Peanut Weed Management Update
Eric P. Prostko
Extension Weed Specialist
Department of Crop & Soil Sciences
The University of Georgia
Tifton
Extension Agent Training - March 2006
2005 ALS-Resistant Pigweed Survey
60 locations, 21 counties
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As of March 1, 2006
Preliminary data
1573 plants treated
1395 plants survived (89%)
≥ 90% survival
– 30 locations = 50%
80-89% survival
– 23 locations = 38%
70-79% survival
– 5 locations = 8%
60-69% survival
– 1 location = 2%
– Jefferson County
50-59% survival
– 1 location = 2%
– Laurens County
Herbicide Programs for ALS-Resistant
Pigweed Management in Peanut
Preplant
incorporated
Preemergence
Prowl or Sonalan
Cracking or early postemergence
(Palmer < 2 in.)
Postemergence
(Palmer < 3 in.)
Gramoxone + Basagran +
Dual Magnum or Outlook
Cobra or Ultra Blazer
Prowl or Sonalan
Valor
Cobra or Ultra Blazer
Prowl or Sonalan
Valor +
Dual Magnum or Outlook
Cobra or Ultra Blazer
*Generic formulations of Dual Magnum and Outlook are available.
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Herbicide Effects on Peanut Seed
Germination, 2005. (@ 250C or 770F)
Tifton
Dawson
Germination - %
100
80
60
40
20
0
B
D
B
D
P
P
Averaged over 3 varieties (GA Green, C-99R, GA-01R); Cadre @ 1.44 oz/A; 2,4-DB @ 1.1 pt/A
A
D
A
D
P
A
D
P
A
D
5
-9
5
0
ed
at
re
5
-7
-4
C
-3
C
nt
U
Herbicide
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Classic Effects on Peanut Yield– 2005
Classic @ 0.5 ozs/A + Activator 90 @ 0.25% v/v
4000
3850
lbs/A
3200
3690
3758
3875
60
72
89
2400
1600
800
Planted: May 2
AP-3
Twin row
Conventional tillage
3 seed/ft
Phorate
6’ X 100’ plots, 3 reps
Weed-free
0
Untreated
Application Date (DAC)
P = 0.5931
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Peanut Yield Response to Delayed
Prowl Timings - 2004
4000
3000
3296
3109
3201
3120
3153
lbs/A
2811
2000
1000
re
at
ed
U
nt
10
9
8
7
2
0
DAP
Averaged over two formulations (Prowl and Prowl H2O applied at 1.00 lb ai/A)
P = 0.198
Peanut Yield Response to Prowl EC
Timings - 2005
5000
4000
4022
4169
4088
lbs/A
3699
3654
3816
3000
2000
1000
U
nt
re
at
ed
15
10
8
7
1
0
DAP
1.0 lb ai/A
LSD 0.05 = 397
LSD 0.10 = 326
Peanut Yield Response to Prowl H2O
Timings - 2005
5000
4000
4235
*
*
4470
lbs/A
3765
3772
3845
4125
3000
2000
1000
U
nt
re
at
ed
15
10
8
7
1
0
DAP
1.0 lb ai/A
LSD 0.05 = 397
LSD 0.10 = 326
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes? (handout)
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Cadre @ 1.44 ozs/A
Headline @ 9 ozs/A
Dual Magnum @ 1.33 pts/A
AMS @ 1 lb/A
COC @ 1 qt/A
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Do you need Gramoxone?
Untreated
PE-07-05
July 18, 2005 (69 DAP)
Ponder Farm
Gramoxone Max @ 8 ozs/A
+ Pledge @ 8 ozs/A + NIS
@ 0.25% v/v (15 DAP)
Fb Cadre @ 1 oz/A + COC
@ 1% v/v (28 DAP)
Cadre @ 1 oz/A + COC
@ 1% v/v (28 DAP)
Gramoxone + Cadre - 2005
Treatment
Test 1 - Tifton
(lbs/A)
Test 2- Attaplugus
(lbs/A)
Untreated
374 e
1474 c
Gramoxone +
Basagran fb
Cadre
2170 bc
(+958)
2736 a
(+501)
Cadre
1212 de
2235 b
P = 0.10
Gramoxone Inteon @ 12 ozs/A + Basagran @ 8 ozs/A + NIS @ 0.25% v/v = $7.08/A + $4.00/A = $11.08/A
$11.08/$0.1775 = 62.4 lbs of peanuts
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Eclipta
Eclipta Control in Peanut
Strongarm @ 0.45 ozs/A
NIS @ 0.25% v/v
20 DAT
Untreated
What weeds does Strongarm control
POST?
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common ragweed
common cocklebur
horseweed
bristly starbur
morningglory
wild radish
eclipta
tropical spiderwort
Label
– TSW suppression
– up to 30 DAC
– NIS
– 18 month cotton
rotation
Common Ragweed Treated with Strongarm @
0.30 ozs/A + NIS @ 0.25% v/v
Before
Lanier County
2005
6 DAT
19 DAT
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
Cobra Effects on Peanut Yield – 2005
Cobra @ 12.5 ozs/A + Herbimax @ 1% v/v
4000
Yield (lbs/A)
3200
3795
3766
a
a
3580
ab
2400
3565
3025
bc
3883
a
ab
1600
800
Planted: May 5
GA Green
Twin row
Conventional tillage
3 seed/ft
Phorate
No Classic
Weed-free
0
15
30
43
58
Application Date (DAP)
74
Untreated
Research Questions?
• Do herbicides influence peanut seed
germination?
• How does Classic effect AP-3?
• Can I put Prowl over-the-top of emerged
peanuts?
• Herbicide/fungicide tank-mixes?
• Do I really need Gramoxone?
• How about eclipta?
• Does Cobra reduce peanut yields?
• What does 2,4-D do to peanut yields?
What does 2,4-D do to peanut yield?
Yield Loss or Gain (%)
2 ozs
45
36
27
18
9
0
-9
-18
-27
-36
-45
15 DAE
4 ozs
8 ozs
30 DAE
12 ozs
45 DAE
Time of Application
Ponder Farm 2005
GA Green
How do the top growers control
weeds?
• 2005 Peanut Achievement
Club
• 21 farms
• 4356 lbs/A
• State average was only
2870 lbs/A
• Weed Control Tactics
– Conventional tillage
• 76% use bottom
plow
– Twin rows (71%)
– Sonalan (81%)
– Strongarm or Valor
• 38% vs. 43%
– Cadre (76%)
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