DISLODGEABLE RESIDUES OF PESTICIDES APPLIED TOTURFGRASS AND IMPLICATIONS FOR GOLFER EXPOSURE

By

RAYMOND H. SNYDER

A THESIS PRESENTED TO THE GRADUATE SCHOOLOF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCE

UNIVERSITY OF FLORIDA

1998

ACKNOWLEDGMENTS

The successful completion of this project and my masters program would not have

been accomplished were it not for the help and support of my graduate committee, family,

and friends. Special thanks go to Dr. Jerry B. Sartain and Dr. Christopher J. Borgert for

continually going above and beyond what is required of a graduate committee chairman

and member. Thanks go to Dr. John L. Cisar for devoting his time, resources, and

experience to me during the course of my masters program.

Field work would not have been successful and enjoyable without the presence and

help of Karen Williams who never hesitated to lend a hand. The help of Kevin and Tracey-Wise is also appreciated. Thanks go to Curtis Elliot for his knowledge and understanding

of chemistry and the world around us. In addition, thanks go to Eva Greene for her help

and humor during my time in and away from the lab.

Special thanks go to the members of the Florida Turfgrass Association for

supporting me and funding this project. In addition, I would like to acknowledge the

United States Golf Association for their assistance.

My fellow graduate students also gave me a great deal of help, humor, and hope

during my graduate program. Their support is much appreciated.

Finally, I am forever thankful to my mother and father for their devotion and desire

to see that their son had whatever he needed to complete this project.

11

TABLE OF CONTENTS

Page

ACKNOWLEDGMENT 11

ABSTRACT VII

Chapter

1. INTRODUCTION .

The Need for Exposure Assessment 1Literature Review 3

Dislodgeability Studies 3Pesticides of Interest 6

Dicamba 62,4 - D 7Isazofos 8Chlorpyrifos 8Fenamiphos 8

II. MATERIALS AND METHODS .

Chemicals ..Analytical Standards.Formulations .Solvents and Reagents .

Method Development .Laboratory Recoveries of Pesticides .

2,4 - D and Dicamba .Isazofos, Chlorpyrifos, and Fenamiphos .

Experimental Site .Putting Green .Rough .

Application of Pesticides to Turfgrass .2,4 - D and Dicamba .Isazofos, Chlorpyrifos, and Fenamiphos .

III

10

1010101111111112131414141515

Sample Collection 15Damp Cheesecloth Wipe 15Damp Cotton Press 16Damp Leather Press 16Golf Ball Putt 16Golf Grip Roll 16Chip and Wipe I 16Chip and Wipe II 17

Experiments 1711 - 12 March 1997 173 - 4 June 1997 1729 - 30 October 1997 1829 - 30 January 1998 185 - 6 March 1998 197 - 8 April 1998 19

Instrumentation 19Isazofos, Chlorpyrifos, and Fenamiphos 192,4 - D and Dicamba 20

III. RESULTS . 21

Method Verification 212,4 - D 21Dicamba 21Isazofos 21Chlorpyrifos 22Fenamiphos 22

Data Modification 22Concentration Correction 22Comparison of Dislodgeability Methods 23

Experimental Results 232,4 - D 23

3 - 4 March 1997 2329 - 30 January 1998 245 - 6 March 1998 257 - 8 April 1998 25

Dicamba 253 - 4 March 1997 2529 - 30 January 1998 265 - 6 March 277 - 8 April 1998 27

Isazofos 273 - 4 June 1997 27

IV

29 - 30 October 1997 .Chlorpyrifos ..

3 - 4 June 1997 .29 - 30 October 1997 .

Fenamiphos.3 - 4 June 1997 .29 - 30 October 1997 .

IV. DISCUSSION ...

2,4 - D and Dicamba .Isazofos, Chlorpyrifos, and Fenamiphos ..

V. RISK ASSESSMENT.Introduction.Exposure Assessment ...

Exposure Setting.Identification of Exposure Pathways.Quantification of Exposure ..

Risk Assessment .2,4 - D .

Model A.Model B.Model C ..Model D.Model E.Model FModel G ..Model H

DicambaModel AModel BModel C .Model D.Model E.Model F .Model G ..Model H.

Isazofos .....Model A ..Model B.Model C ..Model D ...Model E.

v

2929293131313334

3435

37373838383940424243444546474849505051525354555657585859606162

Model F.Model G.ModeIH .

Chlorpyrifos .Model A .Model B .Model C .Model D .~~E .Model F .~~G .Model H .

Fenamiphos .~~A .Model B .Model C .Model D .~~E .Model F .Model G .Model H .

636465666667686970717273747475767778798081

IV. CONCLUSIONS " 82

LITERATURE CITED .

BIOGRAPHICAL SKETCH .

VI

116

120

Abstract of Thesis Presented to the Graduate Schoolof the University of Florida in Partial Fulfillment of the

Requirements for the Degree of Master of Science

DISLODGEABLE RESIDUES OF PESTICIDES APPLIED TOTURFGRASS AND IMPLICATIONS FOR GOLFER EXPOSURE

ByRaymond H. Snyder

December 1998Chairperson: Jerry B. SartainMajor Department: Soil and Water Science

The general public is concerned about exposure to pesticides applied to turf grass

Pesticide exposure may occur because of dislodgeable residues. A study was conducted

to determine the dislodgeability of organophosphate and phenoxy-type pesticides applied

to turf grass and to assess the risk of exposure to those pesticides by dermal and incidental

ingestion pathways.

Dislodgeability was determined using damp cotton fabric, damp leather, golf balls,

golf grips, golf club head, and damp cheesecloth following application, irrigation (when

appropriate), and through a 24 h period after application. A comparison of the damp

cheesecloth wipe, the damp cotton press, and the damp leather press was made. Several

models encompassing golfer behavior and realistic golf course exposure scenarios were

used in conjunction with field data to assess risk.

VB

Isazofos, chlorpyrifos, and fenamiphos were applied to bermudagrass (Cynodon

dactylon L. xc. transvaalensis). 2,4 - 0 and Oicamba were applied to both

bermudagrass and bermudagrass overseeded with Poa trivialis.

Oislodgeable residues of isazofos, chlorpyrifos, and fenamiphos decreased with

irrigation and time. Residues of 2,4 - 0 and dicamba did not decrease until 24 h after

application following irrigation. No differences were found in dislodgeable residues of

2,4 - D and dicamba between overseeded and non-overseeded bermudagrass. There was

no difference in dislodgeable residues of2,4 - 0 and isazofos between the damp

cheesecloth wipe and the damp cotton press. The damp leather press dislodged more

isazofos at 3.75 and 19.50 h after application than the damp cheesecloth wipe and the

damp cotton press. The damp cotton press dislodged less chlorpyrifos than the damp

cheesecloth wipe at 3.75 h after application. The damp leather press dislodged less

chlorpyrifos than the damp cheesecloth wipe and the damp cotton press at 3.75 and 19.50

h after application. The damp cheesecloth wipe dislodged more fenamiphos than the damp

cotton press at 0.30 and 3.75 h after application. The damp leather press dislodged less

fenamiphos than the damp cheesecloth wipe 3.75 h after application.

The risk assessment models used in this study suggest that risk associated with

dermal and incidental ingestion exposure to the organophosphate and phenoxy-type

pesticides will decrease with time after application. Everyday exposure immediately

following pesticide application may exceed the acceptable daily intake levels for chronic

exposure, however, more realistic exposure models estimate doses below the chronic

reference dose.

Vlll

CHAPTER IINTRODUCTION

Pesticides are routinely used on golf courses to control nematodes, insects, fungi,

algae, and weeds. In 1987, an estimated 454 million kg of pesticides were applied in the

United States (Ware, 1987). Their use, however, has not come without considerable

public concern regarding possible toxic and carcinogenic effects which may occur as a

result of human exposure (Getler, 1998, Joyce, 1998).

A route by which golfers may be exposed to pesticides during play is through

dermal exposure. Golfers, generally, have some form of direct or indirect dermal contact

with the turfgrass surface. During the course ofa round, golfers handle golf balls, golf

grips, and golf club faces, all of which are frequently in contact with the turf grass surface.

In some instances, such as the placement of a knee on a golf green or the use of gloves

during play, clothing may serve as a material that dislodges pesticide residues from

turf grass. In addition, golfers, on occasion, make direct dermal contact with their hands.

While it is not unreasonable to assume that golfers are in contact with turf grass

that at some time has been or will be treated with pesticides, it is unreasonable, however,

to assume that this contact produces an adverse affect in humans without an idea of the

potential dose of pesticide received as a result ofthe contact. The mere presence of a

pesticide does not necessarily denote that an adverse effect will occur. A golfer must be

exposed to a sufficient quantity of pesticide in order for an adverse effect to be produced

2

(Borgert et aI. 1994). Exposure is the opportunity for contact. The quantity of pesticide

that is taken into the body is the dose, and it is the dose that determines the effect.

Risk assessments are developed to help determine the toxicological significance of

chemicals encountered in the environment. A risk assessment compares the potential dose

received by exposed individuals with the toxic potency of a chemical. Risk assessment

methodology is widely accepted by the scientific community having been used successfully

in areas such as water quality (Wang, 1994), soil contamination (Hoddinott, 1992), and

pesticide exposure (Borgert et aI., 1994).

In the United States alone, 547 million rounds of golf were played by 26.5 million

golfers in 1997 (Golf Course News, 1998). Unfortunately, little research has been

conducted investigating the potential risk which may exist to this large and growing

portion of the U.S. population. In the past, studies focused on pesticide exposure to

pesticide applicators (Fenske, 1990; Fenske and Elkner, 1990) and crop harvesters (Gold

et aI., 1984, Gunther et aI., 1977; Knaak and Iwata, 1982; McEwen et aI., 1980). While

these studies were helpful in determining measures to minimize pesticide exposure to

applicators and harvesters, few parallels can be drawn to golfer pesticide exposure. This

study was designed to specifically assess several pesticide exposure pathways that can be

related to golfers.

Specific objectives of this study included:

1. Determination of dislodgeable residues of one nematicide, two herbicides, and

two insecticides following their application to turfgrass.

3

2. A comparison of dislodgeable residues from bermudagrass and bermudagrass

overseeded with Poa trivialis.

3. A comparison of dislodgeable residues recovered from several methods on

turfgrass. These methods included damp cheesecloth wipe, damp cotton fabric

press, and damp leather press.

4. A risk assessment based on the field data determining if this exposure may be

toxicologically significant.

Literature Review

Dislodgeability Studies

Concerns regarding pesticide exposure in agriculture have resulted in several

studies pertaining to dislodgeable residues (Borgert et aI., 1994; Cahill et aI., 1975;

Gunther et aI., 1977; McCall et aI., 1986; McEwen et aI., 1980; Southwick et aI., 1986;

Staiff et aI., 1977). Crops range from soybean to citrus. Most all, however, are similar in

that they attempt to determine levels at which dislodgeable residues exist in order to

address concerns regarding human exposure.

Dislodgeable residues from turf grass have also received some attention.

Thompson et al. (1984) used dampened cheesecloth to dislodge 2,4-0 applied to

Kentucky bluegrass (Poa pratensis L.) in both field and growth room studies. In that

study, less than 0.01 % of the applied chemical was dislodged from the turf grass receiving

18 mm of natural rainfall approximately one hour following application. Seven days were

required in order to reach the same levels in turf grass receiving no rainfall. Dissipation of

chlorpyrifos and dichlorvos from a clover (Trifolium sp.) and fescue (Festuca sp.) lawn

4

over time were examined by Goh et al. (1986). Residues were chemically extracted

directly from leaf tissue. Residues of dichlorvos reached safe levels within four hours after

application in irrigated plots and 14 hour in non-irrigated plots. Chlorpyrifos residues

were within safe levels immediately following application in irrigated plots with non-

irrigated plots requiring six hours to reach safe levels. Sears et al. (1987) studied the

effects of time, sunlight, rainfall, mowing and formulation (granular vs liquid) on

dislodgeable residues of diazinon, chlorpyrifos, and isofenphos from Kentucky Bluegrass

(Poa pratensis L.) In this study, the damp cheesecloth wipe method was employed.

Sunlight did not have an effect on the decline of dislodgeable residues. Dislodgeable

residues following the application of diazinon as a liquid were 20 times more than that of

diazinon applied granularly. Rainfall significantly effected dislodgeable residues while

mowing did not. Murphy et al. (1996) used dampened cheesecloth to determine

dislodgeable residues oftriadimefon, MCPP, trichlorfon, and isazofos from 'Penncross'

creeping bentgrass (Agrostis palustris Huds.). Irrigation was found to substantially

reduce dislodgeable residues of trichlorfon and isazofos. Residues of triadimefon and

MCPP were greatest immediately after application and decreased over time.

In most of the above studies, damp cheesecloth was rubbed over a demarcated

area of turf grass treated with a known pesticide. The term "vigorous" is often used to

define the nature of the rub. Unfortunately, this method may be difficult to replicate and

hence draw comparisons to other studies since investigators definitions of "vigorous" may

differ. Therefore, in this study a damp cotton press method will be compared to the damp

cheesecloth wipe method.

5

Currently, no studies have been identified which relate the transfer of dislodgeable

turf grass residues to golfers. Murphy et al. (1996) used the model of Zweig et al. (1985)

to assess the impact of golfer dermal exposure to triadimefon, MCPP, trichlorfon, and

isazofos. The Zweig et al (1985) model determined that the dermal exposure rate (mg h-I)

offruit harvesters was 5 x 103 times the dislodgeable residues (ug cm-2) determined on leaf

tissue. The transfer of dislodgeable residues to fruit harvesters is likely far greater than

that of golfers due to the fruit harvesters extensive and frequent contact with vegetation.

Therefore, while the use of the Zweig (1985) model has been accepted, it is probably an

overestimation of golfer exposure. Nevertheless, using the Zweig (1985) model, Murphy

et al (1996) determined that exposure to dislodgeable residues of triadimefon and MCPP

in a 15-d study was below levels expected to cause adverse health effects. However,

Murphyet al. (1996) found dislodgeable residue levels of isazofos and DDVP, a

transformation product of trichlorfon, at concentrations that may cause adverse effects on

day 2 for DDVP and days 2 and 3 for isazofos.

A search of the literature revealed only one dislodgeability study in which actual

golf equipment was used for sampling. Borgert et. al. (1994) quantified the dislodgeable

residues of three pesticides (diazinon, isazofos, chlorpyrifos) 24 h after application from a

'Tifdwarf bermudagrass (Cynodon dactylon xC transvaalensis), USGA putting green.

Using materials such as cotton fabric, leather, and golf balls the authors developed

preliminary and limited risk calculations estimating toxicological significance associated

with golfer exposure to the green. Residues dislodged by golf grips were estimated in this

study using data collected from pesticides dislodged from leather. A goal of the present

6

study was to expand the dislodgeability database beyond that of dampened cheesecloth

and to include real-life materials in the sampling protocol.

Pesticides of Interest

Dicamba

Dicamba is a benzoic acid herbicide used extensively to control annual and

perennial broadleafweeds. Dicamba effects the health of plant in several ways. Dicamba

causes an increase in the activity of enzymes that loosen cell walls contributing to the

death of the plant. In addition, dicamba, at low concentrations increases RNA, DNA, and

protein synthesis which leads to uncontrolled cell division and growth. Conversely, at

high concentrations, dicamba inhibits cell division and growth (WSSA, Herbicide

Handbook, 1994).

Dicamba readily penetrates plant leaves, roots, and stems, but apparently not as

rapidly as the phenoxyacetic acids such as 2,4 - D. Residues of dicamba on treated plants

can disappear through exudation from the roots into the surrounding soil, metabolism

within the plant, or by loss from leaf surfaces (WSSA, Herbicide Handbook, 1994).

Dicamba is considered to be only slightly volatile from leaf surfaces, therefore, loss of

dicamba via volatilization is probably minimal (Howard, 1991).

Dicamba is slightly toxic by ingestion and slightly toxic by inhalation or dermal

exposure. Dicamba has an acute oral toxicity (LDso) of 1707 mg kg-1 in rats and an acute

dermal toxicity (LDso) greater than 2000 mg kg-1 in rabbits. Evidence suggests that

dicamba is not teratogenic, mutagenic, or carcinogenic, and is unlikely to cause

reproductive effects in humans. Furthermore, evidence suggests that dicamba does not

7

bioaccumulate in mammalian tissue (EXTOXNET, 1996). The oral reference dose (RID)

value for dicamba is 3E-2 mg/kg/day (EP A, 1997).

2,4 -D

2,4 - D is a herbicide extensively used to control a number of broad leaf weeds. Its

effect on plants is quite similar to that of dicamba. Like dicamba, 2,4 - D, at low

concentrations leads to uncontrollable growth and cell division of the plant. At high

concentrations, 2,4 - D inhibits cell division and growth (WSSA, Herbicide Handbook,

1994).

2,4 - D is rapidly taken up by the plant through leaves, stems, and roots. Minor

losses of2,4 - D can be attributed to photodegradation. In addition, minor losses of both

the acid and salt forms of2,4 - D by volatilization occur. The isooctyl and butoxyethyl

ester formulations are considered to be low-volatile esters. Oil-soluble amines are

considered least volatile (WSSA, Herbicide Handbook, 1994).

The acid form of2,4 - D is of slight to moderate toxicity. The acute oral toxicity

(LDso) of2,4 - D ranges from 375 to 666 mg kg-l in rats (EXTOXNET, 1996). The acute

dermal toxicity (LDso) of2,4 - D in rabbits is greater than 2000 mg kg-1 for the acid, 1122

mg kg-1 for the salt, and greater than 5000 mg kg-1 for the isootcyl ester (WSSA,

Herbicide Handbook, 1994). The oral RID value for 2,4 - D is 3K3 mg/kg/day (EPA,

1997). Reproductive, teratogenic, and mutagenic problems associated with 2,4 - D in

humans under normal circumstances are unlikely. The carcinogenic status of2,4 - D is not

clear (EXTOXNET, 1996).

8

Isazofos

Isazofos is an organophosphate insecticide and nematicide. Isazofos acts primarily

as an acetylcholinesterase inhibitor.

Isazofos is considered to be moderately toxic by both oral ingestion and dermal

absorption. The acute oral toxicity (LDso) ofisazofos in rats ranges from 60 (females) to

295 (males) mg kg-I. The acute dermal toxicity (LDso) ofisazofos in rabbits is 1080 mg

kg-I. Based on the acute oral LDso in rats, ingestion of one tablespoon of Triumph 4E (the

product containing isazofos as its active ingredient) may be fatal to an adult human

(MSDS, 1991). The oral RID value for isazofos is 2E-s mg/kg/day (EP A, 1997).

CWorpyrifos

Chlorpyrifos is a broad-spectrum organophosphate insecticide frequently used on

golf courses. Chlorpyrifos acts primarily as a contact poison, with some action as a

stomach poison. It is classified as a General Use Pesticide (GUP) (EXTOXNET, 1996).

CWorpyrifos is moderately toxic to humans. Chlorpyrifos poisoning may affect the

central nervous system, the cardiovascular system, and the respiratory system. The acute

oral toxicity (LDso) of chlorpyrifos in rats is 95 to 270 mg kg-I. The acute dermal toxicity

(LDso) is greater than 2000 mg kg-I in rats, and 1000 to 2000 mg kg-I in rabbits

(EXTOXNET, 1996). The oral RID value is 3E-3 mg/kg/day (EPA, 1997). Current

evidence suggests that chlorpyrifos is not teratogenic, mutagenic, carcinogenic, and does

not adversely affect reproduction (EXTOXNET, 1996).

Fenamiphos

Fenamiphos is an organophosphate nematicide used to control a wide variety of

9

nematode (roundworm) pests. Fenamiphos blocks the enzyme acetylcholinesterase in the

target pest. Products containing fenamiphos must carry the signal word DANGER on

their labels (EXTOXNET, 1996).

Fenamiphos is highly toxic. The acute oral toxicity (LDso) offenamiphos is 2 to 19

mg kg-1 in rats and 56 to 100 mg kg-1 in guinea pigs. The acute dermal toxicity (LDso) is

72 to 154 mg kg-1 (EXTOXNET, 1996). The oral RID value offenarniphos is 2.5E-4

mg/kg/day (EP A, 1997). Current evidence suggests that fenamiphos would not cause

reproductive, teratogenic, mutagenic, and carcinogenic effects in humans (EXTOXNET,

1996).

CHAPTER IIMATERIALS AND METHODS

Chemicals

Analytical Standards

Chlorpyrifos (0,0-diethyl-0-3,5,6-trichlor-2-pyridyl-phosphorothioat), 99% pure,

and fenamiphos (ethyl-4-methythio-3 -methylphenyl-iso-propylphosphoramidat), 98%

pure, were obtained from Riedel-De Haen (Seelze-Hannover, Germany). Isazofos (0-5-

chloro-I-methylethyl I-I H-I ,2, 4-triazol-3 -yl 0,O-diethylphosphorothioate), 46.8% pure,

was obtained from Ciba Geigy Corp. (Greensboro, NC). Dimethylamine salt of dicamba

(3,6 dichloro-O-anisic acid), 48.2% pure, was provided by Sandoz Agro Inc. (Des Plaines,

IL). Dimethylamine salt of2,4 - Dichlorophenoxyacetic acid, 46.70% pure, was obtained

from LESCO Inc. (Rocky River, OH).

Analytical standards ofisazofos, dicamba, and 2,4 - 0 were derived from the

commercially available technical formulations which were also used in the field studies.

Formulations

Commercial pesticide formulations applied during the study were: Truimph 4E,

46.8% isazofos active ingredient (Ciba Geigy Corp., Greensboro, NC); Banvel, 48.2%

dimethylamine salt of dicamba active ingredient (Sandoz Agro Inc., Des Plaines, IL);

Nemacur 3,35% fenamiphos active ingredient (Bayer Corp., Kansas City, MO); Dursban,

44.9% chlorpyrifos active ingredient (DowElanco, Indianapolis, IN); A - 4D Herbicide,

10

11

46.70% dimethylamine salt of2,4 - dichlorophenoxyacetic acid active ingredient (LESCO,

Inc., Rocky River, OH).

Solvents and Reagents

All solvents were purchased from Fisher Scientific Company (Springfield, NJ);

diethyl ether, methylene chloride (MeCI2), hexane, and methanol (MeOH). Sodium

hydroxide (NaOH), sodium chloride (NaCl), and sulfuric acid (H2S04) were purchased

from Fisher (Springfield, NJ). MNNG (l-methyl-3-nitro-I-nitrosoguanidine), 97%, was

obtained from Aldrich Chern. Co. (Milwaukee, WI).

Method Development

Laboratory Recoveries of Pesticides

Cheesecloth (American Fiber & Finishing, Inc., Burlingtion, MA), cotton fabric,

leather, grips, and golf balls were used to dislodge pesticide residues. In order to

determine extraction efficiency, the materials were fortified with standards of each

compound and extracted with the appropriate organic solvent. For purposes of

quantification, untreated materials were extracted and analyzed. Co-extractants that

interfered with pesticides of interest were removed via cleanup steps included in each

extraction method.

2,4 - DlDicamba

HexanelEther was used to extract 2,4 - D and dicamba from cheesecloth, cotton

fabric, and golf balls. Each sample was shaken, in the same glass jar that it had been

placed during sampling, with a solution of90 rnL of water and 10 rnL of IN NaOH for 30

min and then decanted into a 1000 rnL flask. The extraction procedure was repeated three

12

times per sample. From the combined sample, 100 mL was decanted into a 200 mL screw

cap bottle, and 35g NaCl were added. The aliquot was then extracted two times with

hexane/ether solution to remove co-extractants. The hexane/ether phase was discarded.

Following the removal of co-extract ants, the sample was acidifyed using 5 mL of2.88N

H2S04. The acidifyed sample was then extracted three times with 50 mL hexane/ether.

The extract was then evaporated using a rotary evaporator. The pesticides in the

concentrate were then derivitized into their methyl ester form using diazomethane in ether.

Diazomethane was generated in the laboratory without distillation following a laboratory

technique described by Aldrich (Aldrich 1998). The derivitized pesticide concentrate was

increased to a final volume of 10 mL using hexane and decanted into a crimp top vial.

lsazofos/Chlorpyrifos/F enamiphos

Methylene chloride was used to extract isazofos, chlorpyrifos, and fenamiphos

from cheesecloth, cotton fabric, and golf balls. Each sample was shaken, in the same glass

jar that it had been placed during sampling, with ISO mL of methylene chloride for IS min

and then decanted into a 500 mL round-bottom evaporation flask. This procedure was

repeated three times per sample. The solvent extracts were concentrated using a rotary-

evaporator. The pesticide concentrate was increased to a final volume of 10 mL using

methylene chloride and decanted into a crimp top vial.

Due to the presence of co-extractants that result from the direct extraction of

leather and grips with methylene chloride, a modification of the methylene chloride

method described above was necessary for the extraction of isazofos, chlorpyrifos, and

fenamiphos from leather and golf grips to avoid interference with pesticide resolution. An

13

extracting solution comprised of methanol, water, and sulfuric acid was developed. The

extracting solution (150 mL) was added to the jar containing the sample. The sample was

shaken for 30 min and the extracting solution was decanted through a Buchner funnel into

a 500 mL filter flask. The extraction procedure was repeated three times. Solvent

extracts were transfered to alL separatory funnel. Deionized water (200 mL) and

sodium cWoride (60 g) were then added to the separatory funnel and shaken. Methylene

chloride (100 mL) was then added to the separatory funnel and shaken for approximately

2 min. Following shaking, the separatory funnel was placed on a holder allowing the

aqueous and organic phases to separate. The methylene chloride phase was drained into a

250 mL bottle. The extracting procedure was repeated three times. Prior to the transfer

of the solvent extract from the 250 mL bottle to a round-bottom evaporation flask, sodium

chloride (15 g) was added and stirred for approximately 3-5 min. Addition of sodium

cWoride helped to prevent the possible transfer of water to the round-bottom evaporation

flask, thus significantly decreasing the time required to concentrate the extract solution.

Solvent extracts were concentrated using a rotary-evaporator. Pesticide concentrate was

increased to a final volume of 10 mL using methylene chloride and decanted into a crimp

top vial.

Experimental Site

Putting Green

Part of the study was conducted on a 'Tifgreen'/'Tifdwarf bermudagrass

(Cynodon dactylon L. Xc. transvaalensis Davy-Burt) United States Golf Course

Association (USGA) putting green located at the University of Florida's Ft. Lauderdale

14

Research and Education Center (FLREC). The putting green consisted of two sections:

1.) Three-quarters 'Tifdwarf 2.) One-quarter 'Tifgreen'. Both sections were utilized in

this study. The putting green was maintained at 5mm cutting height. Maintenance of the

putting green was similar to that of putting greens located at golf courses throughout

Florida; mowing every morning (except during experimental sampling periods), and

watering and pesticide application (i.e., pesticides of non-interest to this study) as needed.

In order to determine and compare dislodgeable residues from over seeded and

non-over seeded bermudagrass, five 1 x 12 m plots randomized with five non-overseeded

plots were overseeded with rough stalk bluegrass cv.(Poa trivia/is L.) "Cypress" on

January 9, 1997, at a rate of 45 g m-2 and maintained as described above.

Rough

In order to determine dislodgeable residues from a club face (chip and wipe), part

of the study was conducted on a 'Tifway' (Cynodon dactylon L. Xc. tranvaalensis)

bermudagrass rough located adjacent to the USGA putting described above. This area

was maintained at a height of8.5 em. This area was mowed three times a week; water

and pesticide applications (i.e., pesticides of non-interest to this study) were made as

needed.

Application of Pesticides to Turfgrass

All pesticide applications were carried out using aIm width, two nozzle, CO2

backpack sprayer at approximately 30 psi. Applications were made using labeled rates

Total application time never exceeded 15 min.

15

2.4 - D/Dicamba

On the morning of 11 March 1997, 2,4 - D and dicamba were applied at the

following rates: 2,4 - D = 0.058 g a.i. m-2 and dicamba = 0.006 g a.i. m-2 Additional

studies were conducted on 29 - 30 January 1998, 5 - 6 March 1998, and 7 - 8 April 1998

using the same application rates.

Isazofos/CWorpyrifos/F enamiphos

On 3 June 1997, isazophos, chlorpyrifos, and fenamiphos were applied at the

following rates: isazophos = 0.229 g a.i. m-2, chlorpyrifos = 0.229 g a.i. m-2

, fenamiphos =

1.125g a.i. m-2 On 29 October 1997 these pesticides were reapplied at the same rate in

order to conduct additional sampling.

Sample Collection

Several methods of sampling were used in determining dislodgeable residues: I.)

Damp cheesecloth wipe, 2.) Damp cotton cloth press, 3.) Damp leather press, 4.) Golfball

putt,S.) Golf grip roll, 6.) Chip and wipe 1, and 7.) Chip and wipe 11. Each method was

replicated five times for a given sampling time. The areas sampled were marked with

orange-spray paint to prevent overlapping of sampling areas. Samples were placed into

glass jars following collection and immediately stored at -20 C until extraction.

Damp Cheesecloth Wipe

The damp cheesecloth wipe method was executed by firmly wiping a dampened

piece of cheesecloth four times in four directions over an area of the plot demarcated by a

template. This area was 625 cm2 on 11 - 12 March 1997, and 603 cm2 for wipes

conducted on 3 - 4 June 1997,29 - 30 October 1997, 29 - 30 January 1998, and 5-6

16

March 1998. The cheesecloth was held firmly in place using an aluminum holder. A 10 x

10 cm piece of aluminum foil was placed between the cheesecloth and the holder reducing

possible transfer of pesticide onto the holder which could lead to the contamination of

subsequent cheesecloth samples. Both the cheesecloth and aluminum foil were placed in

the glass sampling jar. The cheesecloth as well as the aluminum holder were lOx 20 cm.

Damp Cotton Press

The damp cotton press method was executed by placing a lOx 10 cm piece of

damp cotton on the turf surface overlaid by a 10.5 kg weight for 30 sec.

Damp Leather Press

The damp leather press method was executed by placing lOx 10 cm piece of damp

leather on the turf surface overlaid by a 10.5 kg weight for 30 sec.

Golf Ball Putt

The golf ball putt method was executed by putting a golf ball 36 times over a .5 x

4 m area of the putting green. This method was only conducted on non-overseeded

bermudagrass.

Golf Grip Roll

The golf grip roll method was executed by placing and rolling (three revolutions) a

standard size rubber, golf grip on the turf surface. A metal rod (0.218 kg) was inserted

into the grip to insure firm contact with the turf and to allow the grip to be rolled and

transported without being touched.

Chip and Wipe I

The chip and wipe I method was executed by swinging the golf club (pitching

17

wedge) in such a manner so that the club face made contact with the blades of turf without

penetrating the soil surface. The club was swung five times over a new area of turf each

time. After each swing, the club face and back was wiped with a single, damp piece of

cheesecloth. No attempt was made to remove any blades of turf which may have become

attached to the club face and back while swinging before wiping with cheesecloth. Five

swings constituted one replication of which there were five.

Chip and Wipe II

On 29 - 30 October 1997 a second version of the chip and wipe method was

conducted in conjuction with the chip and wipe I method described above. In this second

version, one swing constituted a replication rather than five.

Experiments

11 - 12 March 1997

This study was conducted over two days beginning on the morning of 11 March

1997 and ending on the morning of 12 March 1997. Dislodgeability samples were taken

from the' Tifgreen' section of the USGA putting green. There were 10 1 x 12 m plots;

five overseeded and five that were not overseeded. Plots were treated with 2,4 - 0 and

dicamba at 9:25 a.ill. (ambient temperature 24C; calm conditions). Dislodgeability

samples were taken from randomly selected, undisturbed locations on each plot. See

Table 1 for sampling schedule and methods.

3 - 4 June 1997

Dislodgeability samples were taken over a two day period beginning on 3 June

1997 and ending on 4 June 1997. The samples were taken from the 'Tifgreen' section.

18

There were five 1 x 12 m plots. Isazofos, chlorpyrifos, and fenamiphos were applied at

1:00 p.m. (ambient temperature 32C; calm conditions). Following the first set of

samplings, approximately 0.34 em of irrigation was applied. Samples were taken from

randomly selected, undisturbed locations on each plot. See Table 2 for sampling schedule

and methods.

29 - 30 October 1997

On 29 - 30 October 1997, additional sampling was conducted to further determine

dislodgeable residues of pesticides between zero and three hours after application. In

addition, the chip and wipe II method was conducted to quantifY the residues dislodged by

just one golf swing. Dislodgeability samples were taken from the 'Tifdwarf section. The

pesticides were applied at 10:55 a.m. (ambient temperature 21C; calm conditions). A

single 1 x 6 m experimental area was utilized. Samples were taken from randomly chosen,

undisturbed locations within the treated area. Immediately following the first set of

sampling, approximately 0.34 em of irrigation was applied to the experimental site. See

Table 3 for sampling schedule and methods.

29 - 30 January 1998

2,4 D and dicamba were applied to the 'Tifdwarf section at the previously

described rates. The application was made at 9:25 a.m. (ambient temperature 18C; calm

conditions). The sampling area was 1 x 7 m. Five replicate samples were taken from

randomly chosen areas using the damp cheesecloth method. The sampling area was

applied with 0.34 em of irrigation the next day before sampling and sampled after the

turf grass was allowed to dry. See table 4 for sampling schedule and method.

19

5 - 6 March 1998

2,4 - D and dicamba were applied to the 'Tifgreen' section at the previously

described rates. A single 1 x 12 m area was used for sampling. At 12:00 p.m. (ambient

temperature 24 C; wind 3 - 7 mph) the pesticides were applied. Five replicate samples

were taken from randomly chosen areas on the plot. Approximately 0.34 cm of irrigation

was applied the following day prior to sampling. See Table 5 for sampling schedule and

method.

7 - 8 April 1998

2,4 - D and dicamba were applied to the 'Tifgreen' section at the previously

described rates. The application was made at 8:50 a.m.(ambient temperature 23C; 5 - 10

mph wind) to four 1 x 12 m plots. Fifteen randomly chosen areas, upon which the golf

ball putting occurred, were marked prior to application. The areas remaining were used

for random sampling via the other methods. Irrigation ( 0.34 cm) was applied on the

morning of 8 April 1998 prior to sampling. See Table 6 for sampling schedule and

method.

Instrumentation

Isazofos/Chlorpyrifos/F enamiphos

The extracted solvent was analyzed by HP 5890 - A series II gas chromatography

with a 10 m x .53 mm, HP - 5 cross linked 5% phenolmethyl silicon capillary column, and

a flame photometric detector. Sample solutions and appropriate standards were injected

using the following instrument parameters: pressure 20 psi; oven temperature 180 - 225 C

@ 10 degrees per minute; injector temperature 200 C; detector temperature 250 C; helium

20

carrier gas flow rate 15 mL/min; oncolumn injection of IuL sample-I; retention time

isazofos = 0.777 min, chlorpyrofos = 1.165 min, and fenamiphos = 2.224 min. The

detection limit was 0.1 ug sample-I for all pesticides.

2,4 - DlDicamba

The extracted solvent was analyzed by HP 5890 series II gas chromatography with

a 20 m x 0.53 mm, HP - 5 cross linked 5% phenolmethyl silicon capillary column, and an

electron capture detector. Sample solutions and appropriate standards were injected using

the following instrument parameters: pressure 20 psi; oven temperature 180 C; injector

temperature 175 C; detector temperature 300 C; helium carrier gas flow rate 15 mL/min;

oncolumn injection of 1 uL sample-I; retention time 2,4 - D = 2.52 min and dicamba =

1.81 min. The detection limit of2,4 - D and dicamba was 0.1 ug/sample.

CHAPTER IIIRESULTS

Method Verification

Recoveries of pesticides from cheesecloth, cotton, leather, golf balls, and golf grips

were determined prior to the extraction of field samples. The GC analysis of all solvent

and blanks resulted in chromatograms with no interferences at the retention times of

interest, except for the determination of2,4-0 and dicamba from leather and golf grips

which, due to presence of GC detectable co-extractants, contained interfering peaks. An

extraction procedure for the recovery of2,4-0 and dicamba from leather and golf grips

could not be developed during the course of this study.

2.4-0

Recovery of2,4 - D using hexane/ether from cheesecloth, cotton fabric, and golf

balls materials was not less than 95 %.

Oicamba

Recovery of dicamba using hexane/ether from cheesecloth, cotton fabric, and golf

balls materials was not less than 95%.

Isazofos

Recovery of isazofos using methylene chloride from cheesecloth, cotton fabric, and

golf balls was not less than 95%. Methylene cWoride proved to be too strong of a solvent

for the extraction of isazofos from leather and golf grips, extracting a number of co-

21

22

extractants that interfered with the peaks of interest. The extracting solution used in place

of methylene cWoride was comprised of methanol, water, and sulfuric acid recovered not

less than 93% of the isazofos applied to both leather and golf grips.

CWorpyrifos

Methylene chloride recovered not less than 95% of the applied chlorpyrifos from

cheesecloth, cotton fabric, and golfballs. The extracting solution described above was

used for the extraction of chlorpyrifos from leather and golf grips due to the presence of

co-extractants resulting from the extraction of leather and golf grips with methylene

chloride. The extracting solution recovered not less than 80% of the applied chlorpyrifos.

Fenarniphos

Methylene cWoride recovered not less than 96% of the fenamiphos applied to

cheesecloth, cotton fabric, and golf balls. The extracting solution used in place of

metWyene chloride for the extraction ofleather and golf grips recovered not less than 93%

of the applied fenamiphos.

Data Modification

Concentration Correction

The percent recovery of cWorpyrifos from leather and golf grips as cited above in

the method verification section was used to adjust the amount of cWorpyrifos recovered

from leather and golf grips. For instance, the quantity of cWorpyrifos as determined by the

GC is adjusted using the percent recovery of chlorpyrifos from leather and golf grips in

Eq. [1].

0.37 ug / 0.80 = 0.46 ug on leather [1]

23

CWorpyrifos was the only analyte adjusted due to the effective extraction of the pesticides

of interest using the extraction procedures described in the methods and materials section.

Comparison of Dislodge ability Methods

The area wiped with damp cheesecloth was 625 cm2 for the study conducted on

3 - 4 March 1997 and 603 cm2 for ensuing studies. The sampling areas for the damp

cotton press and the damp leather press were 100 cm2. Dislodgeable residues recovered

by the damp cheesecloth wipe method were converted to ug/l00 cm2 for purposes of

statistically comparing each dislodgeability method by area.

Damp Cheesecloth Wipe Method: 18.21 ug/625 cm2 = 2.91 ug/IOO cm2 [2]

Damp Cheesecloth Wipe Method: 295.34 ug/603 cm2 = 48.98 ug/l00 cm2 [3]

Experimental Results

2A-D

3 - 4 March 1997

No difference (P<0.05) in the quantity of dislodgeable residues of2,4-D was found

between 'Tifgreen' bermudagrass and 'Tifgreen' bermudagrass overseeded with poa

trivia/is (Table 7). Since no statistical difference was found all dislodgeable residues of

2,4 - D were averaged across both grasses.

Residues dislodged by the damp cheesecloth wipe decreased from day 1 to day 2

(Table 8). At 2 h after application approximately 12.2% ofthe applied 2,4 - D was

recovered as dislodgeable residues. Residues measured 4 h after application decreased by

7%. Only 3% as much residue was recovered at 24 h after application as were recovered

at 2 h.

24

Dislodgeable residues recovered by the damp cotton press decreased with time

(Table 9). Dislodgeable residues of2,4 - D were greatest 2 h after application when 13%

of the applied 2,4 - D was recovered. Residues dissipated by 13% 4 h after application.

At 24 h after application 40 ug m-2 were dislodged by the damp cotton press method.

Dislodgeable residues measured by the golfball putt method were variable over the

course of the 25.5 h sampling period (Table 10). Residues 2 h after application were 1.09

ug sample-I. Residues measured 4.5 h after application decreased to less than 1 ug

sample-I. Residues measured 25.5 h after application (0.77 ug sample-I) were on average

greater than residues at 4.5 h, however, a standard deviation of 1.03 was noted.

The chip and wipe method I sampling was conducted 3, 5, and 25.5 h following

application. Dislodgeable residues were greatest 5 h after application and declined to 0.32

ug sample-I 25.5 h after application (Table 11).

There were no differences (P <0.05) in the dislodgeability of2,4-D between the

damp cheesecloth wipe and damp cotton press methods (equal area basis) from 'Tifgreen'

bermudagrass and 'Tifgreen' bermudagrass overseeded with poa trivialis (Table 7).

29 - 30 January 1998

Dislodgeable residues were the greatest 5 min. following application when 14.2%

ofthe applied pesticide was recovered (Table 12). Residues decreased to 5271.64 ug m-2

(9.1%) and 6534.33 (11.3%) at 4 hand 7 h after application respectively. 2,4 - D residues

measured 3517.91 ug m-2 24 h after application and dropped to 527.86 ug m-2 26 h after

application due to a scheduled irrigation event.

25

5 - 6 March 1998

Dislodgeable residues of2,4 - D using the damp cheesecloth wipe method were at

a maximum 13 min. post - application and decreased with time (Table 13). Residues

measured at 4 and 26.5 h after application were 1193.37 ug m-2 and 84.91 ug m-2

respectively.

Dislodgeable residues of 2,4 - D as determined by the damp cotton press were

greatest 25 min. following application and diminished with time (Table 14). Residues

dissipated to 2410 ug m-2 4 h after application and 434 ug m-2 26.75 h after application.

7 - 8 April 1998

The golfball putt residues of 2,4 - D recovered 5 min. after application averaged

4.89 ug sample-I. Residues taken 4 h after application increased to 6.04 ug sample-I.

Residues 24 h following application decreased averaging 3.62 ug sample-I. Table 15

displays the means and standard deviations of the pesticide dislodged for each sampling

period.

Dislodgeable residues as determined by the chip and wipe method Iprocedure

were greatest 35 min. after application and decreased with time (Table 16). Residues 4.5

and 24.5 h after application were 39.35 and 15.02 ug sample-1 respectively.

Dicamba

3 - 4 March 1997

No difference (P < 0.05) in the amount of dislodgeable residues of dicamba were

found between 'Tifgreen' bermudagrass and 'Tifgreen' bermudagrass overseeded with

26

poa trivialis (Table 7). Since no difference was found, dislodgeable residues of dicamba

were averaged across both grasses.

Dislodgeable residues of dicamba as determined by the damp cheesecloth wipe

differed little at 2 and 4 h after application decreasing 93% 24.5 h after application (Table

17). Maximum residue recovery occurred 4 h post - application (15.60 %).

The damp cotton press dislodged the greatest quantity of residues 2 h after

application (891 ug -Z) with residues decreasing over time (Table 18). Residues recovered

25 h after application were only 1.40% of applied.

Dicamba residues on golf balls decreased with time after application (Table 19).

Peak residues determined 2.5 h post - application averaged 2.42 ug sample-i.

Dislodgeable residues of dicamba as determined by the chip and wipe method I

varied with time (Table 20). Maximum residue recovery was obtained 5 h after

application.

An ANOV A of the damp cheesecloth wipe and the damp cotton press on an equal

area basis revealed a method by time interaction (Table 7). Dislodgeable residues of

dicamba measured by the damp cheesecloth wipe were greater than those of the damp

cotton press only at 4 h after application (Table 21).

29 - 30 January 1998

Dislodgeable residues of dicamba measured using the damp cheesecloth wipe were

highest 5 min. after application (858.71 ug m-Z)with residues decreasing thereafter (Table

22). At 24 h after application dicamba residues dissipated to 321.39 ug m-z. Following a

27

scheduled irrigation event, dicamba residues increased 2.4% between 24 and 26 h after

application.

5 - 6 March 1998

Dislodgeable Residues of dicamba decreased over time as determined by the damp

cheesecloth wipe method (Table 23). Residues were greatest 13 min. after application

with 9.80% of the applied dicamba recovered. By 26.5 h after application less than 1 % of

the dicamba applied was recovered.

The damp cotton press method conducted 25 min. after application dislodged 593

ug m-2 (Table 24). Residues decreased over time with 2.00% of the applied dicamba

dislodged 26.75 h after application.

7 - 8 April 1998

Residues of dicamba dislodged by the golfball putt method decreased over time

(Table 25). Residues recovered 5 min. post - application averaged less than 1 ug sample-I.

Residues recovered on the club face and back using the chip and wipe method I

decreased over time (Table 26). At 35 min. after application dicamba residues averaged

41.53 ug sample-I. Dicamba residues dislodged 4.5 h after application were 91.4 % less

than those recovered 35 min. after application. By 24.5 h after application, dicamba

residues averaged less than 2 ug sample-I.

Isazofos

3 - 4 June 1997

Isazofos residues dislodged by damp cheesecloth 15 min. after application

averaged 3216.25 ug m-2. Isazofos residues decreased 94% following a scheduled

28

irrigation event and an additional 2.5 h of elapsed time (Table 27). At 19.5 h after

application residues averaged 51.58 ug m-2 or 0.02 % of the isazofos applied.

Isazofos residues dislodged by damp cotton decreased over time (Table 28). At 20

min. after application less than 1% of the applied isazofos was recovered. An irrigation

event occurred prior to sampling at 3.5 h after application decreasing residues dislodged at

20 min. by 94%. Recovery ofisazofos residues 19.5 h after application was 0.03%.

Isazofos residues removed by damp leather decreased from 3.75 to 19.75 h

following application (Table 29). Residues dislodged at 35 min. after application were not

available due to an error during extraction of the 35 min. samples.

Isazofos residues recovered from golf balls decreased after irrigation and over time

(Table 30). Isazofos residues dissipated 88% between 42 min. and 4 h after application.

By 20 h after application isazofos residues recovered were less than 0.5 ug sample-I.

Isazofos residues dislodged by golf grips were only recovered 1.24 h after

application (Table 31). At times 4.5 and 20.25 h after application no residues or an

undetectable amount of residues were dislodged.

Isazofos residues dislodged by a golf club head varied little over time (Table 32).

Residues recovered were greatest 4.5 h after application (5.81 ug sample-I). Residues

were lowest 20.5 h after application (3.83 ug sample-I).

There was no difference (P < 0.05) in the quantity ofisazofos dislodged between

the damp cheesecloth wipe and the damp cotton press (Table33, Table 34). However, the

effect of method was significant (P < 0.05) when the damp cheesecloth wipe, damp cotton

press, and damp leather press were compared on an equal area basis at 3.75 and 19.5 h

29

after application (Table 35). Damp leather dislodged 38% and 62% more isazofos than

damp cheesecloth and damp cotton 3.75 h after application (Table 36).

29 - 30 October 1997

Dislodgeable residues of isazofos decreased over time as determined by the chip

and wipe method I procedure (Table 37). Residues recovered 35 min. post - application

dissipated by 65% and 88% at 4 and 25 h after application.

Isazofos residues also decreased over time using the chip and wipe method II

procedure (Table 38). At 22 min. post - application residues averaged 33.33 ug sample-I

A 90% reduction in residues was measured 3.5 h after application.

CWorpyrifos

3 - 4 June 1997

Residues of chlorpyrifos dislodged using damp cheesecloth decreased over time

(Table 39). An irrigation event occurring between the 15 min. and 2.75 h sampling

periods likely contributed to the dissipation of chlorpyrifos residues. A 95% reduction in

residues occurred within this time frame. At 19.5 h after application, 0.01% of the

applied chlorpyrifos was recovered.

Dislodgeable residues of chlorpyrifos decreased over time as measured using the

damp cotton press procedure (Table 40). Residues decreased by 94% between the 20

min. and 3.5 h sampling periods. Again, irrigation most likely helped to diminish

chlorpyrifos residues. A 96% reduction in dislodgeable residues had occurred 19.5 h after

application.

30

A determination of residues dislodged by damp leather 35 min. after application is

not shown because of a mistake occurring during the extraction of time I samples as

previously noted. However, a decrease in residues was observed between 3.75 and 19.75

h after application (Table 41).

Chlorpyrifos residues on golfballs decreased over time (Table 42). An irrigation

event occurring between the 42 min. and 4 h sampling period likely contributed to the

reduction in residues. At 20 h after application only 8% of the residues measured 42 min.

after application were recovered.

Chlorpyrifos residues on golf grips were only detected 1.25 h after application

(Table 43). An average ofless than 1 ug sample"l was detected.

Dislodgeable residues recovered by the chip and wipe method I procedure

fluctuated over time (Table 44). Residues were greatest and most variable 4.5 h after

application increasing 60% as compared to residues recovered 1.5 h after application.

Chlorpyrifos residues dislodged 20.5 h after application decreased 13.4% from residues at

4.5 h after application.

A method by time interaction was found between the damp cheesecloth wipe and

the damp cotton press (Table 33). On an equal area basis, residues dislodged by the damp

cheesecloth wipe were greater (P < 0.05) than residues dislodged by the damp cotton

press at 3.75 h after application (Table 45).

A method by time interaction was found between the damp cheesecloth wipe,

damp cotton press, and damp leather press when compared on an equal area basis at 3.75

and 19.50 h after application (Table 35). The damp cheesecloth wipe dislodged 56% and

31

87% more cWorpyrifos than the damp cotton press and the damp leather press 3.57 h after

application. There was no difference between the damp cheesecloth wipe and damp cotton

press 19.50 h after application. The damp leather press 19.5 h after application dislodged

significantly less cWorpyrifos than damp cheesecloth and damp cotton (Table 46).

29 - 30 October 1997

Dislodgeable residues of chlorpyrifos recovered via the chip and wipe method I

procedure decreased with time (Table 47). Residues 35 min. after application averaged

41.67 ug sample-I. A 72% decrease in residues occurred 4 h after application. By 25 h

after application cWorpyrifos residues had decreased by 80% from the 35 min sampling

period.

CWorpyrifos residues recovered by the chip and wipe method II procedure

decreased with time (Table 48). Dislodgeable residues averaged 28.97 ug sample-l 22

min. after application. Residues decreased 94% and 95% by 3.5 and 25 h respectively,

after application.

Fenamiphos

3 - 4 June 1997

Fenamiphos residues dislodged by damp cheesecloth decreased between 15 min.

and 2.75 h after application (Table 49). The large decrease was likely due to an irrigation

event occurring between sampling, with time after application possibly also a contributing

factor. Residues dislodged 19.5 h after application decreased almost 100% as compared

to residues recovered 15 min after application.

32

Fenamiphos residues recovered by the damp cotton press method decreased over

time with irrigation likely contributing to the dissipation in dislodgeable residues (Table

50). Residues decreased 96% from 20 min after application to 3.5 h after application. A

decrease of 99% from 20 min after application had occurred by 19.5 h after application.

Fenamiphos residues on damp leather decreased over time (Table 51). The damp

leather press at 3.75 h after application recovered only 0.03% of the fenamiphos applied.

Residues dislodged 19.5 h after application reduced 87% from residues recovered 3.75 h

after application.

Fenamiphos residues recovered from golf balls decreased over time and again

likely in part due to irrigation (Table 52). Irrigation likely contributed to the further

dissipation of residues as a 99% reduction in dislodgeable fenamiphos occurred between

42 min and 4 h after application; the period during which the irrigation event occurred.

By 20 h after application less than 0.1 ug sample-1 was detected.

Fenamiphos residues on golf grips were only detectable 1.25 and 20.25 h after

application (Table 53). Residues recovered 20.25 h after application were 93% less than

those residues recovered 1.25 h after application.

Dislodgeable residues of fenamiphos recovered from the chip and wipe method I

procedure on average decreased over time (Table 54). A 58% reduction in residues

occurred between 1.5 and 20.5 h after application.

A significant (P < 0.05) method by time interaction was found between the damp

cheesecloth wipe and the damp cotton press (Table 33). At 0.30 min and 3.75h after

application the damp cheesecloth wipe significantly dislodged a greater quantity of

33

fenamiphos residues than the damp cotton press. By 19.5 h after application no difference

was found between the two methods (Table 55).

A method by time interaction was found among damp cheesecloth, damp cotton,

and damp leather (Table 35) when compared on an equal area basis 3.75 and 19.50 h after

application. Damp cheesecloth dislodged a greater quantity of fenamiphos than damp

cotton and damp leather 3.75 h after application. There was no significance between the

damp cotton press and the damp leather press 3.75 h after application. There was no

significance between the three methods 19.5 h after application (Table 56).

29 - 30 October 1997

Fenamiphos residues dislodged by the chip and wipe method 1 procedure

decreased over time (Table 57). Dislodgeable residues decreased (60%) between 35 min

and 4 h after application. After 25 h a 92% decrease in fenamiphos residues from the 35

min sampling period had occurred.

Residues dislodged by the chip and wipe method II procedure decreased over time

(Table 58). An 84% decrease in fenamiphos residues occurred between 22 min and 3.5 h

after application. By 25 h after application, a 98% reduction occurred from the initial

sampling period.

Unfortunately, the pesticides if interest were not properly applied to the putting

green, therefore, only the chip and wipe methods were reported for this sampling period.

CHAPTER IVDISCUSSION

Dislodgeable Residues

In this study when irrigation was withheld until just prior to sampling 24 h after

application, dislodgeable residues of2,4 - D and dicamba remained relatively persistent

throughout the first day of sampling. However, upon further drying of the applied

material, dislodgeable residues of2,4 - D and dicamba tend to decrease slightly during the

first day the materials were initially applied. The reduction in dislodgeable residues of 2,4

- D and dicamba observed 24 h after application can most likely be attributed to wash-off

by irrigation supplied the next day prior to sampling. Similar observations have been

reported by Nishioka et. al. (1996) and Thompson et. al. (1984) who also saw appreciable

reductions of dislodgeable residues following irrigation and rainfall.

A maximum of only 14 and 15% of the 2,4 - 0 and dicamba applied was

recovered. In comparison, Thompson et. al (1984) recovered less than 4.5% of the 2,4 -

D applied at a rate ofO.01g m-2 Both findings suggest that a large fraction of the applied

pesticides are strongly adsorbed and absorbed by the plant since losses of2,4 - 0 and

dicamba by photo degradation and volatilization are minimal (Herbicide Handbook, 1994).

Surprisingly, no difference was found between the damp cheesecloth wipe and the

damp cotton press methods when compared on an equal area basis. A couple of factors

may have contributed to this finding. A large standard deviation may have masked any

34

35

differences between the two methods. In addition, the weight used in the damp cotton

press method (10.5 kg) may have provided sufficient force to dislodge a large fraction of

the pesticide applied.

Isazofos / Chlorpyrifos / Fenamiphos

Dislodgeable residues of all three organophosphate pesticides decreased rapidly.

The rapid decline of chlorpyrifos residues is in agreement with the findings of Goh et al.

(1986), Sears et al. (1987), and Murphy et al. (1996). Several factors may have

contributed to their rapid dissipation. Irrigation applied after application likely washed a

portion of the applied pesticides from the turf grass canopy into the soil and thatch. Over

time the pesticides are adsorbed and or absorbed by the plant. Finally, all three pesticides

have shown some degree of volatility (EXTOXNET, 1996). It should be noted that

isazofos and chlorpyrifos, which were applied at the same rates, dislodged similar levels of

residues suggesting that within a particular class of pesticide, application rate and not the

pesticide is important.

The ability of each method to dislodge pesticide residues was particular to each

pesticide. No difference was found between the damp cheesecloth wipe and the damp

cotton press when compared on an equal area basis for isazofos with the exception of

sampling at 3.75 h after application. This lack of difference can likely be attributed to a

large standard deviation which masked any significance between the two methods. At

3.75 h after application the damp cheesecloth wipe dislodged more chlorpyrifos than the

damp cotton press indicating that wiping dislodges more chlorpyrifos residues than

pressing because of its more vigorous nature. The same trend was also seen with

36

fenamiphos where the damp cheesecloth wipe dislodged a greater quantity of residues than

the damp cotton press 0.30 and 3.75 h after application. The observation that there was

no difference between the damp cheesecloth wipe and damp cotton press for all three

pesticides 19.5 h after application can likely be attributed to the small quantity of

dislodgeable residues still remained at that point.

A comparison of the different methods, including damp leather, proved to be

interesting. Damp leather dislodged more isazofos at both 3.75 and 19.5 h after

application than damp cheesecloth and damp cotton indicating that isazofos has a greater

degree for the damp leather material than the damp cheesecloth and damp cotton. This

preference for damp leather may be in part due to the lipophilic nature of the isazofos

compound. This phenomenon was not seen with either chlorpyrifos or fenamiphos.