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CORN INSECT MANAGEMENT Scott Stewart WTREC, Jackson, TN University of Tennessee Extension.

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Presentation on theme: "CORN INSECT MANAGEMENT Scott Stewart WTREC, Jackson, TN University of Tennessee Extension."— Presentation transcript:

1 CORN INSECT MANAGEMENT Scott Stewart WTREC, Jackson, TN University of Tennessee Extension

2 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

3 Corn Seed Treatments (company offerings) DeKalb (Monsanto)PioneerSyngenta Acceleron Acceleron + Poncho/VOTiVO PPST 250 PPST Poncho/VOTiVO CruiserMaxx Corn Avicta Complete Corn Clothianidin* (250 Rate) Clothianidin (500 or 1250 Rate) Thiamethoxam* (250) Thiamethoxam (250) Thiamethoxam* (250 Rate) Thiamethoxam (500 Rate) Trifloxystrobin* Azoxystrobin* Clothianidin (1250) Azoxystrobin*Azoxystrobin Metalaxyl* Fludioxonil*AzoxystrobinFludioxonil*Fludioxonil Ipconazole* Mefenoxam*FludioxonilMefenoxam*Mefenoxam Bacillus firmus (VOTiVO) Thiabendazole*MefenoxamThiabendazole*Thiabendazole Abamectin Bacillus firmus (VOTiVO) INSECTDISEASENEMATODE* Base treatments if premium seed treatments are not requested

4 Relative Efficacy of Corn IST P = poor F = fair G = good E = excellent NL = not labeled

5 Corn At-planting Insecticides, Trial , Tennessee

6 Corn At-planting Insecticides, Trial , Tennessee

7 Capture LFR In-furrow Trial Starkville, MS 2012 (Catchot) Bushels/Acre ababcc All with Poncho 250

8 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

9 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

10 Weight (g) per Ear A B C a b b A a Impact of Infestation Timing on Yield SWCB infested, non-Bt plants (Steckel and Stewart) P < Infestation Timing

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

12 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

13 SWCB Moth Trapping  Triggers scouting or spray

14 SWCB Pheromone Trapping Moths/Trap/Week (Henry Co, TN, 2012) Action Thresholds Scout / Spray Spray No

15 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

16 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

17 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

18 Relative Efficacy of Selected Bt Corn Traits (see handout for more inclusive list & refuge requirements)

19 Cotton Counties MISSOURI: Dunklin New Madrid Pemiscot Scott Stoddard 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

20 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

21 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

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

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

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

25 Corn Earworm The most common ear feeding caterpillar

26 Non Bt VT3 SmartStax (90%) SmartStax Test

27 SmartStax Test Non Bt VT3P or SS (40%)

28 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< YieldGard, VT3, Optimum … VT2Pro, VT3P, SmartStax Viptera (VIP3A)90 – 9995

29 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

30 Yield of Top Ten Hybrids (Bu/Acre) 2012 Tennessee Research & Education Center Tests (Allen, et al.) YieldEarly MaturityMedium MaturityFull Maturity 1CB / RWHX / RWVT3P 2CB / RWVT3PCB 3VT3 HX 4CBVT3PHX 5VT2PVT3P 6 CB / RWVT3P 7VIPCBNon- BT 8VT3PCBCB / RW 9VT3P 10HXVT3PNon-Bt

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

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

33 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 0592 a165 a0.2791c b162 a bc c149 b ab d143 b a

34 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)

35 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

36 Questions War Eagle!

37 Aflatoxin Levels in Corn Roy Parker, Texas A&M University, 2011 Test 1 Test 2 No statistically significant differences

38 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.

39 Sugarcane Beetles

40 Final Kernel Damage (cm 2 /ear in center two rows of plot) Early plantingLate Planting cm 2 damage P = , LSD(0.05) = 0.054, CV = 80.4 P < , LSD(0.05) = 0.094, CV = 61.9 b b a a b b ab a

41 Grain yield (B/A) Early plantingLate Planting bu/acre P = , LSD(0.05) = 8.5, CV = 2.8 P = , LSD(0.05) = 16.7, CV = 6.4

42 Simulated CEW Feeding (Blister) Steckel et al.

43 Tennessee - Corn Isolines Comparisons Impact of New Bt Technologies (VT3 Pro, SmartStax, Viptera) Yield (B/A) Location & YearNon-Bt YG or VT3VT3 Pro or SS TN – TN – (207) 233 * TN – * TN – 2009 (demo) TN – TN – 2010 (early) TN – 2010 (late) Average Location & YearNon-BtBt11Viptera TN – TN – * Average of 3 (2008) or 2 hybrids (2009) that were VT Pro or SmartStax

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

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


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