Pesticide Downward Movement in a Bermudagrass System Compared with Movement in a Fallow System.

(1)

Pesticide Downward

Movement in a Bermudagrass

System Compared with

Movement in a Fallow System

**H.D. Cummings*, J.B. Weber, R.B. Leidy, F.H. Yelverton,**

and R.L. Brandenburg

NCSU, Raleigh, NC

(2)

Introduction

• Previous studies have characterized

the downward movement of pesticides

in conventional till systems.

• If regulatory issues of pesticides are

based on downward movement of

(3)

Introduction

• In turf, pesticides are rarely applied to bare

soil.

• In turf, a lower fraction of pesticides reaches

soil.

• In turf, some pesticides are absorbed and

metabolized by plants (biological

degradation).

• Compared to agriculture, knowledge is

(4)

Introduction

• Managed bermudagrass systems are

stratified by pH.

• _{Thatch layers have high levels of organic}

matter.

• Organic matter and pH can influence some

movement of pesticides.

• Thatch layers contain diverse

microorganism populations.

• _{Nutrients and irrigation are applied at}

(5)

Objective

• _{To compare the}

downward

movement of

pesticides in a

bermudagrass

system to

(6)

Materials and Methods

• _{‘Tifway’ hybrid bermudagrass}

maintained at 1.9 cm at the Sandhills

Research Station near Pinehurst, NC

• _{Native soil (Candor sand) (sandy}

siliceous, thermic, Arenic Paleudult)

(7)

Materials and Methods

(continued)

• _{In early May 2001,}

half of the

bermudagrass area

(580 m

2 ) was sprayed

(8)

Materials and Methods

(continued)

• _{The area was tilled}

once.

• _{On May 25, 2001,}

the tilled ground

was fumigated

setting up a split

plot design (Turf

(9)

Materials and Methods

(continued)

• _{In June and August}

of 2001 and May

2002, a total of 40

soil column

lysimeters (91 cm

long x 15 cm in

diameter) were

(10)

Materials and Methods

(continued)

• _{Four herbicides}

• One insecticide

• _{Two replications}

• Applied in July when

turf was actively

growing and in

November when turf

was dormant in 2001

and 2002

Plot size:

2.3 m

2

470 L/ha

Insecticide

applied with

shaker can

Irrigated

with 1 cm of

water

(11)

Treatments

Common

Trade

Rate

Water

Solubility

_K

_oc

Name

(kg ai/ha)

(mg/L)

(mL/g)

Simazine

Princep

2.2

3.5

140 Imazaquin Image

0.56

60

20 Pronamide Kerb

1.7

15

800 Prodiamine Barricade

0.56

0.013 13,000

Fipronil

Chipco

(12)

Pesticide Classification

Simazine

Triazine

Weak base. Cationic

at low pH, binds to

clay and OM

Imazaquin

Imidazolinone Carboxy acid. Anionic

at high pH, binds to

OM at low pH

Pronamide

Amide

Nonionic. Binds weakly

to OM independent of

pH

Prodiamine

Dinitroaniline Nonionic. Binds

strongly to soil

(13)

Materials and Methods

(Continued)

• _{After 140 days, the soil}

column lysimeters were

harvested.

• _{The soil in the lysimeters}

was divided into 8 depth

increments.

• _{Turf tissue was collected}

by depth.

0 – 2 cm

2 – 4 cm

4 – 8 cm

8 – 15 cm

15 – 30 cm

30 – 45 cm

45 – 60 cm

60 – 91 cm

(14)

(15)

Materials and Methods

(Continued)

Sonication removes

adsorbed compounds

from soil (10 g soil).

Rotoevaporator

concentrates

(16)

Materials and Methods

(Continued)

Gas

chromatograph

(GC) separates the

compounds and

determines the

concentration of

the compound of

interest (TSD

(17)

Soil Organic Matter Profile of

Turf and Fallow Soil

525

o

_{C for 16 hours}

2.04 _1.89

1.69 1.89 1.68

1.21 1.20 _0.99 6.13

7.69

2.08 _1.98 _1.84

1.04 1.13 _0.97

0

2

4

6

8

10 0 - 2

2 - 4

4 - 8

8 - 15

15 - 30 30 - 45 45 - 60 60 - 90

Depth (cm)

O

rg

an

ic

m

at

te

r

(%

)

Fallow

Turf

(18)

Soil pH Profile of Bermudagrass

and Fallow Systems

0

1

2

3

4

5

6

7 0 - 2

2 - 4

4 - 8

8 - 15

15 - 30 30 - 45 45 - 60 60 - 90

Depth (cm)

p

H

Fallow

Turf

(19)

Simazine in Soil of Fallow and Turf

Systems after 140 Days of Summer

23 ₁₁

3

33

96

0

50

100

150

200

250

300 0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

Initial Concentration (ppb)

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 8,022 70 ND

Turf 7,735 ND ND

(20)

Simazine in Soil of Fallow and Turf

Systems after 140 Days of Summer

23 ₁₁

3

33

96

0

50

100

150

200

250

300 0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

Initial Concentration (ppb)

(2 days after application)

System 0 – 2 cm 2 – 4 cm 4 – 8 cm

Fallow 8,022 70 ND

Turf 7,735 ND ND

(21)

Simazine in Soil of Fallow and Turf

Systems after 140 Days of Summer

23 ₁₁

3

33

96

0

50

100

150

200

250

300 0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 8,022 70 ND

Turf 7,735 ND ND

(22)

Simazine in Soil of Fallow and Turf

Systems after 140 Days of Winter

112 ₉₀

23

46

238

5 1198

348

32

91

108 ₅₉

104

189

101

0

200

400

600

800 1000

1200

0 - 2

2 - 4

4 - 8

8 - 15 **

15 - 30

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(

µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 9,371 ND ND

Turf 13,369 1,119 ND

ND ND ND ND NA

*

(23)

Imazaquin in Soil of Fallow and Turf

Systems after 140 Days of Summer

83

19

18

24

0

50

100

150

200

250

300

350

400

450

500 0 - 2

2 - 4

4 - 8

8 -15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 259 148 141

Turf 558 400 26

ND ND ND _ND_ND_ND_ND ND ND ND

(24)

Imazaquin in Soil of Fallow and Turf

Systems after 140 Days of Winter

20

453

265

0

50

100

150

200

250

300

350

400

450

500 0 - 2

2 - 4

4 - 8

8 -15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 5,166 569 166

Turf 597 571 155

ND ND ND ND

(25)

Pronamide in Soil of Fallow and Turf

Systems after 140 Days of Summer

96

116

135

20

0

50

100

150

200

250

300

350

400 0 - 2

2 - 4

4 - 8

8 -15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 2,047 ND 70

Turf 3,616 199 ND

ND ND ND ND _ND_ND_ND_ND

(26)

Pronamide in Soil of Fallow and Turf

Systems after 140 Days of Winter

192

204

214

223

218

2

0

50

100

150

200

250

300

350

400 0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

_{Fallow yr 2}

Turf yr 1

Turf yr 2

Turf 4,556 441 ND

ND ND

ND ND ND ND ND ND ND ND

* Fallow year 2 different from Turf year 2.

(27)

Prodiamine in Soil of Fallow and Turf

Systems after 140 Days of Summer

285

16 1158

66

451

64

411

46 ₅

₉

23

0

200

400

600

800 1000

1200

1400

1600

1800

0 - 2

2- 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

System _{0 – 2 cm} _{2 – 4 cm} _{4 – 8 cm} Fallow 809 ND ND

Turf 2,055 ND ND

(28)

Prodiamine in Soil of Fallow and Turf

Systems after 140 Days of Winter

616

13 1083

134

14 1614

7

562

71 ₇

68

109

0

200

400

600

800 1000

1200

1400

1600

1800

0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

Turf 5,118 199 ND

(29)

Fipronil in Soil of Fallow and Turf

Systems after 140 Days of Summer

31

6.8

12

5.9

71

153

16

2.5

4.2

0

50

100

150

200

250

300 0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

Turf 61 ND ND

ND ND ND ND

(30)

Fipronil in Soil of Fallow and Turf

Systems after 140 Days of Winter

40

19

20 ₁₄

3

11

14

10

0

50

100

150

200

250

300 0 - 2

2 - 4

4 - 8

8 - 15

Depth (cm)

P

ar

ts

p

er

B

ill

io

n

(µ

g/

kg

)

Fallow yr 1

Fallow yr 2

Turf yr 1

Turf yr 2

Turf 29 ND ND

ND

(31)

Conclusion

• _{Initial concentrations (2 days) were greater in}

winter except for fipronil in the turf system.

• More movement and higher concentrations tended

to occur in winter (140 days) except for fipronil in

bermudagrass and imazaquin in fallow systems.

(32)

Conclusion

(continued)

• _{Simazine and imazaquin were detected at}

deeper depths and at greater concentrations in

the fallow system than bermudagrass system in

summer.

• _{Pronamide was detected at greater}

concentrations in the bermudagrass system (0-4

cm) than in the fallow system in summer;

however, pronamide was detected at deeper

depths and at greater concentrations in the

fallow system in winter.

• _{Prodiamine movement was not influenced by}

(33)

Conclusion

(continued)

• _{Fipronil was detected at greater}

concentrations in summer in the

bermudagrass system (0-4 cm) than

the fallow system; however, more

(34)

Summary

• Generally, more downward movement and

greater concentrations occurred in winter.

• In bermudagrass, pesticides tended to stay in

the thatch layer (0 – 4 cm).

• In fallow soil, pesticides tended distribute

more uniformly.

• To reduce the potential for leaching, apply

(35)

Final Conclusions

• _{Generally, more downward}

movement and greater pesticide

concentrations occurred in winter.

• _{In bermudagrass, pesticides tended}

to stay in the thatch layer (0 – 4 cm).

• _{In fallow soil, pesticides tended}

(36)

Final Conclusions

• _{Simazine is less likely to move to}

groundwater when applied to

actively growing bermudagrass.

• _{Fipronil can provide season-long}

control (120 day) by causing

(37)