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Timing of Nematicide Applications for Control of Belonolaimus longicaudatus on Golf Course Fairways

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Title:
Timing of Nematicide Applications for Control of Belonolaimus longicaudatus on Golf Course Fairways
Creator:
MCGROARY, PAURIC C.
Copyright Date:
2008

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Subjects / Keywords:
Golf courses ( jstor )
Nematology ( jstor )
Population density ( jstor )
Population growth ( jstor )
Root growth ( jstor )
Roundworms ( jstor )
Soil science ( jstor )
Soil temperature regimes ( jstor )
Soils ( jstor )
Turf grasses ( jstor )
City of Gainesville ( local )

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University of Florida
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University of Florida
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Copyright Pauric C. McGroary. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
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5/31/2008
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659806744 ( OCLC )

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TIMING OF NEMATICIDE APPLICATIONS FOR CONTROL OF Belenolaimus longicaudatus ON GOLF COURSE FAIRWAYS By PAURIC C. MC GROARY A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2007 1

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2007 Pauric C. Mc Groary 2

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ACKNOWLEDGMENTS I would like to thank Dr. William Crow for hi s scientific expertise, persistence, and support. I am also indebted to my other comm ittee supervisors members, Dr. Robert McSorley and Dr. Robin Giblin-Davis, who were always av ailable to answer quest ions and to provide guidance throughout. 3

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TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................3 LIST OF TABLES ...........................................................................................................................6 LIST OF FIGURES .........................................................................................................................7 ABSTRACT.....................................................................................................................................8 CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW..............................................................10 Introduction .............................................................................................................................10 Belonolaimus longicaudatus ...................................................................................................11 Taxonomy ........................................................................................................................11 Biology ............................................................................................................................11 Geographic Distribution ..................................................................................................14 Disease Symptoms and Pathogenicity on Warm-Season Turfgrasses ............................14 Bermudagrass ..................................................................................................................15 Cultural Practices .............................................................................................................16 Objectives ...............................................................................................................................17 2 SEASONAL FLUCTUATIONS OF Belonolaimus longicadatus IN BERMUDAGRASS...............................................................................................................18 Introduction .............................................................................................................................18 Materials and Methods ...........................................................................................................19 Experimental Sites ...........................................................................................................19 Experimental Design .......................................................................................................20 Sampling and Evaluation .................................................................................................21 Data Analysis ...................................................................................................................21 Results .....................................................................................................................................22 Discussion ...............................................................................................................................24 3 TIMING OF NEMATICIDE APPLICAT IONS ON TURF TO REDUCE DAMAGE CAUSED BY Belonolaimus longicaudatu s...........................................................................32 Introduction .............................................................................................................................32 Materials and Methods ...........................................................................................................33 Sampling and Evaluation ........................................................................................................34 Nematodes .......................................................................................................................34 Roots ................................................................................................................................35 Data Analysis ...................................................................................................................35 Results .....................................................................................................................................35 4

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Discussion ...............................................................................................................................36 4 SUMMARY............................................................................................................................ 42 LIST OF REFERENCES ...............................................................................................................45 BIOGRAPHICAL SKETCH .........................................................................................................50 5

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LIST OF TABLES Table page 2-1. Linear regr ession number of Belonolaimus longicaudatus /300 cm3 of soil (Y) on root length 300 cm3 of soil (x) from four golf cour se fairways in Florida sampled monthly. .............................................................................................................................31 6

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LIST OF FIGURES Figure page 2-1 Population densities of Belonolaimus longicaudatus and root lengths from 300 cm3 of soil from bermudagrass and soil temperat ures at the Ft. Lauderdale Research and Education Center, Ft. Lauderdale, FL (J anuary 2005 – December 2005). Data are means standard error. ......................................................................................................27 2-2 Population densities of Belonolaimus longicaudatus and root lengths from 300 cm3 of soil from bermudagrass and soil temperatures at Ironwood Golf Course, Gainesville, FL (February 2005 January 2005) . Data are means standard error. ........28 2-3 Population densities of Belonolaimus longicaudatus and root lengths from 300 cm3 of soil from bermudagrass and soil temperatures at Sandpiper Golf Course, Sun City, FL (March 2006 November 2006). Data are means standard errors. ..........................29 2-4 Population densities of Belonolaimus longicaudatus and root lengths from 300 cm3 of soil from bermudagrass and soil temperatures at Club Renaissance Golf Course, Sun City, FL (March 2006 November 2006). Data are means standard errors. ..........30 3-1 Effects of applicati on time of 1,3-dichloropropene on Belonolaimus longicaudatus population densities at Sandpiper Golf Course, Sun City, FL (March 2006 November 2006). ...............................................................................................................38 3-2 Effects of application time of 1,3-dich loropropene on root le ngth at Sandpiper Golf Course, Sun City, FL (March 2006 Novemb er 2006). Asterisk indicates treatment is different from untreated (P < 0.1). .................................................................................39 3-3 Effects of applicati on time of 1,3-dichloropropene on Belonolaimus longicaudatus population densities at Club Renaissance Go lf Course, Sun City, FL (March 2006 November 2006). ...............................................................................................................40 3-4 Effects of application time of 1,3-dichloropropene on root length at Club Renaissance Golf Course, Sun Cit y, FL (March 2006 November 2006). .......................41 7

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Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science TIMING OF NEMATICIDE APPLICATION FOR CONTROL OF Belonolaimus longicaudatus ON GOLF COURSE FAIRWAYS By Pauric C. Mc Groary May 2007 Chair: William T. Crow Major: Entomology and Nematology Sting nematode ( Belonolaimus longicaudatus ) is an important pest of bermudagrass ( Cynodon dactylon) , and other turfgrasses grown in the southeastern United States. On bermudagrass, B. longicaudatus causes severe damage to late ral roots, decreased water and nutrient uptake, and decreased rates of evapotrans piration leading to reduc ed turf quality, color, and density. Field experiments from January 2005 to March 2007 were conducted to monitor the seasonal dynamics of B. longicaudatus populations, bermudagrass root growth, and soil temperatures on four bermudagrass fairways in Fl orida in order to develop an empirical optimum time for nematicide application. Seasonal fluctuations in B. longicaudatus and root growth varied among locations and years, but similar trends were observed in all four trials for nematodes and root growth. Li near regression models relati ng root length to nematode population densities (0 15 cm depth) were significant ( P 0.10) at three of f our sites. At the FLREC site, root length and nemat ode population were correlated ( P 0.10) in April and May. At the IW site root length was related to nematode population ( P 0.10) in June, September, and October. At the SP site, root length and B. longicaudatus population densities were significantly related (P 0.10) only in July. However, regression analysis did not provided consistent predictive models to charact erize relationships between B. longicaudatus and root length. 8

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In 2006, two field experiments were conducted to compare the effects of early spring, late spring, mid-summer, or early fall applications of the nematicide 1,3-dichloropropene (1,3-D) on sting nematode populations and bermudagrass roots, and to determine the optimum time to apply nematicide treatments to golf course turf in Flor ida. Treatments were untreated control, and 1,3D applied at 46.76 liters/ha in Marc h, May, July, or September. Belonolaimus longicaudatus population densities and root lengt hs were evaluated following tr eatments. At the SP course, 1,3-D application did not reduce ( P 0.10) population densities of B. longicaudatus compared to the untreated control at any sampling date. Ho wever, root length increased compared to the untreated plots after March and May treatments of 1,3-D. Root lengths were greater ( P 0.10) at 4, 12 and 16 weeks following the March 1,3-D treat ment compared with the untreated plots. Root lengths were greater ( P 0.10) at 4, 8 and 12 weeks afte r the May treatment of 1,3-D compared to the untreated. At the CR c ourse, 1,3-D treatments had no effect ( P 0.10) on sting nematode populations or root lengths. These results suggest that the optimum time for nematicide ap plication is when the roots are actively growing. Our results show that maximum root growth and correlation of root growth and nematode numbers occur primarily from April to June, depending on location in the state and seasonal differences. This time pe riod was verified by nematicide timing trials showing optimum benefit from nema ticides applied in March or May. 9

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CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW Introduction Warm-season turfgrasses, such as hybrid bermudagrass (Cynodon L), St. Augustinegrass ( Stenotaphrum ), and seashore paspalum ( Paspalum ), that are grown in the southeastern United States and California are suscep tible to damage by phytoparasitic nematodes (Perry et al., 1970; Rhoades, 1962; Hixson et al., 2004). The most dest ructive nematode to these turfgrasses is the ectoparasitic sting nematode, Belonolaimus longicaudatus Rau (Johnson, 1970; Winchester and Burt, 1964). On bermudagrass, B. longicaudatus causes severe damage to lateral roots, decreased water and nutrient uptake, and decr eased rates of evapotransporation, which can reduce turf quality, colo r, and density (Johnson, 1970; Busey et al., 1991). Current strategies to reduce damage from this pest are limited to preplant or post-plant nematicides (Bekal and Becker, 2003). Howe ver, a review of organophosphates by the U.S Environmental Protection Agency has led to th e withdrawal of ethoprop for use on turf in 2001 and the voluntary cancellation of all product re gistrations of fenamiphos effective 31 May 2007 (Anonymous, 2002). The loss of these organophospha te nematicides has le d to the development of new nematicides and biorationals, and new uses for existing nematicides. One of the most effective of these is 1,3-dic hloropropene (1,3-D), the active ingredient in Curfew Soil Fumigant (Dow AgroSciences, Indianapolis, IN). Crow et al. (2003; 2005) reported that postplant applications of 1,3-D at 55 kg a.i./ha can signifi cantly lower populations of B. longicaudatus on bermudagrass. Use of 1,3-D is typically limited to one application per year. However, a single application of 1,3-D often is insufficient to achieve seas on-long control of B. longicaudatus . Therefore, it is critical to correctly time this application in order to maximize its efficacy. To do 10

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this, it is necessary to have a better understand ing of the factors affec ting the seasonal population dynamics of B. longicaudatus. Belonolaimus longicaudatus Taxonomy Steiner (1949) first established the genus Belonolaimus with the discovery and description of Belonolaimus gracilis . This species was first colle cted from the rhizosphere of slash pine in the Ocala National Forest n ear Ocala, FL. Over the next few years B. gracilis was reported to be a pathogen of strawberry, corn, celery, millet, sorghum, peanut, cotton, soybean and cowpea (Christie, 1952, 1953; Christie et al., 1952; Owens, 1951; Holderman and Graham, 1953). In 1958, Rau described B. longicaudatus, which soon became accepted as the more common sting nematode. The major morphological differences separating these species are that B. longicaudatus has a longer tail and a shorter stylet than B. gracilis (Rau, 1958). Later Rau (1963) described three additional species of Belonolaimus: B. euthychilus , B. maritimus , and B. nortoni . Since then, four more species have been added: B . anama, B . jara, B . lineatus , and B . lolii (Fortuner and Luc, 1987). Recent molecular wo rk by Gozel et al. (2006) suggests that a large amount of genetic variability in the relati vely conserved D2/D3 expansion segments of the large subunit rRNA gene w ithin and between nominal Belonolaimus species should challenge our thinking about how species are defined for this polymorphic genus. Biology Belonolaimus longicaudatus is a bisexual species which exclusively reproduces through amphimixis, with males generally accounting for 40% of the population (Huang and Becker, 1999). The B. longicaudatus life cycle consists of an egg stage, four juvenile stages, four molts, 11

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and an adult stage. Females lay eggs in pairs, one coming from each ovary when food is readily available (Han et al., 2006; Huang and Becker, 1999). At 28 C, B. longicaudatus is able to complete its life cy cle in 24 days on excised corn roots grown in vitro (Huang and Becker, 1999). However in 2006, Han et al. reported variation on the duration of the life cycle among isolates originating from different geographical locations and on different hosts when cultured on excised corn roots at 28 C. Isolates that originated from cotton in Tifton, GA, from bermudagrass in Gainesvi lle, FL, and from potato in Hastings, FL, all completed their life cycle in 18 to 20 days, wherea s isolates from citrus in Lake Alfred, FL, and from corn in Scotland County, NC, completed thei r life cycle in 23 and 25 days respectively. In Florida the highest population level of B. longicaudatus was found on forage grasses during April and May when maximum air temper atures were below 30 C. Furthermore, B. longicaudatus moved deeper into the soil in late spring when soil moisture decreased and temperature increased (Perry and Dickson, 1972). During June and July, numbers of B. longicaudatus decreased when the monthly average air temperature was above 32.2 C (Boyd and Perry, 1970). Soil temperatures ranging betw een 26 to 28 C were the most favorable for B. longicaudatus on 17 tropical grasses in Gainesville, FL (Boyd and Dickson, 1971). In addition, there was no increase in B. longicaudatus juveniles at soil temperat ure of 20 C and juveniles were absent at 35 C on Pensaco la bahiagrass and Pangola digitg rass. The highest reproduction of B. longicaudatus occurred at 26 to 29 C, but the greatest damage on both grasses occurred at 21 to 27 C. Robbins and Barker (1974) found that the highest reproductive rate of B. longicaudatus occurred at 25 to 30 C, and Perry (1965) reported that the reproductive rate was greater at 29.4 C than at 26.7 C. 12

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The optimum storage temperature for B. longicaudatus in soil was 13 C, and rapid decline of nematode populations occurre d at 36 C (Barke r et al., 1969). Belonolaimus longicaudatus can be kept alive in clean water for three to five months at 1.66 C and for eight to ten days at room temperature (Brooks, 1964). Soil moisture also was an important factor in the activity of B. longicaudatus, especially their vertical distribution. Highest populations of B. longicaudatus occurred when soil moisture averaged between 15 and 20% (Brodie and Quattlebaum, 1970). Robbins and Barker (1974) found that reproduction of sting nematode was greate r at a moisture level of 7% than at 30% or 2%. Thames (1959) found that fine-textured soils inhibited the movement and reproductive ability of B. longicaudatus. Robbins and Barker (1974) found that B. longicaudatus increased only in soil with a minimum of 80% sand a maxi mum of 10% clay. Furthermore, Robbins and Barker (1974) found that silca sand with diameter range of 120 to 370 m diameter silica provided the optimum soil particle sizes for reproduction. However, Rhoades (1980) found a Florida population of B. longicaudatus was capable of reproducing as rapidly in steamed or treated muck soils as in fine sandy soils, alt hough they did not reprodu ce well or live long in untreated muck soil. This may indicate that steaming or chemical treatment of the soil may eliminate limiting biotic factors. Hunt et al. (1973) suggested that such biotic factors may influence the electron charge on organic soil part icles and theorized that the primary suppressing agent for motility of B. longicaudatus is a positively charged organic compound. Higher motility of the nematodes occurred in cationic exchange extracts and vice versa in anionic exchange extracts. 13

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Geographic Distribution In the United States , B. longicaudatus has been reported along the Atlantic coastal plain from Virginia to Florida (Holdeman, 1955) and along the Gulf coasts of Alabama (Christie, 1959), Mississippi (Smart and Nguyen, 1991), Loui siana (Holdeman, 1955), and Texas (Christie, 1959). Additionally, B .longicaudatus has been reported in Arka nsas (Riggs, 1961), Kansas (Dickerson et al., 1972), Missour i (Perry and Rhoades, 1982), Oklahoma (Russell and Sturgeon, 1969), New Jersey (Hutchinson and Reed, 1956) , Connecticut (Holdeman, 1955), and more recently in California (Mundo-Ocampo et al 1994). Outside of the United States B. longicaudatus has been reported from Costa Rica (Lopez, 1978) and Mexico (Smart and Nguyen, 1991), and on golf courses in the Bahamas, Bermuda, and Puerto Rico, which had imported turfgrass sod from Florida or Georgia (Perry and Rhoades, 1982). Disease Symptoms and Pathogenicity on Warm-Season Turfgrasses Perry and Rhoades (1982) reported B. longicaudatus as an important pathogen of warm season turfgrasses. Crow (2005) reported that B. longicaudatus, Hoplolaimus galeatus, Hemicycliophora spp., and Meloidogyne .spp. are the most commonly found nematodes on warm season turfgrasses on golf cour ses in Florida. Furthermore, Crow (2005) reported that B. longicaudatus was the nematode most commonly f ound at potentially damaging numbers. Christie (1953) reported that feeding by B. longicaudatus occurs along the sides of the succulent roots causing necrotic le sions at the apices or along the margins of roots, cavities overlapped by external root cells , rupture of cell walls, coagulat ion of the protoplasm of cells bordering the cavities, a nd a maturation of the meristem near lesions. Symptoms caused by B. longicaudatus on turfgrass can vary somewhat depending on inoculum level, turfgrass cultiv ar, and the age of the plant when its roots are first attacked 14

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(Christie, 1959). However, in general the root system of turfgrasses is greatly reduced and exhibits stubby, coarse roots with dark lesions along the root and root tips (Perry and Rhoades, 1982). Shoot symptoms consist of stunting, premat ure wilting, leaf chlorosis, reduction in turf density, and death of turfgrass plant. In greenhouse studies of B. longicaudatus on ‘Ormond’ bermudagrass, a severe reduction in the root systems and in top growth was f ound, combined with a severe yellowing of leaves (Winchester and Burt, 1964). Johnson (1970) repor ted that the number of fibrous roots produced by six bermudagrass cultivars decreased as the nu mber of sting nematode s infecting the plants increased. Additionally, sting nematode parasiti sm on bemudagrass resulted in thin, long, weak stems, reduction in stolon production, and ch lorsis. In greenhouse experiments on St. Augustinegrass, Rhoades (1962) found that B. longicaudatus caused severe chlorosis and a reduction in root weight. Root dry weights and evapotranspiration rates were adversely affected by B. longicaudatus in laboratory studies of susceptib le diploid St. Augustinegrass genotypes when compared with unaffected polyploids (Busey et al., 1991; Giblin-D avis et al., 1992). Hixson et al. (2004) reported that B. longicaudatus was highly pathogenic to seashore paspalum ( Paspalum ) and that B. longicaudatus greatly decreased root growth. Bermudagrass Bermudagrass is a warm season perennial adapte d to tropical and subtropical climates. In Florida, bermudagrass is utilized by 93% of golf courses for playing surfaces (Haydu and Hodges, 2002). It grows best under extended peri ods of high temperatures, mild winters, and moderate to high rainfall. Temperature is th e main environmental factor that limits its adaptability to tropical a nd subtropical areas of the world (Beard, 1973). In general, temperatures below -1.0 C kill the leaves and stems of bermudagrass. Research has demonstrated that bermudagrass will continue to grow with night temperatures as low as 1.0 C 15

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if day temperatures are near 21.0 C. However, when daily temperatures drop below 9.9 C, growth stops and the grass begins to discolor (McCarty et al., 2001) . After the first killing frost, leaves and stems of bermudagrass remain dormant until average daily temperature rises above 9.9 C for several days. In warm frost-free climates, bermudagrass remains green throughout the year, but growth is significantl y reduced at the onset of cool nights. Bermudagrass growth is optimum when air temperatures are between 29 C and 38 C (McCarty et al., 2001) Soil temperatures are also important to the gr owth and development of bermudagrass turf. Soil temperatures above 15.5 C are required for significant shoot gr owth, with optimum temperatures of 27 C to 35 C. Soil temperat ure also greatly influe nces root growth. Bermudagrass looses 50% of its root mass when temperatures drop to -8.0 C to -5.0 C (McCarty et al., 2001). Bermuda grass root growth is optimum between 24C and 35 C. Bermudagrass has a high light requirement a nd does not grow well under shaded conditions. The duration of the light period also influences growth and development of bermudagrass. Both increased light intensity and day length in crease rhizome, stolon, and leaf growth in bermudagrass, whereas in low li ght conditions it develops narrow , elongated leaves; thin upright stems; elongated internode; and weak rhizomes. Consequently, bermudagrass develops a very sparse turf under moderate shade (Beard, 1973). Cultural Practices Effective and consistent management of B. longicaudatus on golf course relies heavily on chemical control tactics such as 1,3-D and Fe namphios. However, many golf courses do not implement such practices due the high costs of chemicals. A cheaper but not as an effective alternative management tactic to chemicals is to implementing sound cultural practices to improve plant health. Such practices include in corporating organic amendments which has been shown to help reduce nematode damage to turf (Giblin-Davis et al ., 1988). In addition 16

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increasing the mowing height also has been shown to improve turf quality (Giblin Davis et al., 1991). In much of the southern United States , overseeding provides a more aesthetically pleasing golf course, and the growin g turf is more tolerant to gol f cart traffic, divots, and weed invasions (Beard, 1973). Howeve r Crow and Lowe, 2005 reported that overseeding may allow for reproduction of B. longicaudatus . Objectives The research reported hereafter was perfor med from January 2005 to March 2007 on four bermudagrass fairway sites naturally infested with B. longicaudatus. The objectives of the research were to: 1. Model the population dynamics of B. longicaudatus in infested bermudagrass in response to temperature and root growth. 2. Utilize population dynamics of B. longicaudatus and root lengths to predict the most effective application time for a nematicide to control B. longicaudatus on bermudagrass in Florida. 17

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CHAPTER 2 SEASONAL FLUCTUATIONS OF Belonolaimus longicadatus IN BERMUDAGRASS Introduction Belonolaimus longicaudatus Rau is an important pest of bermudagrass ( Cynodon dactylon L.) and other turfgrasses grown in the southeastern United States. It is found predominately in soils with >80% sand content (Robbi ns and Barker, 1974). Feeding by B. longicaudatus can cause varying degrees of damage to root system s depending on plant type and age when the root system is first attacked. On bermudagrass, B. longicaudatus feeding typically causes severe damage to lateral roots that decrease water a nd nutrient uptake, but rarely kills the plant (Christie, 1959; Johnson, 1970). However, B. longicaudatus can predispose turfgrass to adverse conditions such as drought stress, heat stress, an d malnutrition which could lead to a reduction in turf quality (Lucas, 1982). Current strategies to reduce damage from this pest are limited to preplant or postplant nematicides (Bekal and Becker, 2003). Howeve r, options for chemical control have been reduced with the withdrawal of ethoprop and the voluntary cancellation of all product registrations of fenamiphos effective 31 May 2007 (Anonymous, 2002). The loss of these organophosphate nematicides has led to the devel opment of new uses for existing nematicides. One of the most promising of these is 1, 3-dichloropropene (1,3-D) th e active ingredient in Curfew Soil Fumigant (Dow Ag roSciences, Indianapolis, IN). Crow et al. (2003; 2005) reported that post-plant applicati ons of 1,3-D at 55 kg a.i./ha signi ficantly lowered populations of B. longicaudatus on bermudagrass. However, 1,3-D is t ypically limited to one application per year on golf courses due to its high applicati on cost. Because 1,3-D has no residual activity, sting nematode numbers can rebound quickly foll owing an application (C row et al., 2005). In order to maximize the efficacy of a single application, 1,3-D should be applied when B. 18

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longicaudatus populations are expected to increase and/ or when they are capable of doing the most damage to the grass roots. Ther efore, the seasonal pop ulation dynamics of B . longicaudatus on bermudagrass must be determined to predict the optimal timing of 1,3-D application. The objective of this study is to monitor the seasonal dynamics of B. longicaudatus, bermudagrass root growth, and soil temperatures on golf course fairways in Florida in order to develop a empirically optimum time for nematicide application. This validit y of this theoretical model will be tested in later studies. Materials and Methods Studies were conducted from January 2005 to March 2007 on four bermudagrass fairway sites naturally infested with B. longicaudatus along with, Hoplolaimus galeatus (Cobb Thorne) Trichodorus sp., Hemicycliophora sp., Mesocriconema sp., and Meloidogyne sp. Trial 1 (January 2005to December 2006) was established at the University of Florida Ft. Lauderdale Research and Education Center (FLREC), Br oward County, FL, and trial 2 (February 2005to January 2006) at the Ironwood Golf Course (IW), Gainesville, FL. Trials 3 and 4 (March 2006November 2006) were established at the Club Rena issance golf course (CR) and at the Sandpiper Golf Club (SP), both in Sun City, FL. Experimental Sites In all trials, golf course fair ways had stands of ‘Tifway 419’ bermudagrass. Soil in the experimental area at the FLREC was classified as Margate fine sand with a composition of 96% sand, 3% silt 1% clay; with 7% organic matter a nd pH 7.1. Soil in the experimental area at IW was classified as Tavares fine sand with a co mposition of 93% sand, 3.7 % silt, 3.3% clay; <1% organic matter and pH 6.5 . Soil at CR and SP was classified as Fort Meade loamy fine sand. At CR the soil had a composition of 95% sand, 3.5% silt, 1.5% clay; <1% organic matter and pH 6.3. Soil at SP was 94% sand, 4.3% silt, 1.7% clay; 3% organic and pH 6.0. Experimental areas 19

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were maintained under golf course fairway c onditions. Mowing, fertilization, and irrigation were provided by the maintenance staff at all si tes. The fairways were mowed three times a week without buckets at a cutting height of 1.3 cm except when weather prevented. Overhead irrigation was applied using an overhead automa tic irrigation system on an as-needed basis determined by the golf course superintendent. At al l sites, soil temperatures were recorded at 15cm depth throughout the experiment using temperature data recorders (StowAway Tidbit, Onset Computer Corp., Bourne, MA). Temperatures were recorded ev er hour and the mean was then calculated for each day and for the entire month. To add to the aesthetics of the golf course for winter play fairways were overs eeded with perennial ryegrass [ Lolium L.] at 250kg seed /ha, in October of 2005 and 2006 at IW and CR. However, six weeks prior to th e initiation of these trials, a selective herbicide Foramsulfuron (Revolver Bayer Environmental Science) was applied at 1Liter/ha to remove pe rennial ryegrass from the research plots. Core aerification was carried out once a year at all sites. No othe r cultural practices were carried out during the experiment. Experimental Design Eight weeks prior to the first sampling date 30 plots, 2-m with 0.5-m borders between plots were arranged in a grid at each site and nematode samples were collected from each plot. Nematode samples consisted of nine soil cores 1.9-cm-diam. 7.5-cm-deep from each plot combined to make a single sample. Nematodes were extracted from a 100-cm 3 subsample using sugar flotation with centrifugation (Jenkins, 1964) and counted using an inverted light microscope at 10 magnification. Twelve plots at the FLREC and IW sites and four plots at the CR and SP sites were used. Belonolaimus longicaudatus population densities in the plots ranged from 10 to 200 nematodes /100 cm 3 soil. 20

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Sampling and Evaluation After the initial nematode sampling to select plots, the protocol was modified so that both nematode and root samples could be extracted from the same cores. Three cores from each plot were removed arbitrarily using tee samplers. At FLREC and IW, the cores were 5-cm-diam. 15-cm-deep, with a total volume of 300 cm 3 . At CR and SP cores were 2.5-cm-diam. 15-cmdeep, with a total volume of 75 cm 3 . Samples were taken at monthly intervals throughout the duration of the trials. Nematodes were extract ed from each individual core using centrifugal flotation (Jenkins, 1964). For ease of compar ison among sites, nematode numbers and root lengths were converted and reported per 300 cm 3 volume. Root samples were obtained from the same co res that were used to determine plantparasitic nematode populations. Roots were ca ught on an 18 mesh ( 1000 m) kitchen sieve and placed into 50-ml plastic centrifuge tubes. Five drops (0.25 ml) of 1% methylene blue mixture was added to 30 ml of tap water to stain the root s. After a minimum of 24 hours in solution, the roots were removed, placed on a 75-m-pore sieve, and washed free of excess dye. Stained roots were placed into a glass bottom tray and s canned on a flat bed scanner (Epson Perfection 4990 Photo) to create a bitmap image of the roots. The bitmap images were imported into the WinRhizo (Regent Instruments, Chemin Sainre-F oy, Quebec) software program to measure root lengths from the scanned images. Data Analysis Linear regression models were used to rela te nematode population densities with root growth and monthly mean soil temperature usin g SAS (SAS Institute, Carry, NC) software. Empirical observations were used to detect s easonal trends in nematode population and root length increases and declines. 21

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Results Seasonal fluctuations in B. longicaudatus populations and root lengths were different for each location (Figs. 2-1; 2-2; 2-3; 2-4). At the FLREC site, initial populations of B. longicaudatus were 91 B. longicaudatus/300 cm 3 of soil in January 2005 (Fig. 2-1). The B. longicaudatus populations declined in February befo re increasing in March. In April, B. longicaudatus populations reached a season high with a mean of 118 B. longicaudatus /300 cm 3 of soil (Fig. 2-1). This wa s followed with a decrease in B. longicaudatus population in May and June to means of 91 and 30 B. longicaudatus/300 cm 3 of soil, respectively (Fig. 2-1). Populations of B. longicaudatus then increased in July before declining through the rest of the year. Belonolaimus longicaudatus populations reached a season lo w in December with a mean of 10 B. longicaudatus /300 cm 3 of soil (Fig. 2-1). Root lengths at the FLREC site followed a similar trend as the B. longicaudatus populations from February through December. Root length increase d from 611 to 696 mm/300 cm 3 of soil before reaching a season high of 1189 mm/300 cm 3 of soil (Fig. 2-1). Root length declined in May and June before in creasing to a mean of 1080 mm/300 cm 3 of soil in July. In August root length declined agai n to a mean of 716 mm/300 cm 3 of soil (Fig. 2-1). Root length remained constant for the next tw o months. Root length declined in November before reaching a season low of 251 mm/300 cm 3 of soil in December (Fig. 2-1). At IW, B. longicaudatus population density was greatest in February with a mean of 130/300 cm 3 of soil (Fig. 2-2). Belonolaimus longicaudatus populations declined from March through May, with means of 91, 80, and 62/300 cm 3 , respectively. In June, B. longicaudatus populations increased slightly to 75/300 cm 3 of soil before declining in July to 14 B. longicaudatus /300 cm 3 of soil (Fig. 2-2). Populations of B. longicaudatus increased again in August and September before declining in October. In November and December B. 22

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longicaudatus population densities remained unchanged be fore reaching a season low in January with a mean of 9 B. longicaudatus /300 cm 3 of soil (Fig. 2-2). Root lengths at IW followed similar trends to that of B. longicaudatus population from March through December. Root lengths declined from March to May and increased in June to a mean root length of 246 mm/300 cm 3 of soil (Fig. 2-2). In September root length s reached a season high with a mean length of 327 mm/300 cm 3 of soil (Figs. 2-2). Root length declin ed from October through December with root lengths of 300, 235, and 185 mm/300 cm 3 of soil (Fig. 2-2). In Janua ry root length increased to 207 mm/300 cm 3 of soil (Fig. 2-2). At the SP site sting nematode populations were more stable, increasing from March to May with means of 172, 240, and 275 sting nematodes/300 cm 3 of soil, respectively (Fig. 2-3). In June, sting nematode populations declined before reaching their highest in July with a mean of 320/300 cm 3 of soil. Populations declined in again in August, reaching their lowest with a mean of 128 sting nematodes/300 cm 3 of soil, respectively (Fig. 2-3). However, in September sting nematode populations increased with a mean of 200/300 cm 3 of soil. In October and November sting population densities d eclined with means of 295 and 102 sting nematodes/300 cm 3 of soil, respectively. Root length at the SP site decreased from Marc h to May with means of 1052, 756, and 476 mm/300 cm 3 of soil, respectively (Fig. 2-3). In June, July and August root length increased with means of 672, 896 and 1388 mm/300 cm 3 of soil. In September root lengths were greatest with 3416 mm/300 cm 3 of soil (Fig. 2-3). Thereafte r root lengths declined to 1060 mm/300 cm 3 of soil in November. At the CR site sting nematode populations were more variable, ra pidly increasing from March to April with means of 353 and 763, resp ectively before reaching a season high in May with 1075/300 cm 3 of soil (Fig. 2-4). From June to Oc tober nematode population declined with 23

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means of 730, 536, 368, and 250/300 cm 3 of soil, respectively. However, in November nematode population increased rapidly to a mean of 488 nematodes/300 cm 3 (Fig. 2-4). Root lengths at CR increased from Ma rch to May with means of 114, 119, and 204 mm/300 cm 3 of soil, respectively. In June root lengths reached a season high of 264 mm/300 cm 3 of soil (Fig. 2-4). In July r oot lengths declined to 167 mm/300 cm 3 of soil before increasing again in August. Root length reach a season low in September with a mean of 131 mm/300 cm 3 . In October root length increased before declin ing in November to a root length mean of 158 mm/300 cm 3 of soil (Fig. 2-4). Linear regression models relating mean root length to nematode population densities (015 cm depth) were significant ( P 0.10) on some sampling dates at FLREC, IW, and SP (Table 21). However at CR, relationships between mean root lengths and nematode population densities models were never significant ( P 0.10) (Table 2-1). At th e FLREC site, linear regression models were significant (P 0.10) in April and May; at IW they were significant in June, September, and October: and at SP, they were signif icant in July (Table 2-1). At all sites, linear regression models relating temperature and B. longicaudatus densities were not significant (P 0.10). Average monthly high and low temperatures at FLREC and IW ranged from 27 to 37 C and 18 to 27 C, respectively. At CR and SP, av erage monthly high and low temperatures ranged from 29 to 34 C and 21 to 26 C, respectively. Discussion Correlations were observed between root length and B. longicaudatus at FLREC, IW, and SP (Table 2-1). However, regression analysis did not provide c onclusive, predictive models to characterize relationships between B. longicaudatus and root length. At most, significant relationships occurred at only 3 of the 4 sites on any one date (e.g., FLREC in April, May; IW in June, September, and October and SP in July). This suggests that root length had an effect on 24

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population densities of B. longicaudatus, but other environmental factors also may have been affecting root growth (Robbins and Barker, 1974; Huang and Beck er, 1999). Furthermore, root lengths could also have been a dversely affected by root pathogens (Elliott, 1995), insects, or by other plant parasitic nematodes (Johnson, 1970). Populations of B. longicaudatus fluctuated greatly at each site (Figs. 2-1; 2-2; 2-3; 2-4). These fluctuations may have been influenced by a combination of food, soil moisture, vertical movement, and temperature. Temperature, moistu re, and vertical movement have great affect on B. longicaudatus population densities (Boyd and Perry, 1970; McSorley and Dickson, 1990; Robbins and Barker, 1974). Furthermore, Cr ow et al. (1997) attr ibuted a decline in B. longicaudatus populations in cotton to quality or absen ce of a food source. However, little work has been done quantifying the effects of each of th ese factors in controlled experiments. Further research examining the combinations of these factors may help in predicting B. longicaudatus population dynamics in the future. Differences in B. longicaudatus behavior among sites could also be attributed to differences in ecotypes. Ha n et al. (2006) reported that the life cycle duration of B. longicaudatus collected from citrus in Lake Alfred, FL was three days longer at 28 C than that of B. longicaudatus collected from bermudagrass in Gainesville, FL. This evidence may suggest that B. longicaudatus populations within Florida may react differently to environmental conditions, which could account for some variation in the population dynamics. Gozel et al. (2006) have recently shown that several distin ct genotypes comprise the polymorphic grouping that is currently considered a single species, i.e., B. longicaudatus. This genetic variability supports the suggestion of differe nt ecotypes or even different cryptic species with differing population dynamics and life history traits. 25

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26 Root length fluctuations were highly variable among sites (Figs. 2-1; 2; 2-3; 2-4). A combination of environmental conditions and main tenance practices may have influenced these seasonal fluctuations (Duble, 1996). At IW, pine tr ees in close proximately to the research site reduced solar irradiance to the plots in June, Ju ly, and August. Reduction in irradiance can cause bermudagrass to thin and loose tu rf coverage (Bunnell et al., 2005), leading to a decline in root growth. These conditions were obs erved at the IW site. Once the plots thinned and lost turfgrass coverage, the plots never recupe rated throughout the duration of the experiment. Temperature differences between sites also coul d have influenced root fluctuat ions at each location (DiPaola et al., 1982). Soil temperatures at the FLREC, SP and CR site were optimum for root growth for three months longer than that at IW. Soil te mperatures were never low enough to cause root growth to completely cease at FLREC, SP, a nd CR. However, at IW , temperatures did fall below the root growth base temperature of 10 C (DiPaola et al., 1982), which could probably influenced root growth. In conclusion, B. longicaudatus and root growth were hi ghly variable among sites. However, both B. longicaudatus populations and root lengths generally increased during the spring months, especially from April to June. Significant correlations between root growth and B. longicaudatus also were observed at some point dur ing the spring at most sites. These results suggest that, depending on location in the state and seasonal differences, April through June may be the optimum time to apply nematicides to turf. Future research in a controlled environment may be more effective in examining the e ffects of root growth and temperature on B. longicaudatus populations.

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Fig. 2-1. Population densities of Belonolaimus longicaudatus and root lengths from 300 cm 3 of soil from bermudagrass and soil temperatures at the Ft. Lauderdale Research and Education Center, Ft. Lauderdale, FL (January 2005 – December 2005). Data are means standard error. 27

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Fig. 2-2. Population densities of Belonolaimus longicaudatus and root lengths from 300 cm 3 of soil from bermudagrass and soil temperatures at Ironwood Golf Course, Gainesville, FL (February 2005 January 2005). Data are means standard error. 28

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Fig. 2-3. Population densities of Belonolaimus longicaudatus and root lengths from 300 cm 3 of soil from bermudagrass and soil temperatures at Sandpiper Golf Course, Sun City, FL (March 2006 November 2006). Data are means standard errors. 29

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30 Fig. 2-4. Population densities of Belonolaimus longicaudatus and root lengths from 300 cm 3 of soil from bermudagrass and soil temperatures at Club Renaissance Golf Course, Sun City, FL (March 2006 November 2006). Data are means standard errors.

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Table 2-1. Linear regression number of Belonolaimus longicaudatus /300 cm 3 of soil (Y) on root length 300 cm 3 of soil (x) from four golf course fa irways in Florida sampled monthly. Month a Y= r P Ft Lauderdale Research Center January ns 0.0032 0.7429 February ns 0.0054 0.6715 March ns 0.0031 0.7483 April 203.2 0.0712x 0.1500 0.0192 May 141.2 0.0423x 0.0820 0.0791 June ns 0.0122 0.5205 July ns 0.0507 0.1868 August ns 0.0047 0.6910 September ns 0.0061 0.6513 October ns 0.0008 0.8760 November ns 0.0048 0.6869 December ns 0.0145 0.4838 Ironwood Golf Course February ns 0.0704 0.1177 March ns 0.0088 0.5858 April ns 0.0154 0.4708 May ns 0.0092 0.5775 June 114.6 0.1587x 0.1800 0.0081 July ns 0.0500 0.1129 August ns 0.0001 0.9512 September 62.15 0.0888x 0.1212 0.0349 October 25.41 0.0355x 0.1121 0.0486 November ns 0.0006 0.8866 December ns 0.0049 0.6887 January ns 0.0192 0.4710 Club Renaissance March ns 0.1012 0.3134 April ns 0.1078 0.2975 May ns 0.2150 0.1289 June ns 0.1859 0.1855 July ns 0.0226 0.6419 August ns 0.0344 0.5639 September ns 0.0177 0.6799 October ns 0.0070 0.4054 November ns 0.1842 0.1639 Sandpiper Golf Course March ns 0.0500 0.4819 April ns 0.1724 0.1795 May ns 0.0001 0.9794 June ns 0.2294 0.1613 July 118.4 0.1474x 0.3015 0.0802 August ns 0.0648 0.4245 September ns 0.1311 0.2475 October ns 0.0044 0.8376 November ns 0.0414 0.5260 a Month of Sampling, ns = not significant, df= 11 31

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CHAPTER 3 TIMING OF NEMATICIDE APPLICATIONS ON TURF TO REDUCE DAMAGE CAUSED BY Belonolaimus longicaudatus Introduction Warm season turfgrasses grown in the southeas tern United States and California, such as hybrid bermudagrass (Cynodon dactylon , are susceptible to damage by phytoparasitic nematodes (Perry et al, 1970; Rhoades, 1962). The most destructive nematode in these turfgrass ecosystems is the ectoparasitic sting nematode, Belonolaimus longicaudatus Rau (Johnson, 1970; Winchester and Burt, 1964). Belonolaimus longicaudatus is a bisexual species which reproduces exclusively via amphimixis (Smart and Nguyen, 1991). It is found primarily in soils with >80% sand content (Robbins and Barker, 1974. In Florida, B. longicaudatus is the most destructive nematode on bermudagrass and is considered a major pest by th e golf course industry in the state (Crow et al., 2003). On bermudagrass, B. longicaudatus causes severe damage to lateral roots, decreased water and nutrient uptake, and decreased rates of evapotranspiration, leading to reduced turf quality, color, and density (Boyd and Perry, 1969; Busey et al., 199;1 Johnson, 1970). Current strategies to reduce damage from this pest are limited to preplant or post-plant nematicides (Bekal and Becker, 2003). Howe ver, a review of organophosphates by the U.S Environmental Protection Agency has led to th e withdrawal of ethoprop for use on turf in 2001 and the voluntary cancellation of all product re gistrations of fenamiphos effective 31 May 2007 (Anonymous, 2002). The loss of these organophosphate nematicides has led to the development of new uses for existing nematicides. One of the most promising of these is 1, 3-dichloropropene (1,3-D) the active ingredient in Curfew Soil Fumigant (Dow Agro Sciences, Indianapolis, IN). Crow et al. (2003; 2005) reported that post-plant applications of 1,3-D at 55 kg a.i./ha lowered populations of B. longicaudatus on bermudagrass. Due to application cost and revenue loss from 32

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the 24-hour reentry requirement for 1,3-D, most gol f courses in Florida can afford to apply 1,3-D only one time per year. Because 1,3-D has no residual activity, it is important to apply the fumigant during the time when it can give the most lasting effect. Theore tically, this would be during a season where roots are actively growin g and nematode populations are increasing. Research on the population dynamics of sting nematode, bermudagrass root growth, and soil temperatures on four bermudagrass sites in Florida were presented in Chapter 2. In those studies it was found that the most sustained period of sting nematode population increase and root development occurred during the spring months. While results of that research suggest that spring might be the optimum time to apply nematicides, this theory needs to be verified experimentally. The objectives of this study were: 1) to compare the effects of early spring, late spring, mid-summer, and early fall applicati ons of 1,3-D on sting ne matode populations and bermudagrass roots, and 2) to determine the optim um time to apply nematicide treatments to golf course turf in Florida. Materials and Method In 2006, trials were established on two golf course fairways in central Florida that were naturally infested with sting nematodes. Tria l 1 was established at the Club Renaissance golf course (CR), Sun City, FL, a nd trial 2 at the Sandpiper Golf Club (SP), Sun City, FL. In both trials, golf course fairways had existing stands of ‘Tifway 419’ bermudagrass. Average monthly high and low temperature ranged from 29 to 34 C, and 21 to 26 C at CR and SP, respectively. The experimental area was main tained under golf course fairway conditions. Mowing, fertilization, and irrigati on were provided by the golf cour se operations staff at both sites. Both golf course fairwa ys were mowed three times a week without buckets at a cutting height of 1.3 cm except when weather prevented. Irrigation was applied on an as-needed basis as determined by the golf course superintendent usi ng an overhead automatic irrigation system. To 33

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add to the aesthetics of the golf course for winter play, the CR fa irway was overseeded in October of 2005 and 2006 with ‘Allsport’ pere nnial ryegrass. The SP course was not overseeded. Core aerification was carried out once per year on both courses. No other cultural practices were carried out dur ing the experiment. Six weeks prior to the first nematicide treatments, 60 plots, 2-m with 0.5-m borders, were arranged in a grid at each site and nematode samples were colle cted from each plot. Nematode samples consisted of nine soil cores 1.9-cm-diam. 7.5-cm-deep combined to make a single sample from each plot. Nematodes were extracted from a 100-cm 3 subsample using sugar flotation with centrifugation (Jen kins, 1964) and counted using an inverted light microscope at 10 magnification. Only plots wi th >25 sting nematodes/100 cm 3 of soil, designated “high risk of damage” by the Florida Nematode Assay La b (Crow et al, 2003), were included in the experiment. The experimental design was a random ized complete block with five treatments and 4 replications. Plots were assigned to blocks based on pretreatme nt counts of sting nematode so that the treatments in each block all had similar initial population densities. The five treatments were 1,3-D applied in March, May, July, or September, and an untreated control. The1,3-D was injected by a commercial applicator (Hendrix and Dail Inc. Palmetto, FL) at a rate of 46.76 liters/ha with a nitrogen gas pressurized a pplication rig. Immediately after nematicide application, approximately 1.25 cm of irrigation was applied as specified in the Curfew Soil Fumigant label. Sampling and Evaluation Nematodes In both trials, three cores (2.5-cm-diam. and 15-cm-depth) were removed arbitrarily from each plot using a tee sampler to determine plant-pa rasitic nematode populations and root lengths. 34

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Nematode samples were taken one day prior to the first nematicide treatments and at monthly intervals thereafter. On months when nematic ide applications were made, the samples were taken the day prior to the appli cation date. Nematodes were extr acted from each soil core using the centrifugal flotati on method (Jenkins, 1964). Following ex traction, plant-parasitic nematodes were counted using an inve rted light microscope. Roots Root samples were obtained from the same co res that were used to determine plantparasitic nematode populations. Roots were caught on a 18 mesh (1000 m) kitchen sieve and placed into 50-ml plastic centrifuge tubes. Roots were then placed into a glass bottom tray and scanned in a flat bed scanner (Epson Perfection 4990 Photo) to create a bitmap image. The bitmap images were imported into the WinRhi zo (Regent Instruments, Chemin Sainre-Foy, Quebec) software program for analysis. This prog ram was used to measure root lengths from the scanned images. Data Analysis Since pretreatment B. longicaudatus means and root lengths were quite variable, analysis of covariance was performed on nematode count data and root lengths to compare adjusted treatment means following 1,3-D application. Diffe rences between treatments and the untreated control were analyzed by Dunnett' s t test. All nematode data we re transformed using log(x+1) for analysis, although the untransformed means are presented. All data analyses were performed using SAS software (SAS Institute, Cary, NC). Results At the SP site, 1,3-D applications did not reduce (P 0.10) population densities of B. longicaudatus (Fig. 3-1) compared to the untreated control at any sampling date. However, root lengths increased after the March and May treatmen ts of 1,3-D compared to the untreated. Root 35

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lengths were greater (P 0.10) at 4, 12, and 16 weeks following the March 1,3-D treatment compared with the untreated contro l. Root lengths were greater ( P 0.10) at 4, 8 and 12 weeks after the May treatment of 1,3-D compared to the untreated (Fig s. 3-2). At the CR site, 1,3-D treatments had no effect (P 0.10) on sting nematode populations (Fig. 3-3), or root lengths (Fig. 3-4). Discussion At either golf course, no visual differences (P 0.1) in turfgrass quali ty, color, or density were observed between untreated control and any of the plot s treated with1,3-D throughout the experimental period (data not s hown). This may have been due to the failure to apply a minimum of 5 kg/ha of water-soluble nitrogen 3 day before treatment or within 30 days following treatment as stated by the label. Luc et al. (2007) reported sim ilar results, with no improvement in turf quality w ith applications of 1,3-D only. At both SP and CR, reductions in B. longicaudatus population following nematicide application were not detected us ing the sampling protocols used in this research. These results differ from previous reports (Crow et al., 2003) which revealed decreases in B. longicaudatus population densities following slit injections of 1,3-D. Howeve r, different sample protocols were used in each study. Crow et al. (2003; 2005) arbitrarily removed nine (2.5-cm-diam and 10.2-cm-depth) cores, compared to three cores (2.5-cm-diam and 15-cm-depth) removed in this experiment. Increasing the number of cores take n may have helped to reduce the variation caused by the spatial distribution of the nematode s. The number of locations sampled is more critical than the size and shape of individual cores because of th e clustered spatial distributions of B. longicaudatus populations (McSorely, 1987 ). Furthermore, in May and July at CR and SP, thunderstorm and heavy rain (5 cm) occurred the night before treatments. Subsequent saturation of the soil may have reduced the efficiency of 1,3-D to diffuse through the rootzone and kill B. 36

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37 longicaudatus . In addition, at CR, the applicator mi sapplied the 1,3-D in May and July which may be why reductions in B. longicaudatus densities were not observe d. Significant increases ( P < 0.1) in root length were observed following 1,3-D treatments in March and May at SP. Crow et al. (2003) reported similar increase in total root length following slit injections of 1,3-D. Furthermore, they also observed a reduction in the numbers of B. longicaudatus which could be one factor contributing to the increase in root length. However, at both SP and CR, no significant reductions in B . longicaudatus populations were observed but increase in root length was observed at SP. This increa se in root length may have been caused either by a decline in B. longicaudatus population densities or a reduction in parasitism after 1,3-D treatments. Findings based on this research suggest that March or May applications of 1,3-D to bermudagrass in Florida are more effective than July or September 1,3-D applications for the improvement of root growth in fairways infested with B. longicaudatus.

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Fig. 3-1. Effects of applicati on time of 1,3-dichloropropene on Belonolaimus longicaudatus population densities at Sandpiper Golf Course, Sun City, FL (March 2006 November 2006). 38

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Fig. 3-2. Effects of application time of 1,3dichloropropene on root length at Sandpiper Golf Course, Sun City, FL (March 2006 November 2006). Asterisk indicates treatmen t is different from untreated (P < 0.1). 39

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Fig. 3-3. Effects of applicati on time of 1,3-dichloropropene on Belonolaimus longicaudatus population densities at Club Renaissance Golf Course, Sun City, FL (March 2006 November 2006). 40

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Fig. 3-4. Effects of application time of 1,3dichloropropene on root length at Club Renaissance Golf Course, Sun City, FL (March 2006 November 2006). 41

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CHAPTER 4 SUMMARY With more than 1,300 golf courses and over th ree million acres of residential landscape (Haydu and Hodges, 2002), Florida is not only a prim e location for golfers but also for the sting nematode Belonolaimus longicaudatus . The data reported herein indicates that seasonal fluctuations of B. longicaudatus densities and bermudagrass root growth are highly variable within the state of Florida. Root growth can influence B. longicaudatus fluctuations. However, regression analysis provided no good predictive models to characterize relationships between B. longicaudatus and root length (Chapter 2) . Our data also suggest that 1, 3-dichloropropene (1,3D) is most effective at improving root growth when applied in March or May. (Chapter 3). In January 2005 and March 2006 four trials; one in North Florida (IW) one in South Florida (FLREC) and two in cen tral Florida (SP and CR), were conducted to monitor the seasonal dynamics of B. longicaudatus, bermudagras root growth, and soil temperatures on golf course fairways in Florida in order to determin e the optimum time for nema ticide application. At the FLREC site populations of B. longicaudatus and root length followed similar trends for most of the study. Both B. longicaudatus population densities and root le ngth increased from February to April and declining in May. In July and August trends between B. longicaudatus densities and root growth were observed again with both B. longicaudatus and root growth increasing and then declining. From September to October B. longicaudatus population densities and root growth remain stable. However, in November and December while B. longicaudatus densities remain steady root length declined. Like FLREC B. longicaudatus population densities and root gr owth shared similar trends at IW. From March through June similar trends were observed between B. longicaudatus population densities and root grow th, with both declining from Ma rch to May and increasing in 42

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June. However, in July B. longicaudatus reduced rapidly while root growth remained stable. From August to October similar trends were observed between B. longicaudatus population densities and root growth with both B. longicaudatus population densities and root lengths increasing in August and September and declini ng in October. For the rest of the study B. longicaudatus population densities remained constant. However root lengths c ontinue to decline in November and December before increasing again in January. At SP, no clear relationship was observed between B. longicaudatus population densities and root lengths. From March through May B. longicaudatus populations increased while root length decreased. In June B. longicaudatus populations decreased while root growth increased. However, in July similar trends were observed between B. longicaudatus populations densities and root length with both increasing. In August B. longicaudatus populations densities reduced while root length continued to increase. Both B. longicaudatus densities and root growth increased in September and declined in October. In November root lengt h continued to decline with B. longicaudatus densities increasing. At CR both B. longicaudatus populations densities and root length increased in April and May. However, in June B. longicaudatus population densities decline and root growth increased. In July both B. longicaudatus population densities and root le ngth declined. In addition, root length continued to declin e from August to October before increasing in November. Belonolaimus longicaudatus populations increased in August and decline in September before increasing and declining again in October and November. In all four trials similar trends were observ ed between nematodes and root lengths. Linear regression models relating mean root length to nematode population densities (0 to 15 cm depth) were significant ( P 0.10) at FLREC, IW and SP. Howe ver, regression analysis provided no 43

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good predictive models to characterize relationships between B. longicaudatus and root length. This suggests that root length had an effect on population densities of B. longicaudatus. However , other environmental factors also had an eff ect. At all sites, linear regression models relating temperature and B. longicaudatus densities were not significant ( P 0.10), although trends were observed, esp ecially at FLREC. In March of 2006 two trials we re initiated to determine the optimum time to apply nematicides. At SP and CP no differences in population densities of B. longicaudatus among treatments were detected (P 0.10) at any sampling date. Howeve r, at SP root length increased after March and May treatments of 1,3-D compared to the untreated control. Root lengths were greater ( P 0.10) at 4, 12 and 16 weeks following the March 1,3-D treatment compared with the untreated control. Root lengths were greater ( P 0.1) at 4, 8 and 12 weeks after the May treatment of 1,3-D compared to the untreated. In conclusion correlations between root growth and B. longicaudatus showed a weak relationship . Furthermore, similar trends were observed between soil temperature and nematodes and root growth especially at FLRE C. The results from this study indicate that applications of 1, 3-D in April July are the most effective in reducing B. longicaudatus densities, and improving root growth. Howe ver, it should be emphasized that the optimum month for treatment may vary from one year to the next and from one location to another. Variation in maintenance practices, rainfall and te mperature from one golf cour se to the next will greatly influence the timing and the res ponses observed from 1,3-D applications. 44

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LIST OF REFERENCES Anonymous. 2002. Fenamiphos: Notice of receipt of request to voluntar ily cancel all product registrations. Federal Register 67:61098. Barker, K. C., J. Nussbaum, and I. A. Nelson. 1969. Effect of storage te mperature and extraction procedures on recovery of plan t parasitic nematodes from field soil. Journal of Nematology 1:240-247. Beard, J. B. 1973. Turfgrass Science and Cultu re. Prentice Hall Englewoods Cliffs, NJ. Bekal, S., and J. O. Becker. 2003. Population dyn amics of the sting nematode in California turfgrass. Plant Disease 84:1081-1084 Boyd, F. T. and D. W. Dickson. 1971. Plant-para sitic nematodes: Occurrence in Florida, sensitivity to temperatures and effect on tropical forage yields. Soil and Crop Science Society of Florida Proceedings 31:267-268. Boyd, F. T., and V. G. Perry. 1970. Effects of seasonal temperatures and certain cultural treatments on sting nematodes in forage gra ss. Soil and Crop Science Society of Florida Proceedings 30:360-365. Brodie, B. B., and B. H. Quattlebaum. 1970. Verti cal distribution and population fluctuations of three nematode species as correlated with soil temperature, moisture and texture. Phytopathology 60:1268. Brooks, A. N. 1964. The sting nematode, Belonolaimus gracilius, Steiner. Proceedings of the Florida State Horticultural Society 14:157-158 Bunnell, T., L. B. McCarty, and W. C. Bridges Jr. 2005. TifEagle’ bermudagrass response to growth factors and mowing height when grown at various hours of sunlight. Crop science 45:575-581. Busey, P., R. M. Giblin-Davis, C. W. Riger, and E. I. Zaenker. 1991. Susceptibility of diploid St. Augustinegrasses to Belonolaimus longicaudatus . Supplement to the Journal of Nematology 23:604-610. Christie, J. R. 1952. Some new nema tode species of critical impor tance to Florida growers. Soil and Crop Science Society of Florida Proceedings 12:1-15. Christie, J. R., A. N. Brooks, and V. G. Perry. 1952. The sting nematode Belonolaimus gracilis , a parasite of major importance on strawberries, celery, and sweet corn in Florida. Phytopathology 42:173-176. Christie, J. R. 1953. Ectoparasitic nema todes of plants. Phytopathology 43:295-297. Christie, J. R. 1959. Plant nematodes: Their bion omics and control. Jack sonville, FL: H. and W.B. Drew. 45

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Crow, W. T., D. W. Dickson, and D. P. Weingartner. 1997. Stubby-root symptoms on cotton induced by Belonolaimus longicaudatus . Journal of Nematology 29:574. Crow, W. T. 2005. How bad are ne matode problems on Florida’s golf courses? Florida Turf Digest 22(1):10-12. Crow, W. T., R. M. Giblin-Davis, and D. W. Lickfeldt. 2003. Slit injection of 1,3dichloropropene for management of Belonolaimus longicaudatus on established bermudagrass. Journal of Nematology 35:302-305. Crow, W. T., J. W. Noling, R. A. Kinloch, J. R. Rich, and R. A. Dunn. 2003. Florida NematodeManagement Guide. Entomology and Nematology Department. University of Florida,Gainesville, FL. Crow, W. T., and T. Lowe. 2005. Effects of fa ll overseeding and nematicide applications on populations of sting nematode. US GA Green Section Record 43:8-11. Crow, W. T., D. W. Lickfeld t, and J. B. Unruh. 2005. Management of sting nematode ( Belonolaimus longicaudatus ) on bermudagrass putting greens with 1,3-dichloropropene. International Turfgrass Societ y Research Journal 10:734-741. Dickerson, O. J., W. G. Willis, F. J. Daine llo, and J. C. Pair. 1972. The sting nematode, Belonolaimus longicudatus , in Kansas. Plant Disease Reporter 56: 957. DiPaola J. M, J. B. Beard, and H. Brawand. 1982. Key events in the seasonal root growth of bermudagrass and St. Augustineg rass. Hort Science:17:829-831 Duble, R. 1996. Turfgrasses: Their Manage ment and Use in the Southern Zone. Texas A&M University Press, College Station, TX. Elliott, M. L. 1995. Disease response of bermudagrass to Gaeumannomyces graminis var. graminis. Plant Disease 79:699-702. Fortuner, R., and M. Luc. 1987. A reappraisa l of Tylenchina (Nemata). 6. The family Belonolaimidae Whitehead, 1960. Revue de Nematologie 10:183-202. Giblin-Davis, R. M., J. L. Cisar, and F. G. Bilz. 1988. Response of nematode populations and growth of fairway managed bermudagrass to application of fertil izer and fenamiphos. Nematropica 18:117-121. Giblin-Davis, R. M., J. L. Cisar, F. G. B ilz, and K. E. Williams. 1991. Management practices affecting phytoparasitic nematodes in 'Tif green' bermudagrass. Nematropica 21:59-69. Giblin-Davis, R. M., P. Busey, and B. J. Center. 1992. Dynamics of Belonolaimus longicaudatus parasitism on a susceptible St. Augustineg rass host. Journal of Nematology 24:432-437. 46

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Gozel, U., B. Adams, K. Nguyen, R. Inserr a, R. Giblin-Davis, and L. Duncan. 2006. A phylogeny of Belonolaimus populations in Florida inferred from DNA sequences. Nematropica. 36:149-165. Han, H.R, D. W, Dickson,and D. P. Weingart ner. 2006. Biological char acterization of five isolates of Belonolaimus longicaudatus . Nematropica 36:25-36 Haydu, J. J., and A. W. Hodges. 2002. Economic im pacts of the Florida golf course industry. University of Florida, Institute of Food a nd Agricultural Sciences, Economic Information Report EIR 02-4. Gainesville, FL : University of Florida. Hixson, A. C., W. T. Crow, R. McSorley, and L. T. Trenholm. 2004. Host status of ‘SeaIsle 1’ seashore paspalum ( Paspalum vaginatum ) to Belonolaimus longicaudatus and Hoplolaimus galeatus . Journal of Nematology 36:493-498. Holdeman, Q. L., and T. W. Graham. 1953. The effect of different plant species on the population trends of the sting nematode . Plant Disease Reporter 37:497-500. Holdeman, Q. L. 1955. The present known distribution of the sting nematode, Belonolaimus gracilis , in the coastal plain of the southeastern United States. Plant Disease Reporter 39:58. Huang, X., and J. O. Becker. 1999. Li fe cycle and mating behavior of Belonolaimus longicaudatus in gnotobiotic culture. J ournal of Nematology 31:70-74. Hunt, P. G., G. C. Smart Jr., a nd C. G. Eno. 1973. Sting nematode, B . longicaudatus, immobility induced by extracts of composted munici pal refuse. Journal of Nematology 5:60-63. Hutchinson, M. T., and J. P. Reed. 1956. The sting nematode, Belonolaimus gracilius, found in New Jersey. Plant Disease Reporter 40:1049. Jenkins, W. R. 1964. A rapid centrifugal-flotation t echnique for separating nematodes from soil. Plant Disease Reporter 48:692. Johnson, A. W. 1970. Pathogenicity and interact ions of three nematode species on six bermudagrasses. Journal of Nematology 2:36-41. Lopez, R. 1978. Belonolaimus, un nuevo integrante de la nematofauna de Costa Rica. Agronomia Costarricense 2:83-85. Luc, J. E., W. T. Crow, J. L. Stimac, J. B. Sartain, R .M. Giblin -Davis. 2007. Effects of Belonolaimus longicaudatus management and nitrogen fertility on turf quality of golf course fairways. Journa l of Nematology 39:62-66. Lucas, L. T. 1982. Population dynamics of Belonolaimus longicaudatus and Criconmella ornata and growth response of bermudagrass and overseeded grasses on golf greens following treatments with nematicides. Journal of Nematology 14:358-363. 47

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McCarty, L. B., A. R. Mazur, and L. C. Miller. 2001. Overseeding. Pp. 356-373. In L. B. McCarty (ed.) Best Golf Course Management Practices. Prentice-Hall, Inc., Upper Saddle River, NJ. McSorley, R. 1987. Extraction of nema todes and sampling methods. Pp. 13-47. In R. H. Brown and B. R. Kerry (eds.) Principles and Pr actices of Nematode Control on Crops. Acad. Press, Orlando, FL. McSorley, R and D. W. Dickson. 1990. Vertical di stribution of plant-pa rasitic nematodes in sandy soil under soybean. Journal of Nematology 1:90-96 Morris, K. N. and R. C. Shearman. 2000. The Na tional turfgrass evalua tion program:assessing new improved turfgrasses. Diversity 16:19-22. Mundo-Ocampo, M., J. O. Becker, and J. G. Baldwin. 1994. Occurrence of Belonolaimus longicaudatus on bermudagrass in the Coachella Valley. Plant Disease 78:529. Ostmeyer, T. 2004. Golf’s extreme makeover. Golf Course Management 72(7): 50-60. Owens, J. V. 1951. The pathological effects of Belonolaimus gracilis on peanuts in Virginia. Phytopathology 41:29. Perry, V.G. 1965. Host parasite relationship of ce rtain nematodes and crop plants in Florida. Florida Agriculture Experiment Station Annual Report., Pp. 115-116. Perry, V. G. and., D. W. Dickson. 1972. The bi ology and control of nematodes affecting agronomic crops. Pp. 96. Annual Research Report of IFAS, Gainesville, FL. Perry, V. G., and H. Rhoades. 1982. The genus Belonolaimus.Pp. 144-149 I n R. D. Riggs, Ed. Nematology in the Southern Region of the Un ited States, Southern Cooperative Series Bulletin 276. Fayetteville, AR: Arkansas Agricu ltural Experiment St ation, University of Arkansas. Perry, V. G., G. C. Smart, and G. C. Horn. 1970. Nematode problems of turfgrasses in Florida and their control. Proceedi ngs of the Florida State Ho rticultural Society 83:489-492. Rau, G. J. 1958. A new species of sting nematode . Proceedings of the HelminthologicalSociety of Washington 25:95-98. Rau, G. J. 1963. Three new species of Belonolaimus (Nematoda: Tylenchida) with additional data on B. longicaudatus and B. gracilis . Proceedings of the Helminthological Society of Washington 30:119-128. Rhoades, H. L. 1962. Effects of sting and st ubby-root nematodes on St. Augustinegrass. Plant Disease Reporter 46:424-427. Rhoades, H. L. 1980. Reproduction of Belonolaimus longicaudatus in treated and untreated muck soil. Nematropica 10:139-140. 48

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Riggs, R. D. 1961. Sting nematode in Ar kansas. Plant Disease Reporter 45:392. Robbins, R. T., and K. R. Barker. 1974. The effect s of soil type, particle size, temperature, and moisture on reproduction of Belonolaimus longicaudatus . Journal of Nematology 6:1-6. Russell, C. C., and R. V. Sturgeon. 1969. Occurrence of Belonolaimus longicaudatus and Ditylenchus dipsaci in Oklahoma. Phytopathology 59:118. Steiner, G. 1949. Plant nematodes the grower should know. Soil and Crop Science Society of Florida Proceedings 4: 72-117. Smart, G. C., and K. B. Nguyen. 1991. Sting and awl nematodes: Belonolaimus spp. And Dolichodorus spp. Pp. 627-667. I n W. R. Nickle, ed. Manual of Agricultural Nematology. New York: Marcel Dekker. Thames, W. H. Jr. 1959. Plant parasitic nemat ode populations of some Florida soil under cultivated and natural conditi ons. Diss. Abstr. 20:1109-1110. Winchester, J. A., and E. O. Burt. 1964. The e ffect and control of sting nematode on Ormond bermudagrass. Plant Disease Reporter 48:625-628. 49

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BIOGRAPHICAL SKETCH Pauric C. Mc Groary was born 13 April 1982 in Letterkenny, Co. Donegal, Ireland, and grew up in Laghy, Co. Donegal, Ireland. In 1999 he graduated from St. Patrick’s College and began studies at University of Central Lancas hire, Preston, England, in the fall of 1999. After graduation from University of Central Lancashi re in 2004, he began stud ies for his Master of Science degree at University of Florida, Gainesville, Florida. 50