Impact of Foliar Insecticides Against Whiteflies on Tomato, 2020

The efficacy of four insecticides against Bemisia tabaci in fall tomatoes was evaluated at the University of Florida—Gulf Coast Research and Education Center (Hillsborough County). Tomato seeds of the FL-91 variety were planted in trays on 6 August and fertilized with the water-soluble fertilizer Jack’s 20-20-20 four times before transplanting. Transplanting in the field was performed on 24 September 2020. Plots were 30-ft long with a 10-ft space between plots and 18” between plants, totaling 15 plants/plot. A drench application with the insecticide dinotefuran (Venom) at the top-labeled soil rate (7.5oz/A) was performed right after transplanting in the four insecticide treatments. Four replicates of each of the six treatments were arranged in an RCB. Two spray treatments were carried out on 29 October (application 1) and 13 November (application 2) with a CO₂ backpack sprayer that delivered 100 gpa at 35 psi, using one nozzle per bed. All treatments included the adjuvant DyneAmic at 0.25%v/v. Treatment efficacy was determined by sampling the 10 center-most plants and counting whitefly immatures at 6 and 12 d after treatment one (DAT1) and 5, and 11 DAT2. The terminal leaflet from the sixth leaf from the top was sampled. The evaluation consisted of counting the total number of eggs, first-instar nymphs (crawlers), mid instars nymphs (second and third), fourth instars and exuviae present on each leaf sample using a microscope. Data were analyzed using ANOVA (proc glimmix) in SAS followed by Tukey’s means separation. All data were square root + 0.375 transformed prior to analysis. Untransformed means are presented in tables. Data on percentage tomato yellow leaf curl virus were collected, but virus incidence was too low for statistical analysis.

There were no differences on egg numbers among the different treatments and the untreated (Table 1).

Table 1.

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	Rate/acre	Total whitefly eggs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.8	15.8	9.3	10.5	12.1
2. Movento	8	11.0	13.8	10.3	2.8	9.4
3. Senstar	10	13.3	11.0	16.0	14.8	13.8
4. Knack	10	7.8	9.0	20.5	22.8	15
5. Courier 40SC	13.6	10.5	19.3	16.3	13.3	14.8
P > F		0.82	0.87	0.74	0.49	Trt: 0.79; Date: 0.89; Trt*Date: 0.92

	Rate/acre	Total whitefly eggs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.8	15.8	9.3	10.5	12.1
2. Movento	8	11.0	13.8	10.3	2.8	9.4
3. Senstar	10	13.3	11.0	16.0	14.8	13.8
4. Knack	10	7.8	9.0	20.5	22.8	15
5. Courier 40SC	13.6	10.5	19.3	16.3	13.3	14.8
P > F		0.82	0.87	0.74	0.49	Trt: 0.79; Date: 0.89; Trt*Date: 0.92

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 1.

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	Rate/acre	Total whitefly eggs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.8	15.8	9.3	10.5	12.1
2. Movento	8	11.0	13.8	10.3	2.8	9.4
3. Senstar	10	13.3	11.0	16.0	14.8	13.8
4. Knack	10	7.8	9.0	20.5	22.8	15
5. Courier 40SC	13.6	10.5	19.3	16.3	13.3	14.8
P > F		0.82	0.87	0.74	0.49	Trt: 0.79; Date: 0.89; Trt*Date: 0.92

	Rate/acre	Total whitefly eggs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.8	15.8	9.3	10.5	12.1
2. Movento	8	11.0	13.8	10.3	2.8	9.4
3. Senstar	10	13.3	11.0	16.0	14.8	13.8
4. Knack	10	7.8	9.0	20.5	22.8	15
5. Courier 40SC	13.6	10.5	19.3	16.3	13.3	14.8
P > F		0.82	0.87	0.74	0.49	Trt: 0.79; Date: 0.89; Trt*Date: 0.92

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

First instar nymphs were significantly lower at 12DAT1 only in the Senstar treatment (Table 2). Total first-instar nymphs were also significantly lower in the Senstar and Knack treatments at 12DAT1, 5DAT2, and 11DAT2 and when treatment dates were pooled than in the untreated control.

Table 2.

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	Rate/acre	Total whitefly first-instar nymphs (Crawlers)^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		20.3	16.0a	15.3a	36.5a	22.0a
2. Movento	8	41.0	9.8ab	8.8ab	17.0ab	19.1a
3. Senstar	10	12.8	2.8b	4.3b	1.3c	5.3b
4. Knack	10	12.0	6.8ab	4.0b	4.0bc	6.7b
5. Courier 40SC	13.6	18.3	5.8ab	17.8a	12.8abc	13.6ab
P > F		0.05	0.02	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.02

	Rate/acre	Total whitefly first-instar nymphs (Crawlers)^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		20.3	16.0a	15.3a	36.5a	22.0a
2. Movento	8	41.0	9.8ab	8.8ab	17.0ab	19.1a
3. Senstar	10	12.8	2.8b	4.3b	1.3c	5.3b
4. Knack	10	12.0	6.8ab	4.0b	4.0bc	6.7b
5. Courier 40SC	13.6	18.3	5.8ab	17.8a	12.8abc	13.6ab
P > F		0.05	0.02	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.02

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 2.

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	Rate/acre	Total whitefly first-instar nymphs (Crawlers)^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		20.3	16.0a	15.3a	36.5a	22.0a
2. Movento	8	41.0	9.8ab	8.8ab	17.0ab	19.1a
3. Senstar	10	12.8	2.8b	4.3b	1.3c	5.3b
4. Knack	10	12.0	6.8ab	4.0b	4.0bc	6.7b
5. Courier 40SC	13.6	18.3	5.8ab	17.8a	12.8abc	13.6ab
P > F		0.05	0.02	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.02

	Rate/acre	Total whitefly first-instar nymphs (Crawlers)^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		20.3	16.0a	15.3a	36.5a	22.0a
2. Movento	8	41.0	9.8ab	8.8ab	17.0ab	19.1a
3. Senstar	10	12.8	2.8b	4.3b	1.3c	5.3b
4. Knack	10	12.0	6.8ab	4.0b	4.0bc	6.7b
5. Courier 40SC	13.6	18.3	5.8ab	17.8a	12.8abc	13.6ab
P > F		0.05	0.02	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.02

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Numbers of mid-instar nymphs (Table 3) were significantly lower in the Movento, Senstar, and Courier treatments at 6DAT1 as well as when total mid-instar nymph counts were pooled across sample dates. There were no significant differences among any treatments and the untreated at 12DAT1. The numbers of mid-instar nymph were significantly lower in all insecticide treatments than the untreated at 11DAT2. Numbers of fourth-instar nymphs (Table 4) were significantly lower in the Movento and Senstar treatments than the other treatments and the untreated at 6DAT1. When total fourth-instar nymphs were pooled across sample dates, the Movento, Senstar, and Courier treatments had significantly lower fourth-instar nymphs than the untreated control. Total fourth-instar nymphs were about 50% lower in the Knack alone treatment than the untreated, but this was not a statistically significant difference.

Table 3.

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Treatment/form.	Rate/acre	Total whitefly mid-instar nymphs (2nd and 3rd)^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		60.5a	38.5	14.5a	37.8a	37.8a
2. Movento	8	16.5b	13.5	7.0ab	5.8b	10.7bc
3. Senstar	10	13.5b	9.0	3.8b	3.0b	7.3c
4. Knack	10	54.0ab	35.3	15.0a	8.3b	28.1a
5. Courier 40SC	13.6	16.8b	10.5	5.0ab	8.8b	10.3bc
P > F		<0.01	0.06	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.51

Treatment/form.	Rate/acre	Total whitefly mid-instar nymphs (2nd and 3rd)^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		60.5a	38.5	14.5a	37.8a	37.8a
2. Movento	8	16.5b	13.5	7.0ab	5.8b	10.7bc
3. Senstar	10	13.5b	9.0	3.8b	3.0b	7.3c
4. Knack	10	54.0ab	35.3	15.0a	8.3b	28.1a
5. Courier 40SC	13.6	16.8b	10.5	5.0ab	8.8b	10.3bc
P > F		<0.01	0.06	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.51

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 3.

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Treatment/form.	Rate/acre	Total whitefly mid-instar nymphs (2nd and 3rd)^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		60.5a	38.5	14.5a	37.8a	37.8a
2. Movento	8	16.5b	13.5	7.0ab	5.8b	10.7bc
3. Senstar	10	13.5b	9.0	3.8b	3.0b	7.3c
4. Knack	10	54.0ab	35.3	15.0a	8.3b	28.1a
5. Courier 40SC	13.6	16.8b	10.5	5.0ab	8.8b	10.3bc
P > F		<0.01	0.06	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.51

Treatment/form.	Rate/acre	Total whitefly mid-instar nymphs (2nd and 3rd)^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		60.5a	38.5	14.5a	37.8a	37.8a
2. Movento	8	16.5b	13.5	7.0ab	5.8b	10.7bc
3. Senstar	10	13.5b	9.0	3.8b	3.0b	7.3c
4. Knack	10	54.0ab	35.3	15.0a	8.3b	28.1a
5. Courier 40SC	13.6	16.8b	10.5	5.0ab	8.8b	10.3bc
P > F		<0.01	0.06	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.51

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 4.

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	Rate/acre	Total whitefly fourth-instar nymphs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		22.8a	24.0	4.0	5.8a	14.1a
2. Movento	8	5.5b	4.3	2.3	1.3ab	3.3b
3. Senstar	10	4.8b	3.8	1.8	0.8b	2.8b
4. Knack	10	12.5ab	12.0	2.8	0.8ab	7.0ab
5. Courier 40SC	13.6	12.3ab	6.0	0.8	0.3b	4.8b
P > F		0.01	<0.07	0.32	0.02	Trt: <0.01; Date: <0.01; Trt*Date: 0.61

	Rate/acre	Total whitefly fourth-instar nymphs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		22.8a	24.0	4.0	5.8a	14.1a
2. Movento	8	5.5b	4.3	2.3	1.3ab	3.3b
3. Senstar	10	4.8b	3.8	1.8	0.8b	2.8b
4. Knack	10	12.5ab	12.0	2.8	0.8ab	7.0ab
5. Courier 40SC	13.6	12.3ab	6.0	0.8	0.3b	4.8b
P > F		0.01	<0.07	0.32	0.02	Trt: <0.01; Date: <0.01; Trt*Date: 0.61

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 4.

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	Rate/acre	Total whitefly fourth-instar nymphs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		22.8a	24.0	4.0	5.8a	14.1a
2. Movento	8	5.5b	4.3	2.3	1.3ab	3.3b
3. Senstar	10	4.8b	3.8	1.8	0.8b	2.8b
4. Knack	10	12.5ab	12.0	2.8	0.8ab	7.0ab
5. Courier 40SC	13.6	12.3ab	6.0	0.8	0.3b	4.8b
P > F		0.01	<0.07	0.32	0.02	Trt: <0.01; Date: <0.01; Trt*Date: 0.61

	Rate/acre	Total whitefly fourth-instar nymphs^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		22.8a	24.0	4.0	5.8a	14.1a
2. Movento	8	5.5b	4.3	2.3	1.3ab	3.3b
3. Senstar	10	4.8b	3.8	1.8	0.8b	2.8b
4. Knack	10	12.5ab	12.0	2.8	0.8ab	7.0ab
5. Courier 40SC	13.6	12.3ab	6.0	0.8	0.3b	4.8b
P > F		0.01	<0.07	0.32	0.02	Trt: <0.01; Date: <0.01; Trt*Date: 0.61

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Total nymphs (Table 5) were significantly lower in the Senstar treatment than the untreated control on each sample date and when total nymphs were pooled across sample dates. Total nymphs were significantly lower in all treatments than the untreated control at 11DAT2.

Table 5.

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Treatment/form.	Rate/acre	Total whitefly nymphs^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		103.5a	78.5a	33.7a	80.0a	73.9a
2. Movento	8	63.0ab	27.5ab	18.0ab	24.0b	33.1ab
3. Senstar	10	31.0b	15.5b	9.8b	5.0b	15.3b
4. Knack	10	78.5ab	54.0ab	21.8ab	13.0b	41.8ab
5. Courier 40SC	13.6	47.3ab	22.3ab	23.5ab	21.8b	28.7ab
P>F		0.03	0.01	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.55

Treatment/form.	Rate/acre	Total whitefly nymphs^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		103.5a	78.5a	33.7a	80.0a	73.9a
2. Movento	8	63.0ab	27.5ab	18.0ab	24.0b	33.1ab
3. Senstar	10	31.0b	15.5b	9.8b	5.0b	15.3b
4. Knack	10	78.5ab	54.0ab	21.8ab	13.0b	41.8ab
5. Courier 40SC	13.6	47.3ab	22.3ab	23.5ab	21.8b	28.7ab
P>F		0.03	0.01	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.55

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 5.

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Treatment/form.	Rate/acre	Total whitefly nymphs^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		103.5a	78.5a	33.7a	80.0a	73.9a
2. Movento	8	63.0ab	27.5ab	18.0ab	24.0b	33.1ab
3. Senstar	10	31.0b	15.5b	9.8b	5.0b	15.3b
4. Knack	10	78.5ab	54.0ab	21.8ab	13.0b	41.8ab
5. Courier 40SC	13.6	47.3ab	22.3ab	23.5ab	21.8b	28.7ab
P>F		0.03	0.01	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.55

Treatment/form.	Rate/acre	Total whitefly nymphs^a
	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		103.5a	78.5a	33.7a	80.0a	73.9a
2. Movento	8	63.0ab	27.5ab	18.0ab	24.0b	33.1ab
3. Senstar	10	31.0b	15.5b	9.8b	5.0b	15.3b
4. Knack	10	78.5ab	54.0ab	21.8ab	13.0b	41.8ab
5. Courier 40SC	13.6	47.3ab	22.3ab	23.5ab	21.8b	28.7ab
P>F		0.03	0.01	<0.01	<0.01	Trt: <0.01; Date: <0.01; Trt*Date: 0.55

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

When exuviae were pooled across sample dates, exuviae were significantly lower in all treatments compared with the control (Table 6). The total number of exuviae was significantly lower in the Senstar treatment than the untreated control on 6DAT1, 12DAT1, and 5DAT2.¹

Table 6.

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	Rate/acre	Total whitefly exuviae^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.0a	24.8a	38.5a	8.8	21.0a
2. Movento	8	6.5ab	3.5ab	5.8ab	2.0	4.4b
3. Senstar	10	3.0b	1.8b	0.8b	0.8	1.6b
4. Knack	10	5.3ab	5.3ab	5.0ab	1.8	4.3b
5. Courier 40SC	13.6	7.5ab	9.5ab	5.3ab	2.5	6.2b
P>F		0.08	0.06	0.04	0.09	Trt: <0.01; Date: 0.22; Trt*Date: 0.51

	Rate/acre	Total whitefly exuviae^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.0a	24.8a	38.5a	8.8	21.0a
2. Movento	8	6.5ab	3.5ab	5.8ab	2.0	4.4b
3. Senstar	10	3.0b	1.8b	0.8b	0.8	1.6b
4. Knack	10	5.3ab	5.3ab	5.0ab	1.8	4.3b
5. Courier 40SC	13.6	7.5ab	9.5ab	5.3ab	2.5	6.2b
P>F		0.08	0.06	0.04	0.09	Trt: <0.01; Date: 0.22; Trt*Date: 0.51

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Table 6.

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	Rate/acre	Total whitefly exuviae^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.0a	24.8a	38.5a	8.8	21.0a
2. Movento	8	6.5ab	3.5ab	5.8ab	2.0	4.4b
3. Senstar	10	3.0b	1.8b	0.8b	0.8	1.6b
4. Knack	10	5.3ab	5.3ab	5.0ab	1.8	4.3b
5. Courier 40SC	13.6	7.5ab	9.5ab	5.3ab	2.5	6.2b
P>F		0.08	0.06	0.04	0.09	Trt: <0.01; Date: 0.22; Trt*Date: 0.51

	Rate/acre	Total whitefly exuviae^a
Treatment/form.	(floz form.)	6DAT1	12DAT1	5DAT2	11DAT2	Total average of all readings
1. Untreated control		12.0a	24.8a	38.5a	8.8	21.0a
2. Movento	8	6.5ab	3.5ab	5.8ab	2.0	4.4b
3. Senstar	10	3.0b	1.8b	0.8b	0.8	1.6b
4. Knack	10	5.3ab	5.3ab	5.0ab	1.8	4.3b
5. Courier 40SC	13.6	7.5ab	9.5ab	5.3ab	2.5	6.2b
P>F		0.08	0.06	0.04	0.09	Trt: <0.01; Date: 0.22; Trt*Date: 0.51

Means within columns followed by a common letter are not significantly different (P ≤ 0.05, Tukey’s).

^aSquare-root + 0.375 transformed data used for analysis, nontransformed means shown in the table.

Footnotes

This research was supported in part by industry gifts of pesticides and/or research funding.

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 [email protected]

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Impact of Foliar Insecticides Against Whiteflies on Tomato, 2020

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Impact of Foliar Insecticides Against Whiteflies on Tomato, 2020

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