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SMALL PLOT ASSESSMENT OF INSECTICIDES AGAINST THE ALFALFA WEEVIL AND PEA APHID, 2006

SMALL PLOT ASSESSMENT OF INSECTICIDES AGAINST THE ALFALFA WEEVIL AND PEA APHID, 2006 (F71) ALFALFA: Medicago sativa (Hybrid) J. R. Whitworth Department of Entomology Kansas State University 123 Waters Hall Manhattan, KS 66506 Phone: (785) 532-5656 Fax: (785) 532-6232 E-mail: jwhitwor@ksu.edu A. Ahmad P. E. Sloderbeck Alfalfa weevil: Hypera postica (Gyllenhal) Pea aphid: Macrosiphum pisi (Kltb.) Nine different insecticide treatments were assessed for control of the alfalfa weevil (AW) larvae and pea aphids. Plots were arranged as a RCB design with 9 treatments and untreated check replicated four times in a field of alfalfa located on a farm in Saline Co., KS. Pre-treatment counts of both insects were made on 13 April 2006. Insecticide treatments were applied on 14 April to a plot size of 15 ft x 20 ft using a Solo back pack sprayer delivering 20 gpa at 30 psi. A bucket-shake method was used to count AW larvae and pea aphids from 40 randomly selected stems (18 April, 21 April) and 10 randomly selected stems (28 April, 5 May) from the center of each plot. The stems were gently cut at ground level and all AW larvae and pea aphids shaken off the stems into a 1 gal. bucket. Then the stems were removed from the bucket carefully and the number of AW larvae and pea aphids counted in the bucket. Data were analyzed using analysis of variance (ANOVA) and means were compared with the LSMEANS procedure (P = 0.05) of PROC GLM (SAS Institute 2003). Differences were not detected among pre-treatment counts for both insects. All treatments had significantly reduced numbers of AW larvae than the untreated check on 4, 7, 14, and 21 DAT. Overall, populations declined after first two evaluations. All treatments had significantly reduced numbers of pea aphid than the untreated check on all sampling dates. Table 1. AW larvae/40 stems AW larvae/10 stems Treatment/ Rate formulation amt prod/acre 4 DAT 7 DAT 14 DAT 21 DAT Untreated control 38.3 ± 2.7a 48.0 ± 2.3a 10.5 ± 1.3a 2.8 ± 0.5a Warrior 1CS 2.56 fl. oz. 1.3 ± 0.6c 3.8 ± 1.2b 0.0 ± 0.0b 0.5 ± 0.5b Warrior 1CS 3.20 fl. oz 0.8 ± 0.5c 5.3 ± 1.4b 0.3 ± 0.3b 0.3 ± 0.3b Warrior 1CS 3.84 fl. oz 0.5 ± 0.3c 5.5 ± 2.3b 0.3 ± 0.3b 0.5 ± 0.3b Lorsban 4E 1.5 pt. 2.3 ± 1.3bc 2.8 ± 0.3b 0.0 ± 0.0b 0.0 ± 0.0b Baythroid XL 2.0 fl. oz 2.5 ± 0.5bc 3.0 ± 1.1b 0.8 ± 0.3b 0.3 ± 0.3b Baythroid XL 2.8 fl. oz 2.5 ± 0.5bc 4.5 ± 0.5b 0.3 ± 0.3b 0.0 ± 0.0b Baythroid XL 2.0 fl. oz + Lorsban 480EC + 8.0 fl. oz 1.5 ± 0.3bc 5.0 ± 1.2b 1.0 ± 0.7b 0.5 ± 0.3b Mustang Max 3.0 fl. oz 2.8 ± 0.5bc 4.0 ± 0.0b 1.3 ± 0.6b 0.5 ± 0.5b Mustang Max 4.0 fl. oz 4.3 ± 0.5bc 2.6 ± 1.3b 1.3 ± 0.6b 0.3 ± 0.3b P < 0.0001 < 0.0001 < 0.0001 < 0.0001 Means within a column followed by the same letter are not significantly different (P > 0.05; PROC GLM; LSMEANS) Table 2. Pea aphid/40 stems Pea aphid/10 stems Treatment/ Rate formulation amt prod/acre 4 DAT 7 DAT 14 DAT 21 DAT Untreated control 115.0 ± 9.8a 84.0 ± 12.5a 161.8 ± 7.4a 162.0 ± 5.1a Warrior 1CS 2.56 fl. oz. 16.3 ± 3.4b 13.3 ± 1.1b 20.5 ± 1.3b 40.0 ± 5.5b Warrior 1CS 3.20 fl. oz 18.8 ± 3.5b 16.3 ± 1.4b 19.8 ± 3.8b 50.5 ± 2.8b Warrior 1CS 3.84 fl. oz 16.5 ± 1.5b 14.8 ± 1.9b 22.5 ± 0.96b 45.5 ± 3.6b Lorsban 4E 1.5 pt. 11.0 ± 3.2b 13.8 ± 1.3b 21.8 ± 1.3b 57.3 ± 2.3b Baythroid XL 2.0 fl. oz 15.0 ± 1.9b 16.0 ± 3.2b 18.0 ± 2.1b 50.5 ± 6.1b Baythroid XL 2.8 fl. oz 15.8 ± 2.5b 18.0 ± 2.7b 22.5 ± 1.0b 48.3 ± 4.6b Baythroid XL + Lorsban 480EC 2.0 fl. oz + 8.0 fl. oz 16.3 ± 2.6b 16.5 ± 2.3b 21.5 ± 2.6b 58.3 ± 4.6b Mustang Max 3.0 fl. oz 11.8 ± 1.1b 11.3 ± 3.3b 18.0 ± 2.7b 43.5 ± 2.7b Mustang Max 4.0 fl. oz 16.8 ± 0.9b 18.5 ± 2.5b 18.5 ± 1.0b 49.8 ± 9.4b P < 0.0001 < 0.0001 < 0.0001 < 0.0001 Means within a column followed by the same letter are not significantly different (P > 0.05; PROC GLM; LSMEANS) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

SMALL PLOT ASSESSMENT OF INSECTICIDES AGAINST THE ALFALFA WEEVIL AND PEA APHID, 2006

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Oxford University Press
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© Published by Oxford University Press.
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2155-9856
DOI
10.1093/amt/33.1.F71
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Abstract

(F71) ALFALFA: Medicago sativa (Hybrid) J. R. Whitworth Department of Entomology Kansas State University 123 Waters Hall Manhattan, KS 66506 Phone: (785) 532-5656 Fax: (785) 532-6232 E-mail: jwhitwor@ksu.edu A. Ahmad P. E. Sloderbeck Alfalfa weevil: Hypera postica (Gyllenhal) Pea aphid: Macrosiphum pisi (Kltb.) Nine different insecticide treatments were assessed for control of the alfalfa weevil (AW) larvae and pea aphids. Plots were arranged as a RCB design with 9 treatments and untreated check replicated four times in a field of alfalfa located on a farm in Saline Co., KS. Pre-treatment counts of both insects were made on 13 April 2006. Insecticide treatments were applied on 14 April to a plot size of 15 ft x 20 ft using a Solo back pack sprayer delivering 20 gpa at 30 psi. A bucket-shake method was used to count AW larvae and pea aphids from 40 randomly selected stems (18 April, 21 April) and 10 randomly selected stems (28 April, 5 May) from the center of each plot. The stems were gently cut at ground level and all AW larvae and pea aphids shaken off the stems into a 1 gal. bucket. Then the stems were removed from the bucket carefully and the number of AW larvae and pea aphids counted in the bucket. Data were analyzed using analysis of variance (ANOVA) and means were compared with the LSMEANS procedure (P = 0.05) of PROC GLM (SAS Institute 2003). Differences were not detected among pre-treatment counts for both insects. All treatments had significantly reduced numbers of AW larvae than the untreated check on 4, 7, 14, and 21 DAT. Overall, populations declined after first two evaluations. All treatments had significantly reduced numbers of pea aphid than the untreated check on all sampling dates. Table 1. AW larvae/40 stems AW larvae/10 stems Treatment/ Rate formulation amt prod/acre 4 DAT 7 DAT 14 DAT 21 DAT Untreated control 38.3 ± 2.7a 48.0 ± 2.3a 10.5 ± 1.3a 2.8 ± 0.5a Warrior 1CS 2.56 fl. oz. 1.3 ± 0.6c 3.8 ± 1.2b 0.0 ± 0.0b 0.5 ± 0.5b Warrior 1CS 3.20 fl. oz 0.8 ± 0.5c 5.3 ± 1.4b 0.3 ± 0.3b 0.3 ± 0.3b Warrior 1CS 3.84 fl. oz 0.5 ± 0.3c 5.5 ± 2.3b 0.3 ± 0.3b 0.5 ± 0.3b Lorsban 4E 1.5 pt. 2.3 ± 1.3bc 2.8 ± 0.3b 0.0 ± 0.0b 0.0 ± 0.0b Baythroid XL 2.0 fl. oz 2.5 ± 0.5bc 3.0 ± 1.1b 0.8 ± 0.3b 0.3 ± 0.3b Baythroid XL 2.8 fl. oz 2.5 ± 0.5bc 4.5 ± 0.5b 0.3 ± 0.3b 0.0 ± 0.0b Baythroid XL 2.0 fl. oz + Lorsban 480EC + 8.0 fl. oz 1.5 ± 0.3bc 5.0 ± 1.2b 1.0 ± 0.7b 0.5 ± 0.3b Mustang Max 3.0 fl. oz 2.8 ± 0.5bc 4.0 ± 0.0b 1.3 ± 0.6b 0.5 ± 0.5b Mustang Max 4.0 fl. oz 4.3 ± 0.5bc 2.6 ± 1.3b 1.3 ± 0.6b 0.3 ± 0.3b P < 0.0001 < 0.0001 < 0.0001 < 0.0001 Means within a column followed by the same letter are not significantly different (P > 0.05; PROC GLM; LSMEANS) Table 2. Pea aphid/40 stems Pea aphid/10 stems Treatment/ Rate formulation amt prod/acre 4 DAT 7 DAT 14 DAT 21 DAT Untreated control 115.0 ± 9.8a 84.0 ± 12.5a 161.8 ± 7.4a 162.0 ± 5.1a Warrior 1CS 2.56 fl. oz. 16.3 ± 3.4b 13.3 ± 1.1b 20.5 ± 1.3b 40.0 ± 5.5b Warrior 1CS 3.20 fl. oz 18.8 ± 3.5b 16.3 ± 1.4b 19.8 ± 3.8b 50.5 ± 2.8b Warrior 1CS 3.84 fl. oz 16.5 ± 1.5b 14.8 ± 1.9b 22.5 ± 0.96b 45.5 ± 3.6b Lorsban 4E 1.5 pt. 11.0 ± 3.2b 13.8 ± 1.3b 21.8 ± 1.3b 57.3 ± 2.3b Baythroid XL 2.0 fl. oz 15.0 ± 1.9b 16.0 ± 3.2b 18.0 ± 2.1b 50.5 ± 6.1b Baythroid XL 2.8 fl. oz 15.8 ± 2.5b 18.0 ± 2.7b 22.5 ± 1.0b 48.3 ± 4.6b Baythroid XL + Lorsban 480EC 2.0 fl. oz + 8.0 fl. oz 16.3 ± 2.6b 16.5 ± 2.3b 21.5 ± 2.6b 58.3 ± 4.6b Mustang Max 3.0 fl. oz 11.8 ± 1.1b 11.3 ± 3.3b 18.0 ± 2.7b 43.5 ± 2.7b Mustang Max 4.0 fl. oz 16.8 ± 0.9b 18.5 ± 2.5b 18.5 ± 1.0b 49.8 ± 9.4b P < 0.0001 < 0.0001 < 0.0001 < 0.0001 Means within a column followed by the same letter are not significantly different (P > 0.05; PROC GLM; LSMEANS)

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Arthropod Management Tests – Oxford University Press

Published: Jan 1, 2008

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