CORN INSECT MANAGEMENTScott Stewart

WTREC, Jackson, TN

University of Tennessee Extension

The Primary Issues

Seed treatments, at-planting insecticides A complex of soil insect pests

Managing non-Bt corn Primarily for corn borers

Bt corn technologies There are just so many options

Corn Seed Treatments (company offerings)

DeKalb (Monsanto) Pioneer Syngenta

AcceleronAcceleron +

Poncho/VOTiVOPPST 250

PPST 1250 + Poncho/VOTiV

O

CruiserMaxx Corn

Avicta Complete

Corn

Clothianidin*

(250 Rate)

Clothianidin(500 or 1250

Rate)

Thiamethoxam*

(250)

Thiamethoxam(250)

Thiamethoxam*

(250 Rate)

Thiamethoxam

(500 Rate)

Trifloxystrobin*

Trifloxystrobin*Azoxystrobi

n*Clothianidin

(1250)Azoxystrobi

n*Azoxystrobi

n

Metalaxyl* Metalaxyl*Fludioxonil

*Azoxystrobin

Fludioxonil*

Fludioxonil

Ipconazole* Ipconazole*Mefenoxam

*Fludioxonil

Mefenoxam*

Mefenoxam

Bacillus firmus(VOTiVO)

Thiabendazole*

MefenoxamThiabendaz

ole*Thiabendaz

ole

Thiabendazole Abamectin

Bacillus firmus(VOTiVO)

INSECT DISEASENEMATO

DE* Base treatments if premium seed treatments are not requested

Trade Name

Billbugs

White

grubsWire-

wormsSeedco

rn maggot

Cut-worm

s

Sugar-cane

beetleStink bugs

Chinch

bugs

Southern corn

rootworm

Poncho 250,

AcceleronP, NL F G E P - F F + F G E

Poncho 500,

Acceleron with

Poncho Votivo

F G G E P - F G F - G G - E E

Poncho 1250,

AcceleronG E E E F - G G G E E

Cruiser Extreme

250P, NL F G E P P P F G - E, NL

Cruiser Extreme

500, Avicta Complete

P, NL G G E P F F F E

Cruiser Extreme

1250G E E E F F G G E

Relative Efficacy of Corn IST

P = poor F = fair G = good E = excellent NL = not labeled

Corn At-planting Insecticides, Trial 12013, Tennessee

P250

P250

+ C

aptu

re

P250

+ C

aptu

re +

Sta

rter

P250

+ B

rigad

e

P250

+ B

rigad

e + S

tarte

r

P250

+ M

. Max

+ S

tarte

r

P500

+ S

tarte

r150

170

190

210

230 221.6 222.8218.6 217.4 219.0 219.6 222.5

Yield (B/A)

Corn At-planting Insecticides, Trial 22013, Tennessee

Untre

ated

Cruiser

500

Ponc

ho 5

00

Captu

re LFR

(4 o

z)

Count

er (6

.5 lb

)

Smar

tCho

ice

(5.5

lb)

Ponc

ho +

Cou

nter

Ponc

ho +

Sm

artC

hoice

150

160

170

180

190

200

210

184.2

202.9

195.0200.1 200.5 200.8

195.5 196.7

Yield (B/A)

Capture LFR In-furrow TrialStarkville, MS 2012 (Catchot)

154.2

149.4

145

138.5

130

135

140

145

150

155

160

Capture LFR 4 oz +Starter

Capture LFR 4 oz Starter Only Untreated

Bush

els/

Acre

aba bc c

All with Poncho 250

Managing Soil Insects

Be proactive in high risk fields New fields Problem fields

Cruiser or Poncho 250 not always enough 500 rates or higher In-furrow bifenthrin (Capture

LFR, Brigade, etc.)• Will also provide protection from

cutworms In-furrow granular insecticides*

* Be careful of insecticide/herbicide interactions

Corn Borers

The primary target of Bt corn Southwestern corn borer European corn borer

The second generations are typically the most destructive Because it is larger and

affects more acres

SWCB

ECB

V6 V14 R2 UNT V8 V14 R2 UNT0

20

40

60

80

100

120

140

160

180

200

Weig

ht

(g)

per

Ear

2010 2011

A

B

C

a

bb

A

a

Impact of Infestation Timing on YieldSWCB infested, non-Bt plants (Steckel and Stewart)

P < 0.0001

P < 0.0001

Infestation Timing

Treating non-Bt corn in the presence of high corn borer populations (Henry Co., TN)

No Inse

cticid

e

Hero (6

oz)

Belt SC (2

oz)5060708090

100110120130140

92

134

120

Yield (B/A) in 2010

No Inse

cticid

e

Disciplin

e (5 oz)

Belt SC (2

oz)50

70

90

110

130

150

170

190

210

148

194203

Yield (B/A) in 2011

Scouting Non-Bt Corn

Whorl stage Pretty easy Look for windowpane-like lesions on

emerging leaves Remove whorls and unfurl leaves to look

for small larvae that are present

Tasseling and later Much more difficult and requires

training

SWCB Moth Trapping

Triggers scouting or spray

SWCB Pheromone TrappingMoths/Trap/Week (Henry Co, TN, 2012)

6-May 16-May 26-May 5-Jun 15-Jun 25-Jun 5-Jul 15-Jul0

100

200

300

400

500

600

Henry (Puryear)

Action Thresholds

Scout / Spray Spray

No

New Southwestern Corn Borer Threshold (Non-Bt Corn)

Treat prior to tasseling when 5 percent or more of plants are found with egg masses or live larvae or 7-10 days after pheromone traps catch an

average of 50 or more moths on a 7 day catch

Beginning at tasseling (VT) and through the milk stage (R3), treat when 10 percent or more of plants are found with egg masses or live larvae or 7-10 days after pheromone traps catch an

average of 100 or more moths on a 7 day catch

Insecticide SelectionRefer to Local Extension Recommendations

First Generation (whorl) Many labeled

pyrethroid insecticides Baythroid XL Brigade (bifenthrin) Karate or Warrior II Mustang Max Etc.

Others as in tassel stage

Second Generation (tassel) Intrepid Belt SC Besiege Prevathon Tracer Pyrethroids as in

whorl stageDirect spray into whorls as much as possibleTypically requires aerial application

The Many Bt Corn Technologies

Bt corn is the primary means used to control corn borers

Many available Bt trait packages (old and new)

May or may not include Bt traits for western or northern corn rootworm

Trademarked Brands Corn borers Cutworm Corn

earwormFall

armyworm WCRW

YieldGard CB Excellent Poor Fair Fair None

Herculex Excellent Good Poor Good None

Herculex XTRA Excellent Good Poor Good Excellent

Agrisure CB/LL Excellent Poor Fair Fair None

Genuity VT Double Pro (VT2P) Excellent Poor Good Very Good None

Genuity VT Triple Pro (VT3P) Excellent Poor Good Very Good Excellent

Genuity or Dow AgroSciences SmartStax (GENSS or SSX) Excellent Good Good Very Good Excellent

Agrisure Viptera 3110 Excellent Good Excellent Excellent None

Agrisure Viptera 3111 Excellent Good Excellent Excellent Good

Optimum Intrasect Excellent Good Fair Very Good None

Optimum AcreMax Extra Excellent Good Fair Very Good Excellent

Relative Efficacy of Selected Bt Corn Traits

(see handout for more inclusive list & refuge requirements)

Cotton Counties

MISSOURI:Dunklin

New MadridPemiscot

ScottStoddard

Products with Bt rootworm traits require an “in-field” refuge

Non-Bt Corn Refuge Requirements

Cotton Counties 50% for the old technologies 20% for the new

VT2P, VT3P, SmartStax, Viptera, Optimum Intrasect, Optimum AcreMax

Corn Counties 20% for the old technologies 20, 10 or 5 % for the new

Refuge in bag (RIB) system for some

Do these refuge requirements make sense?For non-cotton growing areas !!!

5% Refuge of Non-Bt Corn

2+ caterpillar traits, 0 rootworm traitsVT2P, VT2P RIB, Optimum Intrasect,

Optimum AcreMax (RIB), and others

2+ caterpillar traits, 2+ rootworm traitsSmartStax or SmartStax RIB, Optimum

Acre XTreme (RIB), and others

Confirmed Resistance to Bt Traits

Fall armyworm to Cry 1F Herculex or Herculex Xtra Component of SmartStax, Optimum Intrasect

and Optimum AcreMax products

Western corn rootworm to Cry3 Bb1 VT3 and VT3P Component of SmartStax

Rotate fields to non-corn crops, rotate Bt rootworm traits, use at-planting insecticide and don’t use Bt rootworm traits if they are not needed

Close and

Major Pest

Far and

Minor

Pest

a

b

cccc

P < 0.0001 (LSD = 89.2)

Opt. In-trasect

Viptera Herculex YieldGard CB

NonBt 1 NonBt 20

50

100

150

200

250

300

350

400

450

All the Bt lep traits provide near perfect control of SWCB and ECB

SWCB and ECB InjuryCM Tunneling per 20 Stalks (TN, 2010)

Bt corn in the presence of corn borersYield (Milan, TN, 2011)

SmartStax Non-Bt120

125

130

135

140

145

150

155

160

155.4

132.5

a b

Bushels/Acre

Leaf Injury Score for FAW Catchot, 2010, Starkville, MS

9 8.7 8.7

7

2.7 2.7

0123456789

10

Leaf Injury Score (9-1 scale, 9 = no damage)

a a ba

c c

Vipte

ra

Opt

imum

Intras

ect

Her

cule

x

Corn EarwormThe most common ear feeding caterpillar

Non Bt

VT3

SmartStax(90%)

SmartStax Test - 2009

SmartStax Test - 2010

Non Bt

VT3P or SS(40%)

Approximate Reduction in Kernel Damage Compared with Non-Bt Corn

(Summarized Across Multiple University Trials, Corn Earworm)

Bt TraitsRange of Reduction

(%)

Average Reduction

(%)Herculex and HXX < 0 - 30 15

YieldGard, VT3, Optimum … 0 - 60 40

VT2Pro, VT3P, SmartStax 40 - 90 75

Viptera (VIP3A) 90 – 99 95

Viptera ... “outperforms triple stacks by 14.3 bu/A under significant corn earworm pressure and up to 32 bu/A under heavy pressure”

Reality Check

Yield of Top Ten Hybrids (Bu/Acre)2012 Tennessee Research & Education Center Tests (Allen, et al.)

Yield Early Maturity

Medium Maturity

Full Maturity

1 CB / RW HX / RW VT3P

2 CB / RW VT3P CB

3 VT3 VT3 HX

4 CB VT3P HX

5 VT2P VT3P VT3P

6 VT3P CB / RW VT3P

7 VIP CB Non- BT

8 VT3P CB CB / RW

9 VT3P VT3P VT3P

10 HX VT3P Non-Bt

Insecticide Trial on Non-Bt Corn Corn Earworm Injury and Yield (TN, 2011)

0

50

100

150

200

Kernel Damage per 10 Ears (prelim.)

Yield (B/A)

P(yield) = 0.9148

P(kernels) = 0.0013

Application at early silking (moderate pressure)

Insecticide Yield Effects on Non-Bt Corn(Tennessee, Stewart, 2012)

Prev

atho

n (8

)

Prev

atho

n (1

2)

Prev

atho

n (1

6)

Prev

atho

n (2

0)

Prev

. (12

) + A

s...

Asan

a XL

(8)

Belt

(2)

Intre

pid

(6)

Besieg

e (8

)

Untre

ated

100

110

120

130

140

150

160

147

137

151

130

142

136

142

153

138 139

Application at Early Silking (P = 0.568)

A lot of CEW but no treatment effects on kernel injury (P = 0.7341)

Simulated Corn Earworm Injury, Milk StageSteckel and Stewart, 2011

# Kernels Injured

# Kernels per Ear

Total Wt (g) per Ear

Wt (g) of Individual Kernels

0 592 a 165 a 0.2791c

30 560 b 162 a 0.2888 bc

60 507 c 149 b 0.2939 ab

120 477 d 143 b 0.3009 a

Spraying Corn for Corn Earworm

Foliar applications for ear stage infestations of corn earworm in field corn are not economically practical

No consistent yield response except in presence of southwestern corn borer

Expect little or no benefit on Bt corn (especially the newer traits) Exposure to insecticides without much yield reward May create secondary pest problems (spider mites)

Take Home About New Bt Corns

University data indicates that the new Bt corn traits will not improve yields in most cases compared with the original Bt technologies

Benefit of reduced refuge requirement Some potential for improved grain quality and reduced

mycotoxins … but not close to a silver bullet IRM ???

• Corn borers – expect multiple Bt toxins to delay resistance• Corn earworm – exposure to multiple Bt toxins without much

reward is concerning

Questions

War Eagle!

Aflatoxin Levels in Corn Roy Parker, Texas A&M University, 2011

DKC 6

8-04

(non

...

DKC 6

8-05

VT3

...

DKC 6

7-22

RR (n

...

DKC 6

7-21

VT3

...

P 33

F85

(non

Bt)

P 33

F87

HX1

Non B

tBt

11

Bt11

+MIR

162

(Vi..

.0

50

100

150

200

250

300

20.1

53.0

197.5

251.8

40.7

85.3

117.4

257.0

97.5

Test 1 Test 2

No statistically significant differences

Japanese Beetles

New Threshold: Treat when 3 or more beetles are present per ear

during the first week of silking.

Infestations are usually worse along

field margins.

Sugarcane Beetles

Final Kernel Damage(cm2/ear in center two rows of plot)

Pure s

tand

5% b

lend

10%

ble

nd

20%

ble

nd0

0.05

0.1

0.15

0.2

0.25 Chart Title

Pure s

tand

5% b

lend

10%

ble

nd

20%

ble

nd0

0.05

0.1

0.15

0.2

0.25 Chart Title

Early planting Late Planting

cm2

dam

ag

e

cm2

dam

ag

e

P = 0.0428, LSD(0.05) = 0.054, CV = 80.4P < 0.0045, LSD(0.05) = 0.094, CV = 61.9

bb

aa

b

bab

a

Grain yield (B/A)

Pure s

tand

5% b

lend

10%

ble

nd

20%

ble

nd100

120

140

160

180

200

162.4159.9 160.9

168.7

Chart Title

Pure s

tand

5% b

lend

10%

ble

nd

20%

ble

nd100

120

140

160

180

200187.9 186.3 188.1

184.1

Chart Title

Early planting Late Planting

bu/a

cre

bu/a

cre

P = 0.6860, LSD(0.05) = 8.5, CV = 2.8P = 0.6439, LSD(0.05) = 16.7, CV = 6.4

Simulated CEW Feeding (Blister)Steckel et al.

Simulated injury by ear-feeding larvae at the blister stage of corn on the number of kernels

per ear, kernel weight per ear and individual kernel weight, 2011.

No. of kernels targeted for injury

No. kernels per ear Total kernel wt (g) Individual kernel wt (g)

0 564.9a 155.2a 0.2744c

30 553.3ab 157.2a 0.2841bc

60 524.8bc 151.2a 0.2880ab

120 514.3c 153.9a 0.2992a

P > F 0.0031 0.7400 0.0007

Means not followed by a common letter are significantly different (Proc MIXED, P < 0.05)

Tennessee - Corn Isolines ComparisonsImpact of New Bt Technologies (VT3 Pro, SmartStax, Viptera)

Yield (B/A)

Location & Year Non-Bt YG or VT3 VT3 Pro or SS

TN – 2007 213 257 242

TN – 2008 207 ---- (207) 233 *

TN – 2009 114 150 127 *TN – 2009 (demo) 144 126 149

TN – 2009 194 206 199

TN – 2010 (early) 147 152 147

TN – 2010 (late) 154 160 160

Average 167.6 179.7 179.5

Location & Year Non-Bt Bt11 Viptera

TN – 2009 135 163 151

TN – 2011 147 172 171

* Average of 3 (2008) or 2 hybrids (2009) that were VT Pro or SmartStax

Yield of Selected Seed Trt’s and In-Furrow Combinations (MS, Catchot)

100

120

140

160

180179 177

167 163 162 162 159 153145 143

Yield

Non-Bt Corn Insecticide TestModerate infestations of SWCB (Application July 16, 2008)

105

126

147

128

0

20

40

60

80

100

120

140

160

SWCB Girdles/360 Row Ft Bushels/A

a

ab b

c

b b

a

Planted May 1