularis as the second most serious in sect pest in Florida just behind the citrus rust mite ( Phyllocoptruta oleivorus )

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20 In Florida, chinch bugs can feed on many sp ecies of lawn grasses but cause th e most severe damage in St. Augustinegrass which is the only species to suffer serious damage from chinch bugs. When the infestation occurred in a mixed lawn containing both St. Augustinegrass and centipedegrass, only the St. Augustinegrass was damage d (K err 1966). Cherry and Nagata (1997) conducted research on southern chinch bugs oviposition on St Augustinegrass varieties and other turf species St. Augustinegrass was significantly more preferred by the southern chinch bug than other species The other three types of chinch bugs can cause damage on different grass species. For instance, B. o cciduus t he western chinch bug can damage b ermudagrass and z oysiagrass lawns causing server e damage. Blissus leucopterous leucopterous can also harm these two grass species (Anderson et al 2006; Eickhoff et al. 2007). M anagement a nd Control Traditionally, control of southern chinch bug is accomplished through use of chemical insecticides (Congdon and Buss, 2002). Reinert and Kerr (1973 ) stated that the use of chemical pesticides was the only effective way to control the pest. Reinert (1978 ) further reported that insecticides may need to be applied to Florida lawns more than six times a year to control the pest. However, Reinert and Niem czyk (1982) reported the occurrence of insecticide resistance in chinch bugs due to the heavy reliance on insecticide use. Lack of rotation among different chemical formulations may increase pesticide resistance of chinch bugs (Congdo n 2004). More recently combined pest management strategies have been adopted due to t he concern s over the repeated use of pesticides ( Congdon and Buss 2002).

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21 Some natural biological control has been noted but has been found to be effective. A Parasite Eumicrosoma ben efica Gahan ( Hym enoptera: Scelionidae ) was reported to attack eggs of B. insularis (Congdon, 2004). Predators such as Pagasa pallipes Stal (Heteroptera: Nabidae) and big eyed bugs were discovered to feed on B. insularis The density of big eyed bugs was po sitively related to the southern chinch bug density (Reinert, 1978 ; Cherry, 2005). Fire ant s were reported to attack B.insularis (Reinert, 1978). However, Cherry (2001) found that imported fire ant s were not able to suppress the B. insularis Host Plant Resistance Reinert and Kerr (1973) indicated that southern chinch bugs could cause great injury and even kill St. Augustinegrass completely and thus should be treated as the most serious insect pest of St. Augusti negrass. Strobel (1971) found that the co st of controlling southern chinch bugs was high, prompting researc h to find resistant varieties. Reinert and Dudeck (1974) screened eleven accessions along with all available commercial cultivars for their chinch bug response FA 108 Flora tam, and FA 118 were highly resistant. They labeled the type of resistance as antibiosis because of high mortality rate s and greatly reduced fertility for surviving adults. Floratam was released as a cultivar jointly by the University of Florida and Texa s A&M University for its resistance to SAD and s outhern chinch bug (Horn et al 1973). production. It is also well adapted to the environmental conditions of Florida and Texa s (Rangasamy et al 200 6 ). However, Floratam has some shortcomings such as its coarse textured leaves and poor cold and shade tolerance (Reinert, 1978) It has also lost its resistance to southern chinch bug (Busey and Center, 1987) Researchers have

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22 attempted to identify the other lines resistant to both SAD and sou thern chinch bug (Bruton et al. 1979; Reinert et al. 1980; Crocker et al. 1982). Floralawn 108) with combined resistance to SAD and southern chinch bug was the only line released (Dud eck et al 1986). In 2 007, Captiva was released as the first diploid cultivar with s outhern chinch bug and plant hopper resistance (Nagata et al 2007 ). Some studies have been done on other warm season grasses. Anderson et al (2006) evaluated both cool season and warm season grasses for their resistance to multiple chinch bugs. They found that the St. Augustinegrass resistant to B. insularis was also resistant to B. o cciduus Heng Moss et al (2002) observed that some b affalog rass ( Buchloe d actyloides ) cultivars were resistant to B. o cciduus Different resistance types and their mechanisms in St. Augustinegrass h ave been studied Rangasamy et al (2006) reported possible antixenosis to southern chinch bugs in both Captiva and FX 10, and antibiosis in Captiva. He further reported possible physical and biochemical mechanisms for host plant resistance The resistant varieties FX 10 and Captiva were reported to have significantly higher lipoxygenase or polyphenol oxidase activity a fter infestation. Moreover, resistant varieties had significantly thicker walls of sclerenchyma cells around the vascular bundle but did not differ from susceptible varieties in their total lignin content. Lab Screening Techniques Four screening methods using confined insects have been used determine southern chinch bug resistance of St. Augustinegrass. These i nclude: the bag test (Reinert 1978 ), the jar test (Crocker et al 1982), the box test (Nagata and Cherry 2003), a nd the tube test (Cherry et al 2012). Further i nformation is needed to determine if the different screening methods provide similar results regarding the

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23 responses of St. Augustinegrass lines to southern chinch bug. Because the effectiveness and accuracy of a screening method is impor tant in the determination of resistance, it is desirable to know if the existing screening methods are equally useful in identifying chinch bug resistance in St. Augustinegrass. Common Carpet g rass Use and D istribution Common c arpetgrass ( Axonopus fissifolius Raddi ) is a perennial warm season grass in the southern United States along coastal areas (Wise, 1961). Common carpetgrass differs from the broadleaf carpetgrass ( Axonopus compressus ) by having a less coarse leaf texture (Smith and Valenzuela, 2002) Common carpetgrass can be used in various locations such as lawns, roadside, cemeteries and similar low maintenance areas (Greene 2007) Growing carpetgrass benefits w eed control by its mat like growth habit which also helps to preserve topsoil on slop es and improves soil structure (Smith and Valenzuela, 2002) General Biology Carpetgrass is stoloniferous with narrow glabrous leaves that are 5 to 20cm in length and 2 6mm in width (Martin, 1975). Leave color varies from light green to medium green with folded vernation (Skerman and Riveros, 1990 Turgeon, 2005 ). It is characterized by compressed two edged stems with short internode s and small flowers. It has hairy ligule with narrow and continuous collars and no auricles (Turgeon, 2005) Its inflor escence usually contains two to three branches with two rows of alternately arranged spikelets (about 2mm long) (Martin, 1975).

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24 Reproduction and Ploidy L evel Common carpetgrass can be reproduced both sexually via seed and vegetatively via sod, sprigs or plugs It can be cross pollinated in the field and also self pollinated (Heath et al. 1985 Watson and Burson, 1985 ). Watson and Dallwitz (1992) reported most species of common carpetgrass to be allopolyp loid generated from interspecific hybridization within the Axonopus genus Common carpetgrass has been reported with various ploidy levels including diploid (2n=2x=20) (Gould and S oderstrom, 1967; Norrmann et al. 1994 ), tetraploid (2n=4x=40) ( Gould 1968; Hickenbick et al. 1975) h exaploi d (2n=6x=60) (Davidse and Pohl, 1978 ) and octoplo id (2n=8x=80) (Hickenbick et al. 1975) Common c arpet g rass is long day plant that flowers normally under 12 14h photoperiod Cold temperature (<15 o C ) can inhibi t flowering (Knight and Bennett, 1953)

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25 CHAPTER 2 EFFECT OF TIME AND METHODOLOGIES IN DETERMING ST. AUGUSTINEGRASS RESISTANCE TO SOUTHERN CHINCH BUGS Introduction St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze, is used as lawn grass throughout the southern United States for its wide adaptation to varying environmental conditions The southern chinch bug, Blissus insularis Barber, is the In secticidal application was the primary method of control of the southern chinch bug before the release of resistant Floratam St. Augustinegrass in 1973 (Horn et al. 1973). Unfortunately southern chinch bug damage on Floratam was first reported in Florida in 1985 (Busey and C enter, 1987) showing its loss of host plant resistance as was later confirmed by Cherry and Nagata (1997) Busey (1990) identified several new lines of St. Augustinegrass resistant to southern chinch bug s which led to development of t he variety FX 10 St. Augustinegrass, resistan t to southern chinch bug (Busey, 1993). Howev er, FX 10 was never extensively grown due to several negative characteristics including a very course appe arance and tough texture (Busey, 1993). More recently, Nagat a and Cherry (2003) reported on the resistance of NUF 76 St. Augustinegrass to southern chinc h bug. NUF 76 is unique because, for the first time, resistance to southern chinch bug was identified within a diploid line of St. Augustinegrass, unlike polyploid s such as Floratam and FX 10. Mechanisms of resistance in NUF 76 have been reported by Rangasamy et al. (2006, 2009a, b). Although NUF 76 has been shown to be widely resistant to southern chinch bug population s in Florida (Nagata and Cherry, 2003), Reinert (2008) and Reinert et al. (2011) reported that it is not resistant to some Texas populations. NUF 76

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26 has been name d Captiva for marketing purposes and is currently produced for sale in Florida and Texas. Most screening methods to measure ho st plant resistance of St. Augustinegrass to southern chinch bugs have measured nymphal and/or adult survival in no choice tests Those tests fall into 4 types with examples as follows. Reinert and Dudeck (1974) used insects and excised stolons enclosed in plastic bags. Crocker et al. (1982) used insects and excised stolons in glass jars. Nagata and Cherry (2003) tested insects in pla stic boxes containing a stolon attached to the plant. Lastly, Cherry et al. (2011) tested insects in plastic tubes containing a stolon attached to the plant. Besides using different screening methods, different time intervals have also been used to measure mortality rate. However, efficacy of these various procedures in determining St. Augustinegrass resistance to southern chinc h bug has not been compared. The objective of this study was to determine the effect of time and methodologies in determining St. Augustinegrass resistance to southern chinch bugs. Materials and Methods Bag T est St. Augustinegrass grass genotypes used in o ur tests were Captiva, Floratam, NUF 216 and FX 10. These varieties range in resistance to southern chinch bugs from Captiva (resistant), Floratam (once resistant, now susceptible), NUF 216(resistant) and FX 10(resistant). Plants were planted into 10 cm d iam. pots filled with a mixture of 50% sand and 50% Fafard #2 mix, and each pot received 1 g of fertilizer (Scotts 14 14 14). Chinch bugs were collected by vacuuming infested lawns in Palm Beach Co., FL. Collected debris were stored in buckets filled wit h fresh St. Augustinegrass clippings for food at 18 C until testing. A dult chinch bug s (Figure 2 1) w ere collected by sorting

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27 through debri s when needed. M ortality was recorded on 3, 7, 14, 21 and 28 d after insects were placed into bags. This time interval was used to cover the range used in all prev ious tests from 3 d (Reinert, 1974) to 28 d (Cherry and Nagata, 1997). Fifteen cm of terminal stolon s of the 4 varieties w ere cut from the potted plants and wrapped with a wet cotton ball at the cut end and each stolon was placed into a 3.78 L clear plastic bag (Figure 2 2) Thereafter, 10 randomly selected adult chinch bugs were p laced in to each bag, and the bag seale d Except for 3 d check, stolons were replaced after each reading. Tests were conducted at 28 C and 12d/12l photoperiod. Jar T est C hinch bug s, St. Augustinegrass varieties, ambient conditions and time intervals used in this test were as previously descri b ed. Fifteen cm terminal stolons of the 4 varieties were cut from the potted plants and inserted into a 26 ml vial containing water and sealed with parafilm. Each vial and 10 adult chinch bugs were p laced into a 0.95 L wide mouth clear glass jar and covered with insect screen cloth s ecured by a s crew on ring (Figure 2 3) Except for 3 d check, we replaced the stolons after each reading. Box T est C hinch bug s, St. Augustinegrass varieties, ambient conditions and time intervals used in this test were as previously descri b ed. Polypropylene opaque food storage containers 28 16 11 cm (l w h) were used in this test. The central part of each lid was removed leaving approx. 3cm around the sealing edge. A 6mm diameter hole was drilled half way up on one of the 16 cm sides. A channel was then cut from the top of the box to the hole. A potted plant was p laced beside the box. Strips of P arafilm were wrapped around the stolon where it would pass through the channel. F laps were bent on each side of the channel to help with the passing and positioning o f the stolon within

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28 the hole. A 15 cm stolon attached to the plant was placed in each box. Tape was used to cover the channel from both inside and outside (Figure 2 4) Ten adult chinch bugs were placed into each box. An insect screen cloth was placed on top of the box stabilized by the lid. Plants were watered as needed. Tube T est C hinch bug s, St. Augustinegrass varieties, ambient conditions and time intervals used in this test were as previously descri b ed. A 15 cm stolon attached to a plant was placed in a 22 cm long, 4 cm diameter, clear plastic tube A sponge was wrap ped around the stolon and wedged into the tube end next to the potted plant (Figure 2 5) Ten adult chinch bugs were placed into the tub e. The other end of the tube was covered with insect screen cloth held in place by a rubber band. Statistical A nalysis The 4 methods using the 4 varieties were conducted at the same time in a replication. Eight replications were conducted from November 2011 to July 2012. Overall survival in whole plant methods (box and tube) versus excised plant methods (bag and jar) was compared at each time inte rval in contrast tests using analysis of variance ( SAS, 2012). Differences in s urvival among different cultivars, times and different methods were det ermined using LSD analysis (SAS, 2012). Results and Discussion The 4 testing methods fell into 2 general c ategories. The box and tube tests used stolons attached to plants whereas bag and jar tests used excised stolons. Survival means of box or tube tests were significantly greater than the means of bag or jar tests at night times. Surviv al means in bag or jar tests were never significantly greater than that of the box or tube tests (Table1) Contrast analysis further showed differences in

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29 survival between the whole plant methods (box and tube) versus excised stolon methods (bag a nd jar). At all 5 time interval s, survivorship was significantly greater in the whole plant methods than the excised stolon methods. Chinch bug survival using whole plant methods and excised stolon methods is shown in Tables 2 and 3, respectively. At the 3 d interval, only 1 variety (F X 10) was found to be resistant (i. e. significantly different from Floratam) in one method (jar test). At 7 days, we found 7 times in the 3 resistant varieties in 3 methods (box, tube, jar). At 14 days, resistance was found 9 times in the 3 resistant vari eties in all 4 methods. Both at 21 and 28 d resistance was found 10 times in the 3 resistant varieties in all 4 methods. As noted earlier, researchers have used different methods, time intervals and ambient temperatures to determine St. Augustinegrass res istance to southern chinch bugs. Overall, our tests confirm earlier tests that show Captiva, NUF 216 and FX 10 are resistant to southern chinch bugs and Floratam is susceptible. However, our data also clearly show that the measurement of resistance may be affected by different factors. For example, overall chinch bug survival was higher in tests using whole plants than in tests using excised stolons. Also, the bag test gave the most erratic results of the 4 methods and never did show Captiva to be resistant which the other three methods demonstrated The bag test also did not find NUF 216 to be resistant in week 3 and 4 In contrast, the other 3 tests showed NUF 216 consistently resistant in both weeks. Reinert (1978) noted that condensation in plastic bags caused unexpected high mortality, a problem also experienced by Crocker et al (1982) who switched to glass

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30 jars. We also noted condensation in the bags and also were concerned with stolons drying out infrequently in the bags. The effect of time in determining resistance was also very evident. In our tests, shorter time intervals in measuring mortality may result in not measuring resistance in a variety. Lastly, the effect of temperature was not measured in our study. However, in previous tests, temperatures have ranged from 25 C (Cherry et al 2011) to 35 C (Crocker et al 1982). Because insects are poikilothermic, it is probable that increa sed temperature will reduce time intervals needed to determine resistance because of increased mortality caused by biochemical antibiosis. For example, Rangasamy et al. (2009b) reported increased oxidative responses in resist ance St. Augustinegrass varieti es to southern chinch bug feeding. In summary, researchers should carefully consider method, time and temperature as important variables in determining St. Augustinegrass resistance to southern chinch bugs. Conclusions Both the time and methodologies have a great impact on screening for southern chinch bug resistance in St. Augustinegrass. The effective time for screening should not be as short as 3d and is not necessary for longer than 28d. Different screening methods vary in their ability to detect resis tant varieties. The differences need to be considered when using different methods. Future study can determine the influence of temperature and other factors on the use of appropriate time and methodologies for screening southern chinch bug resistance.

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31 Table 2 1. No. of adult southern chinch bugs surviving (out of 10) at different intervals (days) on four varieties using four different methods. Methods Days In Test 3 7 14 21 28 Tube 8.52.3A 5.33.1A 3.23.7A 1.92.7A 1.22.3A Box 7.82.5AB 5.72.9A 2.82.8AB 1.82.6A 1.32.1A Jar 7.52.6B 3.52.9B 1.92.7BC 1.12.0A 0.81.6AB Bag 7.82.1AB 4.82.4A 1.62.1C 1.01.6A 0.30.7B Means SD within each column followed by the same letter are not significantly survival of four varieties. Contrast value of whole plant (tube and box) versus excised stolon methods (jar and bag) were F=3.86, p=0.05 at 3 days, F=14.25, p<0.01 at 7 days, F=10.59, p<0.01 at 14 days, F=5.91, p=0.02 at 21 days, F=6.78, p=0.01 at 28 days.

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32 Table 2 2. No. of adult southern chinch bugs surviving (out of 10) at different intervals (days) using whole p lants Box Tube Variety 3 7 14 21 28 3 7 14 21 28 Floratam 7.5A2.4 6.8A2.4 5.0A2.7 4.1A3.1 3.2A2.9 9.5A0.9 8.1A2.2 6.8A3.2 5.3A2.8 4.1A3.0 Captiva 8.6A 2.4 7.0A2.5 3.0A2.6 1.3B2.4 1.1B2.1 8.3A2.5 5.1B2.9 3.1B3.4 1.1B1.6 0.6B1.2 NUF 216 8.4A1.9 6.5A2.1 3.1A2.6 1.6B1.8 0.9B1.0 8.1A3.0 4.8B3.4 3.1B4.0 1.1B2.1 0.0B0.0 FX 10 6.6A3.1 2.5B2.2 0.3B0.5 0.1B0.4 0.0B0.0 8.3A2.4 3.5B2.3 0.4B0.5 0.0B0.0 0.0B0.0 Means SD etermined with an LSD test (SAS, 2012).

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33 Table 2 3. No. of adult southern chinch bugs surviving (out of 10) at different intervals (days) using excised stolons Bag Jar Variety 3 7 14 21 28 3 7 14 21 28 Floratam 7.1A2.9 5.1A2.6 3.0A3.0 1.9A2.1 0.3A0.5 9.0A0.8 6.0A3.5 5.0A3.3 3.4A2.4 2.6A2.4 Captiva 8.8A 1.3 6.0A2.5 2.1AB2.2 1.6A2.1 0.9AB1.1 7.4AB2.1 2.8B2.0 1.3B2.2 0.8B1.8 0.4B0.7 NUF 216 7.6A1.6 4.0A2.2 0.9B0.6 0.6AB0.5 0.3AB0.5 7.1AB2.6 3.3B2.6 0.8B0.9 0.3B0.5 0.3B0.5 FX 10 7.5A2.1 4.0A1.9 0.5B0.9 0.0B0.0 0.0B0.0 6.4B3.6 2.1B2.2 0.5B0.8 0.1B0.4 0.0B0.0 *Means SD ned with an LSD test (SAS, 2012 )

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34 Figure 2 1 S outhern chinch bugs From left to right are nymph, short wing adult and long wing adult Photo courtesy of Ron Cherry.

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35 Figure 2 2 Bag test Photo courtesy of Long Ma

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36 Figure 2 3 Jar test Photo courtesy of Long Ma

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37 Figure 2 4 Box test Photo courtesy of Long Ma.

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38 Figure 2 5 Tube test Photo courtesy of Long Ma.

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39 CHAPTER 3 TEST ON SEED SET RATE OF COMMON CARPETGRASS Introduction Common Carpetgrass ( Axonopus fissifolius ) is a perennial warm season grass used as low maintenance applications in the southern United States along coastal areas (Wis e, 1961). It has a medium to coarse leaf texture compared to tropical carpetgrass ( Axonopus compressus ) with a coarse to very coarse leaf texture (Smith and Valenzuela, 2002) Common carpetgrass can be used in various locations such as lawns, roadside, cemeteries and similar low maintenance areas (Greene, 2007) .Common carpetgrass is competitive against weed s, helps to prevent soil erosion and improves soi l quality (Smith and Valenzuela, 2002) Carpetgrass is stoloniferous with leaves th at are 5 to 20cm in length and 2 6mm in width (Martin, 1975). Leave color various from light green to medium green (Skerman and Riveros, 1990). It is characterized by compressed two edged stems with short internode and small flowers. It has hairy type ligu le with narrow and continuous collars but no auricles (Turgeon, 2005). Its inflorescence usually contains two to three branches with spikelets (about 2mm long) arranged in two neat rows (Martin, 1975). Common carpetgrass can be reproduced both sexually v ia seed and vegetatively via sod, sprigs or plugs. It can cross pollinate and self pollinate (Heath et al 1985 Watson and Burson, 1985 ). Watson and Dallwitz (1992) reported most species to be allopolyp loid generated from interspecific hybridization withi n the Axonopus genus. Common carpetgrass has a base chromosome number of ten (x=10) and ploidy levels include: diploid (2n=2x=20) (Gould and Soderstrom, 1967; Norrmann et al 1994 ),

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40 tetraploid (2n=4x=40) ( Gould 1968; Hickenbick et al 1975) h exaploid (2n=6x=60) (Davidse and Pohl, 1978 ) and octoploid (2n=8x=80) (Hickenbick et al 1975) Carpetgrass flowers under long day conditions with normally 12 14h photoperiod. Cold temperature (<15 o C ) can inhibit flowering (Knight and Bennett, 1953). Carpet gra ss germplasm collection include s both seed derived and natural collections. Greene et al (2008a, 2008b) reported the extent of variation among those germplasm collections based on both morphological trait s and turf performance trait s They also mad e compa risons between these two groups and conc luded that morphological trait s were more effective identifying variation between two groups. Wang et al (2010) showed that the seed derived population had less genetic variability than natural collections using AFL P marker based molecular analysis Because carpet grass primarily propagated through seed, it is desirable to understand if a single elite clone could produce adequate seed or if cross pollination is needed (i.e. synthetic cultivars) for suitable seed pro duction. The primary objective of the following study was to determine if seed set of carpetgrass differs under selfing or cross pollination conditions. M aterial s and M ethod s Plant s Materials Common C arpet grass germplasm collection used in this study was provided by Dr. Kevin Kenworthy in Agronomy Department, University of Florida, Gainesville, FL. This germplasm was previously characterized for many traits by Greene et al. (2008a and 2008b). Ten accessions w ere randomly selected from the germplasm and veg etatively propagate d to produce 4 plants per accession and planted in 10 cm pots using metro mix 900 potting soil They were arranged in a randomized complete block

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41 design with four replications in the greenhouse using automatic irrigation All plants were trimmed to a uniform height after establishment. The experiment started on September 2012 and ended on December 2012 Greene et al ( 2008b) grouped 176 accessions within the germplasm collections into 32 clusters based on their morphologic al traits The 10 accessions selected in this test fit into 9 separate clusters. Seed Set Rate E valuation During flowering, t hree inflorescences from each pot were covered with a glassine bag prior to anthesis. The bottom of each bag is folded and stabilized by a paper clip to prevent seed loss Open pollination among these forty plants was powered by wind in the greenhouse. As the curtains on both sides of the greenhouse were up for most of the time, the environ mental condition was almost the same as outside. Upon maturity, the covered inflorescences along with three open pollinated inflorescences from each pot were harvested and dried at 50 C 55 C for 2 d The N umber of branches, number of spikelets per branch and number of seed were counted for each inflorescence Inflorescences were soaked in 50% bleach f or 2h for accurate seed counting Seed set rate per inflorescence w as calculated using the formula: seed set rate = ( #seed / #spikelets per inflorescence ) x 1 00% S tatistical A nalysis Variance components for number of branches, spikelets per branch and seed set rate were calculated using SAS PROC VARCOMP procedure (SAS 2012 ). Genotypes and replications were considered random effects. Differences in seed set rate among ten genotypes were analyzed using LSD test for self pollination and open pollination separately (SAS, 2012).

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42 Broad sense h eritab ilities ( H 2 ) for the number of branches, spikelets per branch and seed set rate were calculat ed using the formula below (Hallauer, 1970 ): where is variance of genotypes represents variance of residuals and R is the number of replication. C ontrast test s were performed using SAS t o determine if the differences existed within genotypes for seed set rate between selfing and open pollination (SAS, 2012) Results and Discussion Watson and Burson (1985 ) reported that the common carpetgrass can be cross pollinated in the field, and single plant can be self pollinated in the greenhouse when isolated. However a comparison of seed set between self and cross pollination has not been quantified. S imilar tests have been conducted on bermudagrass and the seed set rates for both self and open pollination are hi ghly variable. Bermudagrass are highly self incompatible and s eed set rate ranged from 0.004 to 0.036 for self pollination and 0.028 to 0.446 for open pollination ( Richardson et al. 1978; Kenna et al. 1983) Acua et al (2007) reported the seed set of sexually reproduced bahiagrass ( Paspalum notatum Flgg ) to be on average 0.12 and 0.39 for self pollination and open pollination respectively. In this experiment, we measured seed set rate for both pollination type s and also the number of b ranches along with spikelets per branch. Number of spikelets per branch and seed set rate for self and cross pollination had a wide range of variation (Table 3 1) The n umber of spikelets per branch range d from 12 to 39, seed set rate under self pollinatio n from 0.20 to 0.88, and seed set rate for open pollination from 0.18 to 0.93. T he mean seed set rates for self and open

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43 pollination were 0.54 and 0.53 respectively indicating that carpetgrass sets seed equally well under both pollination conditions. Estimate s of variance (Table 3 2 ) indicated that the genotype was the primary variance component contributing to observed phenotypes. As this experiment does not have replication s over years, the environmental variance component cannot be determined. The r elative ly high error variance for number of branches and spikelets per branch may probably contain large environment al variance. Considering the low original value, the real genotypic variations among carpetgrass populations is high despite the low genotyp ic variance showed in the table Contribution of genotypic effect was also reflected in the broad sense heritability. Number of branches has mod erate broad sense heritability while the other three traits have relatively high broad sense of heritability (0. 53 0.88). From the breedi ng perspective, there is a potential to improve the population mean for seed set rate of both self polli nation and open pollination because of their relatively low variance. In the c ontrast test (Table 3 3 ), three out of ten genotypes had significantly different means for seed set rate between self pollination an d open pollination. Genotype UFA10 had a higher percent seed set under selfing than when open pollinated; whereas, UFA29 and UFA32 both exhibited g reater seed set when open pollinated. Overall, these results indicate that pollination type does not influence seed set and that carpetgrass is both self and cross compatible. Results from LSD test (Table 3 3) showed that seed set rate for self and open po llination varies greatly among ten genotypes. Genotype UFA38 had superior self compatibility; whereas, UFA15 had good cross compatibility.

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44 Greene (2008b) has previously reported a broad sense heritability for number of branches per seed head as 0.34 R esults from this experiment are very similar ( H 2 = 0.32) This indicated that the ten accessions selected are representative of the entire germplasm collection evaluated by Greene et al (2008b) for branches per seed head. Therefore, it is likely that thes e ten plants are also representative of the larger collection for number of seeds, seed set rate and compatibility assessments Con c lusions Broad sense her itabilities from this study were similar to those previously reported in carpetgrass for other traits While all traits indicated good heritability, the varia nces for seed set rate were low. But comparing to the low original value, real genotypic variations may be high among carpetgrass populations. Therefore, there is a potential to increase seed set thr ough breed ing. The genotype variance for the number of branches per inflorescence was high providing good evidence that seed production could also be increased by breeding for greater numbers of branches on seed heads. The results on differences of seed se t rates between self and open pollination have important meanings to breeding programs. Because seed set does not differ between pollination methods different types of breeding methods could be utilized for the improvement of carpetgrass. Of extreme value is the knowledge that an identified superior clone could be commercialized with no effect on seed production versus the extra effort required to produce a synthetic cultivar if self incompatibility was an issue.

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45 Table 3 1. Minimum, maximum and mean values for number of branches, spikelets per branch and seed set rate under self and open pollination Seed set rate #Branch Spikelets/Branch Self pollinated Open pollinated Min 2 12 0.2 0.18 Max 4 39 0.88 0.93 Mean 3 25.23 0.54 0.53 Table 3 2 Estimate of variance components and broad sense heritabilities for number of branches, spikelets per branch and seed set rate under self and open pollination Variance estimates Source #Branch Spikelets/Branch Seed set rate Self pollinated Open pollinated Genotype(G) 0.03 7.68 0.0207 0.0175 Replication(R) 0 0 0.0007 0.0023 Error 0.25 24.29 0.0108 0.0147 H 2 0.32 0.53 0.88 0.83 Table 3 3 Seed set rates under different pollination methods and comparison of mean values within each genotype Self pollinated Open pollinated Genotype Mean Range Mean Range F value Pr > F 2 0.63ABC 0.43 0.83 0.65AB 0.59 0.70 0.08 0.8 10 0.25D 0.20 0.30 0.39BC 0.35 0.41 53.34 <0.01 ** 15 0.67AB 0.60 0.73 0.7A 0.53 0.93 0.11 0.76 21 0.56ABC 0.38 0.69 0.61AB 0.53 0.79 1.09 0.37 29 0.39CD 0.30 0.42 0.27C 0.18 0.32 66.94 <0.01** 32 0.58ABC 0.49 0.68 0.42ABC 0.33 0.52 12.69 0.04* 38 0.79A 0.68 0.88 0.58AB 0.37 0.76 5.89 0.09 60 0.43BCD 0.31 0.60 0.42ABC 0.18 0.66 0.01 0.94 72 0.59ABC 0.52 0.65 0.64AB 0.50 0.74 0.9 0.41 99 0.57ABC 0.42 0.77 0.64AB 0.46 0.87 3.11 0.53 Means within each column followed by the same letter are not significantly different P value with a each genotype means significant difference between self pollination and open pollination

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46 LIST OF REFERENCES Acua, C. A. A. R. Blount, K. H. Quesenberry, W. W. Hanna, K. E. Kenworthy. 2007. Reproductive c haracter ization of bahiagrass germplasm. Crop Science. 47: 1711 1717 Ander son, W.G., T.M. Heng Moss, and F.P. Baxendale. 2006. Evaluation of cool and warm season grasses for resistance to multiple chinch bug (Hemiptera: Blissidae) species. Journal of Economic Entomology. 9 9(1):203 211 Atilano, R.A., and P. Busey. 1983. Susceptibility of St. Augustinegrass germplasm to Pyricularia grisea. Plant Disease. 67:782 783. Barber H. G. 1918. A new species of leptoglossus: a new b lissus and varieties. Brooklyn Ent. Soc. Bull 13: 35 39. Beard, B. 1989. Turfgrass water stress: drought resist ance components, physiological m echanisms, and species genotype diversity The 6th International Turfgrass Research Conference Beyer, A. H. 1924. Chinch bug control on St. Augustinegrass. Fl orida State Hort. Soc. Proc. 37: 216 219. Bruton, B.D., R. W. Toler, and J. A. Reinert. 1979. Combined resistance in St. Augustinegrass to the southern chinch bug and the St. Augustine decline strain of p anicum mosaic virus. Plant Dis ease 67: 171 172. Busey, P. 1986. Morphological identification of St. Augustinegrass cultivars. Crop. Sci ence. 35: 322 327. Busey, P. 1990 Polyploid Stenotaphrum germplas m: resistance to the polyploid d amaging population southern chinch bug. Crop Sci ence 30:588 593. Busey, P. 1993. Registration of FX 10 St. Augustinegrass. Crop Sci ence. 33: 214 215. Busey, P. 1995. Genetic diversity and vulnerability of St. Augustinegrass. Crop Sci ence 35:322 327. Busey, P. 1996. Wilt avoidance in St. Augustinegrass germplasm. HortScience 31:135 1138. Busey, P. 2003. St. Augustinegrass. In M.D. Casler an d R.R. Duncan (eds.) Turfgrass b iology, genetics, and breeding. John Wiley and Sons, Inc. Hoboken, N.J. Busey, P., T. K. Broschat, and B. J. Center. 1982. Classification of St. Augustinegrass. Crop Sci ence 22: 469 473.

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47 Busey, P. and B. J. Center. 1987. Southern chinch bug (Hemiptera: Heteroptera: Lygaeidae) overcomes resistance in St. Augustinegrass. J ournal of E con omic E ntomol ogy 80: 608 611. Busey, P and E. H. Davis. 1991. Turf grass in the shade environment. Fl orida State Hort. Soc. Proc. 104: 353 358. Busey, P and R. W. White. 1993. South Florida: A center of origin for turfgrass production. Int Turfgrass Soc. J. 863 869. Busey, P. and E. I. Zaenker. 1992. Resistance bioassay from southern chinch bug (Heteroptera: Lygaeidae) excreta. J ourn al of E con omic E ntomol ogy 85: 2032 2038. Cherry, R. H. 2001. Spatial distribution of southern chinch bugs (Hemiptera: Lygae idae) in St. Augustinegrass. Florida Entomo l ogist 84:151 153. Cherry, R.H. 2005 Interrelationship of big eyed bugs (Hemiptera: Lygaeidae) and s outhern chinch bugs (Hemiptera: Lygaeidae) in Florida lawns. Journal of Entomological Science, 40(4), 385. Cherry, R., H. Lu, A. Wright, P. Roberts and Y. Luo. 2012. Effect of silicon on r esistance of St. Augustinegrass to southern c hi nch bugs (Hemiptera: Blissidae) and plant disease. J ournal of Entomological Science. 47(1 ): 17 26 Cherry, R.H., and R. T. Nagata. 1997. Ovipositional prefe rence and survival of southern c hinch bugs (Blissus insularis Barber) on different g rasses. Int. Turfgrass Soc. J. 8: 981 986. Cherry, R., A. Wright, R. Raid and Y. Luo. 2011. St. A ugustinegrass to southern chinch b ugs (Hemiptera: Blissidae) and g rey leaf spot disease Journal Entomol ogical. Sci. 46(2): 96 101. Congdon, C., 2004. S outhern chinch bug b lissus insularis b arber ( Heteroptera: Blissdae ) Management in St. Augustinegrass. Congdon, C., and E. A. Buss. 2002. Southern chinch bug ma nagement on St. Augustinegrass. Fla. Coop Ext. Serv. Eny 325. Crocker, R L ., R. W. Toler and C. L. Simpson. 1982. Bioassay of St. Augustinegrass lines for r esistance to southern chinch bug (Hemiptera:L ygaeidae) and to St. Augustine decline virus. Journal of Econ omic Entomol ogy 75:515 516. Davidse, G., and R.W. Pohl. 1978. Chromosome numbers of tropical A merican g rasses (Gramineae) 5. Ann. Mo. Bot. Gard.65(2):637 649. Dudeck, A.E., C.H. Peacock and J.C. Wildmon. 1993. Physiological and growth responses of St. Augustinegrass cultivars to sali nity. HortScience. 28:46 48.

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48 Dudeck, A.E., J. Augustinegrass. Crop Sci ence 26: 1033. Eden, W. G., and R. L. Self. 1960. Controlling chinch bug on St. Augustinegrass lawns Auburn Uni. Agric. Exp. Sta. Prog. Rprt. No.7. Erickson, J .E., J. L. Cisar, J. C. Volin and G. H. Snyder. 2001. Comparing nitrogen r unoff and leaching between newly e stablished St. Augustinegrass turf and an alternative residential l andscape Crop Sci ence 41:1889 1895 Eickhoof, T. E., T. M. Heng Moss, and F. P. Baxendale. 2007. Evaluation of w arm S eason turfgrasses for r esistance to the Chinch Bug, Blissus occiduus Genovesi A.D ., R. W. Jessup, M C. Engelke and B. L. Burson. 2009. Interploid St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] hybrids recovered by e mbryo rescue In Vitro Cellular & Developmental Biology Plant 45(6): 659 666. Gould, F.W. 1968. Chromosome numbers of Texas grasses. Can. J. Bot. 46 (10):1315 1325. Gould, F.W., and T.R. Soderstrom. 1967. Chromosome numbers of tropical American G rasses. Am. J. Bot. 54(6):676 683. Greene, N. 2007. Germplasm colle ction evaluation, and characterization of common c arpetgrass. Ph. D. Dissertation, University of Florida. Greene N., K. Kenworthy, K. Quesenberry, J. Unruh and J. Sartain. 2008 a Variability and heritability estimates of com mon carpetgrass. Crop. Science. 48: 2017 2025. Greene N., K. Kenworthy, K. Quesenberry, J. U nruh and J. Sartain. 2008 b Diversity and relatedness of common carpet grass germplasm. Crop. Science. 48: 2298 2304. Hallauer, A.R. 1970. Genetic variability for yield after four cycles of reciprocal R ecurrent selections in maize. Crop Sci ence 10:482 485. H amilton, C. C. 1935. The control of insect pests of lawn and golf courses. N. J. Agric. Exp.Sta. Circ. 34. Heath, M.E., R.F. Barnes, and D.S. Metcalfe. 1985. Forages: t he science of g rassland a griculture. Iowa State University Press, IA. pp. 255 262. Heng M oss, T.M., F.P. Baxendale, and T. P. Riordan. 2002. Evaluation of Buffalograss Germplasm for Resistance to Blissus occiduus (Hemiptera: Lygaeidae) Journal of economic entomology. 95(5): 1054 1058.

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49 Hickenbick, M.C.M., J.F.M. Valls, F.M. Salzano, and M.I.B. Moraes Fernandes. 1975. Cytogenetic and evolutionary relationships in the genus Axonopus (Gramineae). Cytologia (Tokyo) 40:185 204. Horn, G C ., A.E. Dudeck and R. W. Toler. 1973. Floratam St. Augustinegrass: a fast growing n ew variety for ornamental turf resistant to St. Augustinegrass decline and C hinch bugs. University of Florida, Agricultural Experiment Station. Circ. S 224. Kenna, M. P ., C. M Talia ferro, and W. L. Richardson. 1 983. Comparative fertility and s eed yields of p ar ental Bermudagrass clones and their s i nglecross F1 and F2 p opulations. Crop Sci ence. 23: 1133 1135 Kerr, S.H. 1966. Biology of the lawn ch inch bug, Blissus insularis. The Florida Entomol ogist. 49: 9 18. Knight, W. E ., and H. W. Bennett 1953. Pr eliminary report of the effect of photoperiod and T emperature on the flowering and growth of several southern grasses. Agronomy. Journal. 45: 268 269. Komblas, K. N. 1962. Biology and control of the lawn chinch bug, Blissus leucopterous I nsularis Barber, MSc Thesis. Louisiana State University, Baton Rouge, LA Kutiert, L. C., and G. C. Nutter. 1952. Chinch bug control a nd subsequent renovation of St. Augustinegrass lawn. University of Florida, Agricultural Experiment Station. Circ. S 50: 1 10. Long, J. A ., and E C. Bashaw. 1961. Microsporogenesis and chromosome numbe rs in St. Augustinegrass. Crop Sci ence 1: 41 43. Lu, H., and R. Cherry. 2012. New Sources of Southern Chinch Bug (Hemiptera : Blissidae) Resistance in St. Augustinegrass Varieties. Journal of Entomolo gical Science. 47:291 296. Marcum, K B., and C. L. Murdock. 1990. Growth responses, ion relations, and osmotic adaptations of eleven C4 turfgrasses to s alinity Agron omy Journal. 82: 892 896. Martin, R.J. 1975. A review of carpetgrass (Axonopus affi nis ) in relation to the I mprovement of carpetgrass based pasture. Trop ical Grasslands 9:9 19. Meyer, M J ., M. A. Smith and S. L. Knight. 1989. Salinity effects on St. Augustinegrass: A n ovel system to qua ntify stress response, Journal of plant n utrition, 12:7, 893 908 Milla Lewis, S., B. Ma, C. Arella no, M. Zuleta, W. Reynolds and L. Tredway. 2011 Evaluation of St. Augustinegrass (Stenotaph rum secundatum (Walt.) Kuntze) G ermplasm for gray leaf spot resistance. In: Proceedings of the ASA International Annual Meeting, San Antonio, TX. 16 19 Oct.

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50 Milla Lewis S R ., M. Zuleta, G. A. Esbroeck, K. H. Quesenberry and K. E. Kenworthy. 2013. Cytological and molecular characterization of genetic diversity in Stenotaphrum. Crop Science. 47(7): 839 844. Miller, G.L. and L. B. McCarty. 2001. Water relations and rooting characteristics of three stenotaphrum secundatum turf cultivars grown under water deficit conditions. Int.Turfgrass Soc. Res. J. 9:323 327. Nagata, R., P. Busey, R. Cherry. 2007. NUF 76, a diploid St. Augustine grass resistant to two insect pest. Sod Solutions. Nagata, R ., and R. Cherry. 2003. New source of chinch bug (Hemiptera:Lygaeidae) resistance in a diploid selection of St. Augustinegrass. J ournal of Entomol ogical Science. 38: 654 659. Norrmann, G.A., C.L. Quarin, and T.J. Killeen. 1994. Chromosome numbers in b olivian grasses (Gramineae). Ann. Missouri Bot. Gard. 81:768 774. Rainbolt, C., Cherry, R., Nagata, R., & Bittencourt, M. 2006 Effect of southern chinch bug (Hemiptera: Lygaeidae) on weed establishmen t in St. Augustinegrass. J ournal of Entomological Science. 41(4), 405. Rangasamy, M., H. J. McAuslane, R. H. Cherry and R. T. Nagata. 2006. Categories of resistance in St. Augustinegrass lines to southern chinch bug (Hem iptera: Blissidae). Journal of E con omic E ntomology. 99: 1446 1451. Rangasamy, M., B. Rathinasabapathi, H. McAuslane, R. Cherry and R. Nagata. 2009a. Role of leaf sheath lignification and anatomy in resistance a gainst southern chinch bug (Hemiptera: Bli ssidae) in St. Augustinegrass J ournal of E co n omic Entomology. 102: 432 439 Rangasamy, M., B. Rathinasabapathi, H. McAuslane, R. Cherry and R. Nagata. 2009b. Oxidative responses of St. Augustinegrass to feeding of the s outhern chinch bug, Blissus insul aris Barber. Journal of Economic Entomology. 35: 796 805. Reinert, J. 1978. Antibiosis to the southern chinch bug by St. Augustinegrass accessions. Journal of Econ omic e ntomol ogy. 71: 21 24. Reinert, J. 2008. Do we have St. Augustinegrass with resistance to the Texas b iotype of super chinch bugs? No! The Pallet. June: 6, 10, 16, 18. Reinert, J.A., B. D. Bruton, and R. W. Toler. 1980. Resistance of St. Augustinegrass lines for resistance to southern chinch bug (Hemiptera: Lygaeidae) and to St. Augustinegrass decline strain of panicum mosaic virus. Journal of E con omic Entomol ogy. 73: 602 604.

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51 Reinert, J.A., P. Busey and F.G. Bilz. 1986. Old world St. Augustinegrass resistant to the southern chinch bug (Heteroptera: Lygaeidae). Journal of Economic Entomology. 79:1073 1075. Reinert, J., A. Chandra and M. Engelke. 2011. Susceptibility of genera and C ultivars of turfgrass to southern chinch bug Blissus insularis (Hemiptera: Blissidae). Florida Entomol ogist. 94: 158 163 R einert, J.A., and A.E. Dudeck. 1974. Southern chinch bug resistance in St. Augustinegrass. J ournal of Economic Entomology. 67: 275 277 Reinert, J.A., and S. H. Kerr. 1973. Bionomics and control of lawn chinch b ugs. Bull. Entomol. Soc. Am.19: 91 92. Re inert, J., and H. Niemczyk. 1982 Insecticide resistance in epigeal insect pests of turfgrass: southern c hinch bug resistance to organophosphates in Florida. Advances in Turfgrass Entomology. Hammer Graphics, Inc., Piqua, OH, 77 80. Riordan, T.P., V.D. Meier, J.A. Long and J.T. Gruis. 1980. Registration of Seville St. Augustinegrass (Reg. No. 66). Crop Sci ence. 20: 824 825. Richardson, W. L., C. M. Taliaferro, and R. M. Ab ring. 1978. Fertility of eight b ermudagrass clones and open p ollina ted progeny from them. Crop Sci ence 18: 33 2 334 SAS.2012 SAS Institute. Cary, NC Satterthwaite, L N ., A. W. Hodges, J. J. Hay du and J. L. Cisar. 2009. An agronomic and e Sauer, J.D. 1972. Revision of Stenotuphrum (Gramineae Taniceae) with attention to its h istorical geography. Brittoniu 24:202 222. Sifers, S and J. Beard. 1999. Dr ought resist ance in warm season turfgrasses. Golf C ours e manage September. Skerman, P.J. and F. Riveros. 1990. Tropical grasses. Food and Agriculture Organization of the United Nations. Rome, Italy. Smith, J. and H. Valenzuela. 2002. Cover crops: c arpetgrass. Cooperative Extension Service Publication. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. Smith, M. A ., and P. C. Whiteman. 1983. Evaluation of tropical grasses in inc r easing shade u nder coconut canopies. Exp t Agric. 19: 153 161. Strobel, J. 1971. Turfgrass. Fla. Turf Grass Manag. Conf. Proc. 19: 19 28.

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52 Trenholm, L E ., J. B. Unruh and J. B. Sartain. 2012. Nitrate l eaching and t urf q uality in e stablished Floratam Empire oysiagrass J ournal of Environmental Quality 41:793 799 Turgeon, A.J. 2005. Turfgrass m anagement. 7th ed. Prentice Hall, Inc., New Jersey V an Duzee, E. P. 1886. Occurrence of the chinch bug (Blissus leucopterous (Say)) at Buffalo. N.Y. Can. Entomol. 18: 209 210. Vittum, P.J., M. G. Villani, and H. Tashiro. 1999 Turfgrass insects of the United States and Canada, 2nd ed. Cornell University Press, Ithaca, NY. Wang Z., K. Kenworthy and Y. Wu. 2010. Genetic diversity of common carpetgrass r evealed by amplified fragmen t length polymorphism markers. Crop. Sci ence 50:1366 1374. Watson, J. R. 1925. The chinch bug on St. Augustinegrass lawns. University of Florida, Agricultural Experiment Station. Circ. Bull.: 371. Watson, V.H., and B.L. Burson. 1985. Bahiagrass, carpetgra ss, and dallisgrass Watson, L. and M.J. Dallwitz. 1992. The Grass Genera of the World. CAB International,Wallingford, Oxon, UK. Webster, F. M. 1907. The chinch bug. U.S. Dept. Agric. Circ. 69. White, R. W. and P. Busey. 1987. History of t urfgrass production in Florida. Fl orida State Hort. Soc. Proc. 100:167 174. Wilson, R. N. 1929. The chinch bug in relation to St. Augustinegrass. U.S. Dept. of Agric. Circ. 51. Wise, L.N. 1961. The Lawn Book. Bowden Press Inc., Decatur, Georgia. pp. 47 49.

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53 BIOGRAPHICAL SKETCH Long Ma grew up in Zhejiang, China H e graduated from Hangzhou No.4 High S chool in 2007. That fall, he began undergraduate study at Guangxi University Guangxi, China. In the summer of 2011 he received a b tural science. In August 2011 he began to study at Unive rsity of Florida for degree in horticulture department