Ear Pests and Damage to Organic, Conventional and Bt-Protected Sweet Corn Grown in Central Kentucky

2009 ◽  
Vol 44 (4) ◽  
pp. 383-390
Author(s):  
John D. Sedlacek ◽  
Karen L. Friley ◽  
Steve L. Hillman
Keyword(s):  
Helicoverpa Zea ◽  
European Corn Borer ◽  
Sweet Corn ◽  
Crop Protection ◽  
Fall Armyworm ◽  
Corn Earworm ◽  
Genetically Engineered ◽  
Corn Borer ◽  
Sap Beetles ◽  
Southwestern Corn Borer

Sweet corn (Zea mays L. var. rugosa) was grown in replicated plots in 2004 and 2006 using organic, conventional, and genetically-engineered (Bt) production practices. Organic plots were treated with Entrust® (Dow AgroSciences LLC, Indianapolis, IN) whereas conventional and Bt sweet corn plots were treated with Warrior® (Syngenta Crop Protection, Inc., Greensboro, NC). All plots were treated once at silk emergence. Organic and conventional plots were treated again 1 wk later. Twenty-five ears were harvested from row centers in each treatment subplot to quantify ear pests and assess ear damage. The highest number of corn earworm, Helicoverpa zea (Boddie), larvae were found on organically-grown sweet corn. European corn borer, Ostrinia nubilalis (Hübner); southwestern corn borer, Diatraea grandiosella Dyar; and fall armyworm, Spodoptera frugiperda (J.E. Smith), larvae were not found as frequently. Neither corn earworm nor European corn borer larvae were found on Bt sweet corn ears. Sap beetles, Carpophilus lugubris Murray, were found on all 3 types of sweet corn. Organically and conventionally-grown sweet corn had a greater number of tip-damaged ears and numbers of damaged kernels per ear than Bt sweet corn. Ear length and weight were the same for all 3 types of sweet corn. Based on the information generated in this study, growing late-planted sweet corn organically or conventionally on a large commercial scale with a limited spray program and without using other types of ear pest management does not appear to be a practical or profitable option in central Kentucky.

scholarly journals Optimum Timing of an Application of Corn Oil and Bacillus thuringiensis to Control Lepidopteran Pests in Sweet Corn

2004 ◽  
Vol 14 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Rosalind Cook ◽  
Anne Carter ◽  
Pamela Westgate ◽  
Ruth Hazzard
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
European Corn Borer ◽  
Sweet Corn ◽  
Corn Oil ◽  
Corn Earworm ◽  
Larval Feeding ◽  
Corn Borer ◽  
Late Planting ◽  
All Treatment

Corn oil and Bacillus thuringiensis ssp. kurstaki (Bt) applied directly into the silk channel of a corn ear has been shown to be an effective pesticide against corn earworm, Helicoverpa zea (CEW), and european corn borer, Ostrinia nubilalis (ECB). Field studies were conducted in 2000 and 2001 to determine the influence of application timing on ear quality at harvest. Two blocks of corn were planted during each year to observe treatment effects under varying populations of the two insect species. The treatment consisted of 0.5 mL (0.017 floz) of food grade corn oil containing a suspension of Bt at 0.08 g (0.003 oz) a.i. per ear applied directly into the silk channel at the husk opening. One treatment application was made on each silk day 3 through 11 from first silk; silk day 1 was the first day that 50% or more of ears had 2.5 cm (1 inch) of silk protruding from the husk. One treatment did not receive the oil + Bt suspension. All ears were harvested at milk stage, on silk day 25. The number of CEW larvae in treated ears increased with later application days in 2000, but not in 2001. Damage from larval feeding was mainly found near the tip of the ear, and damage ratings were lower compared to untreated ears for all treatment days for both plantings in 2000, and through application day 8 in the late planting of 2001. ECB larvae were reduced for all treatment days in both plantings in 2000 and the late planting of 2001. The percentage of ears rated as marketable (i.e., free of feeding damage) ranged from 71% to 100% in treated plots compared to 30% to 77% in the untreated plots. There was a linear decrease in marketability with later application days in two of the four plantings. The greatest decrease in marketability was after application day 7. Because the oil application affects kernel development at the tip, the length of ear with under-developed kernels, or cone tip, was measured. The number of ears with cone tip decreased linearly with the later application days in all plantings. There was 10% conetip or less after day 7 in 2000 and day 6 in 2001. The best combination of effective insect control resulting in the highest rates of marketable ears with the least degree of cone tip was achieved in this experiment by application of oil + Bt suspension on day 7. Year to year variation in the environment would suggest a range from day 6 to 8.

scholarly journals Recurrent Full-sib Family Selection for Husk Extension in Sweet Corn

2019 ◽  
Vol 144 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Virginia M. Moore ◽  
William F. Tracy
Keyword(s):  
Helicoverpa Zea ◽  
European Corn Borer ◽  
Recurrent Selection ◽  
Sweet Corn ◽  
Corn Earworm ◽  
Direct Selection ◽  
Initial Population ◽  
Family Selection ◽  
Corn Borer ◽  
Selection For

Corn earworm (Helicoverpa zea) is a costly and destructive pest in sweet corn (Zea mays) production. A recurrent selection experiment was conducted to assess the feasibility of selecting a sweet corn population for longer husks without shortening the ears and to determine whether direct selection for longer husks confers improved resistance to the corn earworm. The initial population was derived from crosses between long- and tight-husked inbred lines (A684su, A685su, and A686su) originally selected for resistance to the european corn borer (Ostrinia nubilalis) and a high-quality commercial hybrid parent (‘Super Sweet Jubilee Plus’). Three cycles of recurrent full-sib family selection were conducted from 2014 to 2016, with a selection intensity of ≈10% per cycle. In 2017, the cycles of selection were evaluated and compared with common commercial cultivars for husk extension, ear length, rate of corn earworm infestation, and extent of corn earworm damage. Ears were artificially infested with corn earworm eggs suspended in an agar solution. The population was successfully selected for longer husk extension without shortening the ears, but the increase in husk extension did not correspond to an increase in corn earworm resistance. Further evaluation is needed to determine whether long husk extension is ineffective as a source of corn earworm resistance, whether it is more effective in combination with other resistance traits, whether greater differences in husk extension are needed to confer biologically significant differences in corn earworm resistance, or whether improved inoculation methods could improve differentiation between genotypes.

scholarly journals CONTROL OF CORN EARWORM AND EUROPEAN CORN BORER ON SWEET CORN, 1998

1999 ◽  
Vol 24 (1) ◽  
Author(s):  
P. K. O'Rourke ◽  
E. C. Burkness ◽  
W. D. Hutchison
Keyword(s):  
European Corn Borer ◽  
Sweet Corn ◽  
Corn Earworm ◽  
Corn Borer

scholarly journals Evaluation of Efficacy of Selected Conventional and Experimental Insecticides and Bt Hybrids for Control of Corn Earworm and European Corn Borer on Sweet Corn, 1997

1998 ◽  
Vol 23 (1) ◽  
pp. 99-100
Author(s):  
J. T. Shaw ◽  
R. Weinzierl ◽  
J. W. Finger
Keyword(s):  
European Corn Borer ◽  
Sweet Corn ◽  
Corn Earworm ◽  
Compressed Air ◽  
Hollow Cone ◽  
Corn Hybrids ◽  
Corn Borer ◽  
Chemical Treatments ◽  
Untreated Check ◽  
High Clearance

Abstract The tests were arranged in a RCB design with four replications. Each plot consisted of four rows, each being 30 inches wide and 50 ft long. Thirty-foot-wide alleys were established between the four replications. Insecticides were applied to the middle two rows of each plot, leaving two untreated rows between adjoining plots. Twelve insecticide treatments were compared with two Br-sweet corn hybrids (Heritage Bt and Bonus Bt) and their non-Bt isolines to two untreated controls. The 12 chemical treatments and the two untreated checks were planted with the Silver King variety sweet corn. Two untreated check plots were included in each replication and were averaged for the ANOVA. Treatments were applied very four to five days beginning on 8 Aug at 8% silk. All insecticide treatments were applied with a modified John Deere 6000 high-clearance vehicle (HCV) with a rear-mounted boom. Six Conejet (TX VS-8) hollow-cone nozzles (three per row) were calibrated to deliver 30.1 gpa at 40 psi and a speed of 2.5 mph, utilizing a compressed air system. Four nozzles (two per row) were attached to drops and directed the spray towards the ear zone area, a third nozzle (one per row) was mounted directly over the row with the spray being directed into the whorl (tassel) area.

Mortality of Two Lepidopterans in Response to Selected Commercial Formulations of Bacillus thuringiensis Berliner2

1999 ◽  
Vol 34 (3) ◽  
pp. 273-285
Author(s):  
Richard L. Ridgway ◽  
Robert R. Farrar
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
European Corn Borer ◽  
Uv Light ◽  
Field Studies ◽  
Corn Earworm ◽  
The Other ◽  
Speed Of Kill ◽  
Matrix Formulation ◽  
Corn Borer

Five commercial granular formulations of Bacillus thuringiensis Berliner marketed for controlling the European corn borer, Ostrinia nubilalis (Hübner), were compared for insecticidal activity using treated discs of bean leaves. Three formulations, Dipel 10G®, Full-Bac ECBG™, and Strike BT®, were similar in terms of both mortality and speed of kill. A formulation containing a strain of B. thuringiensis developed by plasmid fusion, Condor G®, caused mortality similar to the other three formulations, but the speed of kill was slower. A fifth formulation containing a B. thuringiensis toxin produced by Pseudomonas fluorescens Migula as result of a gene transfer, M-Peril™, caused substantially less mortality than any of the other formulations. An experimental water dispersible formulation, based on a previously developed granular matrix formulation containing B. thuringiensis and a nutrient-based phagostimulant, caused significantly higher mortality of the European corn borer than a similar formulation without the phagostimulant. Simulated field studies were conducted to study the effects of the phagostimulant on feeding and protection of B. thuringiensis from ultraviolet (UV) light. Bean plants treated with B. thuringiensis and the phagostimulant were exposed to different UV regimes outdoors under canopies made of specialized acrylic plastics and then infested with larvae of the corn earworm, Helicoverpa zea (Boddie). A significant interaction between the UV regimes and the phagostimulant was found, indicating that the phagostimulant acted both as a feeding stimulant and as a UV protectant to enhance the activity of B. thuringiensis.

scholarly journals The nucleopolyhedroviruses of Rachiplusia ou and Anagrapha falcifera are isolates of the same virus

1999 ◽  
Vol 80 (10) ◽  
pp. 2793-2798 ◽  
Author(s):  
Robert L. Harrison ◽  
Bryony C. Bonning
Keyword(s):  
Heliothis Virescens ◽  
Helicoverpa Zea ◽  
European Corn Borer ◽  
Biological Activities ◽  
Corn Earworm ◽  
Tobacco Budworm ◽  
Predicted Amino Acid Sequence ◽  
Corn Borer ◽  
Anagrapha Falcifera ◽  
Relationship Of

The 7·8 kb EcoRI-G fragment of Rachiplusia ou multicapsid nucleopolyhedrovirus (RoMNPV), containing the polyhedrin gene, was cloned and sequenced. The sequence of the fragment was 92·3% identical to the sequence of the corresponding region in the Autographa californica (Ac)MNPV genome. A comparison of the EcoRI-G sequence with other MNPV sequences revealed that RoMNPV was most closely related to AcMNPV. However, the predicted amino acid sequence of RoMNPV polyhedrin shared more sequence identity with the polyhedrin of Orygia pseudotsugata MNPV. In addition, the RoMNPV sequence was almost completely identical (99·9%) to a previously published 6·3 kb sequence of Anagrapha falcifera MNPV (AfMNPV). The Eco RI and HindIII restriction fragment profiles of RoMNPV and AfMNPV also were nearly identical, with an additional EcoRI band detected in RoMNPV DNA. Bioassays of these viruses with three different hosts (the European corn borer, Ostrinia nubilalis H übner, the corn earworm, Helicoverpa zea Boddie, and the tobacco budworm, Heliothis virescens Fabricius) failed to detect any differences in the biological activities of RoMNPV and AfMNPV. These results indicate that RoMNPV and AfMNPV are different isolates of the same virus. The taxonomic relationship of Ro/AfMNPV and AcMNPV is discussed.

scholarly journals ACTION SPECTRUM OF Baculovirus spodoptera ON LEPIDOPTERA PESTS

2017 ◽  
Vol 16 (1) ◽  
pp. 52
Author(s):  
CAMILA DA SILVA FERNANDES SOUZA ◽  
FERNANDO HERCOS VALICENTE ◽  
MARCOS ANTÔNIO MATIELLO FADINI ◽  
RICARDO ANTÔNIO POLANCZYK
Keyword(s):  
Spodoptera Frugiperda ◽  
Sugar Cane ◽  
Helicoverpa Zea ◽  
First Generation ◽  
Action Spectrum ◽  
Fall Armyworm ◽  
Corn Earworm ◽  
Corn Borer ◽  
Egg Masses ◽  
Diatraea Saccharalis

ABSTRACT - This work evaluated the spectrum of action of Baculovirus spodoptera (SfMNVP) - 6NR on the fall armyworm Spodoptera frugiperda, corn earworm Helicoverpa zea and the sugar cane borer Diatraea saccharalis, species of economic importance in maize. For the bioassays, corn leaves immersed in a baculovirus suspension were used for baculovirus inoculation in fall armyworm and earworm and pieces of sugar cane for the corn borer. The foods were immersed in viral solutions of different baculovirus concentrations determined in a Neubauer chamber. The control only distilled water was used instead of the baculovirus suspension. The larvae fed for 48 hours and were then transferred to an artificial diet, without the baculovirus. After evaluating mortality, the development of the offspring (F1) was accompanied, evaluating the parameters: mortality, pupation and the number of egg masses in the first generation. The baculovirus was specific to fall armyworm and innocuous to earworm and the corn borer in the first generation. In the second generation, baculovirus was innocuous for all three species. The percentage of pupation showed an inverse relation with mortality for the three species in two generations. The number of egg masses in F1 was lower in S. frugiperda, did not change for D. saccharalis and higher in H. zea.Keywords: Helicoverpa zea, Spodoptera frugiperda, Diatraea saccharalis, entomopathogenie virus.ESPECTRO DE AÇÃO DE Baculovirus spodoptera A LEPIDÓPTEROS PRAGARESUMO - Neste trabalho foi avaliado o espectro de ação do Baculovirus spodoptera (SfMNVP) - 6NR à lagarta-do-cartucho Spodoptera frugiperda, à lagarta-da-espiga Helicoverpa zea e à broca-da-milho Diatraea saccharalis, espécies de importância econômica na cultura do milho. Para a realização dos bioensaios foram utilizadas folhas de milho imersas em suspensão com o baculovírus em concentrações determinadas em câmara de Neubauer, para lagarta-do-cartucho e para lagarta-da-espiga. Para broca-do-milho o substrato utilizado foi colmo de cana-de-açúcar. Na testemunha foi utilizada somente água destilada ao invés da suspensão com o baculovírus. As lagartas se alimentaram por 48 horas, após este período, foram transferidas para dieta artificial sem o bacilovírus. Após a avaliação da mortalidade,odesenvolvimento da prole (F1) foi acompanhado sendo avaliados os parâmetros: mortalidade, pupação e o número de massas de ovos na primeira geração. O baculovírus foi especifico para lagarta-do-cartucho e inócuo tanto para lagarta-da-espiga quanto para broca-do-milho na primeira geração. Na segunda geração, o baculovírus foi inócuo para as três espécies. A porcentagem de pupação apresentou relação inversa com a mortalidade para as três espécies nas duas gerações. O número de massas de ovos na F1 foi menor em S. frugiperda, não alterado para D. saccharalis e maior em H. zea.Palavras-chave: Helicoverpa zea, Spodoptera frugiperda, Diatraea saccharalis, vírus entomopatogênico.

scholarly journals Control of European Corn Borer and Corn Earworm on Sweet Corn, 1997

1998 ◽  
Vol 23 (1) ◽  
pp. 94-94
Author(s):  
E. C. Burkness ◽  
P. K. O'Rourke ◽  
W. D. Hutchison
Keyword(s):  
European Corn Borer ◽  
Sweet Corn ◽  
Corn Earworm ◽  
Corn Borer
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