Insecticide Efficacy Against Alfalfa Weevil and Blue Alfalfa Aphid, 2016*

Author Notes

The objective of the study was to evaluate the efficacy of the insecticidal compounds used against AW larvae and against BAA on alfalfa grown for hay production under desert growing conditions. A field study was conducted during the spring 2016 at the UC Desert Research and Extension Center, Holtville, CA. A stand of alfalfa, VAR. ‘CUF 101’ was used for the experiment. The experimental design was RCB using four replicates with 10 insecticidal treatments and an untreated check. Plots measured 20 ft by 50 ft and insecticide treatments were applied on 4 Mar 2016, using a Lee Spider Spray Trac Tractor equipped with 13 TJ-60 11003VS nozzles on a spray boom applying a 20 ft swath broadcast application, operated at 50 psi, delivering 52 gpa. The larval AW and BAA populations were measured in each plot with a standard 15-inch diameter insect net consisting of ten 180° sweeps; means reported in the tables are per sweep. Insect samples were collected on 3 Mar, 1-day pre-treatment (1-DPT) and 7 Mar or 3-days after treatment (3-DAT), 11 Mar (7-DAT), 14 Mar (10-DAT), and 18 Mar (14-DAT). Sweep samples were bagged, labeled, and frozen for later counting of AW larvae and BAA in the laboratory. Post treatment averages (PTA) were calculated for each treatment. Data sets were analyzed using a two-way ANOVA and means separated by Least Significant Difference Test (LSD) (P ≤ 0.05).

The 2016 AW levels were lower than typical for Imperial Valley alfalfa during Mar but the BAA levels were higher than typical and increased rapidly during Mar. There were no differences among the treatments for AW larvae on 3 and 7 Mar (Table 1). On 11 Mar, the plots treated with of Cobalt Advanced, Steward EC at 11.3 fl oz/acre, Beleaf 50SG + Steward EC, Steward EC + Dimethoate 2.67EC, Fastac CS, Mustang, or Baythroid XL each has significantly (P = 0.05) fewer AW larvae than the untreated check plots. All insecticide treatments, except Dimethoate 2.67EC and Steward EC at 11.3 fl oz/acre, resulted in fewer AW larvae than the untreated check on 18 Mar. All insecticide treatments, except Dimethoate 2.67EC, resulted in fewer AW larvae than the untreated check on 14 Mar and for the PTAs. Beleaf 50SG + Steward EC provided the highest level of AW larval control with no larvae present after application. There were no differences among the treatments for BAA on 3, 7, and 11 Mar (Table 2). All insecticide treatments resulted in fewer BAA than the untreated check on 14 Mar. All insecticide treatments except Lorsban 4EC resulted in fewer BAA than the untreated check on 18 Mar and for the PTAs. Assail 30SG at 5 oz/acre had the lowest BAA means on 14 and 18 Mar and for the PTA. None of the insecticide treatments resulted in any injury to the alfalfa plants.

Table 1

	Alfalfa weevil larvae per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT^a	11 Mar 7 DAT^a	14 Mar 10 DAT	18 Mar 14 DAT	PTA^a
Untreated Check	–	6.75 a	2.25 a	3.25 a	2.25 a	2.50 a	2.56 a
Cobalt Advanced	32 fl oz	11.00 a	0.25 a	0.00 c	0.50 bc	0.25 bc	0.25 cde
Beleaf 50SG	2.8 oz	9.50 a	0.75 a	3.00 ab	0.50 bc	0.75 bc	1.25 a–d
Steward EC	11.3 fl oz	9.25 a	1.50 a	0.25 c	0.25 c	1.25 abc	0.81 b–e
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	9.00 a	0.00 a	0.00 c	0.00 c	0.00 c	0.00 e
Sivanto 200SL	10.5 fl oz	8.75 a	0.25 a	1.25 abc	0.00 c	0.00 c	0.38 cde
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	10.00 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde
Dimethoate 2.67EC	24 fl oz	13.75 a	2.50 a	3.75 ab	1.50 ab	1.50 ab	2.31 ab
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	14.25 a	0.00 a	0.25 c	0.50 bc	0.00 c	0.19 de
Fastac CS	3.8 fl oz	15.25 a	0.25 a	0.25 c	0.50 bc	0.25 bc	0.31 cde
Mustang	4.3 fl oz	9.75 a	0.00 a	0.25 c	0.25 c	0.50 bc	0.25 cde
Baythroid XL	2.8 fl oz	6.25 a	0.25 a	0.50 bc	0.25 c	0.00 c	0.25 cde
Lorsban 4E	32 fl oz	12.75 a	2.50 a	2.00 abc	1.00 bc	0.75 bc	1.56 abc
Assail 30SG	5 oz	6.50 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde

	Alfalfa weevil larvae per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT^a	11 Mar 7 DAT^a	14 Mar 10 DAT	18 Mar 14 DAT	PTA^a
Untreated Check	–	6.75 a	2.25 a	3.25 a	2.25 a	2.50 a	2.56 a
Cobalt Advanced	32 fl oz	11.00 a	0.25 a	0.00 c	0.50 bc	0.25 bc	0.25 cde
Beleaf 50SG	2.8 oz	9.50 a	0.75 a	3.00 ab	0.50 bc	0.75 bc	1.25 a–d
Steward EC	11.3 fl oz	9.25 a	1.50 a	0.25 c	0.25 c	1.25 abc	0.81 b–e
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	9.00 a	0.00 a	0.00 c	0.00 c	0.00 c	0.00 e
Sivanto 200SL	10.5 fl oz	8.75 a	0.25 a	1.25 abc	0.00 c	0.00 c	0.38 cde
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	10.00 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde
Dimethoate 2.67EC	24 fl oz	13.75 a	2.50 a	3.75 ab	1.50 ab	1.50 ab	2.31 ab
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	14.25 a	0.00 a	0.25 c	0.50 bc	0.00 c	0.19 de
Fastac CS	3.8 fl oz	15.25 a	0.25 a	0.25 c	0.50 bc	0.25 bc	0.31 cde
Mustang	4.3 fl oz	9.75 a	0.00 a	0.25 c	0.25 c	0.50 bc	0.25 cde
Baythroid XL	2.8 fl oz	6.25 a	0.25 a	0.50 bc	0.25 c	0.00 c	0.25 cde
Lorsban 4E	32 fl oz	12.75 a	2.50 a	2.00 abc	1.00 bc	0.75 bc	1.56 abc
Assail 30SG	5 oz	6.50 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde

Means within columns followed by the same letter are not significantly different, LSD Test; P > 0.05. DPT = days pre-treatment; DAT = days after treatment; PTA = post-treatment average.

Log₁₀ (X + 1) transformed data used for analysis, back transformed means shown in the table.

Table 1

	Alfalfa weevil larvae per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT^a	11 Mar 7 DAT^a	14 Mar 10 DAT	18 Mar 14 DAT	PTA^a
Untreated Check	–	6.75 a	2.25 a	3.25 a	2.25 a	2.50 a	2.56 a
Cobalt Advanced	32 fl oz	11.00 a	0.25 a	0.00 c	0.50 bc	0.25 bc	0.25 cde
Beleaf 50SG	2.8 oz	9.50 a	0.75 a	3.00 ab	0.50 bc	0.75 bc	1.25 a–d
Steward EC	11.3 fl oz	9.25 a	1.50 a	0.25 c	0.25 c	1.25 abc	0.81 b–e
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	9.00 a	0.00 a	0.00 c	0.00 c	0.00 c	0.00 e
Sivanto 200SL	10.5 fl oz	8.75 a	0.25 a	1.25 abc	0.00 c	0.00 c	0.38 cde
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	10.00 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde
Dimethoate 2.67EC	24 fl oz	13.75 a	2.50 a	3.75 ab	1.50 ab	1.50 ab	2.31 ab
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	14.25 a	0.00 a	0.25 c	0.50 bc	0.00 c	0.19 de
Fastac CS	3.8 fl oz	15.25 a	0.25 a	0.25 c	0.50 bc	0.25 bc	0.31 cde
Mustang	4.3 fl oz	9.75 a	0.00 a	0.25 c	0.25 c	0.50 bc	0.25 cde
Baythroid XL	2.8 fl oz	6.25 a	0.25 a	0.50 bc	0.25 c	0.00 c	0.25 cde
Lorsban 4E	32 fl oz	12.75 a	2.50 a	2.00 abc	1.00 bc	0.75 bc	1.56 abc
Assail 30SG	5 oz	6.50 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde

	Alfalfa weevil larvae per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT^a	11 Mar 7 DAT^a	14 Mar 10 DAT	18 Mar 14 DAT	PTA^a
Untreated Check	–	6.75 a	2.25 a	3.25 a	2.25 a	2.50 a	2.56 a
Cobalt Advanced	32 fl oz	11.00 a	0.25 a	0.00 c	0.50 bc	0.25 bc	0.25 cde
Beleaf 50SG	2.8 oz	9.50 a	0.75 a	3.00 ab	0.50 bc	0.75 bc	1.25 a–d
Steward EC	11.3 fl oz	9.25 a	1.50 a	0.25 c	0.25 c	1.25 abc	0.81 b–e
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	9.00 a	0.00 a	0.00 c	0.00 c	0.00 c	0.00 e
Sivanto 200SL	10.5 fl oz	8.75 a	0.25 a	1.25 abc	0.00 c	0.00 c	0.38 cde
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	10.00 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde
Dimethoate 2.67EC	24 fl oz	13.75 a	2.50 a	3.75 ab	1.50 ab	1.50 ab	2.31 ab
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	14.25 a	0.00 a	0.25 c	0.50 bc	0.00 c	0.19 de
Fastac CS	3.8 fl oz	15.25 a	0.25 a	0.25 c	0.50 bc	0.25 bc	0.31 cde
Mustang	4.3 fl oz	9.75 a	0.00 a	0.25 c	0.25 c	0.50 bc	0.25 cde
Baythroid XL	2.8 fl oz	6.25 a	0.25 a	0.50 bc	0.25 c	0.00 c	0.25 cde
Lorsban 4E	32 fl oz	12.75 a	2.50 a	2.00 abc	1.00 bc	0.75 bc	1.56 abc
Assail 30SG	5 oz	6.50 a	0.25 a	1.00 abc	0.25 c	0.00 c	0.38 cde

Means within columns followed by the same letter are not significantly different, LSD Test; P > 0.05. DPT = days pre-treatment; DAT = days after treatment; PTA = post-treatment average.

Log₁₀ (X + 1) transformed data used for analysis, back transformed means shown in the table.

Table 2

	Blue alfalfa aphids per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT	11 Mar 7 DAT	14 Mar 10 DAT	18 Mar 14 DAT	PTA
Untreated Check	–	51.0 a	26.0 a	791.0 a	862.0 a	1406.0 a	771.3 a
Cobalt Advanced	32 fl oz	66.0 a	9.8 a	749.3 a	426.0 bcd	1092.0 c	569.3 bcd
Beleaf 50SG	2.8 oz	85.3 a	6.0 a	621.0 a	316.0 bcd	773.5 def	429.1 def
Steward EC	11.3 fl oz	59.3 a	19.3 a	767.8 a	413.8 bcd	795.5 def	499.1 cde
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	76.3 a	10.3 a	891.0 a	454.5 bcd	801.5 def	539.3 cd
Sivanto 200SL	10.5 fl oz	64.0 a	6.5 a	575.8 a	252.8 cd	699.25 ef	383.6 ef
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	57.8 a	3.0 a	706.5 a	505.5 bc	882.75 cde	524.4 cde
Dimethoate 2.67EC	24 fl oz	73.8 a	14.0 a	762.8 a	530.3 bc	986.5 cd	573.4 cde
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	53.0 a	26.8 a	731.8 a	408.3 bcd	722.25 def	472.3 c-f
Fastac CS	3.8 fl oz	50.3 a	26.5 a	718.5 a	446.5 bcd	942.75 cde	533.6 cd
Mustang	4.3 fl oz	66.3 a	11.3 a	745.5 a	467.0 bcd	1122.00 bc	586.4 bc
Baythroid XL	2.8 fl oz	61.0 a	16.0 a	649.0 a	470.8 bcd	1102.75 c	559.6 bcd
Lorsban 4E	32 fl oz	49.5 a	12.8 a	888.0 a	548.3 b	1376.0 ab	706.3 ab
Assail 30SG	5 oz	66.5 a	16.8 a	566.0 a	190.3 d	530.25 f	325.8 f

	Blue alfalfa aphids per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT	11 Mar 7 DAT	14 Mar 10 DAT	18 Mar 14 DAT	PTA
Untreated Check	–	51.0 a	26.0 a	791.0 a	862.0 a	1406.0 a	771.3 a
Cobalt Advanced	32 fl oz	66.0 a	9.8 a	749.3 a	426.0 bcd	1092.0 c	569.3 bcd
Beleaf 50SG	2.8 oz	85.3 a	6.0 a	621.0 a	316.0 bcd	773.5 def	429.1 def
Steward EC	11.3 fl oz	59.3 a	19.3 a	767.8 a	413.8 bcd	795.5 def	499.1 cde
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	76.3 a	10.3 a	891.0 a	454.5 bcd	801.5 def	539.3 cd
Sivanto 200SL	10.5 fl oz	64.0 a	6.5 a	575.8 a	252.8 cd	699.25 ef	383.6 ef
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	57.8 a	3.0 a	706.5 a	505.5 bc	882.75 cde	524.4 cde
Dimethoate 2.67EC	24 fl oz	73.8 a	14.0 a	762.8 a	530.3 bc	986.5 cd	573.4 cde
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	53.0 a	26.8 a	731.8 a	408.3 bcd	722.25 def	472.3 c-f
Fastac CS	3.8 fl oz	50.3 a	26.5 a	718.5 a	446.5 bcd	942.75 cde	533.6 cd
Mustang	4.3 fl oz	66.3 a	11.3 a	745.5 a	467.0 bcd	1122.00 bc	586.4 bc
Baythroid XL	2.8 fl oz	61.0 a	16.0 a	649.0 a	470.8 bcd	1102.75 c	559.6 bcd
Lorsban 4E	32 fl oz	49.5 a	12.8 a	888.0 a	548.3 b	1376.0 ab	706.3 ab
Assail 30SG	5 oz	66.5 a	16.8 a	566.0 a	190.3 d	530.25 f	325.8 f

Means within columns followed by the same letter are not significantly different, LSD Test; P > 0.05. DPT = days pre-treatment; DAT = days after treatment; PTA = post-treatment average.

Table 2

	Blue alfalfa aphids per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT	11 Mar 7 DAT	14 Mar 10 DAT	18 Mar 14 DAT	PTA
Untreated Check	–	51.0 a	26.0 a	791.0 a	862.0 a	1406.0 a	771.3 a
Cobalt Advanced	32 fl oz	66.0 a	9.8 a	749.3 a	426.0 bcd	1092.0 c	569.3 bcd
Beleaf 50SG	2.8 oz	85.3 a	6.0 a	621.0 a	316.0 bcd	773.5 def	429.1 def
Steward EC	11.3 fl oz	59.3 a	19.3 a	767.8 a	413.8 bcd	795.5 def	499.1 cde
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	76.3 a	10.3 a	891.0 a	454.5 bcd	801.5 def	539.3 cd
Sivanto 200SL	10.5 fl oz	64.0 a	6.5 a	575.8 a	252.8 cd	699.25 ef	383.6 ef
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	57.8 a	3.0 a	706.5 a	505.5 bc	882.75 cde	524.4 cde
Dimethoate 2.67EC	24 fl oz	73.8 a	14.0 a	762.8 a	530.3 bc	986.5 cd	573.4 cde
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	53.0 a	26.8 a	731.8 a	408.3 bcd	722.25 def	472.3 c-f
Fastac CS	3.8 fl oz	50.3 a	26.5 a	718.5 a	446.5 bcd	942.75 cde	533.6 cd
Mustang	4.3 fl oz	66.3 a	11.3 a	745.5 a	467.0 bcd	1122.00 bc	586.4 bc
Baythroid XL	2.8 fl oz	61.0 a	16.0 a	649.0 a	470.8 bcd	1102.75 c	559.6 bcd
Lorsban 4E	32 fl oz	49.5 a	12.8 a	888.0 a	548.3 b	1376.0 ab	706.3 ab
Assail 30SG	5 oz	66.5 a	16.8 a	566.0 a	190.3 d	530.25 f	325.8 f

	Blue alfalfa aphids per 10 sweeps
Treatment/formulation	Rate amt/acre	3 Mar 1DPT	7 Mar 3 DAT	11 Mar 7 DAT	14 Mar 10 DAT	18 Mar 14 DAT	PTA
Untreated Check	–	51.0 a	26.0 a	791.0 a	862.0 a	1406.0 a	771.3 a
Cobalt Advanced	32 fl oz	66.0 a	9.8 a	749.3 a	426.0 bcd	1092.0 c	569.3 bcd
Beleaf 50SG	2.8 oz	85.3 a	6.0 a	621.0 a	316.0 bcd	773.5 def	429.1 def
Steward EC	11.3 fl oz	59.3 a	19.3 a	767.8 a	413.8 bcd	795.5 def	499.1 cde
Beleaf 50SG + Steward EC	2.8 oz + 11.3 fl oz	76.3 a	10.3 a	891.0 a	454.5 bcd	801.5 def	539.3 cd
Sivanto 200SL	10.5 fl oz	64.0 a	6.5 a	575.8 a	252.8 cd	699.25 ef	383.6 ef
Sivanto 200SL + Steward EC	10.5fl oz11.3 fl oz	57.8 a	3.0 a	706.5 a	505.5 bc	882.75 cde	524.4 cde
Dimethoate 2.67EC	24 fl oz	73.8 a	14.0 a	762.8 a	530.3 bc	986.5 cd	573.4 cde
Steward EC + Dimethoate 2.67EC	11.3 fl oz24 fl oz	53.0 a	26.8 a	731.8 a	408.3 bcd	722.25 def	472.3 c-f
Fastac CS	3.8 fl oz	50.3 a	26.5 a	718.5 a	446.5 bcd	942.75 cde	533.6 cd
Mustang	4.3 fl oz	66.3 a	11.3 a	745.5 a	467.0 bcd	1122.00 bc	586.4 bc
Baythroid XL	2.8 fl oz	61.0 a	16.0 a	649.0 a	470.8 bcd	1102.75 c	559.6 bcd
Lorsban 4E	32 fl oz	49.5 a	12.8 a	888.0 a	548.3 b	1376.0 ab	706.3 ab
Assail 30SG	5 oz	66.5 a	16.8 a	566.0 a	190.3 d	530.25 f	325.8 f

Means within columns followed by the same letter are not significantly different, LSD Test; P > 0.05. DPT = days pre-treatment; DAT = days after treatment; PTA = post-treatment average.

Author notes

This research was supported by industry gifts of products and research funding.

Section Editor: Donald Cook

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]

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Article Contents

Insecticide Efficacy Against Alfalfa Weevil and Blue Alfalfa Aphid, 2016*

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