Weed Control Without Methyl Bromide

Drs. Stanley Culpepper and Ted Webster

University of Georgia and USDA-ARS

Tifton, Georgia

Methyl Bromide

Phasing out of the marketplace 1999 = 25% reduction

2001 = 25% reduction

2003 = 20% reduction

2005 = gone

(reduce methyl bromide ai over time)

Global Methyl Bromide Use

Preplant

Durable

Perishable

Commodity

Structural

Chemical interm

66%

Countries Using Methyl Bromide U.S.ItalyJapanSpainFranceMexicoBrazilTurkeyBelgiumMoroccoGreeceSouth AfricaChinaCosta Rica

37%

Replacing Methyl Bromide

A multi-tactic approach is needed and should include the following:

– application of weed biology

– cultural practices

– fumigants

– herbicides

Yellow Nutsedge:Yellow Nutsedge: - Yellow florets- Yellow florets - All tubers attached to - All tubers attached to mother tubermother tuber - Suppressed by bentazon - Suppressed by bentazon and metolachlorand metolachlor - Leaves: long drawn-out tip- Leaves: long drawn-out tip

Purple Nutsedge:Purple Nutsedge: - Dark red/purple florets- Dark red/purple florets - Forms chains of tubers- Forms chains of tubers - Not suppressed with - Not suppressed with bentazon or metolachlorbentazon or metolachlor - Leaves: short, abrupt tip- Leaves: short, abrupt tip

Chain of Purple Nutsedge TubersChain of Purple Nutsedge Tubers

Yellow NutsedgeYellow NutsedgePurple NutsedgePurple Nutsedge

Objective: Evaluate the Spatial Dynamics of Yellow Objective: Evaluate the Spatial Dynamics of Yellow and Purple Nutsedge and Purple Nutsedge

Expansion After 3 Months Expansion After 3 Months (From a Single Planted Tuber)(From a Single Planted Tuber)

Purple and Yellow Nutsedge Density: 3 and 6 Months of Growth

Following Planting of 1 Tuber

3 Months of Growth

Nu

tsed

ge D

ensi

ty (

Sh

oots

per

Pat

ch)

0

50

100

150

200

250

300

350

6 Months of Growth

Purple Nutsedge

Yellow Nutsedge

Purple Nutsedge

Yellow Nutsedge

29 22

323

135

Alternatives to Methyl Bromide Alternatives to Methyl Bromide for Weed Management?for Weed Management?

1 Soil Solarization/Organic AmendmentsSoil Solarization/Organic Amendments– Requires a hot and cloudless climateRequires a hot and cloudless climate– Studies have shown that:Studies have shown that:

• solarization can reduce pests prior to plantingsolarization can reduce pests prior to planting

• crop yields can be increasedcrop yields can be increased

• effects can be extended through several seasons effects can be extended through several seasons

– Research has focused on pathogens and Research has focused on pathogens and nematodes - only a handful of studies on nematodes - only a handful of studies on weedsweeds

How hot does the soil temperature get underneath plastic?

Is it hot enough to kill nutsedge?

• Yellow Nutsedge:Yellow Nutsedge:• 113 F for 8 hours = 113 F for 8 hours = >> 90% Tuber Viability 90% Tuber Viability• 122122+ + F for 15 minutes = F for 15 minutes = << 50% Tuber Viability 50% Tuber Viability

• Purple Nutsedge:Purple Nutsedge:• 122 F for 8 hours = > 70% Tuber Viability122 F for 8 hours = > 70% Tuber Viability• 131 F for 4 hours = 131 F for 4 hours = << 20% Tuber Viability 20% Tuber Viability• 140 F for 1 hour = < 5% Tuber Viability140 F for 1 hour = < 5% Tuber Viability

• How hot can we get our soils? How hot can we get our soils?

• How long can they stay this hot?How long can they stay this hot?

Preliminary ConclusionsPreliminary ConclusionsLethal Temperature/Duration of Exposure:Lethal Temperature/Duration of Exposure:

Alternatives to Methyl Bromide Alternatives to Methyl Bromide for Weed Management?for Weed Management?

2 Fumigants:Fumigants:• ChloropicrinChloropicrin• Metam SodiumMetam Sodium• Methyl IodideMethyl Iodide• Telone, Telone IITelone, Telone II• Telone C17/C35Telone C17/C35

Methyl Bromide

chickweed crabgrass goosegrass crowfootgrass pigweed morningglory? purslane nutgrass

Telone II, Telone C-17/35, Chloropicrin

No mention of specific weeds controlled

Non-treated Telone Broadcast Telone In Bed

25 GPA 35 GPA

Photos taken from Florida Field Day. Bill Stall, 2000.

Metam Sodium

chickweed dandelion ragweed lambsquarters pigweed nightshades purslane nutsedge, morningglory - suppression

Metam Sodium

Nutsedge –

1) May be suppressed if actively growing and a high use rate is applied (75 gal/A).

2) More often roots and shoots will be controlled, but the tuber will remain viable and re-grow at a later time.

METHYL BROMIDE: 400 LBS (98%)METHYL BROMIDE: 400 LBS (98%)

NONTREATED CONTROLNONTREATED CONTROL

Purple Nutsedge Through Plastic in Purple Nutsedge Through Plastic in Squash: Shoots/PlotSquash: Shoots/Plot

• Methyl Bromide (392 Lbs/A - Fumigated):Methyl Bromide (392 Lbs/A - Fumigated):– 1998: 99% lower than UTC (*)1998: 99% lower than UTC (*)– 1999: 99% lower than UTC (*)1999: 99% lower than UTC (*)

• Telone C-35 EC (12 Gal/A) - Drip:Telone C-35 EC (12 Gal/A) - Drip:– 1998: 81% lower than UTC (*)1998: 81% lower than UTC (*)– 1999: 40% greater than UTC (NS)1999: 40% greater than UTC (NS)

Purple Nutsedge Through Plastic in Purple Nutsedge Through Plastic in Squash: Shoots/PlotSquash: Shoots/Plot

• Methyl Bromide (392 Lbs/A - Fumigated):Methyl Bromide (392 Lbs/A - Fumigated):– 1998: 99% lower than UTC (*)1998: 99% lower than UTC (*)– 1999: 99% lower than UTC (*)1999: 99% lower than UTC (*)

• Telone C-35 EC (12 Gal/A) - Drip:Telone C-35 EC (12 Gal/A) - Drip:– 1998: 81% lower than UTC (*)1998: 81% lower than UTC (*)– 1999: 40% greater than UTC (NS)1999: 40% greater than UTC (NS)

Purple Nutsedge Through Plastic in Purple Nutsedge Through Plastic in Squash: Shoots/PlotSquash: Shoots/Plot

• Methyl Bromide (392 Lbs/A - Fumigated):Methyl Bromide (392 Lbs/A - Fumigated):– 1998: 99% lower than UTC (*)1998: 99% lower than UTC (*)– 1999: 99% lower than UTC (*)1999: 99% lower than UTC (*)

• Telone II + Chloropicrin + Vapam Telone II + Chloropicrin + Vapam (12 Gal/A - Chisel ) and (6.6 + 50 Gal/A - Drip)(12 Gal/A - Chisel ) and (6.6 + 50 Gal/A - Drip)::– 1999 Early Season: 76% lower than UTC (*)1999 Early Season: 76% lower than UTC (*)– 1999 Late Season: 22% greater than UTC (NS)1999 Late Season: 22% greater than UTC (NS)

Nontreated ControlNontreated ControlTelone II + Chloropicrin + VapamTelone II + Chloropicrin + Vapam (12 Gal/A - Chisel ) and (6.6 + 50 Gal/A - Drip)(12 Gal/A - Chisel ) and (6.6 + 50 Gal/A - Drip)

13 Days After Treatment13 Days After Treatment

• Methyl Iodide (392 Lbs/A - Drip):Methyl Iodide (392 Lbs/A - Drip):– 1998: 81% lower than UTC (*)1998: 81% lower than UTC (*)– 1999: 21% greater than UTC (NS)1999: 21% greater than UTC (NS)

Purple Nutsedge Through Plastic: Purple Nutsedge Through Plastic: Shoots/PlotShoots/Plot

Alternatives to Methyl Bromide Alternatives to Methyl Bromide for Weed Management?for Weed Management?

3 HerbicidesHerbicides– Limited # of Registered CompoundsLimited # of Registered Compounds

• Cucurbits (3-5) - no nutsedge materialsCucurbits (3-5) - no nutsedge materials

• Eggplant (4) - no nutsedge materialsEggplant (4) - no nutsedge materials

• Pepper (5) - no nutsedge materialsPepper (5) - no nutsedge materials

• Squash (4) - no nutsedge materialsSquash (4) - no nutsedge materials

• Tomato (7) - Tillam for nutsedge suppressionTomato (7) - Tillam for nutsedge suppression

– IR-4 is working to increase this listIR-4 is working to increase this list

Sandea

Gowan

Halosulfuron-methyl

75% active ingredient

MAY be labeled in FL in 2001

Ever labeled in GA????

Rate unknown -- probably 0.024 lb ai/A

Sandea for Vegetable Weed Control

1-3 inch 1-9 inch

passionflower cocklebur

redroot pigweed ragweed

pokeweed velvetleaf

yellow nutsedge - suppression purple nutsedge - suppression

2 to 3 weeks residual weed control

Yellow Nutsedge Control with Sandea Applied PRE in Watermelon.*

0

20

40

60

80

100

0.5 oz

0.75 oz

1.0 oz

*In cooperation with Ken Lewis, Crisp County, 2000. Rating 21 days after treatment.

% c

ontr

ol

Yellow Nutsedge Control with Sandea Applied POST in Watermelon.*

0

20

40

60

80

100

0.5 oz

0.75 oz

1.0 oz% c

ontr

ol

*In cooperation with Ken Lewis, Crisp County, 2000. Rating 21 days after treatment.

Nontreated Sandea (0.024 lb ai/A)

Sandea

Potential Crops (in order of crop tolerance?)

tomato

0

200

400

600

800

1000

medium large X-large

none

0.5 oz/A

1.0 oz/A

*In cooperation with Joel Hudgins, Decatur County, 2000.

Number of Tomato Boxes Per Acre After Sandea Treatments. Spring, 2000.*

0

500

1000

1500

2000

2500

3000

total number of boxes

none

0.5 oz/A

1.0 oz/A

*In cooperation with Joel Hudgins, Decatur County, 2000.

Number of Tomato Boxes Per Acre After Sandea Treatments. Spring, 2000.*

0

200

400

600

800

1000

medium large X-large

none

0.5 oz/A

1.0 oz/A

*In cooperation with Joel Hudgins, Decatur County, 2000.

Number of Tomato Boxes Per Acre After Sandea Treatments. Fall, 2000.*

Sandea

Potential Crops (in order of crop tolerance?)

tomato

cucumber

pumpkin

cantaloupe

watermelon

Nontreated Sandea (0.024 lb ai/A)

Watermelon farm in Crisp County, May 2000. Treatment at 1-leaf.

Watermelon Injury with Sandea Applied PRE in Watermelon.*

0

20

40

60

80

100

0.5 oz

0.75 oz

1.0 oz

*In cooperation with Ken Lewis, Crisp County, 2000. Rating 21 days after treatment.

% in

jury

0

20

40

60

80

100

0.5 oz

0.75 oz

1.0 oz

Watermelon Injury with Sandea Applied POST to 3-inch Watermelon.*

*In cooperation with Ken Lewis, Crisp County, 2000. Rating 5 days after treatment.

% in

jury

0

20

40

60

80

100

0.5 oz

0.75 oz

1.0 oz

Watermelon Injury with Sandea Applied POST to 14-inch Watermelon.*

*In cooperation with Ken Lewis, Crisp County, 2000. Rating 5 days after treatment.

% in

jury