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EVALUATION OF INSECTICIDES FOR CONTROL OF CORN INSECT PESTS IN SWEET CORN, 2003

EVALUATION OF INSECTICIDES FOR CONTROL OF CORN INSECT PESTS IN SWEET CORN, 2003 (E34) CORN (SWEET): Zea mays L., ‘GSS 5771’ EVALUATION OF INSECTICIDES FOR CONTROL OF CORN INSECT PESTS IN SWEET CORN, 2003 Gregg S. Nuessly Everglades Research and Education Center, UF/IFAS 3200 E. Palm Beach Rd. Belle Glade, FL 33430-8003 Phone: (561) 993-1500 Fax: (561) 993-1582 E-mail: gsn@ifas.ufl.edu Matthew G. Hentz Fall armyworm (FAW): Spodoptera frugiperda (J.E. Smith) Corn earworm (CEW): Helicoverpa zea (Boddie) Euxesta stigmatias Loew FAW is a serious pest of sweet corn in Florida that normally requires intensive management with insecticides during vegetative and reproductive stages to produce a marketable crop. CEW typically attacks the ears later in the season and frequently requires insecticide treatments in the spring months throughout the state. Euxesta stigmatias larvae attack the corn silk, ears and cob rendering the ears unmarketable. The purpose of this trial was to compare two newer insecticides against standard insecticides for control of the above pests. The trial was conducted at the Everglades Research and Education Center, Belle Glade, FL in a Lauderhill organic soil (i.e., euic, hyperthermic Lithic Medisaprists). Yellow sweet corn seeds (Novartis Seeds ‘GSS 5771’) were planted 20 Aug 2003, 9 inches apart on 30-inch centers using a John Deere Max Merge planter. The study was arranged in a RCB design with four replicates. Plots were 30 ft long, six rows wide, and separated by 5 ft planted, untreated buffers. Blocks were separated on all sides by 15 ft of unplanted buffers. Treatments for naturally occurring FAW were begun once infestation levels reached above a 20% threshold level. Insecticides were applied on 10, 17, 24 Sep, and 1, 8, 14 and 17 Oct using a compressed air spray system mounted on a high clearance spider spray track tractor at 40 psi (nozzle pressure) using 8005 EVS TeeJet nozzles at 15-inch centers across the six-row boom. Insecticides were applied in spray volumes of 30 gpa on the first four dates and 55 gpa on the last three dates. Induce spray adjuvant was added at 0.25% v/v to all treatments, including the water check. Pretreatment (8 Sep) and post treatment samples to evaluate the treatments consisted of examining 10 randomly selected plants in each of the center three rows in each plot (30 plants per treatment replicate) for live FAW larvae. Thirty ears per treatment plot were harvested on 20 Oct and examined for FAW, CEW and E. stigmatias damage. Data were subjected to ANOVA and means were separated using LSD (P ≤ 0.05). Pre-treatment FAW infestation levels were average for this time of year and surpassed the threshold within several weeks after planting. Mean whorl infestation varied from 34 to 52% before the first treatment date (Table 1). All treatments resulted in a reduction of infested plants following the initial treatment. A significant rate response was observed for Diamond and Warrior at all sample dates following treatment initiation. The low rate of Warrior required a second treatment to reduce armyworm infestation below the 20% threshold, whereas the low rate of Diamond required a third treatment to reach this level. The high rates of Diamond and Warrior outperformed Lannate and were equivalent with Avaunt after the second application. Movement of late instar FAW among plants as tassels began to emerge on 1 Oct resulted in higher percentage whorl infestations on 7 Oct in treatment plots previously exhibiting high levels of suppression (i.e., Diamond at 12 fl oz product/acre and Warrior at 3.6 fl oz product/acre) and lower levels in the highly damaged water check plots. This affect carried over into the ears with higher levels of Lepidoptera damage than expected in the plots treated with high rates relative to the low rates of Diamond and Warrior (Table 2). FAW population pressure remained average to above average during the plant reproductive phase. Pressure by both the otitid E. stigmatias and CEW were unseasonably high for the Belle Glade area of southern Florida during October 2003. Avaunt, Diamond, Lannate and Warrior reduced ear damage by Lepidoptera and E. stigmatias compared with the water check, but the rates and frequencies of application were not adequate to prevent unacceptable levels of damage by these insects to this sensitive crop. Table 1. Percentage infested plants Treatment/ Rate amt formulation product/acre 8 Sep 16 Sep 23 Sep 7 Oct Avaunt 30WG 3.5 oz 34.2a 17.5c 21.7c 7.5bc Diamond 0.83EC 9 fl oz 50.0a 35.8b 49.2b 18.3ab Diamond 0.83EC 12 fl oz 35.0a 7.5c 9.2d 1.7c Lannate 2.4LV 18 fl oz 38.3a 17.5c 30.8c 10.0abc Warrior T 1E 3.2 fl oz 52.5a 35.0b 32.5c 19.2a Warrior T 1E 3.8 fl oz 48.3a 10.0c 12.5d 2.5c Water check -- 42.5a 81.7a 80.8a 10.8abc Means followed by the same letters in a column are not significantly different (P > 0.05, LSD). Table 2. Treatment/ Rate amt Lepidoptera E. stigmatias a b formulation product/acre damage rating FAW/ear CEW/ear damage rating Avaunt 30WG 3.5 oz 1.33c 0.11cd 0.08c 2.9b Diamond 0.83EC 9 fl oz 1.41c 0.34a 0.04c 2.3c Diamond 0.83EC 12 fl oz 1.96b 0.02d 0.28a 2.8b Lannate 2.4LV 18 fl oz 1.43c 0.26ab 0.08c 2.9b Warrior (T) 1E 3.2 fl oz 1.35c 0.16bc 0.01c 2.2c Warrior (T) 1E 3.8 fl oz 1.42c 0.08cd 0.18b 2.8b Water check -- 2.62a 0.28ab 0.18b 3.3a Means followed by the same letters in a column are not significantly different (P > 0.05, LSD). Lepidoptera damage: 1, silk damage: 2, husk damage: and 3, silk or husk plus kernel damage. E. stigmatias damage: 1, silk damage; 2, silk plus < top 25% of ear with kernels damaged; 3, silk plus < top 50% of ear with kernels damaged; 4, silk plus >50% of ear with kernels damaged. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

EVALUATION OF INSECTICIDES FOR CONTROL OF CORN INSECT PESTS IN SWEET CORN, 2003

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10.1093/amt/30.1.E34
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Abstract

(E34) CORN (SWEET): Zea mays L., ‘GSS 5771’ EVALUATION OF INSECTICIDES FOR CONTROL OF CORN INSECT PESTS IN SWEET CORN, 2003 Gregg S. Nuessly Everglades Research and Education Center, UF/IFAS 3200 E. Palm Beach Rd. Belle Glade, FL 33430-8003 Phone: (561) 993-1500 Fax: (561) 993-1582 E-mail: gsn@ifas.ufl.edu Matthew G. Hentz Fall armyworm (FAW): Spodoptera frugiperda (J.E. Smith) Corn earworm (CEW): Helicoverpa zea (Boddie) Euxesta stigmatias Loew FAW is a serious pest of sweet corn in Florida that normally requires intensive management with insecticides during vegetative and reproductive stages to produce a marketable crop. CEW typically attacks the ears later in the season and frequently requires insecticide treatments in the spring months throughout the state. Euxesta stigmatias larvae attack the corn silk, ears and cob rendering the ears unmarketable. The purpose of this trial was to compare two newer insecticides against standard insecticides for control of the above pests. The trial was conducted at the Everglades Research and Education Center, Belle Glade, FL in a Lauderhill organic soil (i.e., euic, hyperthermic Lithic Medisaprists). Yellow sweet corn seeds (Novartis Seeds ‘GSS 5771’) were planted 20 Aug 2003, 9 inches apart on 30-inch centers using a John Deere Max Merge planter. The study was arranged in a RCB design with four replicates. Plots were 30 ft long, six rows wide, and separated by 5 ft planted, untreated buffers. Blocks were separated on all sides by 15 ft of unplanted buffers. Treatments for naturally occurring FAW were begun once infestation levels reached above a 20% threshold level. Insecticides were applied on 10, 17, 24 Sep, and 1, 8, 14 and 17 Oct using a compressed air spray system mounted on a high clearance spider spray track tractor at 40 psi (nozzle pressure) using 8005 EVS TeeJet nozzles at 15-inch centers across the six-row boom. Insecticides were applied in spray volumes of 30 gpa on the first four dates and 55 gpa on the last three dates. Induce spray adjuvant was added at 0.25% v/v to all treatments, including the water check. Pretreatment (8 Sep) and post treatment samples to evaluate the treatments consisted of examining 10 randomly selected plants in each of the center three rows in each plot (30 plants per treatment replicate) for live FAW larvae. Thirty ears per treatment plot were harvested on 20 Oct and examined for FAW, CEW and E. stigmatias damage. Data were subjected to ANOVA and means were separated using LSD (P ≤ 0.05). Pre-treatment FAW infestation levels were average for this time of year and surpassed the threshold within several weeks after planting. Mean whorl infestation varied from 34 to 52% before the first treatment date (Table 1). All treatments resulted in a reduction of infested plants following the initial treatment. A significant rate response was observed for Diamond and Warrior at all sample dates following treatment initiation. The low rate of Warrior required a second treatment to reduce armyworm infestation below the 20% threshold, whereas the low rate of Diamond required a third treatment to reach this level. The high rates of Diamond and Warrior outperformed Lannate and were equivalent with Avaunt after the second application. Movement of late instar FAW among plants as tassels began to emerge on 1 Oct resulted in higher percentage whorl infestations on 7 Oct in treatment plots previously exhibiting high levels of suppression (i.e., Diamond at 12 fl oz product/acre and Warrior at 3.6 fl oz product/acre) and lower levels in the highly damaged water check plots. This affect carried over into the ears with higher levels of Lepidoptera damage than expected in the plots treated with high rates relative to the low rates of Diamond and Warrior (Table 2). FAW population pressure remained average to above average during the plant reproductive phase. Pressure by both the otitid E. stigmatias and CEW were unseasonably high for the Belle Glade area of southern Florida during October 2003. Avaunt, Diamond, Lannate and Warrior reduced ear damage by Lepidoptera and E. stigmatias compared with the water check, but the rates and frequencies of application were not adequate to prevent unacceptable levels of damage by these insects to this sensitive crop. Table 1. Percentage infested plants Treatment/ Rate amt formulation product/acre 8 Sep 16 Sep 23 Sep 7 Oct Avaunt 30WG 3.5 oz 34.2a 17.5c 21.7c 7.5bc Diamond 0.83EC 9 fl oz 50.0a 35.8b 49.2b 18.3ab Diamond 0.83EC 12 fl oz 35.0a 7.5c 9.2d 1.7c Lannate 2.4LV 18 fl oz 38.3a 17.5c 30.8c 10.0abc Warrior T 1E 3.2 fl oz 52.5a 35.0b 32.5c 19.2a Warrior T 1E 3.8 fl oz 48.3a 10.0c 12.5d 2.5c Water check -- 42.5a 81.7a 80.8a 10.8abc Means followed by the same letters in a column are not significantly different (P > 0.05, LSD). Table 2. Treatment/ Rate amt Lepidoptera E. stigmatias a b formulation product/acre damage rating FAW/ear CEW/ear damage rating Avaunt 30WG 3.5 oz 1.33c 0.11cd 0.08c 2.9b Diamond 0.83EC 9 fl oz 1.41c 0.34a 0.04c 2.3c Diamond 0.83EC 12 fl oz 1.96b 0.02d 0.28a 2.8b Lannate 2.4LV 18 fl oz 1.43c 0.26ab 0.08c 2.9b Warrior (T) 1E 3.2 fl oz 1.35c 0.16bc 0.01c 2.2c Warrior (T) 1E 3.8 fl oz 1.42c 0.08cd 0.18b 2.8b Water check -- 2.62a 0.28ab 0.18b 3.3a Means followed by the same letters in a column are not significantly different (P > 0.05, LSD). Lepidoptera damage: 1, silk damage: 2, husk damage: and 3, silk or husk plus kernel damage. E. stigmatias damage: 1, silk damage; 2, silk plus < top 25% of ear with kernels damaged; 3, silk plus < top 50% of ear with kernels damaged; 4, silk plus >50% of ear with kernels damaged.

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Arthropod Management TestsOxford University Press

Published: Jan 1, 2005

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