Large-scale Hydrilla Control Projects

Dean Jones1, Jeremy Slade2, Michael Netherland3

1Osceola County Extension2Center for Aquatic and Invasive Plants - UF

3US Army Engineer Research and Development Center

Why Manage Hydrilla ?

• Provides Structure and Food– Hydrilla- same role as native plants– Clears up the water (clarity…not quality)– Does not produce toxins (e.g., golden algae)

• AVM hydrilla/Waterfowl deaths

• Often valued by Fishing & Hunting Communities– “ Fishing the Edge” “Ringneck duck buffet”

• Growth Rate and Ability to Occupy Vast Areas – Access, Flood Control, Fishery Mgmt.– Water Quality (dissolved oxygen, temp.)– “Just leave us a little”

Is there a right amount of an invasive plant ?

If so, then how do you maintain that level ?

Commonly Used Herbicides in Florida

Product Use Rate (ppm) Notes

Diquat (1958) 0.15 to 0.37 Short exposure requirement;

Turbidity impacts efficacy

Endothall (1960) 1.0 to 3.0 Key contact for Hydrilla; Combination Treatments

Fluridone (1986) 0.01 to 0.09Large-scale mgmt; hydrilla,

control can take 1 to 3 months

Imazamox (2008) 0.05 to 0.2 Growth Regulation of Hydrilla

Penoxsulam (2007) 0.01 to 0.09 Large-scale Hydrilla Mgmt.

Aquathol K (2 ppm)

• Kissimmee Chain

of Lakes– Tohopekaliga (Toho)

– Cypress

– Hatchineha

– Kissimmee

• Lake Jackson

• Lake Istokpoga

• Orange Lake

• Lake Seminole

• Twin Lakes

• Lakes Dexter & Woodruff

• Winter Park Chain– Virginia

– Osceola

– Mizell

– Maitland

– Minnehaha

Lake Toho 2008/09 - 7250 ac (32%)Toho 22,500 ac

Lake Toho 2009/10 - 3000 ac (13%)Toho 22,500 ac

Lake Cypress 2010 - 1745 ac (44%)Cypress 4,000 ac

Lake Hatchineha 2009 - 640 ac (10%)

12

34 5

67

Hatchineha 6,650 ac

Lake Kissimmee 2010 - 2300 ac (7%)Kissimmee 35,000 ac

Lake Jackson 2010 - 315 ac (32%)Jackson 1,000 ac

Aquathol K (1 ppm) + Galleon (20 ppb)

• Lake Tohopekaliga– Goblet’s Cove

– Cypress Cove

• Lake Kissimmee

• Orange Lake

• Lake Bumby

• Lake Haines

• Twin Lakes

• Lake Tracy

• Lake Smart

• Lake Maude

Aquathol K (1 ppm) + Clearcast (75 ppb)

• Lake Hatchineha

• Lake Cypress

• Lake Istokpoga

• Lake Jessie

• Lake Silver

Aquathol K + Reward

• Lochloosa Lake– 25-50 acre blocks

• 1 ppm + .370 ppm

• 2 ppm + .370 ppm

• 3 ppm + .370 ppm

• Orange Lake

• Lake Rousseau

Lochloosa 6,000 ac

Clearcast + Galleon

• Lake Eaton- 50 ppb + 5 ppb

• Lake Lawne- 75 ppb + 7 ppb

Lawne 156 acEaton 200 ac

Galleon (15-20 ppb)

• Cypress

• Tracy

• Hartridge

• Jackson

Cypress 4,000 ac

Tracy 136 ac

Large-Scale Herbicide Monitoring

• Fluridone Resistant Hydrilla (Arias et al. 2004)

• Evaluate other available herbicides for hydrilla control while documenting efficacy and longevity of large-scale applications

• Document impacts to non-target vegetation

Data Collection

• Herbicide Residues

• Water Quality

• Herbicide Selectivity – Hydrilla/Vallisneria Grids

• Herbicide Efficacy and Longevity – Fathometer Transects

• Plant Surveys

Lake Tohopekaliga

Herbicide Residues

End

otha

ll (m

g ae

/L)

0.0

0.2

0.4

0.6

0.8

1.0

1.2Trt 4 SurfaceTrt 4 MiddleTrt 4 Bottom

Collection Date

12/2

/09

12/3

/09

12/4

/09

12/6

/09

12/7

/09

12/8

/09

12/1

0/09

12/1

1/09

12/1

2/09

12/1

4/09

12/1

5/09

12/1

6/09

12/1

/09

12/5

/09

12/9

/09

12/1

3/09

12/1

7/09

End

otha

ll (m

g ae

/L)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Trt 5 SurfaceTrt 5 MiddleTrt 5 Bottom

45

Herbicide Residues

16

Collection Date

2/3/

10

2/4/

10

2/5/

10

2/7/

10

2/8/

10

2/9/

10

2/11

/10

2/12

/10

2/13

/10

2/15

/10

2/16

/10

2/17

/10

2/2/

10

2/6/

10

2/10

/10

2/14

/10

2/18

/10

End

otha

ll (m

g ae

/L)

0.0

0.5

1.0

1.5

2.0

2.5

3.0Ref 1 Ref 2 Ref 3 Ref 4 Ref 5 Ref 6 Ref 7

Collection Date

2/3/

10

2/4/

10

2/5/

10

2/7/

10

2/8/

10

2/9/

10

2/11

/10

2/12

/10

2/13

/10

2/15

/10

2/16

/10

2/17

/10

2/2/

10

2/6/

10

2/10

/10

2/14

/10

2/18

/10

End

otha

ll (m

g ae

/L)

0.0

0.5

1.0

1.5

2.0

2.5

3.0Trt 1 Trt 2 Trt 3 Trt 4 Trt 5

23

4

5

1

2

3

4

5

7

16

Water Quality

Collection Date12

/14/

08

12/1

6/08

12

/18/

08

12/2

0/08

12

/22/

08

12/2

4/08

12

/26/

08

12/2

8/08

12

/30/

08

1/1/

09

1/3/

09

1/5/

09

1/7/

09

1/9/

09

1/11

/09

1/

13/0

9

1/15

/09

1/

17/0

9

1/19

/09

1/

21/0

9

1/23

/09

1/

25/0

9

1/27

/09

1/

29/0

9

Dis

solv

ed O

xyge

n (m

g/L)

6

7

8

9

10

11

12

Collection Date

12/1

4/08

12

/16/

08

12/1

8/08

12

/20/

08

12/2

2/08

12

/24/

08

12/2

6/08

12

/28/

08

12/3

0/08

1/

1/09

1/

3/09

1/

5/09

1/

7/09

1/

9/09

1/

11/0

9

1/13

/09

1/

15/0

9

1/17

/09

1/

19/0

9

1/21

/09

1/

23/0

9

1/25

/09

1/

27/0

9

1/29

/09

Tem

pera

ture

(C)

10

12

14

16

18

20

22

Water Quality

Collection Date

12/17

/08

12/21

/08

12/25

/08

12/29

/08

1/2/09

12/15

/08

12/19

/08

12/23

/08

12/27

/08

12/31

/08

Trt 4 surface Trt 4 middepth Trt 4 bottom

Collection Date

12/17

/08

12/21

/08

12/25

/08

12/29

/08

1/2/09

12/15

/08

12/19

/08

12/23

/08

12/27

/08

12/31

/08

Tem

pera

ture

(C)

17

18

19

20

21

Trt 3 surface Trt 3 middepth Trt 3 bottom

Trt 2 surface Trt 2 middepth Trt 2 bottom

Tem

pera

ture

(C)

17

18

19

20

21

Trt 1 surface Trt 1 middepth Trt 1 bottom

Water Quality

Collection Date

12/17

/08

12/21

/08

12/25

/08

12/29

/08

1/2/09

12/15

/08

12/19

/08

12/23

/08

12/27

/08

12/31

/08

Trt 4 surface Trt 4 middepth Trt 4 bottom

Collection Date

12/17

/08

12/21

/08

12/25

/08

12/29

/08

1/2/09

12/15

/08

12/19

/08

12/23

/08

12/27

/08

12/31

/08

Dis

solv

ed O

xyge

n (m

g/L)

4

5

6

7

8

9

10

11

12

Trt 3 surface Trt 3 middepth Trt 3 bottom

Trt 2 surface Trt 2 middepth Trt 2 bottom

Dis

solv

ed O

xyge

n (m

g/L)

4

5

6

7

8

9

10

11

12

Trt 1 surface Trt 1 middepth Trt 1 bottom

Plant Sampling

Tohopekaliga Selectivity Grids50:50

Mea

n H

ydril

la B

iom

ass

(g D

W; n

= 4

8)50

:50

Grid

0

2

4

6

8

10

12

14

16

18

Collection Date

Sept 2008 Mar 2009 Jun 2009 Sept 2009 Feb 2010

Mea

n V

allis

neria

Bio

mas

s (g

DW

; n =

48)

50:5

0 G

rid

0

2

4

6

8

10

12

14

16

18

Tohopekaliga Selectivity GridsM

ean

Hyd

rilla

Bio

mas

s (g

DW

; n =

48)

Hyd

rilla

dom

inat

ed g

rid

0

5

10

15

20

25

30

Collection Date

Sept 2008 Mar 2009 Jun 2009 Sept 2009 Feb 2010

Mea

n V

allis

neria

Bio

mas

s (g

DW

; n =

48)

Hyd

rilla

dom

inat

ed g

rid

0

5

10

15

20

25

30

Mea

n H

ydril

la B

iom

ass

(g D

W; n

=48

)V

allis

neria

dom

inat

ed g

rid

0

5

10

15

20

25

Collection Date

Sept 2008 Mar 2009 Jun 2009 Sept 2009 Feb 2010

Mea

n V

allis

neria

Bio

mas

s (g

DW

; n =

48)

Val

lisne

ria d

omin

ated

grid

0

5

10

15

20

25

Hydrilla Dominated Vallisneria Dominated

Herbicide Efficacy-Fathometer Transects

1.3 Miles

December 15, 2008Toho Transect 5 6

April 30, 2009Toho Transect 5 6

August 19, 2009Toho Transect 5 6

Fathometer Transects

• Percent Volume Infested (PVI)– Height of infestation

– [(Σ vegetation height/ Σ bottom depth)100]

• Percent Area Covered (PAC) – Bottom coverage

– [(Σ vegetation presence/ Σ total number of soundings analyzed)100]

Fathometer Transects

• Lake Toho Transect Middle Block Site 5 to 6– Percent Volume Infested (PVI)

• Dec 2008 45.7%

• April 2009 1.0%

• Aug 2009 8.8%

– Percent Area Covered (PAC) • Dec 2008 98%

• April 2009 14%

• Aug 2009 32%

Plant Surveys