Corn Insect Management Scott 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 Acceleron Acceleron + Poncho/VOTiVO PPST 250 PPST 1250 + Poncho/VOTiVO CruiserMaxx Corn Avicta Complete Corn Clothianidin* (250 Rate) Clothianidin (500 or 1250 Rate) Thiamethoxam* (250) Thiamethoxam (500 Rate) Trifloxystrobin* Azoxystrobin* (1250) Azoxystrobin Metalaxyl* Fludioxonil* Fludioxonil Ipconazole* Mefenoxam* Mefenoxam Bacillus firmus (VOTiVO) Thiabendazole* Thiabendazole Abamectin INSECT DISEASE NEMATODE * Base treatments if premium seed treatments are not requested

Relative Efficacy of Corn IST Trade Name Billbugs White grubs Wire-worms Seedcorn maggot Cut-worms Sugar-cane beetle Stink bugs Chinch bugs Southern corn rootworm Poncho 250, Acceleron P, NL F G E P - F F + Poncho 500, Acceleron with Poncho Votivo F - G G - E Poncho 1250, Acceleron Cruiser Extreme 250 P G - E, NL Cruiser Extreme 500, Avicta Complete Cruiser Extreme 1250 P = poor F = fair G = good E = excellent NL = not labeled

Corn At-planting Insecticides, Trial 1 2013, Tennessee

Corn At-planting Insecticides, Trial 2 2013, Tennessee

Capture LFR In-furrow Trial Starkville, MS 2012 (Catchot) All with Poncho 250 Bushels/Acre a ab bc c

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

Impact of Infestation Timing on Yield SWCB infested, non-Bt plants (Steckel and Stewart) Weight (g) per Ear b C 2010 2011 Infestation Timing

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

Scouting Non-Bt Corn Whorl stage Tasseling and later 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 Trapping Moths/Trap/Week (Henry Co, TN, 2012) Spray Scout / Spray Action Thresholds 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 Selection Refer 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 stage Direct spray into whorls as much as possible Typically 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

Relative Efficacy of Selected Bt Corn Traits (see handout for more inclusive list & refuge requirements) Trademarked Brands Corn borers Cutworm Corn earworm Fall armyworm WCRW YieldGard CB Excellent Poor Fair None Herculex Good Herculex XTRA Agrisure CB/LL Genuity VT Double Pro (VT2P) Very Good Genuity VT Triple Pro (VT3P) Genuity or Dow AgroSciences SmartStax (GENSS or SSX) Agrisure Viptera 3110 Agrisure Viptera 3111 Optimum Intrasect Optimum AcreMax Extra

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 Cotton Counties MISSOURI: Dunklin New Madrid Pemiscot Scott Stoddard Products with Bt rootworm traits require an “in-field” refuge

Do these refuge requirements make sense? For non-cotton growing areas !!! 5% Refuge of Non-Bt Corn 2+ caterpillar traits, 0 rootworm traits VT2P, VT2P RIB, Optimum Intrasect, Optimum AcreMax (RIB), and others 2+ caterpillar traits, 2+ rootworm traits SmartStax or SmartStax RIB, Optimum Acre XTreme (RIB), and others

Confirmed Resistance to Bt Traits Far and Minor Pest 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

All the Bt lep traits provide near perfect control of SWCB and ECB SWCB and ECB Injury CM Tunneling per 20 Stalks (TN, 2010) a P < 0.0001 (LSD = 89.2) b All the Bt lep traits provide near perfect control of SWCB and ECB c c c c

Bt corn in the presence of corn borers Yield (Milan, TN, 2011) Bushels/Acre a b

Leaf Injury Score for FAW Catchot, 2010, Starkville, MS Leaf Injury Score (9-1 scale, 9 = no damage) a a a b c c Herculex Optimum Intrasect Viptera

Corn Earworm The most common ear feeding caterpillar

SmartStax Test - 2009 SmartStax (90%) Non Bt VT3

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 Traits Range 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

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

Yield of Top Ten Hybrids (Bu/Acre) 2012 Tennessee Research & Education Center Tests (Allen, et al.) Early Maturity Medium Maturity Full Maturity 1 CB / RW HX / RW VT3P 2 CB 3 VT3 HX 4 5 VT2P 6 7 VIP Non- BT 8 9 10 Non-Bt

Insecticide Trial on Non-Bt Corn Corn Earworm Injury and Yield (TN, 2011) Application at early silking (moderate pressure) P(yield) = 0.9148 P(kernels) = 0.0013

Insecticide Yield Effects on Non-Bt Corn (Tennessee, Stewart, 2012) A lot of CEW but no treatment effects on kernel injury (P = 0.7341)

Simulated Corn Earworm Injury, Milk Stage Steckel and Stewart, 2011 # Kernels Injured # Kernels per Ear Total Wt (g) per Ear Wt (g) of Individual Kernels 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 Test 1 Test 2 No statistically significant differences

Infestations are usually worse along field margins. 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) Early planting Late Planting P < 0.0045, LSD(0.05) = 0.094, CV = 61.9 P = 0.0428, LSD(0.05) = 0.054, CV = 80.4 a a cm2 damage cm2 damage a ab b b b b

Grain yield (B/A) Early planting Late Planting bu/acre bu/acre P = 0.6439, LSD(0.05) = 16.7, CV = 6.4 P = 0.6860, LSD(0.05) = 8.5, CV = 2.8 bu/acre bu/acre

Simulated CEW Feeding (Blister) Steckel et al.

Tennessee - Corn Isolines Comparisons Impact 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) 144 126 149 194 206 199 TN – 2010 (early) 147 152 TN – 2010 (late) 154 160 Average 167.6 179.7 179.5 Bt11 Viptera 135 163 151 TN – 2011 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)

Non-Bt Corn Insecticide Test Moderate infestations of SWCB (Application July 16, 2008) Planted May 1