Project Title: Developing Stink Bug Thresholds for the Early Soybean Production System on the Upper Gulf Coast. 3 rd Year of Study.

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Gabriella Day
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1 Project Title: Developing Stink Bug Thresholds for the Erly Soyben Production System on the Upper Gulf Cost. 3 rd Yer of Study. Principl Investigtor: M.O. Wy Associte Professor, Entomology Texs Agriculturl Reserch & Extension Center 1509 Aggie Drive Beumont, TX Tel: (409) Fx: (409) E-mil: mowy@esrg.tmu.edu Introduction The Erly Soyben Production System (ESPS) involves plnting erly group soybens in mid-april nd hrvesting in August/September which llows soybens to complete pod-fill before drought conditions set in, typiclly in August. Insect pressure from Lepidopter defolitors cn be voided in the ESPS but frequently stink bug dmge is severe. Currently, little dt exist reltive to stink bug dmge nd soyben stge of growth in the ESPS. Thus, the objectives of this experiment re to quntify the reltionship between stink bug popultions over time nd dmge to ESPS soybens in terms of stge of growth, nd to extend this informtion to clientele. This informtion will identify soyben growth stges most susceptible to stink bug dmge which will ssist frmers in mking more timely pplictions of stink bug control mesures. Mterils nd Methods The experiment (3 rd yer of study) ws conducted t the TAMU Agriculturl Reserch nd Extension Center t Beumont in The experiment ws originlly designed s rndomized complete block with six tretments nd four replictions. Tretments being: 1) untreted, 2) control stink bugs from R1 to, 3) control stink bugs from R4 to, 4) control stink bugs from to, 5) control stink bugs from to nd 6) control stink bugs from to. Plot size ws 18 rows (30 inches between rows) x 90 ft. On 6 Apr, plots were plnted with DP4690 RR. On 9 Apr before soyben emergence, plots were spryed by trctor-rig with Squdron t 3 pt/cre nd Roundup UltrMx t 2 qt/cre. On 11 Apr, soybens emerged through Levc soil to produce good stnd. Some phytotoxicity ws observed in plots in repliction IV where Permit pplied to nerby rice drifted. On 12 My, plots were spryed by trctor-rig with Roundup UltrMx t 2 qt/cre. On 19 My, soybens were R1,V7. On 29 My, insects were not observed in plots nd soybens were R2/3, V9-11. On 30 My, plots were spryed with Dimilin 2L t 4 oz/cre. Appliction ws mde with two-person spry rig (13 nozzles, tip size, 21.7 ft spry swth, 12.3 gp finl spry volume). This insecticide ws pplied to provide long-lsting control of Lepidopter with no effect on stink bugs. Thus, the objective ws to eliminte Lepidopter defolition in ll plots to detect tretment effects due to stink bugs. On 22 Jun when soybens were, stink bugs were first observed in plots. Insects were smpled in ll plots on the following dtes: 24 Jun, 30 Jun, 7 Jul, 17 Jul,

2 Jul, 30 Jul, 7 Aug nd 14 Aug. Smples consisted of 20 sweeps in ech plot using 15 inch dim sweep net. The contents of the net were plced in plstic bg, frozen, thwed t lter dte, nd rthropods identified nd counted. Orthene 75S t 1.0 lb (AI)/cre ws pplied to control stink bugs in the following tretments nd dtes: Tretment Dte of Orthene 75S ppliction / (Stink bugs controlled from:) stge of soyben growth ÿ Jun 25/ ÿ Jul 2/ ÿ ÿ Jul 9/beginning ÿ Jul 25/beginning ÿ ÿ Aug 9/ ÿ Orthene 75S ws spryed with the sme rig nd methods employed for ppliction of Dimilin 2L. On 22 Aug, two rows 20 ft long in ech plot were cut with Jri sickle-br cutter. Cut soybens were threshed nd yields djusted to 13% moisture. Smples of seed from ech plot were rted for qulity. Insect counts were trnsformed using x nd ll dt nlyzed using ANOVA nd DMRT. Results The Dimilin 2L ppliction effectively controlled Lepidopter (Tbles 1-4). In fct, on ll smple dtes, verge no. of Lepidopter lrve ws less thn two per 20 sweeps (Tble 4). Thus, Lepidopter dmge did not msk tretment effects. Threecornered lflf hopper (TCAH) nymph densities were low throughout the experiment but dult densities in the untreted reched n verge of bout 10 per 20 sweeps on 7 Jul during pod-fill (Tbles 10-12). However, this is bout ½ the economic threshold density; thus, TCAH lso probbly did not msk tretment effects. Popultions of ll other rthropods, except stink bugs, were low on ll smple dtes (Tbles 13-17). 109

3 As previously stted, stink bugs were first observed in plots round 22 Jun when soybens were (beginning seed or pod-fill). Since stink bugs did not infest the experiment until, tretments designed to control stink bugs from R1 to nd R4 to were merged with the untreted. Thus, the untreted consisted of 12 replictions. Two species of stink bugs; southern green stink bug (SGSB), Nezr viridul nd brown stink bug (BSB), Euschistus servus; were collected in the smples. By fr the most bundnt ws SGSB which mde up bout 80% of the collected stink bugs. Popultions of stink bugs in the untreted drmticlly incresed during / nd decresed shrply in lte /erly (Tbles 5-9). This observtion is consistent with those mde during similr experiments conducted in 1999 nd Nymphs were quite bundnt during which mens dults were reproducing in the plots. Stink bug popultions incresed, peked nd decresed during reltively short time period (24 Jun - 17 Jul) when soybens were in pod-fill (Figs. 5-7). Orthene 75S pplictions effectively controlled stink bugs t the desired stges of soyben growth (Tble 9 nd Figs. 5-7). But popultions of stink bugs in the untreted hd lredy decresed drmticlly by lte. So, popultion differences in the untreted compred to 6 nd 6 tretments re reltively smll. Yield ws significntly higher in the 6 tretment thn the untreted (15.5 bu/cre more) (Tble 18). Clerly, high densities of stink bugs (pek of bout 35 nymphs nd dults per 20 sweeps or n verge of 1.75 per sweep) during pod-fill drsticlly reduced yield. These dt show tht ESPS soybens on the Upper Gulf Cost must be protected from stink bug dmge during pod-fill. A single ppliction of n insecticide with residul stink bug ctivity t beginning my be sufficient to provide seson-long protection since dt suggest nturl popultions drmticlly decrese during lte. Although yields were not significntly different for 6 nd 6 tretments compred to the untreted, these tretments outyielded the untreted 3.5 nd 4.7 bu/cre, respectively. This suggests tht protection from reltively low densities of stink bugs during nd my result in yield increses. Seed qulity ws significntly better in the 6 tretment (Tble 18). 110

4 Tble 1. Soyben looper densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. soyben looper/20 sweeps controlled from: Untreted 0.6 b b b NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 2. Green cloverworm densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. green cloverworm/20 sweeps controlled from: Untreted NS NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 111

5 Tble 3. Velvetben cterpillr densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. velvetben cterpillr/20 sweeps controlled from: Untreted NS NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 4. Lepidoptern lrvl densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. lepidoptern lrve/20 sweeps controlled from: Untreted NS NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 112

6 Tble 5. Phytophgous stink bug nymph densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. phytophgous stink bug nymphs/20 sweeps controlled from: Untreted b b 0.3 b b b b 0.8 NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 6. Southern green stink bug dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. southern green stink bug dults/20 sweeps controlled from: Untreted b b c 0.8 c 0 b bc 5.3 bc 0 b b NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 113

7 Tble 7. Brown stink bug dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. brown stink bug dults/20 sweeps controlled from: Untreted b 0.6 b b 0.3 b b 0.8 b 0 NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 8. Phytophgous stink bug dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. phytophgous stink bug dults/20 sweeps controlled from: Untreted b b 0.8 c 0.5 b b 0.3 b b NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 114

8 Tble 9. Phytophgous stink bug nymph + dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. phytophgous stink bug nymphs + dults/20 sweeps controlled from: Untreted b b 1.3 c 0.8 b 0.3 b 0.3 b b 0.3 b 0.8 b 1.3 b b b NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 115 Tble 10. Threecornered lflf hopper nymph densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. threecornered lflf hopper nymphs/20 sweeps controlled from: Untreted NS NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT).

9 Tble 11. Threecornered lflf hopper dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. threecornered lflf hopper dults/20 sweeps controlled from: Untreted b b 1.0 b 0.5 b 0.3 b 0.3 b 0.8 c 0 b b 0.5 b 1.0 b b b 1.3 bc 0 b NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 12. Threecornered lflf hopper nymph + dult densities reltive to MGIV soyben stge of development, Bmt., TX, 2001 Men no. threecornered lflf hopper nymphs + dults/20 sweeps controlled from: Untreted b 1.0 b 0.5 b 0.3 b 0.3 b 0.8 b 0 b b 0.5 b 1.0 b b b 1.3 b 0 b NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 116

10 Tble 13. Orthoptern nymph nd dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. orthoptern nymphs + dults/20 sweeps controlled from: Untreted b 0 c 0 b b b 0.3 bc 0.5 b b b 0 b b NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 117 Tble 14. Bnded cucumber beetle densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. bnded cucumber beetle/20 sweeps controlled from: Untreted b b b NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT).

11 Tble 15. Lefhopper nymph nd dult densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. lefhopper nymphs + dults/20 sweeps controlled from: Untreted b b b NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 16. Ambush bug densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. mbush bugs/20 sweeps controlled from: Untreted NS NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 118

12 Tble 17. Spider densities reltive to MGIV soyben stge of development, Beumont, TX, 2001 Men no. spiders/20 sweeps controlled from: Untreted NS NS NS NS NS NS NS NS Mens in column followed by the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). Tble 18. Yield, seed qulity nd seed size for MGIV soyben, Beumont, TX, 2001 Stink bugs Yield Seed qulity b Seed size c controlled from: bu/a (1-5) (no. seed/lb) Untreted 22.6 b b b b b b b Yield djusted to 13% moisture. Mens with the sme or no letter re not significntly different t the 7% level (ANOVA nd DMRT). b Seed qulity: 1 = excellent, 5 = very poor. Mens with the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). c Mens with the sme or no letter re not significntly different t the 5% level (ANOVA nd DMRT). 119

13 Avg. no. stink bug nymphs/20 sweeps Fig. 1. No. stink bug nymphs in ESPS experiment. Beumont, TX Untreted /24 6/30 7/7 7/17 7/23 Dte/growth stge 7/30 8/7 8/14

14 Avg. no. stink bug dults (SGSB+BSB)/20 sweeps Fig. 2. No. stink bug dults in ESPS experiment. Beumont, TX Untreted /24 6/30 7/7 7/17 Dte/growth stge 7/23 7/30 8/7 8/14

15 Avg. no. stink bug nymphs+dults/20 sweeps Fig. 3. No. stink bug nymphs+dults in ESPS experiment. Beumont, TX Untreted /24 6/30 7/7 7/17 7/23 Dte/growth stge 7/30 8/7 8/14

16 20 Fig. 4. No. TCAH (nymphs+dults) in ESPS experiment. Beumont, TX Untreted Avg. no. TCAH (N+A)/20 sweeps /24 6/30 7/7 7/17 7/23 7/30 8/7 8/14 Dte/growth stge

17 Avg. no. stink bug nymphs+dults/20 sweeps Fig. 5. No. stink bug nymphs+dults in ESPS experiment. Untreted vs to tretment. Beumont, TX /24 6/30 7/02 7/09 6/30 7/7 7/17 7/23 7/30 Untreted Economic Threshold Insecticide Appliction 8/7 8/09 8/ Dte/growth stge

18 Avg. no. stink bug nymphs+dults/20 sweeps Fig. 6. No. stink bug nymphs+dults in ESPS experiment. Untreted vs to tretment. Beumont, TX /09 Untreted Economic Threshold Insecticide Appliction 8/ /24 6/30 7/7 7/17 7/23 7/30 8/7 8/14 Dte/growth stge

19 Avg. no. stink bug nymphs+dults/20 sweeps Fig. 7. No. stink bug nymphs+dults in ESPS experiment. Untreted vs to tretment. Beumont, TX /25 Untreted Economic Threshold Insecticide Appliction 8/ /24 6/30 7/7 7/17 7/23 7/30 8/7 8/14 Dte/growth stge

Table of Contents. Evaluation of Southern Regional MGVI, MGVII and MGVIII Soybean Lines in Cooperation with Dr. Jim Heitholt...16

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