Rice Weed Management

Eric Webster

How to Manage Hard to Control (Escaped) Mid-Season Grasses when

Herbicide Programs Don’t Go As Planned

Barnyard-grass

Amazonsprangletop

Nealley’ssprangletop

Fall panicum

Broadleaf signalgrass

Creepingrivergrass

Brookspaspalum

Water paspalum Knotgrass

Beyond C S S S C S T S S

Bolero + Pro S S S S S T T S S

Clearpath C S S S C T T C S

Clincher C C S C C S T C C

Facet C T T S C T T T T

Grasp C T T T T S T T T

Newpath S S S S C S T C S

Obey C S T S S T T T S

Propanil S S S S S T T S S

RebelEx C* C* S* S* S* S* T S* C*

Regiment C T T T T T T T T

RiceBeaux S S S S S T T S S

RiceStar HT C C C S C S T C C

Strada S T T S T T T T T

C – Control; S – Suppression; T – Tolerant; * Potential for antagonism

Mid-Season Grass Management

Do not Cut Herbicide Program in an Effort to Save Money

Importance of Early Application

Profit over Herbicide Cost vs. Newpath Application Timing

100

150

200

250

300

350

400

450

500

550

Newpath Early fbNewpath 2 WAE

Newpath 1 WAE fbNewpath 3 WAE

Newpath 2 WAE fbNewpath 4 WAE

Newpath 3 WAE fbNewpath 5 WAE

Newpath 4 WAE fbNewpath 6 WAE

$304/A

$198/A$235/A

$186/A

Importance of Early Application for Nealley’s Sprangletop

5349

6788

60105916 5922

55955516

6310

5000

5250

5500

5750

6000

6250

6500

6750

7000

NT 1 2 3 4 5 6 WF

Rice Yield following RiceStar HT Timings on Nealley’s Sprangletop

RiceStar HT Application - Weeks after Emergence

lb/A

Nealley’s Sprangletop• Annual • Is often a perennial is south Louisiana • Prolific seed producer• Seed viable at maturity• Not extremely competitive• Must apply herbicides early - Previous slide delaying RiceStar HT

application from 1-6 wk, lose 32 lb/day or 1120 lb/A• Program approach is best• Postemergence 24 oz/A RiceStar HT

Newpath plus Propanil Programs

Different Propanil Formulations Applied in the Early or Late Newpath Application

2000

3000

4000

5000

6000

7000

No Propanil Stam EC RiceShot EC Stam SC SuperWham Stam EDF

Early LateYield lb/A

Different Propanil Formulations Applied in the Early or Late NewpathApplication, Net returns over Herbicide Costs

400

450

500

550

600

650

700

750

800

No Propanil Stam EC RiceShot EC Stam SC SuperWham Stam EDF

Early Late

$36.5/A

$52.6/A $56.7/A $64.8/A $60.7/A $93.1/A

163%

121%

170%

129%

116%

111%

154%

140%

148%

113%

Use of Residual Herbicides in a Clearfield System

Spend More/Make More

Residual Herbicides Evaluated

Yield of Clearfield Rice Treated with Residual Herbicides

5000

5200

5400

5600

5800

6000

6200

6400

6600

6800

7000

7200

No Residual Command Facet Grasp Prowl H2O

Ric

e Yi

eld

(lb/A

)

Newpath Beyond

Residual Herbicides Evaluated

Net Returns over Herbicide Cost

600

625

650

675

700

725

750

775

800

825

850

No Residual Command Facet Grasp Prowl H2O

Newpath Beyond

Ret

urns

($/A

) ove

r her

bici

de c

ost

0%

111%

106%

114%

121%122%123%

121%

114%

112%

$14/A $35/A $33/A $11/A

How has Production Changed

Louisiana Long Grain Rice Acreage as Percent of Total Crop

0

20

40

60

80

100

120

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Conventional ClearfieldC

ypre

ss

Cyp

ress

Coc

odrie

Coc

odrie

Coc

odrie

Coc

odrie

Coc

odrie

Coc

odrie

Che

nier

e

Che

nier

e

CL

151

CL

151

CL

151

Coc

odrie

Che

nier

eC

L 11

1CL

151

Che

nier

e

Che

nier

e

CL

111

Che

nier

eC

L 13

1C

ocod

rieC

L 16

1

CL

121

CL

161

CL

161 C

L 16

1

Che

nier

eC

L 11

1CL

151

Average Rice Yields in Louisiana from 1990 to 2015

4000

4500

5000

5500

6000

6500

7000

7500

310 lb/A550 lb/A

820 lb/A

400 lb/A

1200 lb/A

1910 lb/A970 lb/A

Data from www.nass.usda.gov

Long grain Rice Acreage as Percent of Total Crop vs. Yield Increase

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Conventional ClearfieldC

ypre

ss

Cyp

ress

Coc

odrie

Coc

odrie

Coc

odrie

Coc

odrie

Coc

odrie

Coc

odrie

Che

nier

e

Che

nier

e

CL

151

CL

151

CL

151

Coc

odrie

Che

nier

eC

L 11

1CL

151

Che

nier

e

Che

nier

e

CL

111

Che

nier

eC

L 13

1C

ocod

rieC

L 16

1

CL

121

CL

161

CL

161 C

L 16

1

Che

nier

eC

L 11

1CL

151

4500

5000

5500

6000

6500

7000

7500

• Cutting herbicide rates to save money• Delaying application timing, want to do it one time • Reduced rates often costs more

• Added applications• Reduced control from added applications • Often get into salvage situations – nobody wins• Yield loss due to lack of control

• Realized red rice not eliminated• New/old weed problems you forgot about

Things that Occurred this Year

• A herbicide is not always the best option• Cutting herbicide rates to save money is not a good idea• Nealley’s sprangletop management is not cheap• Apply POST herbicides to small weeds• Know what goes in tank and why• Coverage is important, higher speed, less coverage• Will Provisia rice help? Be prepared to follow stewardship• We have resistance but we can manage it• If you think you have resistance, assume you have it• Rice weed management in Louisiana some of best in last

2-3 years

Conclusion

Questions