peanut weed control update 2001
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Peanut Weed Control Update 2001
Dr. Eric P. Prostko
Extension Weed Specialist
University of Georgia
Tifton
Topic for Discussion
• Cadre * reduced rates
* cotton rotations
• paraquat• Strongarm• Valor• other stuff
Reduced Rates of Cadre?
• efficacy issues
• rotation issues
• liability
The Response of Weeds to Various Cadre Rates in Georgia
0
20
40
60
80
100
P. nutsedge Y. nutsedge sicklepod P. sida
0.36 oz/A0.72 oz/A1.1 oz/A1.44 oz/A
Webster et al. 1997 Applied EPOST (C-2L)
The Response of Weeds to Various Cadre Rates in Georgia
0
20
40
60
80
100
smallflowermorningglory
annualmorningglory
cocklebur bristly starbur
0.36 oz/A0.72 oz/A1.1 oz/A1.44 oz/A
Webster et al. 1997 Applied EPOST (C-2L)
The Response of Weeds to Various Cadre Rates in Georgia
0
20
40
60
80
100
coffee senna Florida beggarweed
0.36 oz/A0.72 oz/A1.1 oz/A1.44 oz/A
Webster et al. 1997 Applied EPOST(C-2L)
Reduced rates of Cadre work if…...
• the weed is susceptible
• good growing conditions exist
• the application is timely (small weeds)
Full rates help to overcome variability of application dueto weed size, improper sprayer calibration, environmental conditions, etc.
Cadre/Cotton Rotation Issue
• new research results
Cotton Response to Cadre Residues in North Carolina
0
1000
2000
3000
4000
5000
1992 1993-94
Year
Yie
ld (
lbs/
A)
Untreated Cadre (0.5x) Cadre (1X) Cadre (2X)
York et al., 2000 DES 119
Cotton Yield Response to PPI Applications of Cadre
0
1000
2000
3000
4000
0.032 0.016 0.008 0.004 0.002 0.001 0
Cadre Rate (lb ai/A)
Seed
Cot
ton
Yie
ld (
lbs/
A)
Averaged over 2 varieties(DP33B, SG501BG/RR) Tifton, GA 2000LSD 0.05 = 336
**
Cotton Yield Response to PRE Applications of Cadre
0
1000
2000
3000
0.032 0.016 0.008 0.004 0.002 0.001 0
Cadre Rate (lb ai/A)
Seed
Cot
ton
Yie
ld (
lbs/
A)
Averaged over 2 varieties(ST4892RR/BG, ST4691BG) Plains, GA 2000LSD 0.05 = 712
**
*
Cotton Variety Response to Cadre at 8 PPB - 9 WAT
0 10 20 30 40 50 60
Delta Pearl
DP33B
DP5415
DP458
ST4892
STX9903
BXN47
FM989
AP6101
GA161
SG125
Injury (%)
Culpepper, 2000Tifton, GA LSD 0.05 = 17
Cotton Variety Response to Cadre at 16 PPB - 9 WAT
0 20 40 60 80 100
Delta Pearl
DP33B
DP5415
DP458
ST4892
STX9903
BXN47
FM989
AP6101
GA161
SG125
Injury (%)
Culpepper, 2000Tifton, GA LSD 0.05 = 17
Cadre Carryover in CottonBrooks County - 2000
674 lbs 770 lbs 770 lbs
1540 lbs 1348 lbs 1220 lbs
738 lbs/A(lint yield)
1369 lbs/A
6/09/006/09/00
Cadre/Cotton RotationsWhat can growers do?
• follow 18 month restriction
• reduced rates of Cadre?
• Cadre on irrigated fields only?
• optimum pH and nutrient levels
• plant suspect fields last
Paraquat Formulations
Boa GramoxoneMax
Starfire
manufacturer Griffin Syngenta Syngenta
lb ai/gal 2.5 3.0 1.5
ozs/A 6.6 5.5 11
Cost/A $1.50 $1.59 $2.75
Smallflower Morningglory Control with Various Formulations of Paraquat
Test 1 - 15 DAT
83 87 83
0
20
40
60
80
100
Con
trol
(%
)
Starfire Boa GramoxoneMax
Averaged over 3 rates of Basagran
(P = 0.15)
Tifton, GA 2000
Weed Control with Various Paraquat Formulations
Test 2 - 5 DAT
75
100 100
73
10092
78
100 97
0
25
50
75
100
smallflower mg Fla. Pusley annual grass
Starfire Boa GramoxoneMax
Tifton, GA 2000Averaged over 3 rates of Basagran
(P = 0.72) (P = 0.45) (P = 0.15)
Weed Control with Various Paraquat Formulations
Test 2 - 14 DAT
8797
56
8797
51
8697
51
0
25
50
75
100
smallflower mg Fla. Pusley y. nutsedge
Starfire Boa GramoxoneMax
Tifton, GA 2000Averaged over 3 rates of Basagran
(P = 0.53) (P = 0.82) (P = 0.40)
Improving At-Crack Applications
• calibrate sprayer
• SMALL WEEDS (2”)
• nozzle selection (XR TeeJet, TwinJet)
• higher water volumes (15 GPA+) improve coverage
• lower pressures (30 PSI) reduce drift and evaporation
How would you rate the overall performance of Strongarm in your county?
8
4943
00
15
30
45
60
75
Poor Fair Good Excellent
%
2000 UGA County Agent Survey
What were the weeds that most frequently escaped control of Strongarm?
7872
2217
0
20
40
60
80
100
sicklepod nutsedge beggarweed pigweed
%
2000 UGA County Agent Survey
Strongarm - Does it work?Attapulgus - 7 WAP
Untreated Strongarm + Prowl (PPI)
PE-01-00
Untreated Strongarm ($23.50/A)
Strongarm fb Cadre - 1 oz/ACOC - 1% v/v
($44.77/A)Gramoxone Max - 5.5 oz/A
Storm - 1 pt/A2,4-DB - 1 pt/A
NIS - 0.125% v/vfb Cadre - 1 oz/A
COC - 1% v/v($35.14/A) 28 DAT
StrongarmHow Should It Be Used in GA?
• use where starbur, eclipta, poinsettia, and copperleaf are problems
• tank-mix with DNA
• irrigate in if possible
• variable on nutsedge
• poor sicklepod control
Strongarm Label Update2001
“at cracking” applications
split applications
snapbean rotation = 9 months
Strongarm/Cadre CombinationsConcerns?
• cost/A
• rotations
* peanut (anytime)
* soybeans (9 m)
* snapbean (9 m)
* IR corn (10 m)
• ALS resistance
Valor 50WDG
• Valent
• flumioxazin• N-phenylphthalimide derivative• PPO oxidase inhibitor• PRE• 2-3 ozs/A • label in April 2001 (I hope!!)
Why do we need Valor??
• Florida beggarweed
• rotation restrictions
• mode of action
• reduced costs/A?
• market competition
But, it is not the Holy Grail!!
Why does Valor have to be applied PRE in peanuts?
• PPI treatments less effective
Bristly Starbur Control with Valor @ 3 ozs/A
77
58
20
9280
58
0
20
40
60
80
100
5 WAP 8 WAP 13 WAP
Time
Con
trol
(%
)
PPIPRE
Attapulgus, 2000
Why does Valor have to be applied PRE in peanuts?
• PPI treatments less effective
• POST treatments can cause excessive crop injury!
Valor Injury on Peanuts
Although Valor has many strengths, growers/dealers need to be made aware of
its weaknesses such as . . . .
• cocklebur
• nutsedge
• sicklepod
• increased crop injury with delayed applications
Do soil applied herbicides cause yield reductions?
Peanut Yield As Influenced By PRE Herbicides
5767 57695456
5838
0
1500
3000
4500
6000
Untreated Strongarm Valor Spartan
Herbicide
lbs/
A
Averaged over 2 varieties (GA Green, C99R) * LSD (0.05) = 561 weed-free
Reduced Tillage Weed Control Research Results
• 2,4-D, Clarity, and Harmony Extra
Peanut yield response to preplant herbicide applications in Georgia, 2000.
0
1000
2000
3000
4000
5000
2,4-D amine(1.1 pt/A)
2,4-D ester(1.1 pt/A)
Clarity HarmonyExtra
Herbicide
lbs/
A
30 DBP 15 DBP 7 DBP 0 DBP None
*Averaged over 4 locations (P = 0.45)
(0.5 pt/A)(0.6 oz/A)
University ofGeorgia
ExtensionWeed Science(gaweed.com)
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