Whole-Farm Weed Management Practices For Palmer Amaranth Control - - PowerPoint PPT Presentation

Eric P. Prostko, Ph.D. Professor and Extension Weed Specialist

• Dept. Crop & Soil Sciences

Whole-Farm Weed Management Practices For Palmer Amaranth Control

Current Weed Control Programs in GA Are Focused on 1 Weed!

Important Things We Know About Palmer Amaranth

n

Well-adapted to Georgia!

q

Native to Sonoran desert

n

Separate male and female plants

n

Lots of seed!!!!

q

400,000 – 500,000/female plant

n

Seed do not last long in soil

q

20% germ after 30 months

n

Seed do not emerge from deep depths (≥ 3-4”)

n

Seed need light to germinate

n

Resistance trait moves in pollen

q

At least 1000 feet!!

Herbicide-Resistant Palmer Amaranth in GA

n ALS (2000) n Glyphosate (2005) n Atrazine (2009) n ALS + GLY (2009) n DNA + ALS + GLY (2010) n ALS + GLY + ATZ (2011)

Pigweed Control is not impossible!!!! Common Reasons for Failure: 1) did not start clean 2) did not use a residual 3) residual did not get activated 4) POST applications are too late 5) short arms and deep pockets

What one man can do, so can another! Sumter County - June 28, 2011 (Prowl + Valor fb Cadre)

Our Biggest Challenges

Irrigation/Rainfall Farm Size/Weed Size

Rainfall Totals

Midville, GA

inches Month

Source: UGA Automated Weather

A Question For You

n How many acres can

you effectively and safely spray in 1 day?

q How many total acres

need to be sprayed?

q What if it rains? q What if it is windy?

Palmer Amaranth Growth 22 days after starting clean

June 22, 2011 Attapulgus, GA

Activated Activated Residual Herbicides are the key! Residual Herbicides are the key! (Likely will need 2 (Likely will need 2-

• 4 depending upon the crop)

4 depending upon the crop)

Cotton Peanut Corn Sorghum Soybean Valor Valor Atrazine Atrazine Valor Reflex Dual Magnum Dual Magnum Dual Magnum Envive Dual Magnum Warrant (?) Warrant Warrant Reflex Warrant Prefix Diuron Dual Magnum Warrant Metribuzin

Boundary TriCor Authority MTZ

Top 10 Reasons Why I Like Corn in a GA Crop Rotation!

(unless you are a dairyman with long-term ryegrass/ field corn/ sorghum rotation)

1.

Atrazine

2.

Atrazine

3.

Atrazine

4.

Atrazine

5.

Atrazine

6.

Atrazine

7.

Atrazine

8.

Atrazine

9.

Atrazine

• 10. Atrazine

Atrazine 4L @ 2 qts/A + COC @ 1% v/v Atrazine 4L @ 2 qts/A + COC @ 1% v/v Applied to 4 Applied to 4” ”-

• 9

9” ” Palmer Amaranth (6 Palmer Amaranth (6” ” average) average) Photo Photo 13 DAT 13 DAT

Atrazine 4L @ 2 qts/A + COC @ 1% v/v Atrazine 4L @ 2 qts/A + COC @ 1% v/v Applied to 4 Applied to 4” ”-

• 9

9” ” Palmer Amaranth (6 Palmer Amaranth (6” ” average) average) Photo Photo 28 28 DAT DAT

Future of Atrazine?

n

In April 2010, EPA stated that no additional testing is warranted to address the issue

• f atrazine and amphibian

gonadal development.

n

On May 6, 2011, Save The Frogs petitioned the EPA to ban the use and production of atrazine.

n

Public comments were accepted until November 14, 2011

n

??

Post Post-

• Harvest Palmer Amaranth

Harvest Palmer Amaranth Populations Populations Must

Must be Managed!

be Managed!

Post-Harvest (Corn) Pigweed Problems

n Decreasing daylight hastens

flower and seed production

q

Flowering (3-4 weeks)

q

Seed production (2-3 weeks)

q

Some germination at 410F (8%)

n Control Options

q

Mowing/Tillage (>6” weeds)

q

Herbicides (<6” weeds)

n

No small grain

q

Gramoxone + Dual Magnum or Warrant (?)

n

Small Grain planted soon

q

Gramoxone + 2,4-D or dicamba

n When can we stop worrying

about seed production?

Keeley et al. 1987. Weed Science 35:199-204 Steckel et al., 2004. Weed Science 52:217-221

Post-Harvest Control of Palmer Amaranth

(6” average: 2” -17” range at application)

CN-01B-11 September 15 30 DAT

NTC

Gramoxone Inteon 2SL @ 3 pt/ A 2,4-D Amine 3.8SL @ 1 pt/ A Primary @ 1% v/ v Gramoxone Inteon 2SL @ 3 pt/ A Clarity 4SL @ 8 oz/ A Primary @ 1% v/ v

Post-Harvest Control of Palmer Amaranth

(6” average: 2” -17” range at application)

CN-01B-11 September 15 30 DAT

NTC

Gramoxone Inteon 2SL @ 3 pt/ A Dual M agnum 7.62EC @ 16 oz/ A Primary @ 1% v/ v Gramoxone Inteon 2SL @ 3 pt/ A Warrant 3M E @ 48 oz/ A Primary @ 1% v/ v

Palmer Amaranth Control Tactics For Every Row Crop

n

Starting Clean

n

Tillage

n

Extreme Cover Crops

n

Residual Herbicides

q

Irrigation

q

Incorporation (dryland)

n

Timely POST’s

n

Post-Harvest (Corn)

n

Others

q

Hand-Weeding

q

Non-Selective Applicators (only for peanuts)

Non-Selective Applicators

The Influence of Wipe Percentage on the Control of Palmer Amaranth with Gramoxone Inteon (50% solution) in the Grassworks WeedWiper

Wipe Percentage (%) Control (%)

Data from 8 Field trials (2009-2011)

Future Concerns

n Abuse of Ignite n Increased use of Dual

Magnum and Warrant

n Increased use of PPO

herbicides

q Valor and Reflex

Questions/ Discussion?

www.gaweed.com