Comparing Volatility of Three Forms of 2,4-D when Applied in the Field

Culpepper, Richburg, Sosnoskie, Braxton

Future Technology

Herbicide Cost of $39/A

Technology of Today

Herbicide Cost of $59/A

Sensitivity of Non 2,4-D Resistant Cotton to 2,4-D

2,4-D resistant

Sensitivity of Vegetables to 2,4-D

2011 GA Vegetable Facts

• Approximately 200,000 acres

• 40 different vegetables grown

• 3rd largest vegetable producing state for A

• Farm Gate Value: $1,200,000,000

Many of these crops are grown in the same areas often by the same growers.

Off Target Movement Concern

• Physical drift

• Volatility

Off Target Movement Concern

• Physical drift = related to someone most likely not following label recommendations

• Volatility = one can do everything perfect and there can still be a serious issue

Objective

Volatility needs to be eliminated or at least know exactly how far it could move

2,4-D Choline

2,4-D Amine

2,4-D Ester

2,4-D Ester

2,4-D Amine

2,4-D Choline

N 2010Sunbelt Ag Expo

N 2011

2,4-D Ester

2,4-D Amine

2,4-D Choline

Sunbelt Ag Expo

S

SESW

EW

N

NENW

Potted cotton plants placed in all directions @ 5, 10, 20, 40, 80 and 160 ft

Treated area = 90 foot by 90 foot

Potted plants each year = 1728Four plants per location for 48 hrs, 1st 24 h, 2nd 24 h.

S

SESW

EW

N

NENW

N 2011Sunbelt Ag Expo

MethodsMix location: off site

Rate: 2 lb ae/A glyphosate + 2 lb ae/A 2,4-D

Application: FF 11002 DG, 25 PSI, 15 GPA

Time of day: before 10 am

Soil: 88% sand, 12% silt; pre-irrigated

Controls for Methods

Truck ride (2010, 2011): no damage

Herbicide application (2011): no damage

Plant contact (2011): no damage

65

75

85

95

800

930

1100

1230

1400

1530

1700

1830

2000

2130

2300 30 200

330

500

630

9/9/2010 9/10/2010 9/11/2010

2010 Temperature (F)

Max soil temp range 99-103 F; mix of clouds and sun; max sustained wind 8 mph.

Application Sept 9.

8 am 7 am

2011 Temperature (F)

65

75

85

95

Aug. 30 Aug. 31 Sept. 1

Application Aug 30.

Max soil temp ranged 106-113 F; completely sunny; max sustained wind 11 mph.

8 am 7 am

Visual Cotton Injury

Heights

Nodes

Cotton Injury (%) as Influenced by Distance. In-field 48 hours. 2010.

0

20

40

60

80

5345

38

205

0

5 10 40 16020 80

Data pooled over direction.

Distance

= Ester = Amine = Choline

Form x distance (P ≤ 0.05)Ester > Amine, Choline, for all distances

Ester: 5 > 10 > 20 > 40 > 80 > 160Amine: 5 > 10 > 20–160

Amine 5–10 > Choline 5-10

Cotton Injury (%) as Influenced by Distance. In-field 48 hours. 2011.

0

20

40

60

80

7369

58

38

204

5 10 40 16020 80

= Ester

Data pooled over direction.

= Amine

Distance

= Choline

Form x distance (P ≤ 0.05)Ester > Amine, Choline, for all distances

Ester: 5 > 10 > 20 > 40 > 80 > 160Amine: 5 > 10 > 20–160

Amine 5–10 > Choline 5-10

Choline

Ester

Cotton Injury (%) from Ester as Influenced by Distance & Time. 2010.

0

20

40

60

80

5 10 4020 80

= 0-48 h

Data pooled over direction.

= 0-24 h = 24-48 h

Distance (ft)

Time x distance (P ≤ 0.05)0-48 h ≥ 0-24 h ≥ 24-48 h, for all distances

Cotton Injury (%) as Influenced by Duration In-Field. 2011.

0

20

40

60

80

5 10 4020 80

= 0-48 h

Data pooled over direction.

= 0-24 h = 24-48 h

Distance (ft)

Time x distance (P ≤ 0.05)0-48 h ≥ 0-24 h ≥ 24-48 h, for all distances

Cotton Injury (%) by Ester as Influenced by Direction. In-field 48 hours.

0

20

40

60

80

N NE SE NWE

Data pooled over distance

S SW W

Direction

= 2010 = 2011

S

SESW

EW

N

NENW

Application to 2 pm (0 to 5.5 mph)

2 to 5 pm (4-11 mph)

5 to 9 pm (11 to 0 mph)

2011 Wind Direction. Day of Application

Volatility Injury to Cotton: Tunnel Data

20 plants assigned a location number

Cotton Injury (%) as Influenced by Tunnel. 2010.

0

20

40

60

80

Ester Amine Choline

= 0-48 h = 0-24 h = 24-48 h

Data pooled over 20 plants for each herbicide and time interval.

0-48 h: Ester > Amine > Choline0-24 h: Ester > Amine > Choline

24-48 h: Ester > Amine = Choline

Cotton Injury (%) as Influenced by Tunnel. 2011.

0

20

40

60

80

Ester Amine Choline

= 0-48 h

Data pooled over 20 plants for each herbicide and time interval.

= 0-24 h = 24-48 h

0-48 h: Ester > Amine > Choline0-24 h: Ester > Amine = Choline

24-48 h: Ester > Amine = Choline

Conclusions

1. Ester formulation should not be applied in Georgia during similar conditions.

2. Choline formulation offers the lowest potential for off-target movement from volatility.

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