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Beet armyworm (BAW), Spodoptera exigua (Hübner)
Alfalfa caterpillar (AC), Colias eurytheme Boisduval
Alfalfa webworm (AWW), Loxostege cereralis (Zeller)
Alfalfa | Medicago sativa
alfalfa caterpillar | Colias eurytheme, alfalfa webworm | Loxostege cereralis, beet armyworm | Spodoptera exigua

The objective of the study was to evaluate the efficacy of insecticides used against worm pests (larvae of BAW, AC, and AWW) on alfalfa grown for hay production under desert growing conditions. An insecticide efficacy trial was conducted at the UC Desert Research and Extension Center, Holtville, CA, on a stand of CUF-101 alfalfa. The experimental design was RCB using four replicates with five insecticide treatments and an untreated check. Plots were 30-ft wide by 50-ft long. Formulations and rates for each compound are provided, and test materials were applied on 29 Jul 2016 at the specified rate equivalencies listed in the tables. Each broadcast spray application was made as a single 30-ft wide swath, through 17 nozzles (TJ-60 11003VS), using a hand-held, CO2 propelled sprayer that delivered 44.2 gpa, operated at 55 psi. An adjuvant, Hasten, modified vegetable oil (Wilbur-Ellis Company), was applied at 0.25% vol/vol with all insecticide tank mixture. Pretreatment evaluations of insect populations were made on 28 Jul or 1 day pre treatment (1 DPT). Posttreatment evaluations were made on the following specified dates and days after application (DAA) 1, 5, 8, and 12 Aug 2016 (3 DAA, 7 DAA, 10 DAA, and 14 DAA). The posttreatment averages (PTA) were calculated for each treatment. On each sampling date, ten 180° sweeps per replicate were collected with a standard 15-inch diameter sweep net. Sweep samples were bagged, labeled, and frozen for later counting of BAW, AC, and AWW larvae in the laboratory using a binocular dissecting microscope. Treatment means were analyzed using two-way ANOVA and means separated by a protected LSD (P ≤ 0.05).

The levels of BAW, AC, and AWW were low for Jul and Aug in the Imperial Valley, CA. There were no differences among the treatment means for BAW on 28 Jul (1 DPT) and on 1 Aug (3 DAA) (Table 1). All insecticide treatments except Warrior II 2.09CS, resulted in significantly (P = 0.05) fewer BAW than the untreated check on 5 Aug (7 DAT), 8 Aug (10 DAT), 12 Aug (14 DAT), and for the PTAs. There were no differences among the treatment means for AC on 28 Jul (1 DPT), 8 Aug (10 DAA), and on 12 Aug (14 DAA) (Table 2). All insecticide treatments resulted in significantly fewer AC than the untreated check on 1 Aug (3 DAA), 5 Aug (7 DAA), and for the PTAs. There were no differences among the treatment means for AWW on 28 Jul (1 DPT), 1 Aug (3 DAA), 8 Aug (10 DAA), and 12 Aug (14 DAA) (Table 3). All of the insecticide treatments resulted in significantly fewer AWW than the untreated check on 5 Aug (7 DAA). Only Coragen 1.67SC, Steward EC, Belt 480 SC and Intrepid 2F resulted in PTAs for AWW that were lower than the PTA for the untreated check. There were no symptoms of phytotoxicty apparent on any alfalfa plants following insecticide applications.

Beet armyworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Aug 7 DAA8 Auga 10 DAA12 Aug 14 DAAPTA
Untreated check–1.00 a1.25 a2.00 ab1.50 a1.00 a1.44 a
Coragen 1.67SC40.75 a0.00 a0.00 c0.25 b0.00 b0.06 b
Steward EC100.50 a0.25 a0.00 c0.00 b0.00 b0.06 b
Lorsban 4E321.25 a0.25 a0.50 bc0.00 b0.25 b0.25 b
Warrior II 2.09CS1.920.50 a0.50 a2.50 a2.25 a1.00 a1.56 a
Belt 480 SC20.75 a1.00 a0.00 c0.00 b0.00 b0.25 b
Intrepid 2F100.50 a0.00 a0.00 c0.00 b0.00 b0.00 b
Mustang EW4.32.00 a0.00 a0.00 c0.00 b0.00 b0.00 b
Beet armyworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Aug 7 DAA8 Auga 10 DAA12 Aug 14 DAAPTA
Untreated check–1.00 a1.25 a2.00 ab1.50 a1.00 a1.44 a
Coragen 1.67SC40.75 a0.00 a0.00 c0.25 b0.00 b0.06 b
Steward EC100.50 a0.25 a0.00 c0.00 b0.00 b0.06 b
Lorsban 4E321.25 a0.25 a0.50 bc0.00 b0.25 b0.25 b
Warrior II 2.09CS1.920.50 a0.50 a2.50 a2.25 a1.00 a1.56 a
Belt 480 SC20.75 a1.00 a0.00 c0.00 b0.00 b0.25 b
Intrepid 2F100.50 a0.00 a0.00 c0.00 b0.00 b0.00 b
Mustang EW4.32.00 a0.00 a0.00 c0.00 b0.00 b0.00 b

Means within columns followed by the same letter are not significantly different. LSD, P = 0.05.

Log10 (x + 1) transformed data were used for analysis but actual means are reported.

Beet armyworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Aug 7 DAA8 Auga 10 DAA12 Aug 14 DAAPTA
Untreated check–1.00 a1.25 a2.00 ab1.50 a1.00 a1.44 a
Coragen 1.67SC40.75 a0.00 a0.00 c0.25 b0.00 b0.06 b
Steward EC100.50 a0.25 a0.00 c0.00 b0.00 b0.06 b
Lorsban 4E321.25 a0.25 a0.50 bc0.00 b0.25 b0.25 b
Warrior II 2.09CS1.920.50 a0.50 a2.50 a2.25 a1.00 a1.56 a
Belt 480 SC20.75 a1.00 a0.00 c0.00 b0.00 b0.25 b
Intrepid 2F100.50 a0.00 a0.00 c0.00 b0.00 b0.00 b
Mustang EW4.32.00 a0.00 a0.00 c0.00 b0.00 b0.00 b
Beet armyworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Aug 7 DAA8 Auga 10 DAA12 Aug 14 DAAPTA
Untreated check–1.00 a1.25 a2.00 ab1.50 a1.00 a1.44 a
Coragen 1.67SC40.75 a0.00 a0.00 c0.25 b0.00 b0.06 b
Steward EC100.50 a0.25 a0.00 c0.00 b0.00 b0.06 b
Lorsban 4E321.25 a0.25 a0.50 bc0.00 b0.25 b0.25 b
Warrior II 2.09CS1.920.50 a0.50 a2.50 a2.25 a1.00 a1.56 a
Belt 480 SC20.75 a1.00 a0.00 c0.00 b0.00 b0.25 b
Intrepid 2F100.50 a0.00 a0.00 c0.00 b0.00 b0.00 b
Mustang EW4.32.00 a0.00 a0.00 c0.00 b0.00 b0.00 b

Means within columns followed by the same letter are not significantly different. LSD, P = 0.05.

Log10 (x + 1) transformed data were used for analysis but actual means are reported.

Alfalfa caterpillars per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Auga 3 DAA5 Aug 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTAa
Untreated check–3.00 a1.25 a0.50 a0.25 a0.75 a0.69 a
Coragen 1.67SC44.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Steward EC103.00 a0.00 b0.00 b0.00 a0.00 a0.00 b
Lorsban 4E324.25 a0.25 b0.00 b0.00 a0.00 a0.06 b
Warrior II 2.09CS1.923.00 a0.00 b0.00 b0.25 a0.00 a0.13 b
Belt 480 SC22.75 a0.25 b0.00 b0.00 a0.00 a0.06 b
Intrepid 2F105.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Mustang EW4.33.00 a0.00 b0.00 b0.00 a0.00 a0.00 b
Alfalfa caterpillars per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Auga 3 DAA5 Aug 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTAa
Untreated check–3.00 a1.25 a0.50 a0.25 a0.75 a0.69 a
Coragen 1.67SC44.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Steward EC103.00 a0.00 b0.00 b0.00 a0.00 a0.00 b
Lorsban 4E324.25 a0.25 b0.00 b0.00 a0.00 a0.06 b
Warrior II 2.09CS1.923.00 a0.00 b0.00 b0.25 a0.00 a0.13 b
Belt 480 SC22.75 a0.25 b0.00 b0.00 a0.00 a0.06 b
Intrepid 2F105.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Mustang EW4.33.00 a0.00 b0.00 b0.00 a0.00 a0.00 b

Means within columns followed by the same letter are not significantly different. LSD, P = 0.05.

aLog10 (x + 1) transformed data were used for analysis but actual means are reported.

Alfalfa caterpillars per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Auga 3 DAA5 Aug 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTAa
Untreated check–3.00 a1.25 a0.50 a0.25 a0.75 a0.69 a
Coragen 1.67SC44.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Steward EC103.00 a0.00 b0.00 b0.00 a0.00 a0.00 b
Lorsban 4E324.25 a0.25 b0.00 b0.00 a0.00 a0.06 b
Warrior II 2.09CS1.923.00 a0.00 b0.00 b0.25 a0.00 a0.13 b
Belt 480 SC22.75 a0.25 b0.00 b0.00 a0.00 a0.06 b
Intrepid 2F105.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Mustang EW4.33.00 a0.00 b0.00 b0.00 a0.00 a0.00 b
Alfalfa caterpillars per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Auga 3 DAA5 Aug 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTAa
Untreated check–3.00 a1.25 a0.50 a0.25 a0.75 a0.69 a
Coragen 1.67SC44.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Steward EC103.00 a0.00 b0.00 b0.00 a0.00 a0.00 b
Lorsban 4E324.25 a0.25 b0.00 b0.00 a0.00 a0.06 b
Warrior II 2.09CS1.923.00 a0.00 b0.00 b0.25 a0.00 a0.13 b
Belt 480 SC22.75 a0.25 b0.00 b0.00 a0.00 a0.06 b
Intrepid 2F105.25 a0.00 b0.00 b0.00 a0.00 a0.00 b
Mustang EW4.33.00 a0.00 b0.00 b0.00 a0.00 a0.00 b

Means within columns followed by the same letter are not significantly different. LSD, P = 0.05.

aLog10 (x + 1) transformed data were used for analysis but actual means are reported.

Alfalfa webworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Auga 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTA
Untreated check–1.50 a0.50 a0.75 a0.50 a0.25 a0.50 b
Coragen 1.67SC40.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Steward EC100.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Lorsban 4E320.50 b0.00 a0.00 b0.50 a0.00 a0.13 bc
Warrior II 2.09CS1.920.00 b0.75 a1.50 a0.75 a0.75 a0.94 a
Belt 480 SC20.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Intrepid 2F100.75 ab0.00 a0.00 b0.00 a0.00 a0.00 c
Mustang EW4.30.00 b0.00 a0.00 b0.25 a0.25 a0.13 bc
Alfalfa webworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Auga 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTA
Untreated check–1.50 a0.50 a0.75 a0.50 a0.25 a0.50 b
Coragen 1.67SC40.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Steward EC100.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Lorsban 4E320.50 b0.00 a0.00 b0.50 a0.00 a0.13 bc
Warrior II 2.09CS1.920.00 b0.75 a1.50 a0.75 a0.75 a0.94 a
Belt 480 SC20.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Intrepid 2F100.75 ab0.00 a0.00 b0.00 a0.00 a0.00 c
Mustang EW4.30.00 b0.00 a0.00 b0.25 a0.25 a0.13 bc

Means within columns followed by the same letter are not significantly different. LSD, P = 0.05.

a

Log10 (x + 1) transformed data were used for analysis but actual means are reported.

Alfalfa webworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Auga 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTA
Untreated check–1.50 a0.50 a0.75 a0.50 a0.25 a0.50 b
Coragen 1.67SC40.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Steward EC100.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Lorsban 4E320.50 b0.00 a0.00 b0.50 a0.00 a0.13 bc
Warrior II 2.09CS1.920.00 b0.75 a1.50 a0.75 a0.75 a0.94 a
Belt 480 SC20.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Intrepid 2F100.75 ab0.00 a0.00 b0.00 a0.00 a0.00 c
Mustang EW4.30.00 b0.00 a0.00 b0.25 a0.25 a0.13 bc
Alfalfa webworms per 10 sweeps
TreatmentRate fl oz/acre28 Jul 1 DPT1 Aug 3 DAA5 Auga 7 DAA8 Aug 10 DAA12 Aug 14 DAAPTA
Untreated check–1.50 a0.50 a0.75 a0.50 a0.25 a0.50 b
Coragen 1.67SC40.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Steward EC100.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Lorsban 4E320.50 b0.00 a0.00 b0.50 a0.00 a0.13 bc
Warrior II 2.09CS1.920.00 b0.75 a1.50 a0.75 a0.75 a0.94 a
Belt 480 SC20.25 b0.00 a0.00 b0.00 a0.00 a0.00 c
Intrepid 2F100.75 ab0.00 a0.00 b0.00 a0.00 a0.00 c
Mustang EW4.30.00 b0.00 a0.00 b0.25 a0.25 a0.13 bc

Means within columns followed by the same letter are not significantly different. LSD, P = 0.05.

a

Log10 (x + 1) transformed data were used for analysis but actual means are reported.

*

This research was supported by industry gifts.

Author notes

Subject Editor: Donald Cook

© The Author 2017. Published by Oxford University Press on behalf of the Entomological Society of America.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://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 [email protected]
Issue Section:
Section F: Field & Cereal Crops
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