University of Georgia

Tifton Campus

Culpepper, Webster, Rucker,

Sumner, Beard, Langston, Mayfield

2008 Methyl Bromide Alternatives Conference:

DMDS or the 3-WAY: Which is More Effective in GA

2007 Large Acreage On-Farm Trials

2007 On-Farm Comparisons

Fumigant and mulch options:1. 3-WAY under LDPE 2. MIDAS under Blockade 3. DMDS under LDPE4. MB under Blockade

DMDS under LDPE mulch

Boxes of Bell Pepper for Total Harvest. Data presented as % of MB. 2007.*

Jumbo X-Large Large Chopper

MB 100 a 100 a 100 a 100 a

MIDAS 98 a 97 a 88 a 104 a

DMDS 85 b 88 a 85 a 94 a

3-WAY 110 a 85 a 84 a 107 a

*Data totaled over three harvests.

MB fruit: Jumbo (14%), X-Large (32%), Large (27%), and Chopper (26%).

2008 Objectives Confirm the most effective mixture of DMDS and

chloropicrin was a 79:21 when applied under high barrier mulch.

Define the rate needed under high barrier mulch.

Compare the most effective DMDS system to the standard in a large acreage on farm trial.

Focus on annual grasses and pigweeds.

Formulation and Rate Experiment: Ponder Farm

Treatments

Factorial treatment arrangement (3 reps):

Formulations (DMDS/Pic) Rates79:21 30 Gal/A90:10 40 Gal/A100:0 50 Gal/A

60 Gal/A

Blockade Mulch

Treatments

Additional treatments:

1. 3-WAY (12/150/75) LDPE mulch2. DMDS 79:21 60 Gal LDPE mulch3. Non-treated control Blockade mulch

Materials and Methods

Applications were made on Feb 17

Soil temperatures were 60 F at injection

Soil moisture was 95% of field capacity.

Sandy loam soil type

Plot size 1 bed (2 rows of pepper) by 50 ft

Materials and Methods

Yellow nutsedge and large crabgrass

Plant growth

Nematodes

Yield (4 harvests of Jumbo fruit)

Percent yellow nutsedge control at harvest as impacted by DMDS formulation and rate.

TyTy, GA 2008.*

0

20

40

60

80

10098 a

50 G 30 G 90:10 100:040 G

100 a

Rate Main Effect

100 a

99 a

98 a

100 a

97 b

Formulation Main Effect

60 G 79:21

*Values within main effect followed by the same letter are not different at P = 0.05

Percent large crabgrass control at harvest as impacted by DMDS formulation and rate.

TyTy, GA 2008.*

0

20

40

60

80

100

50 G 30 G 90:10 100:040 G

55 b

Rate Main Effect

75 a 66

b49 c

69 a

42 c

Formulation Main Effect

60 G 79:21

*Values within main effect followed by the same letter are not different at P = 0.05

33 d

Percent large crabgrass control 55 d after fumigating as impacted by DMDS formulation

and rate. TyTy, GA 2008.*

0

20

40

60

80

100

50 G 30 G 90:10 100:040 G

98 a

Rate Main Effect

99 a

98 a

98 a

97 a

96 a

Formulation Main Effect

60 G 79:21

*Values within main effect followed by the same letter are not different at P = 0.05

94 b

Plant Heights and Nematodes

1. Plant heights taken 20 and 50 DAP with no differences.

2. No nematodes present in the study.

Jumbo fruit number per plot as impacted by DMDS formulation and rate. TyTy, GA 2008.*

0

40

80

120

160

200

50 G 30 G 90:10 100:040 G

181 b

Rate Main Effect

203197 194

210 a

175 b

Formulation Main Effect

60 G 79:21

*Values within main effect followed by the same letter are not different at P = 0.05

162 *

0

20

40

60

80

100

DMDS 79:21 60 G Bloc

3-WAY LDPE

90 b

100 a

DMDS 79:21 60 G LDPE

*Values within main effect followed by the same letter are not different at P = 0.05

Percent yellow nutsedge control at harvest as impacted by DMDS formulation and rate.

TyTy, GA 2008.*

100 a

0

20

40

60

80

100

DMDS 79:21 60 G Bloc

3-WAY LDPE

33 c

89 b

DMDS 79:21 60 G LDPE

*Values within main effect followed by the same letter are not different at P = 0.05

Percent large crabrass control at harvest as impacted by DMDS formulation and rate.

TyTy, GA 2008.*

100 a

0

100

200

300

DMDS 79:21 60 G Bloc

3-WAY LDPE

66 b

244 a

DMDS 79:21 60 G LDPE

*Values within main effect followed by the same letter are not different at P = 0.05

270 a

Jumbo fruit number per plot as impacted by DMDS formulation and rate. TyTy, GA 2008.*

On Farm Experiment

On Farm Trial

1.Four treatments:

DMDS 79:21 60, 50, 40 G Blockade mulch

3-WAY 12/150/75 under LDPE

2. Plots 3 rows by 1200 feet

3. Four Replications

Measurements taken:

1. Weeds emerging through mulch or plant hole

2. Crop height

3. Pathogens

4. Nematodes

5. Pepper Harvest (4 times)

6. Packing House Grades

Note moisture and compaction

Note moisture and compaction

Number of Purple Nutsedge, Crabgrass, and Livid Amaranth Plants/A with MB Alternatives in Pepper.

LTF, Spring 2008.*

Purple nutsedge

Livid amaranth

Large crabgrass

DMDS 40 G 122 a 91 c 620 c

DMDS 50 G 78 a 62 b 553 bc

DMDS 60 G 65 a 37 a 456 b

3-WAY 99 a 22 a 149 a

*Values within species followed by the same letter are not different at P = 0.05 Nutsedge and amaranth counts are at harvest, crabgrass counts early season followed by two applications of Select during the season.

Plant Height and Nematodes

1. No differences in crop growth

2. No differences in disease or nematodes

48 people picking

5 truck drivers

12 UGA dumpers

Once a week for 4 weeks

Harvest 1: 3 hrHarvest 2: 3 hrHarvest 3: 5 hrHarvest 4: 5 hr

Harvest 1: 2 hrHarvest 2: 2 hrHarvest 3: 6 hrHarvest 4: 5 hr

Grades: Jumbo, X-Large, Large, Medium, Suntan, Chopper

Boxes of Bell Pepper. LTF, Spring 2008.*

Jumbo

(Harvest 1-4)

Total Fruit

(Harvests 1-4)

DMDS 40 G 282 b 1160 b

DMDS 50 G 332 a 1275 ab

DMDS 60 G 335 a 1320 a

3-WAY 350 a 1393 a

CONCLUSIONS

3-WAY: continues to perform well in the spring and continues to perform poorly on nutsedge in the fall

CONCLUSIONS

DMDS:

1. 79:21 formulation is the most effective

2. 45 to 50 G in spring but 50 to 60 gallons in fall, depending on herbicides

3. Excellent nutsedge control; needs help on annual grasses, pigweed, and likely

other small seeded annual broadleaf weeds.

4. Smell and cost must be addressed.

ON FARM COOPERATOR

Bill Brim, LTF

Questions or Comments?