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EFFICACY OF FOLIAR INSECTICIDES FOR MANAGEMENT OF SILVERLEAF ON SQUASH, 2003B

EFFICACY OF FOLIAR INSECTICIDES FOR MANAGEMENT OF SILVERLEAF ON SQUASH, 2003B (E73) SQUASH (SUMMER): Cucurbita pepo L. EFFICACY OF FOLIAR INSECTICIDES FOR MANAGEMENT OF SILVERLEAF ON SQUASH, 2003B Alton N. Sparks, Jr. Georgia Cooperative Extension Service P.O. Box 1209 Tifton, GA 31793 Phone: (229) 386-3424 Fax: (229) 386-7133 E-mail: asparks@uga.edu David G. Riley University of Georgia Coastal Plain Experiment Station P.O. Box 748 Tifton, GA 31793 Phone: (229) 386 3374 Fax: (229) 386-3086 E-mail: dgr@tifton.uga.edu Silverleaf whitefly (SLWF): Bemisia argentifolii Bellows & Perring, Sweetpotato whitefly Biotype B, Bemisia tabaci (Gennadius) A yellow crookneck squash was direct seeded for this test, with two rows on 6-ft-wide beds. Experimental plots were two rows wide and 23 ft long. Treatments were arranged in a RCB design with four replications. All insecticide treatments were tank mixed with Dyne-Amic at 0.5% v/v. Applications were made on 15 and 23 Sep and 1 Oct with a CO -pressurized (50 psi) backpack sprayer calibrated to deliver 30 gpa. Treatments were applied with three ceramic hollow-cone nozzles per row (one over-the-top, 1 on drops on each side of the row). Oil was applied for virus suppression across the entire test on 9, 11 and 19 Sep. SLWF populations were monitored in each plot by random selection of five leaves per plot and counting all whitefly adults on each leaf. Plots were visually rated for severity of silverleaf symptoms on foliage, which results from SLWF feeding. A 1 to 5 scale was used as follows: 1 = little or no silverleaf (except on older leaves); 2 = silverleaf symptoms minor but apparent (good control); 3 = silverleaf symptoms obvious through most of plot; 4 = silverleaf symptoms moderate to heavy throughout plot; 5 = All or nearly all leaves with severe silverleaf symptoms. On each harvest date, all fruit of harvestable size were collected from each plot and weighed. All fruit, except solid green fruit (virus infected), were categorized by color based on a 1 to 11 scale where 1 = white; 2 = near white; 3 = cream colored; 4 = intermediate to 3 and 5; 5 = a “normal” bright yellow of a yellow squash; 6 = intermediate to 5 and 7; 7 = orangish-yellow; etc. The number of fruit in each color category was recorded. Data were subjected to ANOVA and means were separated using LSD (P ≤ 0.05). All insecticide treatments provided suppression of whitefly adult populations. All insecticides improved silverleaf ratings (Table 1), with the greatest improvement obtained with Assail and V-10112. Both Assail and V-10112 showed significant rate effects on the Oct 2 silverleaf ratings, with the higher rates of both products providing better suppression of silverleaf symptoms. All of the insecticide treatments improved fruit color as compared to the check (Table 2). Assail and V-10112 generally provided larger increases in the percent of fruit in the darker categories than the Danitol+Endosulfan treatment. Both Assail and V- 10112 showed a trend for a rate effect, with the higher rates providing a greater increase in darker fruit. Assail and V-10112 showed great promise as foliar insecticides for management of silverleaf whitefly and related problems in squash. Table 1. No. of SLWF adults per leaf Silverleaf ratings Treatment/ Rate formulation lb (AI)/acre 16 Sep 24 Sep 2 Oct 24 Sep 2 Oct Untreated check -- 5.45a 3.40a 4.60a 5.00a 5.00a Danitol 2.4EC + 0.3 + Thiodan 3EC 0.75 1.60b 0.20c 1.65b 4.25a 3.75b Assail 70WP 0.048 1.20b 1.55b 1.05b 2.50b 2.75c Assail 70WP 0.074 1.50b 0.95bc 0.95b 2.50b 2.00d V-10112 20SG 0.088 1.10b 1.30bc 0.85b 2.75b 2.75c V-10112 20SG 0.13 0.95b 0.85bc 0.70b 2.50b 1.75d Numbers within columns followed by the same letter are not significantly different (P > 0.05, LSD). All insecticide treatments were tank mixed with Dyne-Amic at 0.5% v/v. Silverleaf rating: 1 = little or no silverleaf (except on older leaves); 2 = silverleaf symptoms minor but apparent (good control); 3 = silverleaf symptoms obvious through most of plot; 4 = silverleaf symptoms moderate to heavy throughout plot; 5 = All or nearly all leaves with severe silverleaf symptoms. Table 2. Squash color scale No. of fruit rated 4 or darker No. of fruit rated 2 Treatment/ Rate formulation lb (AI)/acre 3 Oct 9 Oct Total 3 Oct 9 Oct Total Untreated check -- 17.7c 15.7d 15.6d 20.0a 33.3a 31.7a Danitol 2.4EC + 0.3 + Thiodan 3EC 0.75 32.7c 63.2c 57.0c 5.4b 1.8b 2.9b Assail 70WP 0.048 57.6b 66.7bc 63.5bc 1.3b 0.0b 0.5b Assail 70WP 0.074 76.7ab 78.3a 77.7a 0.0b 0.5b 0.4b V-10112 20SG 0.088 72.2ab 70.0abc 70.5ab 0.0b 0.6b 0.4b V-10112 20SG 0.13 90.0a 77.3ab 80.2a 0.0b 0.0b 0.0b Numbers within columns followed by the same letter are not significantly different (P > 0.05, LSD). All insecticide treatments were tank mixed with Dyne-Amic at 0.5% v/v. Squash color scale: 1 = white; 2 = near white; 3 = cream colored; 4 = intermediate to 3 and 5; 5 = a “normal” bright yellow of a yellow squash; 6 = intermediate to 5 and 7; 7 = orangish-yellow. Very few fruit are rated above 5 and none rated as a true 1. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

EFFICACY OF FOLIAR INSECTICIDES FOR MANAGEMENT OF SILVERLEAF ON SQUASH, 2003B

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10.1093/amt/30.1.E73
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Abstract

(E73) SQUASH (SUMMER): Cucurbita pepo L. EFFICACY OF FOLIAR INSECTICIDES FOR MANAGEMENT OF SILVERLEAF ON SQUASH, 2003B Alton N. Sparks, Jr. Georgia Cooperative Extension Service P.O. Box 1209 Tifton, GA 31793 Phone: (229) 386-3424 Fax: (229) 386-7133 E-mail: asparks@uga.edu David G. Riley University of Georgia Coastal Plain Experiment Station P.O. Box 748 Tifton, GA 31793 Phone: (229) 386 3374 Fax: (229) 386-3086 E-mail: dgr@tifton.uga.edu Silverleaf whitefly (SLWF): Bemisia argentifolii Bellows & Perring, Sweetpotato whitefly Biotype B, Bemisia tabaci (Gennadius) A yellow crookneck squash was direct seeded for this test, with two rows on 6-ft-wide beds. Experimental plots were two rows wide and 23 ft long. Treatments were arranged in a RCB design with four replications. All insecticide treatments were tank mixed with Dyne-Amic at 0.5% v/v. Applications were made on 15 and 23 Sep and 1 Oct with a CO -pressurized (50 psi) backpack sprayer calibrated to deliver 30 gpa. Treatments were applied with three ceramic hollow-cone nozzles per row (one over-the-top, 1 on drops on each side of the row). Oil was applied for virus suppression across the entire test on 9, 11 and 19 Sep. SLWF populations were monitored in each plot by random selection of five leaves per plot and counting all whitefly adults on each leaf. Plots were visually rated for severity of silverleaf symptoms on foliage, which results from SLWF feeding. A 1 to 5 scale was used as follows: 1 = little or no silverleaf (except on older leaves); 2 = silverleaf symptoms minor but apparent (good control); 3 = silverleaf symptoms obvious through most of plot; 4 = silverleaf symptoms moderate to heavy throughout plot; 5 = All or nearly all leaves with severe silverleaf symptoms. On each harvest date, all fruit of harvestable size were collected from each plot and weighed. All fruit, except solid green fruit (virus infected), were categorized by color based on a 1 to 11 scale where 1 = white; 2 = near white; 3 = cream colored; 4 = intermediate to 3 and 5; 5 = a “normal” bright yellow of a yellow squash; 6 = intermediate to 5 and 7; 7 = orangish-yellow; etc. The number of fruit in each color category was recorded. Data were subjected to ANOVA and means were separated using LSD (P ≤ 0.05). All insecticide treatments provided suppression of whitefly adult populations. All insecticides improved silverleaf ratings (Table 1), with the greatest improvement obtained with Assail and V-10112. Both Assail and V-10112 showed significant rate effects on the Oct 2 silverleaf ratings, with the higher rates of both products providing better suppression of silverleaf symptoms. All of the insecticide treatments improved fruit color as compared to the check (Table 2). Assail and V-10112 generally provided larger increases in the percent of fruit in the darker categories than the Danitol+Endosulfan treatment. Both Assail and V- 10112 showed a trend for a rate effect, with the higher rates providing a greater increase in darker fruit. Assail and V-10112 showed great promise as foliar insecticides for management of silverleaf whitefly and related problems in squash. Table 1. No. of SLWF adults per leaf Silverleaf ratings Treatment/ Rate formulation lb (AI)/acre 16 Sep 24 Sep 2 Oct 24 Sep 2 Oct Untreated check -- 5.45a 3.40a 4.60a 5.00a 5.00a Danitol 2.4EC + 0.3 + Thiodan 3EC 0.75 1.60b 0.20c 1.65b 4.25a 3.75b Assail 70WP 0.048 1.20b 1.55b 1.05b 2.50b 2.75c Assail 70WP 0.074 1.50b 0.95bc 0.95b 2.50b 2.00d V-10112 20SG 0.088 1.10b 1.30bc 0.85b 2.75b 2.75c V-10112 20SG 0.13 0.95b 0.85bc 0.70b 2.50b 1.75d Numbers within columns followed by the same letter are not significantly different (P > 0.05, LSD). All insecticide treatments were tank mixed with Dyne-Amic at 0.5% v/v. Silverleaf rating: 1 = little or no silverleaf (except on older leaves); 2 = silverleaf symptoms minor but apparent (good control); 3 = silverleaf symptoms obvious through most of plot; 4 = silverleaf symptoms moderate to heavy throughout plot; 5 = All or nearly all leaves with severe silverleaf symptoms. Table 2. Squash color scale No. of fruit rated 4 or darker No. of fruit rated 2 Treatment/ Rate formulation lb (AI)/acre 3 Oct 9 Oct Total 3 Oct 9 Oct Total Untreated check -- 17.7c 15.7d 15.6d 20.0a 33.3a 31.7a Danitol 2.4EC + 0.3 + Thiodan 3EC 0.75 32.7c 63.2c 57.0c 5.4b 1.8b 2.9b Assail 70WP 0.048 57.6b 66.7bc 63.5bc 1.3b 0.0b 0.5b Assail 70WP 0.074 76.7ab 78.3a 77.7a 0.0b 0.5b 0.4b V-10112 20SG 0.088 72.2ab 70.0abc 70.5ab 0.0b 0.6b 0.4b V-10112 20SG 0.13 90.0a 77.3ab 80.2a 0.0b 0.0b 0.0b Numbers within columns followed by the same letter are not significantly different (P > 0.05, LSD). All insecticide treatments were tank mixed with Dyne-Amic at 0.5% v/v. Squash color scale: 1 = white; 2 = near white; 3 = cream colored; 4 = intermediate to 3 and 5; 5 = a “normal” bright yellow of a yellow squash; 6 = intermediate to 5 and 7; 7 = orangish-yellow. Very few fruit are rated above 5 and none rated as a true 1.

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Arthropod Management TestsOxford University Press

Published: Jan 1, 2005

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