EVALUATION OF SEED AND IN-FURROW AT-PLANTING APPLIED INSECTICIDES ON SORGHUM Texs Agriculturl Experiment Sttion, Corpus Christi, TX, nd Michel nd Wlter Kuck Frm, Lvc County, 1999 Roy D. Prker, Emil D. Bethke III, Shnnon Deforest nd Anthony Netrdus Extension Entomologist, Extension Agent-IPM nd County Extension Agents Corpus Christi, Robstown, Hllettsville nd Cuero, Texs, respectively OBJECTIVES: Field tests were conducted on sorghum in Nueces nd Lvc Counties to evlute systemic seed nd in-furrow pplied insecticides. Objectives were to mesure the impct of tretments on soil nd folir insect pests, nd to ccess impct on grin sorghum yields. MATERIALS/METHODS: Test 1. Sorghum DK45 hybrid ws plnted t the Texs Agriculturl Experiment Sttion in Nueces County t 68,780 kernels/cre with cone plnter on 11 Mr in sndy cly lom soil (50% snd, 26% silt, 24% cly) with 1.1% orgnic mtter nd soil ph of 8.1. The soil temperture t-plnting ws 74 F, excellent soil moisture ws present nd cotton hd been plnted on the site in the previous seson. Gmmsn ws pplied to the seed s plnter box tretment. Furdn 4F ws pplied into the seed furrow through single XR 8002-VS nozzle oriented with the row t 7.36 gp totl volume nd 30 psi t speed of 3 mph. Counter 15G ws pplied with stndrd John Deere bnders (T-bnd). Fertilizer pplied ws 100-14-0+0.6 Zn/cre nd the herbicide ws trzine 4L (1.0 qt/cre). Plots 4 rows wide (38-inch row spcing) x 30 ft were rrnged in RCB design with 4 replictions. A totl of 7.6 inches of rin ws received during the growing seson. Tretment effects were determined by (1) estimting the number of corn lef phids (CLA) in 10 plnt whorls 37, 51, 55 nd 60 dys fter plnting (DAP), (2) counting the number of greenbugs (GB) on 10 lower leves 51, 55 nd 60 DAP, (3) Counting the number of plnts on 13.75 ft on ech of the center two rows of ech plot nd (4) hrvesting by hnd 13.75 ft row from ech of the center two rows in ech plot on 13 Jul. Pnicles were thrshed for grin yield with lbortory mchine. Thrshed grin weights were corrected to 14% moisture. Test 2. DK 45 hybrid sorghum ws plnted 15 Mr on commercil frm in Lvc County ner Shiner, TX. The soil ws sndy cly lom. Soil moisture for plnting ws excellent nd it ws 63 F t the 4-inch depth. The seeding rte ws 63,500 per cre on rows with 38-inch centers. Seed nd grnulr insecticides were dispensed with John Deere model 7100 plnter nd corn hs been plnted on the test site the previous seson. Fertilizer pplied ws 79-40-13 + 0.5 qt zinc nd herbicide Dul II Mgnum 7.64 lb/gl (0.7 qt/cre) ws pplied in 14-inch bnd. Plots were 3 rows wide nd the verge plot length ws 580 ft. Tretments were replicted 3 times nd rrnged in RCB design. Grnulr insecticide ws pplied in pproximtely 6-inch bnd nd Gmmsn ws mixed with seed s plnter box tretment. Tretment effects were determined by (1) counting plnts on 13.75 ft row t one loction in the center two rows of ech plot, estimting the number of GB on 10 lower leves nd determining presence or bsence of CLA 8
in plnt whorls ll t 43 DAP; (2) counting chinch bugs behind 10 lower leves in ech plot 64 dys fter plnting nd (3) hrvesting entire plots with commercil mchine on 23 Jul. Sorghum weights were corrected to 14% moisture stndrd. RESULTS/DISCUSSION: Test 1. Significntly more CLA were found in untreted nd Gmmsn treted sorghum 37 DAP compred with Adge, Counter nd Gucho tretments (Tble 1). By 51 DAP, none of the insecticide tretments contined sttisticlly fewer numbers of CLA thn the untreted sorghum but, numericlly, CLA in Adge nd Gucho tretments were extremely low nd they remined low reltive to the untreted sorghum t 55 nd 60 DAP. The seson verge number of CLA were sttisticlly fewer in Adge nd Gucho treted sorghum compred to ll other tretments. Likewise (Tble 2), GB were lower in Adge nd Gucho treted sorghum nd, to lesser extent, there were fewer in the Counter treted sorghum compred to untreted sorghum throughout the evlution period (51, 55 nd 60 DAP). No differences were found in plnt popultion (Tble 3). Surprisingly, only Gmmsn treted sorghum produced significntly more grin compred with the untreted sorghum, lthough there ws not sttisticl difference between the Gmmsn compred with Adge nd Gucho. Test 2. Sttisticl differences in plnt popultions were observed but resons for these differences were not pprent (Tble 4). Reduced plnt popultion, t lest numericlly, occurred in Counter treted sorghum. GB numbers were not found to differ sttisticlly; these numbers were extremely low t 43 DAP. Adge nd Gucho treted sorghum hd fewer CLA infested whorls thn other tretments nd these lso seprted sttisticlly from ech other. Even so, infesttions did not persist but short period. A chinch bug infesttion developed but counts 64 DAP did not differ sttisticlly nor were differences found in grin yields. ACKNOWLEDGMENTS: Novrtis Crop Protection, Americn Cynmid Compny, Gustfson Inc. nd FMC Corportion re thnked for providing funds for conduct of this study. Apprecition is expressed to Michel nd Wlter Kuck for their time nd equipment in conducting the study. 9
Test 1 Tble 1. Corn lef phid numbers in sorghum treted with insecticide t-plnting, Texs Agriculturl Experiment Sttion, Corpus Christi, TX, 1999. Tretment/ Corn lef phids/10 plnts rte 37 DAP b 51 DAP 55 DAP 60 DAP Seson vg (8.0 oz/cwt seed) 7.5 b 16.5 c 2.0 c 13 b 9.7 c b Gmmsn DS (5.4 oz/cwt seed) 925.0 107.5 bc 672.5 b 1125 707.5 (5.1 oz/cwt seed) 0.0 b 3.5 c 0.0 c 0 b 0.8 c Counter 15G (4.0 oz/1000 ft row) 312.5 b 262.5 b 177.5 c 850 400.6 b Furdn 4F (16.0 oz/cre) 25.0 b 625.0 750.0 825 556.3 b Untreted 1312.5 170.0 bc 337.5 bc 550 b 592.5 b LSD (P=0.05) 546.4 231.6 352.2 600.5 220.6 P>F.0001.0001.0002.0010.0000 Mens in column followed by the sme letter re not significntly different by ANOVA (LSD). Gmmsn (33.5% cptn + 16.6% lindne). DAP = Dys After Plnting corresponding to 4/17, 5/1, 5/5 nd 5/10. 10
Tble 2. Greenbugs in sorghum treted with insecticide t-plnting, Texs Agriculturl Experiment Sttion, Corpus Christi, TX, 1999. Tretment/ Greenbugs/10 lower leves rte 51 DAP b 55 DAP 60 DAP Seson vg (8.0 oz/cwt seed) 0.3 d 2.3 b 3.8 c 2.1 b b Gmmsn DS (5.4 oz/cwt seed) 97.5 b 297.5 305.8 b 233.6 (5.1 oz/cwt seed) 0.0 d 0.5 b 0.3 c 0.3 b Counter 15G (4.0 oz/1000 ft row) 54.3 c 74.3 b 141.3 bc 89.9 b Furdn 4F (16.0 oz/cre) 167.3 365.0 346.3 292.8 Untreted 113.8 b 231.3 252.5 b 199.2 LSD (P=0.05) 38.14 146.4 169.7 105.14 P>F.0000.0000.0003.0000 Mens in column followed by the sme letter re not significntly different by ANOVA (LSD). Gmmsn (33.5% cptn + 16.6% lindne). DAP = Dys After Plnting corresponding to 5/1, 5/5 nd 5/10. 11
Tble 3. Plnt popultion nd yield in sorghum treted with insecticide t-plnting, Texs Agriculturl Experiment Sttion, Corpus Christi, TX, 1999. Tretment/rte Plnts (1000's/cre) Yield (lb/cre) (8.0 oz/cwt seed) 63.5 4346 bc Gmmsn DS (5.4 oz/cwt seed) 54.6 4504 (5.1 oz/cwt seed) 62.8 4364 b Counter 15G (4.0 oz/1000 ft row) 64.0 4100 c Furdn 4F (16.0 oz/cre) 63.4 4219 bc Untreted 63.3 4133 bc LSD (P=0.05) NS 248.34 P>F.3337.0062 Mens in column followed by the sme letter re not significntly different by ANOVA (LSD). Gmmsn (33.5% cptn + 16.6% lindne). 12
Test 2 Tble 4. Plnt popultion, insect infesttion nd yield in sorghum treted with grnulr nd seed tretment insecticides, Michel nd Wlter Kuck Frm, Lvc County, TX, 1999. Greenbugs Corn lef phid Chinch bugs Tretment/rte Plnts (1000's/cre) per 10 lower leves b % infested whorls per 10 lower leves c Yield (lb/cre) (8.0 oz/cwt seed) 58.0 bc 0.3 46.7 b 37.0 4947 Gmmsn (5.4 oz/cwt seed) 63.3 b 27.3 100 91.7 5015 (5.1 oz/cwt seed) 69.7 0.3 0.0 c 69.3 5333 Counter 20CR (3.0 oz/1000 ft row) 47.3 c 10.7 100 97.7 5059 Counter 20CR + Gmmsn (3.0 oz/1000 ft row + 5.4 oz/cwt seed) 53.0 bc 2.7 100 103.7 5067 Untreted 57.0 bc 3.3 100 64.3 5002 LSD (P=0.05) 12.9 NS 35.1 NS NS P>F.0392.4815.0003.1156.1360 Mens in column followed by the sme letter re not significntly different by ANOVA (P=0.05; LSD). Gmmsn (33.5% cptn + 16.6% lindne). b Counts were mde on 4/27 or 43 dys fter plnting. C Counts were mde on 5/18 or 64 dys fter plnting by counting for chinch bugs behind the lef sheth. 13