Managing Palmer Amaranth in Peanut Eric P. Prostko Extension Weed - - PowerPoint PPT Presentation

Managing Palmer Amaranth in Peanut

Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia

Palmer Amaranth in Georgia

Some facts that should scare you!

• 1 Palmer amaranth plant per

meter (3.2 ft) of row can reduce peanut yield by 28%.

• 1 Palmer amaranth plant per

meter (3.2 ft) of crop row can result in the production of ~162,000,000 seed/acre.

Source: Burke et al., 2007. Weed Technology 21:367-371

R-Palmer amaranth seed longevity

Length of burial

0 mon. 3 mon. 6 mon. 9 mon.

Percent (%) viable

40 50 60 70 80 90 100 0.5" 1" 4" 16"

Source: Dr. Lynn Sosnoskie - UGA

Palmer Amaranth Control in Peanuts

• Deep tillage or extreme

cover crops

• Start Clean!!!!!
• Use a residual!!!

– Do you have ALS or DNA resistance? – Are you willing to use Valor? – Dryland or Irrigated?

• Spray when plants are

small (<3”)

• Rope-wick Applications

– last resort

No Deep Tillage Deep Turn

No Herbicide Treatment

Late-season Glyphosate-Resistant Palmer Control in Dryland Conservation Tillage Cotton. Macon Co., GA 2008.*

20 40 60 80

W heat cover Rye cover

50 b 74 a

Included: Prowl + Reflex PRE Roundup + Dual Magnum POST Direx + MSMA PD

%

Weed-free Seedbed???

Palmer Amaranth Control in Peanuts

Macon County, GA – 2007 (38 DAT)

NTC Valor SX 51WG @ 3 oz/A

Palmer Amaranth Control in Peanuts

Macon County, GA – 2007 (38 DAT)

NTC Dual Magnum 7.62EC @ 1 pt/A

GR-Pigweed Control in Peanuts – 2008 Macon County – 91 DAP

NTC

Prowl H2O @ 2.1 pt/A (PRE) Valor SX 51WG @ 3 oz/A (PRE) Cadre 2AS @ 4 oz/A (41 DAP)+ Peptoil @ 1% v/v (41 DAP)

If residual herbicides are not activated on a timely basis with a reliable water source, pigweed control will be very difficult, maybe even impossible!

May 2008 Rainfall Distribution in Tifton (CPES)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Day

Dryland crops planted before May 9 or after May 16 did not get enough rain to activate residual herbicides!!! First rainfall event > 0.5” in June occurred on June 15 (1.03”)

0.33” 0.02” 0.06”

May-June 2008 Rainfall Distribution in Midville

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 13 14 15 16 17 18 19 20 2 1 2 2 2 3 24 25 26 27 28 29 30 31

May

Crops planted from May 21-June 21 did not receive enough rainfall to activate herbicides (0.26” total). June Rainfall = 0.62” which occurred as follows:12 (0.08”); 22 (0.36”); 26 (0.08”); 29 (0.10”)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

June

May-June 2008 Rainfall Distribution in Moultrie

0.2 0.4 0.6 0.8 1

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 13 14 15 16 17 18 19 20 2 1 2 2 2 3 24 25 26 27 28 29 30 31

May 0.2 0.4 0.6 0.8 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

June

Dryland Systems

• Growers need to think

about mechanical herbicide incorporation

• Will help but not a

guarantee

• Success will depend

upon…… – operator – Implement – Soil conditions

• Dual Magnum

– PPI (1 pt/A) – POST (1 pt/A)

Can you mechanically incorporate Valor?

• Only labeled for PRE

applications

• May lose 25-50% of

weed control when mechanically incorporated (PPI)

• Valent not liable for

reduced performance if applied PPI

Palmer Amaranth Control with Valor No-Till vs. Strip (40 DAT)

13 60 53 53 50 81 86 89 20 40 60 80 100 1 2 3 4 Valor R ate/A C

• ntrol - %

. Strip N

• -Till

Source: Culpepper Macon County C22-08

What about the generic formulations of metolachlor?

• Me-Too-Lachlor,

Parallel PCS, Stalwart

• Frequently, but not

always, they do not last as long as Dual Magnum

Palmer Amaranth Control in Peanut with Dual Magnum and Stalwart

20 40 60 80 100 11 18 23 38 53 94 Tim e (DAT) Control - % . Dual M agnum Stalwart

PE-03-07 Both applied at 1 pt/A *Significantly different at 53 DAT and 94 DAT (P = 0.10)

* *

Will these herbicides control large pigweeds?

GR-Pigweed Control in Peanuts – 2008 Macon County – 91 DAP

NTC

Prowl H2O @ 2.1 pt/A (PRE) Gramoxone Inteon @ 12 oz/A (21 DAP) + Storm @ 1 pt/A + LI-700 @ 0.25% v/v (21 DAP) Cadre @ 4 ozA (41 DAP) + Peptoil @ 1% v/v (41 DAP)

GR-Pigweed Control in Peanuts – 2008 Macon County – 91 DAP

NTC

Prowl H2O @ 2.1 pt/A (PRE) Ultra Blazer @ 1 pt/A (21 DAP) + LI-700 @ 0.25% v/v (21 DAP) Cobra 2EC @ 12.5 oz/A (41 DAP) + Peptoil @ 1% v/v (41 DAP)

Palmer Amaranth Control with Ultra Blazer and 2,4-DB - 2008

NTC Ultra Blazer @ 1.5 pt/A LI-700 @ 0.25% v/v

Treatments applied to 2-10” tall pigweed , 6.23” average height Photo 16 DAT

Ultra Blazer @ 1.5 pt/A 2,4-DB @ 18 oz/A LI-700 @ 0.25% v/v

Palmer Amaranth Control with Cobra and 2,4-DB - 2008

NTC Cobra @ 12.5 oz/A 2,4-DB @ 18 oz/A Peptoil @ 1% v/v

Treatments applied to 2-10” tall pigweed , 6.23” average height Photo 16 DAT

Cobra @ 12.5 oz/A Peptoil @ 1% v/v

2,4-DB fb Cobra or Ultra Blazer????? (has only been successful ¼ times)

POST: June 5 (17” tall pigweed) POST2: June 9 Photos taken 24 days after POST application Untreated Cobra 2EC @ 12.5 oz/A Agrioil @ 1% v/v POST 2,4-DB 1.75SL @ 1.1 pt/A + Agrioil @ 1% v/v (POST) fb Cobra 2EC @ 12.5 oz/A Agrioil @ 1% v/v POST2

Rope-wick Applicators

• Only thing labeled

(sort of) is glyphosate – Label says row middles

• At this time of year,

yields not influenced

• Benefits

– Harvestability – Fungicide spray deposition – Seed bank – REVENGE!!!!

Custer’s Last Stand

Possible Herbicide Programs (Assuming ALS Resistance)

• Irrigated

– Prowl/Sonalan + Valor (PRE) – Cobra or Ultra Blazer + Dual Magnum (POST)

• 2-3” tall pigweed
• Dryland

– Prowl/Sonalan (PPI) – Paraquat + Storm + Dual Magnum (CRACK) – Cobra or Ultra Blazer + Dual Magnum (POST)

• 2-3” tall pigweed
• Total Maximum Amount of Dual Magnum that can used per year is 45 oz/A
• 90 day PHI

We are overusing the PPO inhibiting herbicides!!!!!!!!

• Resistance has already been

reported in other areas!!!

• Common waterhemp

– 2001 (Kansas) – 2002 (Illinois) – 2003 (Missouri)

• Common ragweed

– 2005 (Delaware)

• Wild poinsettia

– 2004 (Brazil)

For More Weed Science Info www.gaweed.com

www.gaweed.com