2007 Peanut Weed Management Update for County Agents

Eric P. ProstkoExtension Weed Specialist

Department of Crop & Soil SciencesThe University of Georgia

Extension Agent Training – December 2006

Changes in 2007 Pest Control Handbook – Peanut Weed Control• Added Firestorm (generic paraquat) where

appropriate

• Included Aim in burndown sections

• Added generic metolachlors but still included the following warning: The generic formulations of metolachlor (Parallel, Stalwart, Me-Too-Lachlor) have not provided the same length of residual control of certain weeds as similar rates of Dual Magnum formulations in some UGA field trials.

• Added a specific control rec for tropical spiderwort

• Table for ALS/GR-resistant pigweed control

• Added Propel (generic Outlook)

• Zorial to Solicam

Firestorm

• Chemtura – Great Lakes Chemical Corp. + Crompton Corp.

• 3 lb/gallon of paraquat• Similar formulation as Gramoxone Max• 5.4 to 10.8 ozs/A = normal rates

• preplant burndown up to 24 hours after planting

• Up to 2 ozs/A– $5.00/oz

• Tank-mix with glyphosate

IMPOSE

• Generic liquid Cadre• From Makhteshim Agan of North America

(MANA)

How/Why do we let pigweeds get this big????

Will these herbicides control large pigweeds?

Cobra 2EC @ 12.5 ozs/A + COC @ 1% v/v applied to 17” tall pigweed

1 DAT 4 DAT

7 DAT 16 DAT

Cadre @ 4 ozs/A + 2,4-DB @ 1.1 pt/A + COC @ 1% v/v – 34 DAT

Applied to 17” tall pigweed

2,4-DB/Cobra Test – 2006

POST: June 5 (17” tall pigweed)POST2: June 9Photos taken 24 days after POST application

Untreated Cobra 2EC @ 12.5 oz/AAgrioil @ 1% v/v

POST

2,4-DB 1.75SL @ 1.1 pt/A +Agrioil @ 1% v/v (POST)

fbCobra 2EC @ 12.5 oz/A

Agrioil @ 1% v/vPOST2

Palmer Amaranth Control with Cobra and 2,4-DB

0

20

40

60

80

4 DAT 7 DAT 10 DAT 16 DAT 24 DAT 34 DAT

Time

Con

trol

- %

Cobra 2,4-DB Cobra + 2,4-DB 2,4-DB fb Cobra

Cobra @ 12.5 ozs/A2,4-DB @ 1.1 pts/ACOC @ 1% v/v Applied to 17” tall pigweed

How do we manage ALS-resistant Palmer amaranth?

• Need to start using more PRE’S– Valor, Dual Magnum/generics, Outlook– Goal?????

• POST Herbicides– Timeliness– Cobra, Ultra Blazer, Paraquat– Over reliance on PPO’s

• Will need both PRE’s and POST’s• Increased production costs

GR-Pigweed/Soybean Test – II (2006)7 WAP

Untreated Valor @ 2 oz/A (PRE)RUWM (POST)

RUWM (POST)

What if we do not control Palmer amaranth?

Crop

(State) Density Yield Loss Source

Corn

(KS)

0.5-8 plants/m 11-91% Weed Sci.

2001

49:202-208

Soybean

(AK)

0.33-10 plants/m 17-68% Weed Sci.

1994

42:523-527

Grain sorghum

(OK)

1-18 plants/15 m 4-63% Weed Tech.

2004

18:23-29

Peanut

(NC)

1-5 plants/m 28-66% Burke and Wilcut

(in-press)

Cotton

(TX)

1-10 plants/9.1 m 13-54% Weed Tech.

2001

15:408-412

Does Cobra reduce yields??

Peanut (GA Green) Response to Cobra78 DAP - 2006

Untreated Cobra @ 12.5 ozs/AAgrioil @ 1% v/vApplied 30 DAP

3556 lbs/A – Tifton4450 lbs/A - Plains

4003 lbs/A – Tifton4319 lbs/A - Plains

Classic Use in GA Peanuts

0

5

10

15

20

25

30

1993

1995

1997

1999

2001

2003

Year

Acres-%

Classic @ 0.5 ozs/A Applied 62 DAE

7 DAT

AP-3

GA-02C

Classic Effects on TSWV (2000-2006)

-40-32-24-16-808

16243240

50 60 70 80 90 100 110

Classic Timing (DAC)

Ch

ang

e in

TS

WV

- %

11 weed-free field trials in GA

31 data points77% ≤ 8%23% > 8%

Classic Effects on Peanut Yield - 2006

4689

3750

4429

3195

45764211

4459

3564

4546

3266

0

1000

2000

3000

4000

5000

AP-3 GA-02C

Variety

LB

S/A

Untreated 62 DAE 75 DAE 90 DAE 105 DAE

(P = 0.66) (P = 0.37)

Classic @ 0.5 oz/A + 80/20 @ 0.25% v/vWeed-free

Gramoxone Still Works!!!! (for me)

Untreated Gramoxone Inteon (12 oz/A) +Storm (1.5 pt/A) + 80/20 (0.25% v/v)

PE-26-0623 DAT

Speed, Nozzle Tip, GPA Effects7 MPH Tractor Speed

22

3236

1215

21

0

10

20

30

40

50

10 15 20

GPA

Cov

erag

e - %

FF WJ

LSD 0.10 = 3

Gramoxone Inteon (GI) and Basagran (B) Effects on Peanut Yield - 2006

3275 3352 3384

0

1000

2000

3000

4000

Untreated GI @ 8 oz/A GI @ 12 oz/A + B @8 oz/A

Treatment

lbs/

A

GA-02CAveraged over 4 timings (7, 14, 22, 28 DAC)Included 80/20 @ 0.25% v/vWeed-free

P = 0.63

Cadre or Gramoxone fb Cadre???

• 4 field trials conducted in 2005-2006

• 477 lb/A average yield increase when Gramoxone + Basagran was used prior to Cadre compared to Cadre alone

• It only takes a 64 lbs/A increase of peanuts to pay for this treatment

Peanut (GA-02C) Response to Roundup Weathermax – 112 DAP

Roundup Weathermax @ 12 ozs/A Applied 71 DAP

8 DAT

Peanut Yield Loss Caused by Roundup WeatherMax

0

10

20

30

40

50

60

0 2 4 6 8 12

Rate/A (oz)

Yie

ld L

oss

- %

71 DAP 89 DAP 105 DAP

GA-O2CPonder Farm - 2006

www.gaweed.com