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Efficacy of Selected Insecticides Against Alfalfa Weevil and Pea Aphid in Alfalfa, 2021 Efficacy of Selected Insecticides Against Alfalfa Weevil and Pea Aphid in Alfalfa, 2021
Owens, David; Wilkerson, Dylan; Deidesheimer, Joseph
2022-01-01 00:00:00
Alfalfa | Medicago sativa Alfalfa Weevil | Hypera postica (Gyllenhal), Pea Aphid | Acyrthosiphon pisum Harris lambda-cyhalothrin, beta-cyfluthrin, dimethoate, indoxacarb, carbaryl Efficacy of selected insecticides on alfalfa weevil was evaluated at a cooperator field in Hebron, MD (Wicomico County). The cooperator had commented that he had inadequate pyrethroid efficacy the year before. Plots measured 9 ft wide by 25 ft long with 5 ft alleys between replicates. There were seven treatments arranged in an RCB with four replicates. Plots were treated with a CO2 pressurized backpack sprayer with a 9-ft boom equipped with six 11003 nozzles calibrated to deliver 19 gpa at 28 psi. Plots were treated on 9 Apr. One day prior to treatment and 3, 11, and 17 DAT, 15 alfalfa stems were removed from the base of the plants and examined in the lab for weevil larvae and for aphids. All data were subject to ANOVA and Tukey–Kramer HSD means separation. There were significant pretreatment weevil population differences, with Steward (high rate) having significantly more weevils than Warrior II- and Dimethoate-treated plots (Table 1). All treatments resulted in fewer weevils than the untreated check plot 3 and 11 DAT. However, weevil populations were not much reduced from pretreatment samples in Dimethoate-treated plots. Steward (low and high rates) resulted in the greatest reduction in weevil counts at 11 and 17 DAT. Carbaryl resulted in a significant reduction in weevil counts 3 DAT, but counts gradually increased at later sample dates. Pyrethroids resulted in moderate weevil reduction. Table 1. . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Table 1. . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Dimethoate resulted in the greatest and longest lived reduction in aphid counts (Table 2). Aphid counts in pyrethroid plots increased over pretreatment levels at 17 DAT. Carbaryl and Steward treatments did not appear to have any effect on aphids.1 Table 2. . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Table 2. . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Footnotes 1 This research was supported in part by industry gifts of product. © The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
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Arthropod Management Tests
Oxford University Press
http://www.deepdyve.com/lp/oxford-university-press/efficacy-of-selected-insecticides-against-alfalfa-weevil-and-pea-aphid-dBLGnnKwm7
Efficacy of Selected Insecticides Against Alfalfa Weevil and Pea Aphid in Alfalfa, 2021
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Publisher
Oxford University Press
Copyright
Copyright © 2023 Entomological Society of America eISSN
2155-9856 DOI
10.1093/amt/tsac040
Publisher site
See Article on Publisher Site
Abstract
Alfalfa | Medicago sativa Alfalfa Weevil | Hypera postica (Gyllenhal), Pea Aphid | Acyrthosiphon pisum Harris lambda-cyhalothrin, beta-cyfluthrin, dimethoate, indoxacarb, carbaryl Efficacy of selected insecticides on alfalfa weevil was evaluated at a cooperator field in Hebron, MD (Wicomico County). The cooperator had commented that he had inadequate pyrethroid efficacy the year before. Plots measured 9 ft wide by 25 ft long with 5 ft alleys between replicates. There were seven treatments arranged in an RCB with four replicates. Plots were treated with a CO2 pressurized backpack sprayer with a 9-ft boom equipped with six 11003 nozzles calibrated to deliver 19 gpa at 28 psi. Plots were treated on 9 Apr. One day prior to treatment and 3, 11, and 17 DAT, 15 alfalfa stems were removed from the base of the plants and examined in the lab for weevil larvae and for aphids. All data were subject to ANOVA and Tukey–Kramer HSD means separation. There were significant pretreatment weevil population differences, with Steward (high rate) having significantly more weevils than Warrior II- and Dimethoate-treated plots (Table 1). All treatments resulted in fewer weevils than the untreated check plot 3 and 11 DAT. However, weevil populations were not much reduced from pretreatment samples in Dimethoate-treated plots. Steward (low and high rates) resulted in the greatest reduction in weevil counts at 11 and 17 DAT. Carbaryl resulted in a significant reduction in weevil counts 3 DAT, but counts gradually increased at later sample dates. Pyrethroids resulted in moderate weevil reduction. Table 1. . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Table 1. . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 . . Alfalfa weevil larvae per 15 stems . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 14.3ab 20.0a 21.8a 12.3a Warrior II 1.6 11.3b 7.3b 4.5bc 3.3ab Baythroid XL 2.2 18.0ab 9.3b 8.3bc 7.3ab Dimethoate 4EC 12.0 10.8b 7.8b 11.3b 9.8ab Steward EC 6.7 14.8ab 6.0b 1.5c 2.0b Steward EC 11.3 24.3a 4.5b 2.5c 2.0b Carbaryl 4L 24.0 20.5ab 6.3b 8.3bc 11.0ab P > F 0.01 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Dimethoate resulted in the greatest and longest lived reduction in aphid counts (Table 2). Aphid counts in pyrethroid plots increased over pretreatment levels at 17 DAT. Carbaryl and Steward treatments did not appear to have any effect on aphids.1 Table 2. . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Table 2. . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 . . Aphids per 15 stem sample . . . . Treatment/form.a . Rate/acre (fl oz form.) . 1 d PRE . 3 DAT . 11 DAT . 17 DAT . UTC — 7.5 6.3ab 27.0a 21.5b Warrior II 1.6 7.0 4.3b 6.0b 10.5b Baythroid XL 2.2 5.0 7.0ab 12.3ab 18.3b Dimethoate 4E 12.0 8.5 0.5b 4.0b 6.0b Steward EC 6.7 5.5 5.5ab 18.5ab 20.3b Carbaryl 4L 24.0 8.5 8.0ab 11.3ab 31.0ab Steward 11.3 7.7 12.5a 17.5ab 55.8a P > F 0.84 <0.01 <0.01 <0.01 Means within columns followed by a common letter are not significantly different (P < 0.05, Tukey–Kramer HSD). aMakaze (glyphosate) was added to all foliar treatments at a rate of 64 fl oz per acre. Open in new tab Footnotes 1 This research was supported in part by industry gifts of product. © The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
Journal
Arthropod Management Tests
– Oxford University Press
Published: Jan 1, 2022
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