RR Cotton Tolerance to Glyphosate and Managing Difficult to Control Weeds A. Stanley Culpepper

Glyphosate Overtop Prior to 5th Leaf 1. 2 applications 2. applications 10 days apart 3. 2 nodes of growth

Glyphosate Overtop After 4th Leaf?

Lint Cotton Yields in RR Cotton when Treated Topically with Glyphosate at Various Growth Stages b b 1) Ten plants per plot were hand harvested on October 10, 1999 in Moultrie, GA. 2) Roundup Ultra applied at 1 qt/A broadcast over-the-top. Conventional plots treated with standard herbicide system.

Lint Yields (Nodes 5-14) in RR Cotton when Treated Topically with Glyphosate at Various Growth Stages a a a b b 1) Ten plants per plot were hand harvested on October 10, 1999 in Moultrie, GA. 2) Roundup Ultra applied at 1 qt/A broadcast over-the-top. Conventional plots treated with standard herbicide system.

Unopened Bolls in RR Cotton when Treated with Glyphosate Topically at Various Growth Stages 1) Ten plants per plot were hand harvested on October 10, 1999 in Moultrie, GA. 2) Roundup Ultra applied at 1 qt/A broadcast over-the-top. Conventional plots treated with standard herbicide system.

Glyphosate 9-leaf No Glyphosate

Can cause boll shed, delay maturity Glyphosate Overtop After 4th Leaf Stage Can cause boll shed, delay maturity Salvage treatment only

Is Stem Absorption of Glyphosate Directed in RR Cotton a Concern? No noted concerns in field trials Lab data from North Carolina, Georgia, and Mississippi?

Precision PD or hooded sprayers Directing Glyphosate in RR Cotton? Precision PD or hooded sprayers

Precision PD or hooded sprayers Directing Glyphosate in RR Cotton? Precision PD or hooded sprayers Direct spray to the base of the cotton plants

Precision PD or hooded sprayers Directing Glyphosate in RR Cotton? Precision PD or hooded sprayers Direct spray to the base of the cotton plants Contact of spray with cotton leaves should be avoided to the maximum extent possible

Precision PD or hooded sprayers Directing Glyphosate in RR Cotton? Precision PD or hooded sprayers Direct spray to the base of the cotton plants Contact of spray with cotton leaves should be avoided to the maximum extent possible Place nozzles in low position directing a horizontal spray pattern under the cotton leaves to contact weeds in the row

Cotton Yield After Various Glyphosate Applications. Moultrie, 2000.* b b Lint yield (Lb/A) Standard system Topical 1- & 4-lf Topical 1-, 4-, & 12-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 55

Number of Bolls on Nodes 5-10 After Various Glyphosate Applications Number of Bolls on Nodes 5-10 After Various Glyphosate Applications. Moultrie, 2000.* a a a # of bolls/ 6 feet b Standardsystem Topical 1- & 4-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 52

Boll Weights from Nodes 5-10 After Various Glyphosate Applications Boll Weights from Nodes 5-10 After Various Glyphosate Applications. Moultrie, 2000.* a a a Grams/6 feet b Standardsystem Topical 1- & 4-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 52

Number of Bolls on Nodes >10 After Various Glyphosate Applications Number of Bolls on Nodes >10 After Various Glyphosate Applications. Moultrie, 2000.* a a a a # of bolls/6 feet Standardsystem Topical 1- & 4-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = NS

Boll Weights from Nodes >10 After Various Glyphosate Applications Boll Weights from Nodes >10 After Various Glyphosate Applications. Moultrie, 2000.* a a a a Grams/6 feet Standardsystem Topical 1- & 4-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = NS

Number of Vegetative Bolls After Various Glyphosate Applications Number of Vegetative Bolls After Various Glyphosate Applications. Moultrie, 2000.* b # of bolls/6 feet a a a Standardsystem Topical 1- & 4-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 4

Vegetative Boll Weights After Various Glyphosate Applications Vegetative Boll Weights After Various Glyphosate Applications. Moultrie, 2000.* b Grams/6 feet a a a Standardsystem Topical 1- & 4-lf Topical 4-lf PD 8- & 12-lf Topical 4-lf SD 8- & 12-lf *Glyphosate applied at 1.0 lb ai/A. PD = precision directed at cotyledons; SD = sloppy directed 33 to 40% up the plant. Standard system = Prowl + Cotoran fb Staple fb Caparol + MSMA. LSD = 18

Precision and Sloppy Applied Glyphosate

Precision and Sloppy Applied Glyphosate

Directing After 4-leaf Stage? Glyphosate preferred for grasses or perennials Otherwise, conventional chemistry preferred

Glyphosate preferred for grasses or perennials Directing After 4-leaf Stage? Glyphosate preferred for grasses or perennials Otherwise, conventional chemistry preferred 1. Better morningglory control 2. Residual weed control 3. Resistant management strategy 4. Avoid weed shifts 5. Reduce risk of boll shed

Weeds Difficult to Control by Glyphosate?

Burndown Herbicides Gramoxone F Gramoxone + Direx G Glyphosate F Cutleaf Eveningprimrose Response to Burndown Herbicides Treatment Rating Gramoxone F Gramoxone + Direx G Glyphosate F Glyphosate + Direx G Glyphosate + Harmony Extra F-G Glyphosate + Clarity G Glyphosate + 2,4-D E

Cutleaf Eveningprimrose Control by Glyphosate. Tifton, 2000.* *Roundup Ultra applied at 1 qt/A.

Cutleaf Eveningprimrose Control by 2,4-D. Tifton, 2000.* *2,4-D applied at 1 qt/A.

Cutleaf Eveningprimrose Fresh Weights After Treating with Burndown Herbicides. Tifton, 2000.* Grams/plot *Fresh weights taken from 12 plants per plot. Roundup Ultra applied at 2 pt/A and 2,4-D at 1 pt/A.

2,4-D Burndown for Cotton (from fallow land section of labels) No specific language concerning cotton Do not plant any crop in treated fallow land until 3 months after treatment or until chemical has disappeared from soil

Current Recommendations -- 2,4-D Burndown for Cotton 1 pt/acre Alone or Mixed with Glyphosate Applied 45 days before planting Research to date shows effectiveness and crop safety

Cotton Injury from 2.1 mls Per Acre of 2,4-D. Tifton, 2000.

Weeds Difficult to Control by Glyphosate?

USE A DNA HERBICIDE

Florida Pusley Control with Glyphosate and Glyphosate Tank Mixtures Florida Pusley Control with Glyphosate and Glyphosate Tank Mixtures. Tifton, 2000.* 99 a 92 ab 87 bc 81 bc % control *Florida pusley 2 inches. Roundup UltraMAX applied at 1.25 pt; 2,4-D at 1 pt; Direx or Caparol at 1.5 pt.

Weeds Difficult to Control by Glyphosate?

Controlling Yellow and Purple Nutsedge? Nutsedge Control Programs: 1) 2 applications of glyphosate prior to 5th leaf followed by conventional chemistry including 2 lb ai MSMA directed 2) 1 application of glyphosate prior to 5th leaf followed by conventional chemistry including 2 lb ai MSMA directed 3) 2 applications of glyphosate 4) Zorial or Staple?????

Yellow and Purple Nutsedge Control by Glyphosate. Greenhouse. 98 90 * 81 * 82 77 * 70 % control 42 42 Glyphosate (lb) *Purple nutsedge controlled significantly greater than yellow nutsedge. LSD=10

Yellow and Purple Nutsedge Control by MSMA. Greenhouse. 82 * 69 61 % control 48 49 * 42 MSMA (lb) *Yellow nutsedge controlled significantly greater than purple nutsedge. LSD=10

Weeds Difficult to Control by Glyphosate?

Mid-Season Morningglory Control by Glyphosate & Glyphosate/Staple Mixtures. Moultrie, 2000. Pitted Smallflower morningglory morningglory Glyphosate 73 89 Glyphosate + Staple 93 97 Things to consider? 1. Morningglory size at time of application (5 inches here). 2. Will you post-direct with conventional chemistry or glyphosate?

Glyphosate/Staple Tank Mixtures DuPont label allows tank mix of 1.5 pt of Roundup Ultra plus 0.6 oz of Staple per acre broadcast Dupont’s Staple Plus

Smallflower Morningglory Control by Glyphosate Alone and Mixed with Residual Herbicides; Attapulgus, 2000. a a % control a a b Smallflower mg 4 to 5 inches; irrigated environment Roundup (2 pt/A), Bladex (1.5 pt/A), Caparol (1.5 pt/A), Direx (1.5 pt/A), Valor (2 oz/A)

Weeds Difficult to Control by Glyphosate?

Asiatic Dayflower Control by Glyphosate & Glyphosate/Staple Mixtures Asiatic Dayflower Control by Glyphosate & Glyphosate/Staple Mixtures. Grady Co., 2000.* 90 % control 67 Glyphosate Glyphosate + Staple *Dayflower 1 to 5 inches. Ratings 30 days after treatment. Roundup Ultra applied at 1.5 pt/A and Staple at 0.6 oz/A.

Asiatic Dayflower Control by Glyphosate Mixtures at Layby. Grady Co 86 85 81 80 76 67 % control LSD = 10 *Dayflower 1 to 5 inches. Ratings taken 30 days after directing in 8 to 10 inch cotton. Roundup Ultra, Caparol, and Direx applied at 1.5 pt/A. Cobra, Harvade, and Valor applied at 8 oz/A, 8 oz/A, and 2 oz/A, respectively.

Asiatic Dayflower Control by Conventional Layby Herbicides. Grady Co 91 90 90 85 84 82 80 78 78 % control LSD = 9 *Dayflower 1 to 5 inches. Ratings taken 30 days after directing in 8 to 10 inch cotton. Bladex, Caparol, Cotoran, and Direx applied at 2 pt/A. Cobra, Harvade, Linex, MSMA, and Valor applied at 9.6 oz/A, 9 oz/A, 1.5 pt/A, 2.67 pt/A, and 2 oz/A, respectively.

Weeds Difficult to Control by Glyphosate?

Hemp Sesbania Control by Glyphosate. Tifton, 2000.* 86 % control 59 3 inches 7 inches *Roundup Ultra applied at 2 pt/A. Experiment conducted under center irrigation.

1. Increase morningglory control 2. Increase dayflower control Glyphosate + Tank Mix Partner 1. Increase morningglory control 2. Increase dayflower control 3. Residual weed control

Tank Mix Partners-Early Season 1. Staple

RR Cotton Injury from Glyphosate/Staple Mixtures

Tank Mix Partners-Early Season 1. Staple 2. Dual Magnum 3. MSMA

Tank Mix Partners-Late Season 1. Diuron* 5. Harvade* 2. Caparol 6. MSMA 3. Cyanazine* 7. Dual Magnum 4. Cobra 8. Prowl* *Label supports tank mix with Roundup

Tank Mix Partners Tank mixes 1. crop tolerance 2. POST control 3. residual weed control 4. carryover

Tank Mix Partners Consider... weed species and sizes, economics, cotton stage, environment??

Tank Mix Partners Consider... weed species and sizes, economics, cotton stage, environment?? DON’T FORGET ABOUT ANTAGONISM

Texas Panicum Control by Glyphosate Alone and in Mixture with Residual Herbicides. Ponder Farm, 1999. a % control a ab b b Texas panicum 6 to 9 inches; fair to dry environment Roundup (2 pt/A), Bladex (1.5 pt/A), Caparol (1.5 pt/A), Direx (1.5 pt/A), Valor (2 oz/A)

Crowfootgrass Control by Glyphosate Alone and in Mixture with Residual Herbicides. Ponder Farm, 1999. % control a ab b b b Crowfootgrass 3 to 6 inches; fair to dry environment Roundup (2 pt/A), Bladex (1.5 pt/A), Caparol (1.5 pt/A), Direx (1.5 pt/A), Valor (2 oz/A)

Bristly Starbur Control by Glyphosate Alone and Mixed with Residual Herbicides. Attapulgus, 2000. Starbur 4 to 7 inches; irrigated environment Roundup (2 pt/A), Bladex (1.5 pt/A), Caparol (1.5 pt/A), Direx (1.5 pt/A), Valor (2 oz/A)

Palmer Amaranth Control by Glyphosate Alone and Mixed with Residual Herbicides. Attapulgus, 2000. ab ab b b Palmer amaranth 4 to 7 inches; irrigated environment Roundup (2 pt/A), Bladex (1.5 pt/A), Caparol (1.5 pt/A), Direx (1.5 pt/A), Valor (2 oz/A)

Roundup Ultra (1 qt/A) + Caparol (1.5 pt/A)

What’s Wrong With My Cotton? It’s got to be bronze wilt or GLYPHOSATE!!!!!!!!!!