Peanut Weed Control Update2004

Eric P. Prostko

Extension Weed Specialist

Things to Talk About

• Valor • Arrow

• Prowl H20

• newer metolachlor formulations• postemergence Strongarm• reduced rates• glyphosate problems

PeanutsValor Formulations

• 2001: 51 WDG

• 2002-03: 51 WP

• 2004: Valor SX 51WDG

* smaller particles

* dispersing agents

* easier to get into suspension

* 10% price reduction in 04’

PeanutsArrow 2EC• clethodim• POST grass control in broadleaf crops• generic Select• Makhteshim-Agan• 6 -16 ozs/A• price/service

PeanutsProwl H20 3.8CS

• 2004

• 3.8 lbs/gal

• 2.0 pts/A

• water-based

• micro-encapsulated

• less staining

• better for strip-tillage?

• increased price

Prowl H20

pendimethalin EC

Prowl H2O

PeanutsNew Metolachlor Formulations• Cinch

– Dupont

– same as Dual II Magnum– cannot use POST

• Stalwart C– Sipcam Agro USA Inc.

– “old” Dual EC formulation (7.8 lbs/gal)– not labeled for peanut

• Me-Too-Lachlor– Drexel– “old Dual EC formulation (8 lbs/gal)– rates are too low

PeanutsStrongarm Postemergence

• labeled in March 2000• PPI, PRE, AC• broadleaf weeds• 0.45 ozs/A• $15-18/A• 6% of GA acres in 2001• 10 month cotton rotation

restriction• ALS inhibitor

Untreated Strongarm applied17 DAP

Strongarm applied31 DAP

PE-24-0346 DAP

Tropical spiderwort control withPOST applied Strongarm, 2003

Bristly Starbur Control with POSTApplied Strongarm, 2003

PE-27-03 32 DAT

Untreated Strongarm @ 0.45 ozs/A

Strongarm @ 0.113 ozs/A

Untreated Strongarm 0.45 ozs/A + 80/20 @ 0.25% v/v

(Applied 5 WAP)11 WAP

Annual MG Control with POST Applied Strongarm, 2003

PE-15-0367 DAT

Wild poinsettia control with POST herbicides, 2003

Untreated Cadre @ 1.44 ozs/A

Strongarm @ 0.45 ozs/A

Wild Radish Control with POST Applied Strongarm (1”, 3-4 leaf)

Untreated Strongarm0.45 ozs/A

Strongarm0.225 ozs/A

40 DAT

PeanutsStrongarm Postemergence Summary

• good to excellent POST control of several species

• reduced rates on sensitive species such as bristly starbur, annual morningglory, wild radish

• timing and rate are critical on some species such as beggarweed

• no POST control of sicklepod

• not labeled at this time but working on this issue

• rotation restrictions?????

Reduced Rates of Strongarm and Valor - I

PE-01A-0391 DAP

Untreated Strongarm0.45 ozs/A

Valor3 ozs/A

Strongarm0.113 ozs/A

+ Valor

0.75 ozs/A

Reduced Rates of Strongarm and Valor - II

PE-01B-0391 DAP

Untreated Strongarm0.45 ozs/A

Valor3 ozs/A

Strongarm0.113 ozs/A

+ Valor

0.75 ozs/A

Economic Returns from Reduced Rates of Strongarm (S), Valor (V), and Cadre - I

973

798865

1049995 1010

1005 1001 1032

989 984 1022

0

200

400

600

800

1000

1200

S - 0.45 ozs V - 3 ozs S - 0.113 ozs + V -0.75 ozs

$/A

0 0.72 1 1.44

PE-01A-03Tifton

Economic Returns from Reduced Rates of Strongarm (S), Valor (V), and Cadre - II

907

836

916

941

802

949

875 883908

895

837

919

700

750

800

850

900

950

1000

S - 0.45 ozs V - 3 ozs S - 0.113 ozs + V -0.75 ozs

$/A

0 0.72 1 1.44

PE-01B-03Attapulgus

SummaryReduced Rates

• less injurious than Valor at full rate • similar weed control except for tropical spiderwort

and annual mg• when used in total program (pre + post), equivalent

yields and net returns when compared to full rate programs

• same program in one field may not be the best in another field

• digging efficiency/weed seed bank concerns in field with a few escapes?

Glyphosate Mishaps in Peanut!

Roundup WeatherMax vs. Crop Oil

Yield Losses Caused By Roundup Weather Max Applied to Virginia Peanuts @ 30 DAP.

0

10

20

30

40

50

60

70

80

90

0.2 0.4 0.7 1.5 2.9 5.8 11.6 23.3

Roundup WM (ozs/A)

Yie

ld L

oss

(%

)

Source: Adapted from B. Robinson, NCSU(3 years of data)