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INSECTICIDE EFFICACY AGAINST GRASSHOPPER NYMPHS ON SUNFLOWER, 2004

INSECTICIDE EFFICACY AGAINST GRASSHOPPER NYMPHS ON SUNFLOWER, 2004 (F82) SUNFLOWER: Helianthus annuus L. Janet Knodel North Dakota State University North Central Research and Extension Center 5400 Highway 83 S. Minot, ND 58701 Phone: (701) 857-7682 Fax: (701) 857-7676 E-mail: jknodel@ndsuext.nodak.edu Lorilie Atkinson E-mail: latkinso@ndsuext.nodak.edu Twostriped grasshopper: Melanoplus bivittatus (Say) Migratory grasshopper: Melanoplus sanguinipes (Fabricius) Registered and experimental insecticides were evaluated for their efficacy at controlling nymph stage grasshoppers and protecting sunflowers. A field in north central North Dakota near Souris, ND had pretreatment counts of >2 nymphs (1-4 instars) grasshoppers/yd with the majority being twostriped grasshoppers. Plots were 10 ft wide by 30 ft long. A RCB experimental design with three replicates was used. Insecticides were applied at V2 crop stage on 19 Jun using a handheld CO boom sprayer at 40 psi, 10 gpa and fitted with XR 8001VS nozzles. Ten plants were assessed per plot for the percent defoliation at 3, 7, 14, 21, and 28 DAT. Variables were subjected to ANOVA and means compared using Fisher’s PLSD (P ≤ 0.05). At 3 DAT, there were no significant differences among treatments; probably due to the generally low grasshopper populations. Most of the insecticide treatments had significantly lower percent defoliation than the untreated check at 7 and 14 DAT; except for Furadan at 7 and 14 DAT, and Dimilin (1.0 and 2.0 fl oz/acre) at 7 DAT and Dimilin (1.0 fl oz/a) at 14 DAT. At 21 and 28 DAT, the defoliation increased slightly as grasshoppers continued to move into plots to feed and as insecticide residue diminished. As a result, none of the insecticide treatments was significantly different from the untreated check at 21 and 28 DAT indicating reduced control and/or residual activity. Results indicate that most of the insecticides tested were able to reduce grasshopper numbers and protect sunflowers up to14 DAT. % defoliation Treatment/ Rate 3 DAT 7 DAT 14 DAT 21 DAT 28 DAT formulation fl oz/acre V2 V4 V8 V12 V16 Untreated check --- 8.0a 7.9a 6.8a 8.2a 8.9ab Furadan 4EC 16.0 3.3a 3.9ab 7.5a 8.7a 10.0ab Mustang Max 0.8EC 2.8 5.0a 2.5b 3.3b 5.4a 11.5a Mustang Max 0.8EC 4.0 5.6a 1.8b 3.7b 6.0a 10.1ab Baythroid 2EC 2.8 5.2a 2.0b 3.0b 6.6a 9.3ab Asana XL 0.66EC 9.6 4.5a 1.3b 1.4b 5.2a 9.6ab Warrior T 1EC 3.84 4.7a 1.5b 3.1b 6.8a 9.5ab Danitol 2.4EC 10.67 3.5a 1.9b 2.4b 6.3a 9.8ab Dimilin 2L 1.0 5.8a 4.1ab 7.9a 5.7a 7.2b + Prime Oil 16.0 Dimilin 2L 2.0 6.0a 4.1ab 3.9b 5.5a 7.5b + Prime Oil 16.0 Means within a column followed by the same letter are not significantly different (Fisher’s PLSD; P > 0.05). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

INSECTICIDE EFFICACY AGAINST GRASSHOPPER NYMPHS ON SUNFLOWER, 2004

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Abstract

(F82) SUNFLOWER: Helianthus annuus L. Janet Knodel North Dakota State University North Central Research and Extension Center 5400 Highway 83 S. Minot, ND 58701 Phone: (701) 857-7682 Fax: (701) 857-7676 E-mail: jknodel@ndsuext.nodak.edu Lorilie Atkinson E-mail: latkinso@ndsuext.nodak.edu Twostriped grasshopper: Melanoplus bivittatus (Say) Migratory grasshopper: Melanoplus sanguinipes (Fabricius) Registered and experimental insecticides were evaluated for their efficacy at controlling nymph stage grasshoppers and protecting sunflowers. A field in north central North Dakota near Souris, ND had pretreatment counts of >2 nymphs (1-4 instars) grasshoppers/yd with the majority being twostriped grasshoppers. Plots were 10 ft wide by 30 ft long. A RCB experimental design with three replicates was used. Insecticides were applied at V2 crop stage on 19 Jun using a handheld CO boom sprayer at 40 psi, 10 gpa and fitted with XR 8001VS nozzles. Ten plants were assessed per plot for the percent defoliation at 3, 7, 14, 21, and 28 DAT. Variables were subjected to ANOVA and means compared using Fisher’s PLSD (P ≤ 0.05). At 3 DAT, there were no significant differences among treatments; probably due to the generally low grasshopper populations. Most of the insecticide treatments had significantly lower percent defoliation than the untreated check at 7 and 14 DAT; except for Furadan at 7 and 14 DAT, and Dimilin (1.0 and 2.0 fl oz/acre) at 7 DAT and Dimilin (1.0 fl oz/a) at 14 DAT. At 21 and 28 DAT, the defoliation increased slightly as grasshoppers continued to move into plots to feed and as insecticide residue diminished. As a result, none of the insecticide treatments was significantly different from the untreated check at 21 and 28 DAT indicating reduced control and/or residual activity. Results indicate that most of the insecticides tested were able to reduce grasshopper numbers and protect sunflowers up to14 DAT. % defoliation Treatment/ Rate 3 DAT 7 DAT 14 DAT 21 DAT 28 DAT formulation fl oz/acre V2 V4 V8 V12 V16 Untreated check --- 8.0a 7.9a 6.8a 8.2a 8.9ab Furadan 4EC 16.0 3.3a 3.9ab 7.5a 8.7a 10.0ab Mustang Max 0.8EC 2.8 5.0a 2.5b 3.3b 5.4a 11.5a Mustang Max 0.8EC 4.0 5.6a 1.8b 3.7b 6.0a 10.1ab Baythroid 2EC 2.8 5.2a 2.0b 3.0b 6.6a 9.3ab Asana XL 0.66EC 9.6 4.5a 1.3b 1.4b 5.2a 9.6ab Warrior T 1EC 3.84 4.7a 1.5b 3.1b 6.8a 9.5ab Danitol 2.4EC 10.67 3.5a 1.9b 2.4b 6.3a 9.8ab Dimilin 2L 1.0 5.8a 4.1ab 7.9a 5.7a 7.2b + Prime Oil 16.0 Dimilin 2L 2.0 6.0a 4.1ab 3.9b 5.5a 7.5b + Prime Oil 16.0 Means within a column followed by the same letter are not significantly different (Fisher’s PLSD; P > 0.05).

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Arthropod Management Tests – Oxford University Press

Published: Jan 1, 2005

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