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THRIPS CONTROL IN ICEBERG LETTUCE 2012

THRIPS CONTROL IN ICEBERG LETTUCE 2012 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E25 (E25) LETTUCE (HEAD): Lactuca sativa var. capitata L. ‘GRIZZLY’ Eric T. Natwick University of California Agriculture and Natural Resources Desert Research and Extension Center 1050 E. Holton Rd. Holtville, CA 92250 Phone: (760) 352-9474 Fax: (760) 352-0846 E-mail: etnatwick@ucdavis.edu Western flower thrips (WFT): Frankliniella occidentalis (Pergande) The objective of this study was to evaluate the efficacy of insecticides for control of western flower thrips (WFT) on iceberg head lettuce under desert growing conditions. Head lettuce (GRIZZLY) was direct seeded on 19 Oct 2011 at the University of California Desert Research and Extension Center, El Centro, CA into double row beds on 40 inch centers. Stand establishment was achieved using overhead sprinkler irrigation and thereafter, irrigated via furrow. Plots were four beds 13.3 ft wide by 50 ft long and bordered by one untreated buffer bed. The experiment included seven insecticidal treatments and a water treated check. Four replications of each treatment were arranged as a RCB design. Insecticides and the treatment rates are shown in the tables. All insecticide treatments were applied on 18 Jan, 25 Jan and 7 Feb 2012 except the treatment of MustangMax @ 4 fl oz/acre (applied on 18 Jan and 7 Feb) rotating with (r/w) Lannate LV (applied on 25 Jan). All insecticide treatments were foliar sprays applied with a Lee Spider Spray Trac Tractor, 4-row sprayer with three TJ-60 11003VS nozzles per row, a total of 12 nozzles that delivered 50.6 gpa at 25 psi. The adjuvant, DyneAmic (Helena Chemical Co.), was added to all insecticidal spray mixtures at 0.25% vol/vol with the exception of the two Assail 70 WP treatments. Numbers of WFT from ten plants per replicate were recorded on each sampling date. WFT were sampled pre- treatment (PT) on 10 Jan 2012. WFT sampling days after treatment (DAT) included: 23 Jan (5DAT1), 2 Feb (8DAT2) and 15 Feb (8DAT3). All lettuce heads were harvested from 13.1 row ft (0.001 acre) on 17 Feb 2012 and examined for thrips feeding damage, and for market quality heads (no thrips damage). Undamaged head were weighed in kg. Data were recorded as total heads, thrips damaged heads, marketable heads, and kg of marketable heads. Percentages of market quality heads were calculated. Data were analyzed using ANOVA. Differences among means on each sampling date were determined using Least Significant Difference Test (α=0.05). WFT population levels were moderate during this trial. There were no differences among the treatments for WFT larval means from the PT or 8DAT13 samples (Table 1). All insecticide treatments except the two Assail treatments and the Athena treatment had fewer WFT larvae than the water check at 5DAT1. All insecticidal treatments except Assail + Silwet- L77 had lower WFT larval means than the water check on 8DAT2. All insecticide treatments except the two Assail treatments had fewer WFT larvae than the water check for their post-treatment averages (PTA). There were no differences among the treatments for WFT adult means from the PT or 8DAT3 samples (Table 2). All insecticide treatments except the two Assail treatments had fewer WFT adults than the water check at 5DAT1. The water check had more adult WFT than any of the insecticide treatments for the 8DAT2 samples and for the PTA. There were no differences among treatments for total numbers of lettuce heads (Table 3). Only the MustangMax r/w Lannate LV and Radiant insecticide treatments had have fewer thrips damaged lettuce heads than the water check. Only the Radiant, MustangMax r/w Lannate LV, and Athena treatments had more market quality heads and higher percentages of market heads than the water check. Only Radiant and Athena treatments had more kg of market heads than the water check. 1 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E25 Table 1. WFT larvae per plant x y z Treatment oz/acre PT 5DAT 1 8DAT2 8DAT3 PTA MustangMax r/w 4.0 f/b 2.58a 0.63d 0.38d 0.80a 0.60c Lannate LV 40.0 Assail 70 WP 1.7 + 2.70a 1.85ab 1.33abc 1.18a 1.45a +Silwet-L77 0.10% vol/vol Assail 70 WP 1.7 + 1.75a 2.08a 0.95bc 0.70a 1.24ab + Induce 0.25% vol/vol Radiant 7.0 2.53a 0.70cd 0.35d 0.55a 0.53c Hero EW 11.2 1.50a 0.35d 0.45d 0.85a 0.55c Beleaf 2.8 + 2.08a 1.03bcd 0.45d 0.63a 0.70c + Mustang 4.3 Athena 17.0 2.28a 1.55abc 0.60cd 0.45a 0.87bc Water Check --- 2.23a 2.23a 1.73a 1.00a 1.65a Means within columns followed by the same letter are not significantly different LSD; P > 0.05 x y z PT = pre-treatment; DAT = days after treatment; PTA = post treatment average Table 2. WFT adults per plant x y z Treatment oz/acre PT 5DAT 1 8DAT2 8DAT3 PTA MustangMax r/w 4.0 f/b 11.83a 7.80b 4.85c 4.98a 5.88c Lannate LV 40.0 Assail 70 WP 1.7 + 12.45a 10.98a 13.00b 6.55a 10.18b + Silwet-L77 0.10% vol/vol Assail 70 WP 1.7 + 13.33a 9.73ab 13.10b 6.43a 9.75b + Induce 0.25% vol/vol Radiant 7.0 12.40a 4.20c 2.98c 4.70a 3.96d Hero EW 11.2 11.20a 2.75c 5.18c 7.13a 5.02cd Beleaf 2.8 + 10.28a 4.08c 5.05c 4.90a 4.68cd + Mustang 4.3 Athena 17.0 13.93a 4.20c 5.08c 4.53a 4.60cd Water Check --- 12.25a 12.43 16.70a 6.98a 12.03a Means within columns followed by the same letter are not significantly different LSD; P > 0.05 x y z PT = pre-treatment; DAT = days after treatment; PTA = post treatment average Table 3. Lettuce heads per 0.001 acre Total Thrips damage Market quality Kg market % Market Treatment oz/acre heads heads heads heads heads MustangMax r/w 4.0 f/b 28.75a 12.00b 16.75b 8.47bc 58.94b Lannate LV 40.0 Assail 70 WP 1.7 + 29.00a 22.25a 6.75c 1.76e 21.85c + Silwet-L77 0.10% vol/vol Assail 70 WP 1.7 + 27.25a 18.75a 8.50c 5.34cde 31.81c + Induce 0.25% vol/vol Radiant 7.0 28.50a 1.50c 27.00a 17.61a 94.63a Hero EW 11.2 29.25a 19.50a 9.75c 3.72de 33.77c Beleaf 2.8 + 29.75a 19.75a 10.00c 5.82cde 33.95c + Mustang 4.3 Athena 17.0 29.50a 12.00b 17.50b 11.04b 59.45b Water Check --- 29.00a 19.00a 10.00c 6.13cd 34.46c Means within columns followed by the same letter are not significantly different, LSD (P>0.05). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

THRIPS CONTROL IN ICEBERG LETTUCE 2012

Arthropod Management Tests , Volume 38 (1) – Jan 1, 2013

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Abstract

Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E25 (E25) LETTUCE (HEAD): Lactuca sativa var. capitata L. ‘GRIZZLY’ Eric T. Natwick University of California Agriculture and Natural Resources Desert Research and Extension Center 1050 E. Holton Rd. Holtville, CA 92250 Phone: (760) 352-9474 Fax: (760) 352-0846 E-mail: etnatwick@ucdavis.edu Western flower thrips (WFT): Frankliniella occidentalis (Pergande) The objective of this study was to evaluate the efficacy of insecticides for control of western flower thrips (WFT) on iceberg head lettuce under desert growing conditions. Head lettuce (GRIZZLY) was direct seeded on 19 Oct 2011 at the University of California Desert Research and Extension Center, El Centro, CA into double row beds on 40 inch centers. Stand establishment was achieved using overhead sprinkler irrigation and thereafter, irrigated via furrow. Plots were four beds 13.3 ft wide by 50 ft long and bordered by one untreated buffer bed. The experiment included seven insecticidal treatments and a water treated check. Four replications of each treatment were arranged as a RCB design. Insecticides and the treatment rates are shown in the tables. All insecticide treatments were applied on 18 Jan, 25 Jan and 7 Feb 2012 except the treatment of MustangMax @ 4 fl oz/acre (applied on 18 Jan and 7 Feb) rotating with (r/w) Lannate LV (applied on 25 Jan). All insecticide treatments were foliar sprays applied with a Lee Spider Spray Trac Tractor, 4-row sprayer with three TJ-60 11003VS nozzles per row, a total of 12 nozzles that delivered 50.6 gpa at 25 psi. The adjuvant, DyneAmic (Helena Chemical Co.), was added to all insecticidal spray mixtures at 0.25% vol/vol with the exception of the two Assail 70 WP treatments. Numbers of WFT from ten plants per replicate were recorded on each sampling date. WFT were sampled pre- treatment (PT) on 10 Jan 2012. WFT sampling days after treatment (DAT) included: 23 Jan (5DAT1), 2 Feb (8DAT2) and 15 Feb (8DAT3). All lettuce heads were harvested from 13.1 row ft (0.001 acre) on 17 Feb 2012 and examined for thrips feeding damage, and for market quality heads (no thrips damage). Undamaged head were weighed in kg. Data were recorded as total heads, thrips damaged heads, marketable heads, and kg of marketable heads. Percentages of market quality heads were calculated. Data were analyzed using ANOVA. Differences among means on each sampling date were determined using Least Significant Difference Test (α=0.05). WFT population levels were moderate during this trial. There were no differences among the treatments for WFT larval means from the PT or 8DAT13 samples (Table 1). All insecticide treatments except the two Assail treatments and the Athena treatment had fewer WFT larvae than the water check at 5DAT1. All insecticidal treatments except Assail + Silwet- L77 had lower WFT larval means than the water check on 8DAT2. All insecticide treatments except the two Assail treatments had fewer WFT larvae than the water check for their post-treatment averages (PTA). There were no differences among the treatments for WFT adult means from the PT or 8DAT3 samples (Table 2). All insecticide treatments except the two Assail treatments had fewer WFT adults than the water check at 5DAT1. The water check had more adult WFT than any of the insecticide treatments for the 8DAT2 samples and for the PTA. There were no differences among treatments for total numbers of lettuce heads (Table 3). Only the MustangMax r/w Lannate LV and Radiant insecticide treatments had have fewer thrips damaged lettuce heads than the water check. Only the Radiant, MustangMax r/w Lannate LV, and Athena treatments had more market quality heads and higher percentages of market heads than the water check. Only Radiant and Athena treatments had more kg of market heads than the water check. 1 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E25 Table 1. WFT larvae per plant x y z Treatment oz/acre PT 5DAT 1 8DAT2 8DAT3 PTA MustangMax r/w 4.0 f/b 2.58a 0.63d 0.38d 0.80a 0.60c Lannate LV 40.0 Assail 70 WP 1.7 + 2.70a 1.85ab 1.33abc 1.18a 1.45a +Silwet-L77 0.10% vol/vol Assail 70 WP 1.7 + 1.75a 2.08a 0.95bc 0.70a 1.24ab + Induce 0.25% vol/vol Radiant 7.0 2.53a 0.70cd 0.35d 0.55a 0.53c Hero EW 11.2 1.50a 0.35d 0.45d 0.85a 0.55c Beleaf 2.8 + 2.08a 1.03bcd 0.45d 0.63a 0.70c + Mustang 4.3 Athena 17.0 2.28a 1.55abc 0.60cd 0.45a 0.87bc Water Check --- 2.23a 2.23a 1.73a 1.00a 1.65a Means within columns followed by the same letter are not significantly different LSD; P > 0.05 x y z PT = pre-treatment; DAT = days after treatment; PTA = post treatment average Table 2. WFT adults per plant x y z Treatment oz/acre PT 5DAT 1 8DAT2 8DAT3 PTA MustangMax r/w 4.0 f/b 11.83a 7.80b 4.85c 4.98a 5.88c Lannate LV 40.0 Assail 70 WP 1.7 + 12.45a 10.98a 13.00b 6.55a 10.18b + Silwet-L77 0.10% vol/vol Assail 70 WP 1.7 + 13.33a 9.73ab 13.10b 6.43a 9.75b + Induce 0.25% vol/vol Radiant 7.0 12.40a 4.20c 2.98c 4.70a 3.96d Hero EW 11.2 11.20a 2.75c 5.18c 7.13a 5.02cd Beleaf 2.8 + 10.28a 4.08c 5.05c 4.90a 4.68cd + Mustang 4.3 Athena 17.0 13.93a 4.20c 5.08c 4.53a 4.60cd Water Check --- 12.25a 12.43 16.70a 6.98a 12.03a Means within columns followed by the same letter are not significantly different LSD; P > 0.05 x y z PT = pre-treatment; DAT = days after treatment; PTA = post treatment average Table 3. Lettuce heads per 0.001 acre Total Thrips damage Market quality Kg market % Market Treatment oz/acre heads heads heads heads heads MustangMax r/w 4.0 f/b 28.75a 12.00b 16.75b 8.47bc 58.94b Lannate LV 40.0 Assail 70 WP 1.7 + 29.00a 22.25a 6.75c 1.76e 21.85c + Silwet-L77 0.10% vol/vol Assail 70 WP 1.7 + 27.25a 18.75a 8.50c 5.34cde 31.81c + Induce 0.25% vol/vol Radiant 7.0 28.50a 1.50c 27.00a 17.61a 94.63a Hero EW 11.2 29.25a 19.50a 9.75c 3.72de 33.77c Beleaf 2.8 + 29.75a 19.75a 10.00c 5.82cde 33.95c + Mustang 4.3 Athena 17.0 29.50a 12.00b 17.50b 11.04b 59.45b Water Check --- 29.00a 19.00a 10.00c 6.13cd 34.46c Means within columns followed by the same letter are not significantly different, LSD (P>0.05).

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Arthropod Management TestsOxford University Press

Published: Jan 1, 2013

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