Controlling Primrose With Low Rates of 2,4-D Alone and in Tank Mixtures

A. S. Culpepper and A. C. York

University of Georgia

N. C. State University

Conservation Tillage Acreage

1998 2003

GA 12% 40%

NC 30% 55%

Cutleaf Eveningprimrose and Wild Radish are the Most Common Weeds

For Cotton Burndown

0.75 lb ae NTC 0.5 lb ai

glyphosate paraquat

30 DAT- primrose

Literature Review – Primrose Control

Reynolds, Crawford, Jordan. JCS, 2000. 2,4-D (0.75 lb/A) was the most effective tank mix partner with glyphosate or paraquat

Poston, Blaine, Griffin. SWSS, 2003.Control averaged 95% when 2,4-D (0.75 lb/A) was added to glyphosate

Culpepper and York. SWSS, 2002.Most effective tank mix partner with glyphosate or paraquat was 2,4-D (0.5 lb/A)

2,4-D Plant Back Intervals

Barrage HF and Salvo – 30 day prior to plant

Many other 2,4-D’s – 3 months or until disappeared

Objectives

How much 2,4-D alone is needed to control primrose?

How much 2,4-D do we need to add with a non-selective herbicide option to control primrose?

2003 Locations

Rocky Mount*

Tifton*

Methods

Plot size: 6 by 25 feet, GA

12 by 20 feet, NC

Design: RCB

Reps: 4 GA, 3 NC

MPH: 3

GPA: 15

Tips: flat fan

Treatments

2,4-D amine (4 lb ae/gal)

4 oz/A

8 oz/A

12 oz/A

16 oz/A

Treatments

Roundup WeatherMax at 16 oz NC, 21 oz GA

WeatherMax + Valor at 1 oz/A

Gramoxone at 1 qt/A + Caparol at 1 qt/A

Alone or with 4 oz/A of 2,4-D

Primrose Response to 2,4-D. Pooled over Tifton, GA and Rocky Mount, NC. 2003.*

*Primrose 6 to 9 inches at time of application.

2,4-D (oz/A)

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15 DAT

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Primrose Response to 2,4-D. Pooled over Tifton, GA and Rocky Mount, NC. 2003.*

*Primrose 6 to 9 inches at time of application. Statistical comparison is within rating date.

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15 DAT36 DAT

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2,4-D (oz/A)

Primrose Response to 2,4-D. Pooled over Tifton, GA and Rocky Mount, NC. 2003.*

*Primrose 6 to 9 inches at time of application. Statistical comparison is within rating date.

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2,4-D (oz/A)

Large Primrose Response to 2,4-D. Tifton, GA. 2003.*

*Primrose 16 to 20 inches at time of application.

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2,4-D (oz/A)

Large Primrose Response to 2,4-D. Tifton, GA. 2003.*

*Primrose 16 to 20 inches at time of application. Statistical comparison is within rating date.

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2,4-D (oz/A)

Primrose Response to 2,4-D. 6 WAT. Rocky Mount, NC. 2003.

Non-treated Control 8 oz 2,4-D

Primrose Response to 2,4-D. 6 WAT. Rocky Mount, NC. 2003.

Non-treated Control 4 oz 2,4-D

Primrose Response to 2,4-D Mixtures. Pooled over Tifton, GA and Rocky Mount, NC. 2003.*

*Primrose 6 to 9 inches at time of application. Statistical comparison is with and without 2,4-D. Roundup WeatherMax 16 to 21 oz/A, Valor 1 oz/A, Gramoxone 1 qt/A, and Caparol 1 qt/A.

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RoundupGramoxone + Caparol Roundup + Valor

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+ 4 oz 2,4-D

15 DAT

+ 4 oz 2,4-D

+ 4 oz 2,4-D

Primrose Response to 2,4-D Mixtures. Pooled over Tifton, GA and Rocky Mount, NC. 2003.*

*Primrose 6 to 9 inches at time of application. Statistical comparison is with and without 2,4-D. Roundup WeatherMax 16 to 21 oz/A, Valor 1 oz/A, Gramoxone 1 qt/A, and Caparol 1 qt/A.

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RoundupGramoxone + Caparol Roundup + Valor

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43-47 DAT

+ 4 oz 2,4-D

+ 4 oz 2,4-D

+ 4 oz 2,4-D

Primrose Response to WeatherMax. 6 WAT. Rocky Mount, NC. 2003.

Non-treated Control 16 oz WeatherMax

Primrose Response to 2,4-D. 6 WAT. Rocky Mount, NC. 2003.

16 oz WeatherMax + 4 oz 2,4-D

Primrose Response to 2,4-D Mixtures. 6 WAT. Rocky Mount, NC. 2003.

16 oz WeatherMax + 8 oz 2,4-D

Primrose Response to 2,4-D Mixtures. 6 WAT. Rocky Mount, NC. 2003.

WeatherMax + Valor + 4 oz 2,4-D

Conclusions – 2,4-D Alone

1) At 30 DAT, only 12 and 16 oz/A of 2,4-D provided greater than 90% primrose control.

2) By 45 DAT, all rates of 2,4-D provided greater than 90% primrose control.

3) By 56 DAT, primrose control was nearly complete regardless of rate.

4) Primrose size did not appear to matter

5) What rate?? How long can you wait!!!

Conclusions – 2,4-D Mixtures

1) At 15 DAT: Roundup (32%), Roundup + Valor (87%), Gramoxone + Caparol (90%)

2) At 15 DAT: mixing 4 oz/A 2,4-D with Roundup improved control 25%.

3) At 45 DAT: Roundup (71%), Roundup + Valor (81%), Gramoxone + Caparol (81%).

4) At 45 DAT: mixing 4 oz/A of 2,4-D improved control of non-selective treatments by 18 to 28%.

Future Research

1) Results must be confirmed!!

2) Plant back interval to cotton??

QUESTIONS?