Interaction of Trifloxysulfuron (Envoke) and Mepiquat Chloride on Growth and Lint Yield of Cotton...

Interaction of Trifloxysulfuron (Envoke) and Mepiquat Chloride

on Growth and Lint Yield of Cotton

Guy Collins, Alan York, Keith Edmisten, Rick Seagroves, Ranjit Riar, Jamie Hinton, James

Lanier, Gary Hamm, and Andrew Hunt

N.C. State University

Introduction

• Trifloxysulfuron (Envoke®) is a broad-spectrum herbicide used to control broadleaf weeds and sedges in cotton (Gossypium hirsutum L.)

• Postemergence (over-the-top) applications at rates of 5.25 to 7.9 g a.i./ha (0.1 to 0.15 oz/A) beginning at the

5-leaf stage

• Post-directed applications at rates of 7.9 to 13.1 g/ha (0.15 to 0.25 oz/A)

Introduction

• Postemergence applications are typically delayed until the 7- to 8-leaf stage, due to the greater tolerance of larger plants

• Trifloxysulfuron typically causes injury, reduces height, and shortens internodes on cotton (Casteel et al., 2004)

• End-results of trifloxysulfuron applications appear to be similar to the effects of mepiquat chloride

Trifloxysulfuron Injury

Wilting

Discoloration

Stunting

(York, 2005)

Trifloxysulfuron Effects on Plant Height

Shortened internodes and reduced height

(York, 2005)

Mepiquat Chloride Effects on Plant Height

Shortened internodes (Edmisten, 2004)

Reduced height(Edmisten, 2006)

Introduction

• Can these products be tank-mixed?

• Should growers reduce rates of mepiquat chloride on cotton receiving trifloxysulfuron?

• Could mepiquat chloride be eliminated if trifloxysulfuron is used?

Previous Work

Casteel et al., 2004 – found that trifloxysulfuron and mepiquat chloride had similar effects on plant growth, and suggests that tank-mixing may not be feasible

Griffith et al., 2004 – found that 2x rates of trifloxysulfuron decreased the no. of nodes, delayed maturity, and decreased lint yields

Norton and Borrego, 2006 – found decreased lint yield by combining mepiquat chloride with trifloxysulfuron, but minor effects on plant growth

Objectives

• To determine if mepiquat chloride rates can be reduced or eliminated if trifloxysulfuron is used

• To determine if trifloxysulfuron can be tank-mixed with mepiquat chloride, while maintaining adequate plant growth and yields

• To determine if delaying trifloxysulfuron or mepiquat chloride applications could offset the risks of excessively inhibiting plant growth and compromising yields

Hypothesis

We hypothesized that mepiquat chloride

rates could be reduced if trifloxysulfuron

was previously applied, and that delaying

applications of trifloxysulfuron may allow

plants to form adequate fruiting sites,

therefore avoiding yield losses.

Materials and Methods

• Replicated field experiments were conducted in 2005 and 2006 at:

Upper Coastal Plains Research Station (Rocky Mount, N.C. – 2005 and 2006)

Central Crops Research Station (Clayton, N.C. - 2006)

• ST 5599 BR cottonseed was planted at a rate of 3 seeds/foot on May 12, 2005 (Rocky Mount, 2005)


• ST 5599 BR cottonseed was planted at a rate of 3.5 seeds/foot on May 2, 2006 (Rocky Mount, 2006)

• ST 5007 B2RF cottonseed was planted at a rate of 3 seeds/foot on May 3, 2006 (Clayton, 2006)

• Weed control: Glyphosate (Roundup Weathermax) 1.61 L/ha (22 oz/A)

at the 1-leaf and 4-leaf stages

S-Metolachlor (Dual Magnum) 1.4 L/ha (1 pt/A) at the 4-leaf stage

Experimental Design and Treatments

• Experimental Design = RCBD

• Treatments:- 2 Trifloxysulfuron rates- 5 Mepiquat chloride regimes

• Treatments were arranged in a 2 x 5 factorial design

Treatments

Trifloxysulfuron rates:

None

5.25 g/ha (0.1 oz/A)

at 7 DAPHS (days after pin-head square)

Treatments

Mepiquat chloride regimes:

14 DAPHS 21 DAPHS 31 DAPHS

none --- --- ---

1 app. --- 25 g/ha (8 oz/A)

---

1 app. --- 49 g/ha (16 oz/A)

---

2 app. --- 25 g/ha (8 oz/A)

37 g/ha (12 oz/A)

3 app. 18 g/ha (6 oz/A)

25 g/ha (8 oz/A)

37 g/ha (12 oz/A)

Treatments

Additional treatments:

14 DAPHS 21 DAPHS 31 DAPHS

1 Trifloxysulfuron5.25 g/ha(0.1 oz/A)

--- ---

2Trifloxysulfuron

5.25 g/ha(0.1 oz/A)

--- ---

Mepiquat Chloride18 g/ha(6 oz/A)

25 g/ha(8 oz/A)

37 g/ha(12 oz/A)


• All treatments were applied using a

CO2-pressurized backpack sprayer calibrated to deliver 140.3 L/ha (15 GPA)

• All other agronomic practices were conducted according to North Carolina Cotton Extension recommendations

Data Collection

• Plant heights at 36 and 48 DAA (Days after trifloxysulfuron application)

• Percent open bolls in mid September

• Plant heights and plant mapping in mid September

• Seed cotton yields

• Lint percentage and HVI fiber quality

Statistical Analysis

• SAS version 9.1.3

• General Linear Model (Proc GLM)

• Means separated using Fisher’s Protected LSD at α = 0.05

Statistical Analysis

• Due to power of the factorial arrangement, analysis of factorial treatments are reported separately from the additional treatments

• Additional treatments were analyzed in a separate 2 x 3 factorial arrangement to compare the effects of trifloxysulfuron application timing (7 and 14 DAPHS) and the non-treated control

• A mean separation was used to determine if mepiquat chloride rates can be reduced if trifloxysulfuron was previously used

• Due to strong interactions between some factors and locations, and consideration of F-tests, some data will be presented with locations 1 & 2 combined, and location 3 separately

Results

Factorial treatments (no interactions between mepiquat chloride and trifloxysulfuron were significant)

- Data are pooled over all locations unless otherwise specified

Plant Height – Mepiquat main effect1

0

10

20

30

40

50

60

70

80

90

100

36 DAA 48 DAA end-season

none

1 app. - 25 g/ha

1 app. - 49 g/ha

2 app. - 25 + 37 g/ha

3 app. - 18 + 25 + 37 g/ha

A

LSD = 2.65

cm

1Data pooled over all locations

LSD = 3.6 LSD = 4.06

BC BCAB

C

C CC

C CC

A

B

A

B

Bolls/Plant – Mepiquat main effect1

0

2

4

6

8

10

12

14

sympodial bolls total bolls

none

1 app. - 25 g/ha

1 app. - 49 g/ha

2 app. - 25 + 37 g/ha

3 app. - 18 + 25 + 37 g/ha

A

LSD = 0.92

No

.


LSD = 1.08

ABAB

BB

A

ABAB AB

B

Aborts/Plant and Retention– Mepiquat main effect1

LSD = 1.32

No

.


*Denotes significance at p<0.05

0

2

4

6

8

10

12

14

16

18

20

none 1 app. - 25g/ha

1 app. - 49g/ha

2 app. - 25 +37 g/ha

3 app. - 18 +25 + 37 g/ha

30

35

40

45

50

55

aborts

fruit retention

%

LSD = 2.65

A

BB B

B

** *

*

Total Nodes and H/N Ratio– Mepiquat main effect1

0

2

4

6

8

10

12

14

16

18

total nodes height/node ratio

none

1 app. - 25 g/ha

1 app. - 49 g/ha

2 app. - 25 + 37 g/ha

3 app. - 18 + 25 + 37 g/ha

A

LSD = 0.49

No

.


LSD = 0.27

BBB B

AB BC CBC

Position 1 Bolls – Mepiquat main effect1

8.2

8.4

8.6

8.8

9

9.2

9.4

9.6

9.8

10

none

1 app. - 25 g/ha

1 app. - 49 g/ha

2 app. - 25 + 37 g/ha

3 app. - 18 + 25 + 37 g/ha

A

ABA

B

AB

LSD = 0.699

No

.

1Data pooled over RM2005 and RM2006

Lint % - Mepiquat main effect1

40.5

41

41.5

42

42.5

43

43.5

44

none

1 app. - 25 g/ha

1 app. - 49 g/ha

2 app. - 25 + 37 g/ha

3 app. - 18 + 25 + 37 g/ha

A

BCB B

C

LSD = 0.677

Lin

t %

1Data pooled over RM2005 and RM2006

Plant Height – Trifloxysulfuron main effect1

40

50

60

70

80

90

36 DAA 48 DAA End-season

5.25 g/ha 7 DAPHS

none


*Denotes significance at p<0.05

*

* *

LSD = 1.67 LSD = 2.27

LSD = 2.57

cm

Retention, Nodes, and H/N Ratio – Trifloxysulfuron main effect1


Trif. RateSympodial Retention

NodesHeight/Node

Ratio_____%_____ _____no._____ _____no._____

none 52.1 A 16.8 B 4.8 A

5.35 g/ha

7 DAPHS49.9 B 17.3 A 4.3 B

LSD 1.7 0.3 0.2

Boll Distribution – Trifloxysulfuron main effect1


Node Zone None5.25 g/ha

7 DAPHSLSD

_________no._________

4-7 4.13 4.00 ns

8-10 4.02 3.72 0.26

11-13 2.22 2.28 ns

14-16 0.72 0.95 0.18

>16 0.03 0.00 ns

Lint Yields – Trifloxysulfuron main effect1

0

200

400

600

800

1000

1200

1400

1600

1800

none

5.25 g/ha @ 7 DAPHS

AB

A A

RM05 & RM06

LSD = 68.9

Kg

/ha

1Data pooled over RM2005 and RM2006, CL06 separately

CL06

LSD = ns

Sympodial Bolls/Plant and Nodes –

Trifloxysulfuron main effect1

1Data for CL06 only

Trifloxysulfuron Rate

Sympodial bolls

Total nodes

___________no.__________

none 6.8 B 16 B

5.35 g/ha

7 DAPHS7.4 A 16.5 A

LSD 0.55 0.44

Results

Additional treatments (2 x 3 factorial used to determine the effect of application

timing of trifloxysulfuron - no interactions between mepiquat chloride and trifloxysulfuron were significant)

- Data is pooled over all locations unless otherwise specified

Plant Height1

45

55

65

75

85

36 DAA 48 DAA End-season

Trif. 7 DAPHS

NTC

Trif. 14 DAPHS


*Denotes significance at t<0.05 between the NTC and other treatments

*

* *

LSD = 2.34 LSD = 2.21

LSD = 4.14

cm

Total Nodes and H/N Ratio1


Treatment Total Nodes H/N ratio

_____cm_____ _____no._____

NTC 16.9 B 4.96 A

Trifloxysulfuron

7 DAPHS17.6 A 4.58 B

Trifloxysulfuron

14 DAPHS17.5 A 4.46 B

LSD 0.5 0.27

Bolls/Plant by Node Zone1

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

nodes 4-7 nodes 8-10 nodes 11-13 nodes 14-16

NTC

Trif. 7 DAPHS

Trif. 14 DAPHS

LSD = ns

No

.


LSD = ns LSD = ns LSD = ns

Total Bolls/Plant1

0

2

4

6

8

10

12

14

NTC

Trif. 7 DAPHS

Trif. 14 DAPHS

LSD = ns

No

.


Lint Yield1

500

600

700800

9001000

11001200

13001400

1500

NTC

Trif. 7 DAPHS

Trif. 14 DAPHS

LSD = ns

Kg

/ha


Results

Mean separation (to determine if mepiquat chloride rates can be reduced

if prior trifloxysulfuron was used)

- Data is pooled over all locations

Plant Height1

0102030405060708090

100

no mc 25 g/ha 49 g/ha 25 + 37g/ha

18 + 25 +37 g/ha

no Trif.

Trif. 7 DAPHS

cm


LSD = 5.77

AAB

C

DE DDEF

DE DEF DEFEF

Tri

f. 1

4

Tri

f. 1

4 +

MC

B

F

Lint Yield1

500

700

900

1100

1300

1500

1700

no mc 25 g/ha 49 g/ha 25 + 37g/ha

18 + 25 +37 g/ha

no Trif.

Trif. 7 DAPHS

Kg

/ha


LSD = 111.6

A ABC

A

BC

A

C

ABC AB AABC

ABC

C

Tri

f. 1

4

Tri

f. 1

4 +

MC

Conclusions

• The behavior of trifloxysulfuron and mepiquat chloride are independent from each other

• Trifloxysulfuron and mepiquat chloride have similar effects on plant growth and fruiting characteristics – yield response is variable

• No evidence suggests that delaying the application of trifloxysulfuron helps avoid risks associated with stunting

• Some evidence suggests that mepiquat chloride rates can be reduced if trifloxysulfuron is used

• Growers should avoid using trifloxysulfuron on cotton that is stressed or in fields that have a history of early season stress

References

Norton, E.R., and H.J. Borrego. 2006. Evaluation of Envoke by Pix Interaction in Arizona Cotton Production Systems. Arizona Cotton Report (P-145).

Casteel, S.N., K.L. Edmisten, R. Wells, J. Wilcut, J. Spears, and J. Burton. 2004. Cotton’s Response to Mepiquat Chloride, Pyrithiobac, and CGA 362622. N.C. State University Masters thesis.

Griffith, G.M., J.L. Barrentine, M.R. McClelland, and O.C. Sparks. 2004. Effect of Planting Date on Response of Cotton to Envoke. Summaries of Arkansas Cotton Research. pp. 200-203.

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Interaction of Trifloxysulfuron (Envoke) and Mepiquat Chloride on Growth and Lint Yield of Cotton...

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