Peanut Response to Dicamba (Clarity)E.P. Prostko, T.L. Grey, M. Marshall, J.A. Ferrell, D.L. Jordan, B.J. Brecke, P.A. Dotray, W.J. Grichar

APRES 2009

2007 Contaminated 2,4-DB Symptomology

2007 Contaminated 2,4-DB (> 250 ppm or 0.025%)

Lot # Dicamba (%) 2,4-D (%)

FB-01 0 0.294

0.091 (MCPA)

EC-16 0.170 0.110

0.079 (MCPA)

EC-16 0.198 0.104

EL-31 0 0.011

EL-31 0 0.010

EL-31 0 0.012

CE-04 0 0.006

Dicamba-Resistant Crops

• Behrens et al. 2007 Science 316:1185-1188. (Nebraska)

• Transferred gene from Pseudomonas maltophila into tobacco, soybeans, tomatoes

• Monsanto in hot pursuit

dicamba acid

dicamba DGA salt

Dicamba Drift on Soybeans

• 14-93% yield reduction (V3)– Anderson et al. 2004 (SD)

• 15%-22% yield loss (V3); 12-28% yield loss (V7)– Kelley et al. 2005 (IL)

Photo: Purdue University Weed Science

Objectives

• Determine the influence of Clarity rate and timing of application on peanut yield

• Develop a predictive model for future use

Materials and Methods

• 8 locations across Peanut Belt– GA(2), FL(2), SC(1),

NC(1), TX (2),

• RCB design

• 3 X 6 factorial arrangement

– Timing (30, 60, 90 DAP)– Rate (0, 1, 2, 4, 8, 16 oz/A

Clarity)

• 4 replications• Weed-free

Site Descriptions

State Location VarietyPlanting

DateDigging

DateHarvest

Date

Soil Characteristics

OM (%)

Sand(%)

Silt (%)

Clay (%)

FL1 Citra Georgia Green

April 23 August 25 August 28 0.5 97 1 2

FL2 Jay Florida-07 May 12 September 19

September 18 2.1 69 16 15

GA1 Ty Ty AP-3 May 12 September 26

September 29 1.07 94 2 4

GA2 Plains Georgia-02C May 13 October 3 October 7 1.0 40 25 34

NC1 Rocky Mount

VA-98R May 20 October 8 October 14

SC1 Blackville Champs May 19 October 8 October 15

TX1 Lamesa FlavorRunner 458

April 30 October 27 November 5 0.40 67 14 19

TX2 Yoakum Tamrun OL02 June 16 November 3 November 5 1.0 70 16 14

Results

• 5 locations had significant rate X timing interaction– Lamesa, Yoakum, Rocky Mount, Blackville, and TyTy

• 3 locations had no interaction– Plains, Jay, Citra– Rate and timing were significant

Figure 1. Peanut Yield Response to Clarity, Ty Ty, GA (2008).

5037

4481

37773523

1622

664

4898

3841 3780

2469

1714

955

50474891 4800

4136

3509

2198

0

1000

2000

3000

4000

5000

6000

NTC 1 2 4 8 16Clarity Rate/A (oz)

lbs/

A

.

30 DAP 60 DAP 90 DAP

LSD 0.10 = 472

Figure 2. Peanut Yield Response to Clarity, Lamesa, TX (2008).

6555

60795820

5282

4634

2651

6239

5327

4795

4136

2944

1939

6292 6281

5823

5380

4744

4294

0

1000

2000

3000

4000

5000

6000

7000

NTC 1 2 4 8 16Clarity Rate/A (oz)

lbs/

A

.

30 DAP 60 DAP 90 DAP

LSD 0.10 = 620

Figure 3. Peanut Yield Response to Clarity, Yoakum, TX (2008).

3098

23652199

774

454 505

3153

26762551

1729

761

512

2980

2238 2233

1977

910

476

0

500

1000

1500

2000

2500

3000

3500

NTC 1 2 4 8 16Clarity Rate/A (oz)

lbs/

A

.

30 DAP 60 DAP 90 DAP

LSD 0.10 = 210

Figure 4. Peanut Yield Response to Clarity, Rocky Mount, NC (2008).

3540

3020 2919

2241

649

303

3550

3000

2570

1805

1016

351

3894

3528 35503420 3325

3136

0

500

1000

1500

2000

2500

3000

3500

4000

4500

NTC 1 2 4 8 16Clarity Rate/A (oz)

lbs/

A

.

30 DAP 60 DAP 90 DAP

LSD 0.10 = 466

Figure 5. Peanut Yield Response to Clarity, Blackville, SC (2008).

7420

6557

5798

6394

3906

1608

7964

6654

5256

35513316

1456

6319

7620

6336 6230

4858

2485

0

2000

4000

6000

8000

NTC 1 2 4 8 16Clarity Rate/A (oz)

lbs/

A

.

30 DAP 60 DAP 90 DAP

LSD 0.10 = 1208

Figure 6. Peanut Yield Response to Clarity Rate (2008). (pooled over 3 timings)

4764

2510

43104044

2345

40834352

2038

40303931

1972

36363381

1325

34273247

1060

2567

0

1000

2000

3000

4000

5000

6000

Plains Jay Citra

Location

lbs/

A

.

NTC 1 oz 2 oz 4 oz 8 oz 16 oz

Plains LSD 0.10 = 467Jay LSD 0.10 = 599Citra LSD 0.10 = 330

Figure 7. Peanut Yield As Influenced by Clarity Timing (2008). (pooled over 6 rates)

3750

1394

36063874

1945

3569

4236

2286

3851

0

1000

2000

3000

4000

5000

Plains Jay Citra

Timing (DAP)

lbs/

A >

30 DAP 60 DAP 90 DAP

Plains LSD 0.10 = 349Jay LSD 0.10 = 422Citra LSD 0.10 = 203

Peanut Response to Clarity (dicamba) 4SC @ 16 ozs/A

Applied 30 DAP(664 lb/A – 87% loss)

Applied 60 DAP(955 lb/A – 81% loss)

Applied 90 DAP(2198 lb/A – 56% loss)

Photo 107 DAPTy Ty, GA

NTC (4994 lb/A)

Peanut Response to Clarity (dicamba) 4SC @ 8 ozs/A

Applied 30 DAP(1622 lb/A – 67% loss)

Applied 60 DAP(1714 lb/A – 66% loss)

Applied 90 DAP(3509 lb/A – 30% loss)

Photo 107 DAPTy Ty, GA NTC (4994 lb/A)

Peanut Response to Clarity (dicamba) 4SC @ 1 oz/A

Applied 30 DAP(4481 lb/A – 10% loss)

Applied 60 DAP(3841 lb/A – 33% loss)

Applied 90 DAP(4891 lb/A – 2% loss)

Photo 107 DAPTy Ty, GA

NTC (4994 lb/A)

Summary

• Increase Clarity rate = increase peanut yield loss

• Increase peanut age = decreased peanut yield loss– Some locations (13/25) 60 DAP more

sensitive (R3-R4 stage of growth)

• Can get significant peanut yield reductions with as little as 1 oz/A Clarity– 13% average (0%-low, 25%-high)

• Growers need to avoid contamination/drift problems

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