Efficacy of Aquatic Herbicides on Rotala (Rotala rotundifolia)

Carl J. Della Torre III, Lyn A. Gettys and William T. Haller dellatorrec@ufl.edu

Rotala rotundifolia • Rotala, roundleaf toothcup, dwarf rotala

• SE Asia; FL 1996; FLEPPC Category 2

• All-terrain • Round pink stems* • Opposite leaves* • Hot-pink flower spike

Rotala identification • Heterophyllous

Rotala invasion and establishment • Submersed first • Reproduction

• Seeds? • Fragments

Rotala control options: Biological • They don’t like it…

Rotala control options: mechanical

Rotala control options: Chemical • 2,4-D and triclopyr • Canals

Herbicide Efficacy: Screening goals • Previous study:

• 2,4-D, triclopyr = excellent • Diquat = 80% control • Endothall, flumioxazin = poor control

• Evaluate aquatic chemistries for control of

rotala • Good efficacy • Rotations

Herbicide Efficacy: Screening study • Emergent vs. Submersed

• Screening • EC90

Screening study: emergent rotala

Herbicide Efficacy: Emergent screening

MOA a.i. Trade name Applied Rate oz/ac Tank mix

Auxin 2,4-D WeeDestroy 32 – 64 none

Auxin Triclopyr Garlon 3A 128 – 256 none

Auxin Aminopyralid* Milestone 3.5 – 7.0 none

PPO Flumioxazin Clipper 6 – 12 diquat

PPO Carfentrazone Stingray 6.75 – 13.5 diquat

ALS Penoxsulam Galleon SC 2.8 – 5.6 none

ALS Bispyribac Tradewind 1 – 2 diquat

ALS Imazamox Clearcast 64 – 128 glyphosate

EPSPS Glyphosate Refuge 48 – 96 none

HPPD Topramezone Oasis 8 – 16 diquat

unclassified Fluridone Alligare Fluridone 3.85 – 7.7 none

DW foliar screening 3 MAT • Anything with diquat: dead!!

Emergent EC90

MOA a.i. Trade name Rates (foliar)

ALS Penoxsulam Galleon SC 0.35, 0.7, 1.4, 2.8, 5.6, 11.2 oz/ac

ALS Bispyribac Tradewind 0.13, 0.25, 0.5, 1.0, 2.0, 4.0 oz/ac

ALS Imazamox Clearcast 8, 16, 32, 64, 128, 256 oz/ac

HPPD Topramezone Oasis 1, 2, 4, 8, 16, 32 oz/ac

Uncl Fluridone Alligare Fluridone 0.5, 1.0, 1.9, 3.9. 7.7, 15.4 oz/ac

Penoxsulam rate (oz/acres)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

120

140

0 0.7 1.4 2.8 5.6 11.2

EC90 = 18.81 oz/acre95% CI 12.02-43.28 oz/acre

y = 126.3e-0.1224x; r2 = 0.788

Foliar/emergent EC90

Topramezone rate (oz/acres)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

120

140

0 2 4 8 16 32

EC90 = 22.73 oz/acre95% CI 15.72-41.04 oz/acre

y = 147.1e-0.1013x; r2 = 0.912

Fluridone rate (oz/acres)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

120

140

0 0.96 1.93 3.85 7.7 15.4

EC90 = 9 oz/acre95% CI 6.70-13.71 oz/acre

y = 145.4e-0.2559x; r2 = 0.901

Bispyribac rate (oz/acres)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

120

140

0 0.25 0.50 1 2 4

EC90 = 0.80 oz/acre95% CI 0.51-1.82 oz/acre

y = 137.4e-2.8867x; r2 = 0.917

Imazamox rate (oz/acres)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

120

140

0 16 32 64 128 256

EC90 = 56.67 oz/acre95% CI 32.89-145.73 oz/acrey = 124e-0.0429x; r2 = 0.879

Screening study: submersed rotala

MOA a.i. Trade name Applied Rate Tank mix

Auxin 2,4-D WeeDestroy 2 – 4 ppm none

Auxin Triclopyr Ecotriclopyr 3SL 1.25 – 2.5 ppm none

PPO Flumioxazin Clipper 200 – 400 ppb Diquat

PPO Carfentrazone Stingray 100 – 200 ppb Diquat

ALS Penoxsulam Galleon SC 75 – 150 ppb 40 + Aquathol

ALS Bispyribac Tradewind 22.5 – 45 ppb Diquat

ALS Imazamox Clearcast 250 – 500 ppb Diquat

HPPD Topramezone Oasis 25 – 50 ppb Diquat

Unclassified Fluridone Alligare Fluridone 45 – 90 ppb none

Unclassified Endothall Aquathol K 2.5 – 5 ppm none

Unclassified Diquat Reward 0.25 – 0.5 gpaf none

DW submersed screening 3 MAT • Anything with diquat: dead…

Submersed EC90

MOA a.i. Trade name Rates (submersed)

ALS Penoxsulam Galleon SC 9.38, 18.75. 37.5, 75, 150, 300 ppb

ALS Bispyribac Tradewind 2.81, 5.63, 11.25, 22.5, 45, 90 ppb

ALS Imazamox Clearcast 31.25, 62.5, 125, 250, 500, 1000 ppb

HPPD Topramezone Oasis 3.13, 6.25, 12.5, 25, 50, 100 ppb

Uncl Fluridone Alligare Fluridone 5.63, 11.25, 22.5, 45, 90, 180 ppb

Uncl Endothall Aquathol K 0.313, 0.625, 1.25, 2.5, 5, 10 ppm

Bispyribac rate (ppb)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

0 11.25 22.5 45 90

EC90 = > 90 ppb95% CI >90 ->90 ppb

y=65.6768e-0.00542x; r2 = 0.764

Submersed: EC90

Penoxsulam rate (ppb)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

0 37.5 75 150 300

EC90 = >300 ppb95% CI >300 - >300 ppb

y=62.0663e-0.0013x; r2 = 0.764

Imazamox rate (ppb)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

0 125 250 500 1000

EC90 = >1000 ppb95% CI >1000 - >1000ppb

y=61.4576e-0.00083x; r2 = 0.820

Topramezone rate (ppb)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

0 12.5 25 50 100

EC90 = >100ppb95% CI >100 - >100 ppb

y=66.2882e-0.0053x; r2 = 0.888

Endothall rate (ppm)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

0 1.25 2.5 5 10

EC90 = > 10 ppm95% CI >10 ->10 ppm

y=69.617e+0.002x; r2 = 0.471

Fluridone rate (ppb)

Dry

bio

mas

s (g

)

0

20

40

60

80

100

0 22.5 45 90 180

EC90 = 39.03 ppb95% CI 24.47-96.34 ppb

y=76.7281e-0.059x; r2 = 0.925

Controlling Rotala

• Biocontrols • Mechanical • Herbicides

• Diquat, 2,4-D, triclopyr • Foliar = bispyribac, imazamox • Sub = fluridone

Thanks! Questions? dellatorrec@ufl.edu