North Carolina Corn Insect Pest
2014 Update
Dominic Reisig NCSU Entomology
Contents of This Presentation
• Refuge compliance
• Does corn earworm impact corn yield?
• Cry1F-resistant fall armyworm
Research Issues Not in This
Presentation
• Seed treatment value for NC corn
• Resistance development of corn earworm to Bt
• Stink bug management in corn
Traits of Selected, Commercially Available Bt Corn Products
Description
Caterpillar Traits
Rootworm Traits
Agrisure CB/LL
Cry 1AB (Bt11)
None
Agrisure 3000GT
Cry 1AB (Bt11)
Cry 3A (modified)
Herculex I (HX1)
Cry 1F (HX1)
None
Herculex XTRA (HXX)
Cry 1F (HX1)
Cry 34/35Ab1
YieldGard VT Triple (VT3)
Cry 1AB (YGCB)
Cry 3Bb1
Genuity VT Triple Pro (GENVT3P)
Cry 1A.105 + Cry2Ab2
Cry 3Bb1
Genuity VT Double Pro (GENVT2P)
Cry 1A.105 + Cry2Ab2
None
Genuity VT Double Pro RIB (GENVT2P RIB)
Same as above + RIB *
None
Genuity or Dow AgroSciences SmartStax (GENSS or SSX)
Cry 1A.105 + Cry2Ab2 + Cry 1F
(HX1)
Cry 3Bb1 + Cry 34/35Ab1
Genuity or Dow AgroSciences SmartStax RIB (GENSS or
SSX)
Same as above + RIB *
Same as above + RIB *
Agrisure Viptera 3110
Cry 1Ab (Bt11) + VIP3A (MIR162)
None
Agrisure Viptera 3111
Cry 1Ab (Bt11) + VIP3A (MIR162)
Cry 1Ab (Bt11) + VIP3A (MIR162) +
Cry1F (HX1)
Cry 3A (modified)
Optimum Intrasect
Cry1Ab (YGCB) + Cry 1F (HX1)
None
Optimum AcreMax
Cry1Ab (YGCB) + Cry 1F (HX1)
None
Optimum AcreMax Xtra
Cry1Ab (YGCB) + Cry 1F (HX1)
Cry 34/35Ab1
Agrisure Viptera 3220
* Non-Bt Refuge in Bag
None
Slide adapted from Scott Stewart, U. Tennessee
Relative Efficacy of Selected, Commercially Available Bt Corn Products
Agrisure CB/LL
Excellent
Poor
Fair
Good
Western
corn
rootworm
None
Agrisure 3000GT
Herculex I (HX1)
Excellent
Excellent
Poor
Good
Fair
Poor
Good
Very Good *
Good
None
Herculex XTRA (HXX)
Excellent
Good
Poor
Very Good *
Excellent
YieldGard VT Triple (VT3)
Excellent
Poor
Fair
Fair
Excellent
Genuity VT Triple Pro (GENVT3P)
Excellent
Poor
Good
Very Good
Excellent
Genuity VT Double Pro (GENVT2P)
Excellent
Poor
Good
Very Good
None
Genuity VT Double Pro RIB (GENVT2P RIB)
Excellent
Poor
Very Good
None
Genuity or Dow AgroSciences SmartStax (GENSS or SSX)
Excellent
Good
Very Good *
Excellent
Genuity or Dow AgroSciences SmartStax RIB (GENSS or SSX)
Excellent
Good
Very Good *
Excellent
Agrisure Viptera 3110
Excellent
Good
Good
Very
Good
Very
Good
Excellent
Excellent
None
Agrisure Viptera 3111
Excellent
Excellent
Excellent
Good
Agrisure Viptera 3220
Excellent
Excellent
Excellent
None
Optimum Intrasect
Excellent
Fair
Very Good *
None
Optimum AcreMax
Excellent
Fair
Very Good *
None
Optimum AcreMax Xtra
Excellent
Good
Very
Good
Very
Good
Very
Good
Very
Good
Fair
Very Good *
Excellent
Traits / Brands
* Unless Cry1F-resistant fall armyworm is present
Corn
Corn borers Cutworm
Fall armyworm
earworm
Slide adapted from Scott Stewart, U. Tennessee
Refuge Requirements (Southern US) of Selected, Commercially Available Bt Corn Products
Traits / Brands
Refuge Requirement
Agrisure CB/LL
50%
In-field, adjacent, block ½ mile
Agrisure 3000GT
Herculex I (HX1)
50%
50%
In-field, adjacent, block ½ mile
In-field, adjacent, block ½ mile
Herculex XTRA (HXX)
50%
In-field, adjacent
YieldGard VT Triple (VT3)
50%
In-field, adjacent
Genuity VT Triple Pro (GENVT3P)
20%
In-field, adjacent
Genuity VT Triple Pro RIB (GENVT3P RIB)
20% + RIB *
In-field, adjacent
Genuity VT Double Pro (GENVT2P)
20%
In-field, adjacent, block ½ mile
Genuity VT Double Pro RIB (GENVT2P RIB)
20% + RIB *
In-field, adjacent
Genuity or Dow AgroSciences SmartStax (GENSS or SSX)
20%
In-field, adjacent, block ½ mile
Genuity or Dow AgroSciences SmartStax RIB (GENSS or SSX)
20% + RIB *
In-field, adjacent, block ½ mile
Agrisure Viptera 3110
20%
In-field, adjacent, block ½ mile
Agrisure Viptera 3111
20%
In-field, adjacent
Agrisure Viptera 3220
20%
In-field, adjacent, block ½ mile
Optimum Intrasect
20%
In-field, adjacent, block ½ mile
Optimum AcreMax
20% + RIB *
In-field, adjacent, block ½ mile
Optimum AcreMax Xtra
20% + RIB *
In-field, adjacent, block ½ mile
* Non-Bt Refuge in Bag
Slide adapted from Scott Stewart, U. Tennessee
Why refuge?
Slide adapted from Department of Soil and Crop Sciences at Colorado State University
Example Refuge Configurations
Image adapted from Canadian Corn Pest Coalition
Common Refuge Questions
• Can the refuge be protected from lep. pests?
– Yes, using non-Bt insecticides
• How should the refuge hybrid be selected?
– Chose a hybrid with a similar maturity and plant it as
close in time as possible to the Bt hybrid
• What happens to those who don’t plant refuge?
– Required by law through EPA
– Contract occurs at time of purchase of Bt hybrid
– Warning letter on first offense, with compliance
assessment the following year
– No Bt corn after second offense (in consecutive year)
Common Refuge Questions
• Who checks for compliance
– Independent third parties
• Telephone survey, on-farm visits
• Are seed purchases tracked?
– Of course, but companies don’t share information
• How can I know the refuge requirement?
– Check the bag tag
– Online search “refuge calculator”
• Yes, there is an app for that- iPhone and Android…
Occasional midto late-season lep. pests
Cutworm
Common midto late-season lep. pest
Southern
cornstalk borer
Corn earworm
Armyworms
European corn borer
Corn earworm control with Bt hybrids
No control
•
•
•
•
Agrisure RW
Herculex RW
YieldGard Rootworm
YieldGard VT
Rootworm/RR2
Fair-good
•
•
•
•
•
•
Agrisure CB/LL
YieldGard Corn Borer
Agrisure CB/LL/RW
Agrisure GT3000
YieldGard Plus
YieldGard VT Triple
Poor-fair control
• Herculex I
• Herculex XTRA
Very good
• YieldGard VT2 Pro
• YieldGard VT Triple Pro
• SmartStax
Excellent
• Agrisure Viptera
Slide from F.P.F. Reay-Jones, Clemson U.
To date, I have not documented a single yield
loss due to corn earworm feeding in the ear in
North Carolina
Does corn earworm impact yield?
Example of past experiment- 2011
Does Corn Earworm Affect Yield?
• Plots of 14 rows x 50 ft planted in Florence, SC, and in Plymouth, NC
(n = 4 replications).
• Near-isolines for Bt and non-Bt hybrids (HX1; HX1 + YGCB; VT3;
VT2Pro).
• Applications of Prevathon (20 oz/ac) twice a week (15 applications in
Florence, 18 applications in Plymouth) using a backpack sprayer.
• Created treated and untreated subplots
• Sampled 20 ears per plot for corn earworm injury and yield
Area of Kernels Injured by
Earworm in 2012
Florence, SC
= hybrids shared same genetic background
Plymouth, NC
Area of Kernels Injured by
Earworm in 2013
Florence, SC
= hybrids shared same genetic background
Plymouth, NC
Relationship between feeding and
yield
Conclusions
• Corn earworm did not affect yield (NC or SC)
• Hybrids should be chosen based on other
agronomic considerations than earworm
• Bt is probably still necessary for stalk pests
(southern cornstalk borer & European corn borer)
• Some of these genes active against corn earworm
also have activity on other pests
– May have fit for late-planted corn
armyworm
– Aflatoxin level may be reduced by eliminating
earworm, but effect is highly dependent on hybrid
genetics and environment
Non-Bt
Fit only for cattle, will
not accept above this level
Safe for
any use
Cry1F-resistant fall armyworm found
in Hyde County, 2013
What adjustments should we make in
2014?
• Hybrids with Genuity SmartStax, Herculex
and Optimum Intrasect contain Cry1F
– Widestrike countains Cry1F + Cry1Ac
• Closely monitor corn and cotton for resistance
– August
• Plant refuge
• Plant refuge
• Plant refuge