Soybean Weed Control - University of Georgia :: Weed … Soybean Weed Control Many Options •...
Transcript of Soybean Weed Control - University of Georgia :: Weed … Soybean Weed Control Many Options •...
Soybean Weed
Control
Eric P. ProstkoExtension Weed Specialist
Department of Soil & Crop ScienceThe University of Georgia
Conventional Soybean Weed ControlMany Options
• Preemergence– grasses grasses –– Treflan, Prowl, Dual/Generics, Intrro, MicroTreflan, Prowl, Dual/Generics, Intrro, Micro--Tech, Tech,
Outlook, CommandOutlook, Command–– broadleaf broadleaf –– Boundary, Canopy, Sencor, Pursuit, Scepter, Boundary, Canopy, Sencor, Pursuit, Scepter,
Lorox, Python, Valor, Reflex, Valor XLT , Envive, PrefixLorox, Python, Valor, Reflex, Valor XLT , Envive, Prefix
• Postemergence–– grasses grasses –– Assure/Targa, Fusilade, Poast, Select/ArrowAssure/Targa, Fusilade, Poast, Select/Arrow–– broadleaf broadleaf –– Ultra Blazer, Basagran, Cobra, Storm, ClassicUltra Blazer, Basagran, Cobra, Storm, Classic
• Rotation restrictions
Burndown Options for Reduced Tillage Soybean Production Systems
• Primary– Glyphosate– Gramoxone
Inteon/Firestorm/Parazone– Ignite
• Tank-mixes– 2,4-D (7-15 DBP)– Aim (0 DBP)– ET (0 DBP)– Valor (0 DBP)– Harmony Extra (14 DBP)– Express (14 DBP)– Clarity/Vision (14 DBP + 1” rainfall) – Canopy EX (Classic + Express)
• 7-14 DBP DBP = days before planting
U.S. Soybean Acres Planted to Herbicide Resistant Varieties
54
6875
81 85 87 89 91 92
0
20
40
60
80
100
2000 2001 2002 2003 2004 2005 2006 2007 2008
Year
% o
f Acr
es
.
Source: NASS
RR Soybean Weed Control SystemsThings to Think About
• glyphosate prices are increasing– $33/gal (generic 4 lb/gal)– $70/gal RUPM
• current price of RR soybean seed– $44/50 lbs (retail)
• weed resistance issues
R1 - first flower R2 - full bloomR3 - pod initiation R4 – full podR5 – beginning seed R6 - Full seed
R2
R3
To Prevent Yield Loss in RR Soybeans
1 control weeds by 4-5 weeks after planting
or2 control weeds before they
reach 6-9” in heightor
3 control weeds before the V3 stage
Source: Purdue University Extension Weed Science Group(5.4 million acres harvested in in 2008)
Tolerance of GR-Soybean to Late-Season Glyphosate Applications (1.5 lb ai/A)
05
1015202530354045
2000 2001
Year
Bu/
A
V3 R2 R4 V3+R2 V3+R4 V3+R6 NTC
J.K. Norsworthy. 2004. Weed Technology 18:454-457 LSD 0.05 = NS
Soybean Yield As Influenced by Glyphosate Applied at R4 + R6 Stage
51 5148 50 52
49
0
15
30
45
60
0 0.41 0.82 1.23 1.64 2.45
Glyphosate Rate (lb ae/A)
Bu/
A
>
Source: Miller et al., 2008. Weed Technology 22:359-362 THSD 0.05 = NS
Glyphosate + Fungicide Tank-MixesSoybean Rust
• What do labels say?• timing concerns
– Glyphosate = V3– Fungicide = R1 or later
• limited information• preliminary results from
UGA research suggest no major problems
• more data is needed
Glyphosate/Boron/DimilinTank Mixes
• full-bloom to early pod-fill• R2-R3 stage• Is this the best time for
Roundup? (V3)• Crop injury?• No more than 0.25 to 0.5 lb/A
of Boron
Tropical Spiderwort(Benghal Dayflower)
TSW in Georgia
• 2004: 29 counties (light blue)• 2005: 5 counties (black)• 2006: 6 counties (dark blue)• 2007: 2 counties (yellow)• 2008: 2 counties (red)
Tropical Spiderwort Management in RR Soybeans
• timing is critical• EPOST
– Sequence (3 pts/A)• Glyphosate + Dual Magnum
– Extreme (3 pts/A)• Glyphosate + Pursuit
– glyphosate +• Classic or• FirstRate
Tropical Spiderwort Control with Roundup WeatherMax in Soybean -2004
62
8377
71
0
20
40
60
80
100
None Pursuit (4 ozs) Classic (0.5 ozs) FirstRate (0.20ozs)
Tank-Mix
Con
trol -
%
.
Ratings at 20-24 DATAverage of 2 testsRoundup WeatherMax @ 22 ozs/A
Tropical Spiderwort Control in RR Soybeans
Tattnall County - 2005
Untreated Sequence @ 3 pts/A Extreme @ 3 pts/A
33 DAT
Controlling RR Cotton in RR Soybeans
• Preemergence– Canopy 75DG (8 oz/A)– Sencor 4L (8-12 oz/A) – Sencor 75DF (5.3-8 oz/A)
• POST glyphosate tank-mixes– 6” cotton, 3 leaves– Resource (4 ozs/A) - 77%– 2,4-DB (2 ozs/A) - 76%– Reflex (12 ozs/A) - 72%– Classic (0.33 ozs/A) - 62%
• PRE only = 54-87%• POST only = 62-77%• PRE + POST = > 95%
Source: York et al., Weed Technology. 2004. 532-539.
Controlling RR Corn in RR Soybeans
• tank-mix glyphosate with POST grass herbicide
• rate depends on height of corn• Assure II (5-8 ozs/A)• Fusilade (4-8 ozs/A)• Select (4-8 ozs/A)• SelectMax (8-12 ozs/A)• Poast (12-16 ozs/A)• Poast Plus (18-24 ozs/A)• adjuvants
Nutsedge Management in RR Soybeans
• preemergence– Canopy, Envive, Reflex, Dual– yellow nutsedge
• split applications of glyphosate– better on purple than yellow
• glyphosate + Classic– controls yellow – suppresses purple
• glyphosate + Pursuit– better on purple than yellow– rotations/cost
Glyphosate/Manganese Tank-Mixes
• depends upon type of Mn– Mn-EDTA (yes)– Mn-EAA (no)– Mn-LS (no)– MnS04 (no)
• Mn not a problem with Blazer, Classic, Pursuit, or Basagran.
Sources: Bernards et al., 2005 (Weed Technology 19:27-34); Bailey et al., 2002 (Weed Technology 16:792-799); and Heckman et al., 1999 (Journal of Production Agriculture 12:445-448)
Glyphosate Resistance Around the World (15 species)
• rigid ryegrass (1996)**• goosegrass (1997)• horseweed (2000)**• Italian ryegrass (2001)**• hairy fleabane (2003)**• buckhorn plantain (2003)• common ragweed (2004)**• giant ragweed (2004)**• Palmer amaranth (2005)**• common waterhemp (2005)**• johnsongrass (2005)**• wild poinsettia (2005)• sourgrass (2006)• junglerice (2007)• liverseedgrass (2008)
** 9/15 (60%) can be found in the US
Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth.
2004 – 1 county
2005 – 2 counties
2006 – 7 counties
2007 – 10 counties
2008 – screening in progress
GA Confirmed ALS-Resistant Palmer Sites
ALS Soybean HerbicidesClassic, Scepter, PursuitPython, Harmony, Synchrony
Soybean Yield Losses Caused by Palmer Amaranth Plants When They Emerge with Crop
13
33
68
0
20
40
60
80
100
0.32 1.1 9.8
Density (plants/meter)
%
Klingman and Oliver. 1994. Weed Sci. 42:523-527
Pigweed Control in Soybeans
• use a residual herbicide– Canopy, Boundary, Valor, Valor
XLT, Prefix, Dual Magnum/Generics, Sencor, Prowl, Intrro, Treflan, Envive
• ALS or Glyphosate Resistance!!!!
• Spray POST herbicides early!!!!!!
GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co.
NTC Canopy 75WG @ 6 oz/ASB-05-0848 DAT
GR-Pigweed Control in Soybeans - 2008
SB-06-08Macon County48 DAP
NTC Canopy 75DG @ 6 oz/A + Prowl H2O 3.8ASC @ 2.1 pt/A (PRE)
Metribuzin Products on Soybeans
• Sencor• Boundary
– Dual Magnum + Sencor
• Canopy– Sencor + Classic
• Read label• Know soil texture and OM• Varieties• rotations
Crop Rotations forMetribuzin Products
18 months12 months18 monthspeanut
12 months12 months18 monthssorghum
10 months8 months18 monthscotton
4 months4.5 months4 monthswheat
10 months8 months4 monthsField corn
CanopyBoundarySencorCrop
Soybean varieties screened in 2008 that had adequate tolerance to Boundary 6.5EC (2 pt/A),
Canopy 75DG (5 oz/A), and Sencor 75DG (6 oz/A).
• Ag South AGS 568 Asgrow H7242• Asgrow 4903 RR/STS Delta Pineland DP 5634• Delta Pineland DP 6568 Northrup King NKS 80P2• Northrup King NKS 76L9 Northrup King NKS 78G6• Pioneer 95Y40 Pioneer 95Y70• Pioneer 96M60 Pioneer 97M50• Southern States RT5951 Southern States RT4808• Vigoro V61N9 Vigoro V74N9
GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co.
NTC Prefix 5.29EC @ 2 pt/ASB-05-0848 DAT
GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co.
NTC Envive 41.3WG @ 3 oz/ASB-05-0848 DAT
This is what a 2” pigweed looks like!!!!
Harmony GT XP or Harmony SG
• Harmony GT XP (75%)– GT = grass-tank mix– XP = extruded pellet
• Harmony SG (50%)– SG = soluble granules– 1/8 oz/A
• 1st trifoliate until 60 days before harvest• tank-mix with glyphosate• ALS inhibitor• up to 12” tall pigweed?????• variable amounts of soybean injury
Harmony GT on Soybeans(Tift County – 2008)
Harmony not Harmony Extra!!!!!
STS® Soybeans
• STS– Sulfonylurea Tolerant Soybeans
• Non-GMO• first introduced in 1993
• Synchrony XP– 21.5% Classic + 6.9% Harmony– Non-STS POST Use Rate = 0.375 oz/A
• 0.32 oz/A Classic 25DG + 0.035 oz/A Harmony GT– STS POST Use Rate = 0.75 oz/A
• 0.64 oz/A Classic 25DG + 0.07 oz/A Harmony GT
• 2007 UGA Soybean Variety Tests– DP5115RR/S, DP5335RR/S
Be careful when mixing!!Staple, Envoke, Cadre not a good idea!!!!
Burning Wheat StubbleGood or Bad idea?
• probably not good if you need a residual herbicide for pigweed control
• Why??
• may reduce the performance of residual herbicides– 60% adsorption by ash
Weed Control in SoybeansSicklepod
• Conventional* Canopy or Sencor or Python
fb Classic
• Roundup Ready
What’s in the pipeline?
• Liberty-Link • KIH-485• GAT Soybeans• Dicamba, 2,4-D resistance