SW MN IPM RESEARCH - 2017 STUDY: 2017 AMVAC worm on Trit INVESTIGATOR: Bruce Potter - University of Minnesot Extension IPM Trvis Vollmer University of Minnesot Southwest Reserch nd Outrech Center OBJECTIVE: Evlute efficcy ginst corn rootworm (CRW) lrve nd yields of Aztec HC, Index nd no t-plnt insecticide pplied to two refuge hyrids without Bcillus thuringiensis rootworm trit (Bt- RW) pyrmid hyrids. CROP INFORMATION Crop: Corn (Ze mys) Cultivr: See tretment list History: 2013: Cry 3B1 Corn 2014: Cry 3B1 Corn 2015: Cry 3B1 Corn 2016: non-bt Corn PEST INFORMATION This site hd history of Cry 3B1 filure in 2015. Western corn rootworm dominted the popultions with very few northern corn rootworm dults oserved on the studies corn plnts or Trece Pherocon AM trps in 2016 nd 2017. SITE INFORMATION Loction: University of Minnesot Southwest Reserch nd Outrech Center Lmerton, Redwood County, Minnesot Soil fertility (2016 smple): Nme: Normni lom % OM: 4.7 ph: 6.0 P(ry): 21 ppm K: 104 ppm Zn: 1.0 ppm PLANTING INFORMATION Plnting Dte: 5/11/2017 Emergence Dte: 5/23/2017 Plnting Equipment: John Deere (Moline, IL) Mx Emerge 4-row nrrow plnter modified for plot plnting with Precision Plnting LLC (Tremont, IL) vcuum system nd vset meters. Row Spcing: 30-inch Seeding Rte: 34,000 seeds/cre Seeding Depth: 2 inch Soil Temperture: 64 o F Soil Moisture: Dry Precipittion: Aove-verge precipittion fter plnting PLOT MAINTENANCE Tillge Fll 2016: Disc Ripper Tillge Spring 2017: Field cultivtor Fertilizer: 5/10/17 180-60-80 PRE Hericide: 5/10/17 Hrness 2.6 pts/a
POST Hericide: 6/19/17 Insecticide: 5/11/17 Cornerstone Plus 36 fl. Oz./A Prt of study. See Tretment List HARVEST INFORMATION Hrvest equipment: Plot comine (ALMACO, Nevd, IA). The center two rows of ech four-row plot were hrvested. Grin yields were djusted to 15.5% moisture nd 56 pounds/ushel. EXPERIMENTAL DESIGN Study Design: 4 X 3 fctoril Tretments: 12 Replictions: 4 Treted Plot Width: 10 foot (four 30-inch rows) Treted Plot Length: 30 foot TREATMENTS EVALUATED Tretment Fctors Trt Hyrid/Trit Fctor No. Hyrid Insecticide Trit Bt-RW protein(s) 1 DKC 53-58RIB Blend H1 GENVT2PRIB none None I1 Insecticide Fctor 2 DKC 53-58RIB Blend H1 GENVT2PRIB none Aztec HC I2 3 DKC 53-58RIB Blend H1 GENVT2PRIB none Index I3 4 DKC 53-56RIB Blend H2 GENSSRIB Cry 3B1+34/35 A1 None I1 5 DKC 53-56RIB Blend H2 GENSSRIB Cry 3B1+34/35 A1 Aztec HC I2 6 DKC 53-56RIB Blend H2 GENSSRIB Cry 3B1+34/35 A1 Index I3 7 P0157R H3 RR2 none None I1 8 P0157R H3 RR2 none Aztec HC I2 9 P0157R H3 RR2 none Index I3 10 P0297 AMXT H4 AMXT Cry 34/35 A1+mCry3 None I1 11 P0297 AMXT H4 AMXT Cry 34/35 A1+mCry3 Aztec HC I2 12 P0297AMXT H4 AMXT Cry 34/35 A1+mCry I3 H1 H2 H3 H4 Dekl DKC 53-58 Genuity VT2PRIB Doule PRO RIB Complete Dekl DKC 53-56 Genuity SmrtStx RIB Complete Pioneer P0157R Pioneer P0297 AMXT Optimum AcreMx Xtreme Monsnto Compny Monsnto Compny Dupont Pioneer Dupont Pioneer I1 I2 I3 No in-furrow, t-plnt insecticide Aztec HC t 1.5 oz/1000 row-ft w/ Smrt Box meters Index t 12.6 fl oz/cre in-furrow with 5 GPA wter AMVAC Chemicl Corportion AMVAC Chemicl Corportion Tle 1. Hyrids nd insecticides evluted ASSESSMENT METHODS Corn rootworm injury: On July 31, the root systems of five plnts were dug in ech plot. No effort ws mde to differentite refuge plnts in selecting or the susequent rting root systems. After soking overnight, root systems were power-wshed nd corn rootworm injury ws rted. For ech of nodes 5-7, the totl roots nd the numer of roots pruned to 1.5
inches or less were recorded. These dt were used to generte 0-3 node injury scores. Additionl dt on the numer of roots pruned less thn 3 inches nd ny scrring cused y rootworm feeding were lso recorded. lodging: In this study, lodging ssocited with corn rootworm dmge occurred erly nd ws rted when root injury ws ssessed. This first rting ws sujective whole plot 1-5 score: 1) no lodging; 2) occsionl plnts slightly lening; 3) slight lening common or some plnts lodged > 45 degrees; 4) plnts with severe lodging common; 5) Most plnts severely lodged, some my hve root roken nd exposed. On August 1, lodging ws rted s the percentge of the five plnts rted for CRW root injury with goose-necked lower stlks. On Octoer 19, the percentge of plnts were y determining the percentge of the plnts in the center two rows of ech plot lodged. At this lst rting, plnt ws considered lodged if the er ws lodged so low s to present potentil hrvest issues. Stlk lodging: Stlk rot ws prolem in 2017 fields within the geogrphic re of the study. This disese ws ssessed t the sme time s root lodging on Octoer 19. In ddition to recording stlk-lodged plnts, stlks were grsped elow the er nd given gentle push. Stlks tht collpsed were include in the percentge stlk lodged. High percentges of root lodging occurred in some of the plots without Bt-RW nd t-plnt insecticide. This prohiited mking ccurte stlk lodging ssessments nd the level of stlk rot ws likely underestimted for these tretments. RESULTS The 2017 growing seson ws wetter thn norml with the lst 1/2 of My nd the first 1/2 of June verging 2-3 inches ove norml. After plnting, 3.98 inches of rinfll occurred from My 16-21. Western corn rootworm dmge ws severe in this study s well s the djcent corn plntings in this field. A fctoril nlysis of vrince for hyrid (Bt-RW trit), insecticide nd interctions etween hyrid nd insecticide is presented in Tle 2. Mens nd men seprtions y hyrid, t-plnt insecticide, nd ny interctions etween fctors re presented for the yield, rootworm root injury, root nd stlk lodging vriles re presented in Tle 3. Neither Aztec HC nor Index insecticide cused ny visile crop injury symptoms. Neither hyrid nor insecticide significntly ffected erly emergence nd stnd or height t V5 (dt not shown). Differences in root injury cused y rootworms nd its ssocited lodging were highly significnt for hyrid nd tplnt insecticide. Hyrids with nd without Bt-RW trit differed in their response to n t-plnt insecticide ppliction. Without n in-furrow, t-plnt insecticide root node injury scores (NIS) in the hyrids without Bt-RW trit were significntly different with men NIS of 1.7 nd 0.9 with Pioneer 0157 R nd DK 53-58 VT2, respectively. Miniml CRW injury occurred in the SmrtStx RIB nd AMXT Bt-RW pyrmids, regrdless of insecticide. Aztec HC grnules nd Index liquid insecticides provided excellent nd similr rootworm control. Hyrids with Bt-RW pyrmid hd less root lodging thn those without. Both t-plnt insecticides reduced lodging of hyrids without Bt-RW trit to levels similr to the two pyrmid hyrids. Hyrids differed in end-of-seson stlk lodging nd there is evidence tht t-plnt insecticides reduced lodging in this study. This response did not pper consistent mong hyrids. Stlk nd root lodging were confounded in rting of some plots. The men yield of the SmrtStx hyrid ws numericlly c. more thn 20 ushels/cre higher where t-plnt insecticides were pplied ut these differences were not sttisticlly significnt nd did not pper relted rootworm injury (Figure 1).
CONCLUSIONS In the re surrounding the study re, Cry 3B1 (VT3) Hyrid showed dmge similr to RW susceptile hyrids. The pyrmided rootworm trits still pper to e performing well t this site. Lte plnting nd undnt erly growing seson moisture presented idel conditions for t-plnt rootworm insecticide performnce. Both the dry nd liquid in-furrow, t-plnt insecticide formultions performed well nd provided significnt reduction in injury on CRW-susceptile hyrids. Aztec HC nd Index provided higher yield thn untreted hyrids. Yield trends followed rootworm insecticide (α = 0.20). Bt nd insecticide re not the only fctors tht cn influence corn yield in the presence of CRW lrve. system rchitecture, root system regenertive ilities nd genetic ttriutes cn influence hyrid s response to CRW. While yield response to soil insecticide cn indicte tht performnce of Bt-RW trit hs een is reduced, it is importnt to look t root injury nd/or eetle popultions in conjunction with yield when ssessing Btperformnce. Plnts/cre (1-5) rting ISU(0-3) NIS < 0.25 % plnts % plnts % plnts c Bu./cre 6/14/2017 7/13/2017 7/31/2017 7/31/2017 7/31/2017 10/19/2017 10/19/2017 10/31/2017 Repliction 0.0229 **** 0.4508 0.2952 0.01253 0.4051 0.2639 0.2561 0.3766 Hyrid 0.0756 ** 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.1903 * Insecticide 0.1873 * 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.0162 *** 0.0001 **** Hyrid X Insecticide 0.1242 * 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.0001 **** 0.0096 *** 0.1002 ** 1 Node Injury Score (NIS) sed on the percent roots per node pruned < 1.5 inches for nodes 5-7 2 Percent of plnts scoring less thn 0.25 NIS (ISU 0-3) Sujective rting of lodging of plot where 1 = no lodging nd 5 = ll plnts severely lodged Percent plnts lodged elow er % Control c Percent stlks collpsing elow er (push test) *, **, ***, **** : significnt t α = 0.20, 0.10, 0.05, 0.01 respectively Stnd lodging NIS 1 Consist. 2 Lodging Lodging Stlk rot Lodging Yield Tle 2. Fctoril Anlysis of Vrince (ANOVA) for Tle 2. Mens nd men seprtions for corn stnds, yield nd for corn rootworm nd disese ssocited injury. UMN Southwest Reserch nd Outrech Center, Lmerton, MN 2017.
Stnd Lodging NIS 1 Consist. 3 Lodging Lodging Stlk rot Yield Plnts/cre (1-5) rting ISU (0-3) NIS < 0.25 % plnts % plnts % plnts c Bu./cre Rting dte 6/14/2017 7/13/2017 7/31/2017 7/31/2017 7/31/2017 10/19/2017 10/19/2017 10/31/2017 Crop stge V5 VT R1 R1 R1 R6 R6 R6 No. Susmples 2 1 5 1 1 1 1 1 A (Hyrid) MEANS 1 Dekl 53-58 VT2 (no Bt-RW trit) 31387.4-1.9 0.38 61.7 33.3 34.9 1.5 204.8-2 Dekl 53-56 SS(Cry3B1 + Cry34/35 A1) 30588.8-1.0 0.01 c 100.0 0.0 0.2 3.0 215.6-3 Pioneer 0157 R (no Bt-RW trit) 31605.2-1.8 0.61 61.7 25.0 33.4 11.0 208.6-4 Pioneer 0297 AMXT(Cry34/35 A1 + mcry3) 31702.0-1.1 0.01 c 100.0 0.0 0.0 11.8 208.1 - Tukey's HSD P=.05 0.4 0.098 16.7 15.9 3.7 2.6 Stndrd Devition 1104.9 0.4 0.089 15.1 14.4 3.4 2.3 12.2 B (Insecticide) MEANS 30927.6-2.2 0.66 56.3 43.8 49.1 2.0 197.1 31653.6-1.1 0.08 89.8 0.0 2.1 2.3 214.2 31381.4-1.1 0.02 97.5 0.0 0.1 3.0 216.6 Tukey's HSD P=.05 0.3 0.08 13.1 12.5 2.9 2.0 10.6 Stndrd Devition 1104.9 0.4 0.09 15.1 14.4 3.4 2.3 12.2 A (Hyrid) X B (Insecticide) MEANS 1 Dekl 53-58 VT2 30,564.6-3.0 0.88 25.0 cd 100.0 96.5 0.6 e 190.7-1 Dekl 53-58 VT2 32,234.4-1.5 0.22 c 60.0 c 60.0 c 8.1 1.4 e 211.0-1 Dekl 53-58 VT2 31,363.2-1.3 0.04 c 100.0 100.0 0.0 2.4 de 212.6-2 Dekl 53-56 SS 29,403.0-1.0 0.01 c 100.0 0.0 0.0 3.7 cde 200.6-2 Dekl 53-56 SS 31,072.8-1.0 0.02 c 100.0 0.0 0.0 2.2 de 222.1-2 Dekl 53-56 SS 31,290.6-1.0 0.01 c 100.0 0.0 0.5 3.0 de 224.2-3 Pioneer 0157 R 31,581.0-3.5 1.72 0.0 d 75.0 100.0 15.6 187.2-3 Pioneer 0157 R 31,363.2-1.0 0.05 c 95.0 0.0 0.3 9.7 216.4-3 Pioneer 0157 R 31,871.4-1.0 0.05 c 90.0 0.0 0.0 7.7 cd 222.1-4 Pioneer 0297 AMXT 32,161.8-1.3 0.02 c 100.0 0.0 0.0 12.2 209.7-4 Pioneer 0297 AMXT 31,944.0-1.0 0.02 c 100.0 0.0 0.0 9.2 c 207.2-4 Pioneer 0297 AMXT 31,000.2-1.0 0.00 c 100.0 0.0 0.0 11.2 207.4 - Tukey's HSD P=.05-0.97 0.22 37.6 35.8 8.3 5.8 - Stndrd Devition 1,104.9 0.39 0.09 15.1 14.4 3.4 2.3 12.2 Mens followed y sme letter or symol do not significntly differ (P=.05, Tukey's HSD) Men comprisons performed only when AOV Tretment P(F) is significnt t men comprison OSL. 1 Node Injury Score (NIS) sed on the percent roots per node pruned < 1.5 inches for nodes 5-7 2 Node Injury Bsed on the % roots per node pruned to 3 inches or less 3 Percent of plnts scoring less thn 0.25 NIS (ISU 0-3) Sujective rting of lodging of plot where 1 = no lodging nd 5 = ll plnts severely lodged Percent plnts lodged elow er c Percent stlks collpsing elow er (push test) Tle 3. Mens nd men seprtions for corn stnds, yield nd for corn rootworm nd disese ssocited injury. UMN Southwest Reserch nd Outrech Center, Lmerton, MN 2017. % Control
Yield (ushels/cre +/- SEM) 250.0 200.0 150.0 100.0 50.0 0.0 190.7 0.88 * 211.0 212.6 0.22 VT2 VT2 w/ Aztec HC 200.6 222.1 224.2 0.03 0.01 0.02 0.01 VT2 w/index SS SS w/ Aztec HC Lmerton, MN 2017 SS w/ Index 1.72 ** 187.2 RR RR w/ Aztec HC 216.4 222.1 209.7 207.2 207.4 0.05 0.05 0.02 0.01 0.00 RR w/ Index AMXT AMXT w/ AMXT w/ Aztec HC Index 3.00 2.75 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0.00 ISU NIS (0-3) Figure 1. Yield nd root nodl injury scores (red dots) for four corn hyrids (CRW trits) nd two insecticides. Mens nd men seprtions for corn stnds, yield nd for corn rootworm nd disese ssocited injury. Mens with sme letter or symol do not significntly differ (p= 0.05 Tukey s HSD). UMN Southwest Reserch nd Outrech Center, Lmerton, MN 2017. ACKNOWLEDGEMENTS Mtthew Wordes nd Adm Hss provided vlule help in plot mintennce nd root digs nd the root rting process. We would like to thnk AMVAC Chemicl Corportion for their support of this study. Aztec HC nd Index re restricted use insecticides. Alwys red nd follow lel directions Products re mentioned for illustrtive purposes only. Their inclusion does not men endorsement nd their sence does not imply dispprovl. 2018, Regents of the University of Minnesot. All rights reserved. The University of Minnesot Extension is n equl opportunity eductor nd employer. For University of Minnesot Extension crop production informtion: http://www.extension.umn.edu/griculture/crops/