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INSECTICIDE EFFICACY AGAINST WHITEFLY IN CANTALOUPE MELON, 2012

INSECTICIDE EFFICACY AGAINST WHITEFLY IN CANTALOUPE MELON, 2012 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E33 (E33) MELON: Cucumis melo L. var. cantalupensis Naudin, ‘Gold Express’ 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 Sweetpotato whitefly (SWF): Bemisia tabaci (Gennadius) – biotype B The objective of the study was to evaluate the efficacy of various insecticides against sweetpotato whitefly adults and nymphs on spring planted cantaloupe melon under desert growing conditions. An insecticide trial was established on melon at the University of California Desert Research and Extension Center, Holtville, CA. The cantaloupe melon variety ‘Gold Express’ was direct seeded into single row beds, measuring 80 inches center to center, on 31 Mar 2012. Stand establishment was achieved using drip irrigation, which was used thereafter. Plots were two beds wide (13.33 ft) by 50 ft long and bordered by one untreated bed. Included were seven foliar insecticide spray treatments and an untreated check in a st th nd RCB design experiment with four replicates. Insecticide treatments were applied on the 1 , 15 , and 22 of May 2012 at the rate equivalencies listed in the tables. Foliar sprays were applied using a Lee Spider Spray Trac tractor with a spray boom that included five TJ-60 11003VS nozzles per bed, covering two beds (ten nozzles on the boom) applying 43.1 gpa at th 30 psi. Whitefly adults were sampled by examining the 5 leaf from vine tip on 10 random plants per plot. Whitefly eggs and nymphs were counted using a binocular microscope in the laboratory within 1-leaf disk of 1.65 cm on the abaxial leaf surface in the lower left quadrant from 10-melon leaves randomly extracted from each plot. Melon fruit were harvested th th th th from 13.1 row ft, equivalent to 0.002 acre on the 5 , 11 , 18 and 25 of Jun; data from the four sampling dates were then pooled for analysis. Melons were separated by size categories (sizes based on the number of melons of a given size that fit into a standard melon carton). Melon sizes included: 9’s, 12’s, 15’s, 18’s, 23’s and 30’s. All market quality melon fruit from each plot were weighed together and recorded in kg. There were no differences among the treatments for SWF adults, eggs or nymphs on 30 Apr; 1 day prior to applications (DPA). All insecticide treatments had fewer SWF adults than the untreated check on 7 May, 6 days after applications (DAA) one, Table 1. Only the insecticide applications of GF-2860 at 1.78 oz/acre, GF-2860 at 7.14 oz/acre, and Sivanto had fewer SWF adults than the untreated check on 14 May (13-DAA1). All insecticide treatments except Closer, Radiant and GF-2860 at 5.35 oz/acre had fewer SWF adults compared to the untreated check on 21 May, 6-DAA2. Only the insecticide treatments of GF-2860 at 3.57 oz/acre and Radiant did not have fewer SWF adults than the untreated check on 29 May, 8-DAA3. The post treatment averages for all insecticide treatments except Closer and Radiant were significantly lower than the untreated check. There were no differences among the treatments for SWF eggs on any of the individual sampling dates, but all of the insecticide treatments except the three lowest rates of GF-2860 (1.78 oz/acre, 3.57 oz/acre, 5.35 oz/acre) and Radiant had lower PTA for SWF eggs compared to the untreated check, Table 2. There were no differences among the treatments for SWF nymphs on 30 April and 7 May, but all treatments except Radiant had fewer SWF nymphs on 14 May (13-DAA1), Table 3. All insecticide treatment except GF-2860 at 5.35 oz/acre had fewer SWF nymphs than the untreated check on 21 May, 6-DAA2. Only Closer and Sivanto insecticide treatments had fewer SWF nymphs than the untreated check on 29 May, 8-DAA3. Only GF-2860 at 7.14 oz/acre and Sivanto had lower PTA for SWF nymphs compared to the untreated check. Only the Sivanto treatment had more fruit than the untreated check, Table 4. No phytotoxicity symptoms were observed following any of the insecticide treatments. This research was supported by industry gifts. 1 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E33 Table 1. Adult SWF per melon leaf Treatment/ formulation Rate/acre 30 Apr 7 May 14 May 21 May 29 May PTA GF-2860 1.78 oz 2.30a 1.35bc 0.65bc 3.88c 3.50b 2.34c GF-2860 3.57 oz 2.55a 1.18bc 1.05ab 3.40c 6.73a 3.09bc GF-2860 5.35 oz 1.63a 1.20bc 0.85abc 5.70ab 3.63b 2.84bc GF-2860 7.14 oz 1.78a 1.63bc 0.70bc 4.20bc 3.68b 2.55c Closer SC 5.7 fl oz 2.28a 2.15b 1.23a 6.73a 4.00b 3.53ab Radiant 1SC 5.7 fl oz 1.60a 1.10bc 1.25a 6.70a 5.18ab 3.56ab Sivanto 200SL 14.0 fl oz 1.68a 0.53c 0.43c 0.83 d 0.98c 0.69 d Untreated Check --- 1.10a 5.05a 1.30a 6.88a 3.80b 4.26a Means within columns followed by the same letter are not significantly different (P>0.05). Post treatment average. Table 2. SWF eggs per 16.5 cm of melon leaf Treatment/ formulation Rate/acre 30 Apr 7 May 14 May 21 May 29 May PTAz GF-2860 1.78 oz 5.50a 2.25a 0.75a 1.50a 2.75a 1.81abc GF-2860 3.57 oz 2.00a 2.25a 2.25a 0.75a 3.00a 2.06ab GF-2860 5.35 oz 7.25a 4.25a 1.75a 1.25a 3.50a 2.69a GF-2860 7.14 oz 2.25a 3.00a 0.50a 1.00a 0.25a 1.19bc Closer SC 5.7 fl oz 2.75a 1.75a 0.00a 0.75a 0.00a 0.63c Radiant 1SC 5.7 fl oz 4.25a 3.00a 0.75a 0.50a 2.25a 1.63abc Sivanto 200SL 14.0 fl oz 2.75a 0.50a 0.25a 1.00a 1.00a 0.69c Untreated Check --- 2.50a 2.50a 2.75a 2.75a 3.75a 2.94a Means within columns followed by the same letter are not significantly different (P>0.05). Post treatment average. Table 3. SWF nymphs per 16.5 cm of melon leaf Treatment/ x x z formulation Rate/acre 30 Apr 7 May 14 May 21 May 29 May PTA GF-2860 1.78 oz 14.75a 43.25a 22.25b 0.92b 0.87ab 20.69ab GF-2860 3.57 oz 18.25a 30.25a 23.00b 0.96b 1.02ab 18.44ab GF-2860 5.35 oz 20.25a 27.25a 22.25b 1.06ab 1.08ab 18.75ab GF-2860 7.14 oz 19.75a 23.25a 21.50b 0.72bc 0.88ab 15.38bc Closer SC 5.7 fl oz 15.00a 49.50a 16.00bc 0.85bc 0.78bc 19.75ab Radiant 1SC 5.7 fl oz 10.25a 35.75a 39.00a 0.95b 0.99ab 23.19a Sivanto 200SL 14.0 fl oz 14.00a 21.75a 9.50c 0.57c 0.46c 9.13c Untreated Check --- 13.25a 26.75a 34.25a 1.34a 1.17a 25.06a Means within columns followed by the same letter are not significantly different (P>0.05). Log transformed data used for analysis. Post treatment average. Table 4. Kg of fruit and numbers of fruit by size per 0.002 acre Treatment/ Total of formulation Rate/acre Kg Fruit 9's 12’s 15’s 18’s 23’s 30’s all fruit % brix GF-2860 1.78 oz 19.03 0.50 2.75 7.25 2.25b 2.50 2.25 17.50c 10.38 GF-2860 3.57 oz 24.45 0.25 2.00 5.00 9.25a 3.25 0.25 20.00abc 9.83 GF-2860 5.35 oz 25.79 0.50 5.25 7.75 6.25a 2.50 0.75 23.00abc 9.38 GF-2860 7.14 oz 22.33 1.00 2.75 5.75 6.25a 1.75 1.25 18.50bc 9.94 Closer SC 5.7 fl oz 21.59 0.75 0.25 7.00 8.50a 5.50 0.50 22.50ab 9.79 Radiant 1SC 5.7 fl oz 21.19 1.50 3.50 3.00 5.50a 4.00 0.75 18.25c 9.56 Sivanto 200SL 14.0 fl oz 26.02 0.50 2.75 5.75 6.75a 5.00 2.00 22.75a 10.27 Untreated Check --- 21.11 0.50 4.50 5.75 4.75a 2.00 1.00 18.50bc 10.17 Means within columns not followed by any letters are not significantly different (P>0.05). Means within columns followed by the same letter are not significantly different (P>0.05). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

INSECTICIDE EFFICACY AGAINST WHITEFLY IN CANTALOUPE MELON, 2012

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

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Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E33 (E33) MELON: Cucumis melo L. var. cantalupensis Naudin, ‘Gold Express’ 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 Sweetpotato whitefly (SWF): Bemisia tabaci (Gennadius) – biotype B The objective of the study was to evaluate the efficacy of various insecticides against sweetpotato whitefly adults and nymphs on spring planted cantaloupe melon under desert growing conditions. An insecticide trial was established on melon at the University of California Desert Research and Extension Center, Holtville, CA. The cantaloupe melon variety ‘Gold Express’ was direct seeded into single row beds, measuring 80 inches center to center, on 31 Mar 2012. Stand establishment was achieved using drip irrigation, which was used thereafter. Plots were two beds wide (13.33 ft) by 50 ft long and bordered by one untreated bed. Included were seven foliar insecticide spray treatments and an untreated check in a st th nd RCB design experiment with four replicates. Insecticide treatments were applied on the 1 , 15 , and 22 of May 2012 at the rate equivalencies listed in the tables. Foliar sprays were applied using a Lee Spider Spray Trac tractor with a spray boom that included five TJ-60 11003VS nozzles per bed, covering two beds (ten nozzles on the boom) applying 43.1 gpa at th 30 psi. Whitefly adults were sampled by examining the 5 leaf from vine tip on 10 random plants per plot. Whitefly eggs and nymphs were counted using a binocular microscope in the laboratory within 1-leaf disk of 1.65 cm on the abaxial leaf surface in the lower left quadrant from 10-melon leaves randomly extracted from each plot. Melon fruit were harvested th th th th from 13.1 row ft, equivalent to 0.002 acre on the 5 , 11 , 18 and 25 of Jun; data from the four sampling dates were then pooled for analysis. Melons were separated by size categories (sizes based on the number of melons of a given size that fit into a standard melon carton). Melon sizes included: 9’s, 12’s, 15’s, 18’s, 23’s and 30’s. All market quality melon fruit from each plot were weighed together and recorded in kg. There were no differences among the treatments for SWF adults, eggs or nymphs on 30 Apr; 1 day prior to applications (DPA). All insecticide treatments had fewer SWF adults than the untreated check on 7 May, 6 days after applications (DAA) one, Table 1. Only the insecticide applications of GF-2860 at 1.78 oz/acre, GF-2860 at 7.14 oz/acre, and Sivanto had fewer SWF adults than the untreated check on 14 May (13-DAA1). All insecticide treatments except Closer, Radiant and GF-2860 at 5.35 oz/acre had fewer SWF adults compared to the untreated check on 21 May, 6-DAA2. Only the insecticide treatments of GF-2860 at 3.57 oz/acre and Radiant did not have fewer SWF adults than the untreated check on 29 May, 8-DAA3. The post treatment averages for all insecticide treatments except Closer and Radiant were significantly lower than the untreated check. There were no differences among the treatments for SWF eggs on any of the individual sampling dates, but all of the insecticide treatments except the three lowest rates of GF-2860 (1.78 oz/acre, 3.57 oz/acre, 5.35 oz/acre) and Radiant had lower PTA for SWF eggs compared to the untreated check, Table 2. There were no differences among the treatments for SWF nymphs on 30 April and 7 May, but all treatments except Radiant had fewer SWF nymphs on 14 May (13-DAA1), Table 3. All insecticide treatment except GF-2860 at 5.35 oz/acre had fewer SWF nymphs than the untreated check on 21 May, 6-DAA2. Only Closer and Sivanto insecticide treatments had fewer SWF nymphs than the untreated check on 29 May, 8-DAA3. Only GF-2860 at 7.14 oz/acre and Sivanto had lower PTA for SWF nymphs compared to the untreated check. Only the Sivanto treatment had more fruit than the untreated check, Table 4. No phytotoxicity symptoms were observed following any of the insecticide treatments. This research was supported by industry gifts. 1 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.E33 Table 1. Adult SWF per melon leaf Treatment/ formulation Rate/acre 30 Apr 7 May 14 May 21 May 29 May PTA GF-2860 1.78 oz 2.30a 1.35bc 0.65bc 3.88c 3.50b 2.34c GF-2860 3.57 oz 2.55a 1.18bc 1.05ab 3.40c 6.73a 3.09bc GF-2860 5.35 oz 1.63a 1.20bc 0.85abc 5.70ab 3.63b 2.84bc GF-2860 7.14 oz 1.78a 1.63bc 0.70bc 4.20bc 3.68b 2.55c Closer SC 5.7 fl oz 2.28a 2.15b 1.23a 6.73a 4.00b 3.53ab Radiant 1SC 5.7 fl oz 1.60a 1.10bc 1.25a 6.70a 5.18ab 3.56ab Sivanto 200SL 14.0 fl oz 1.68a 0.53c 0.43c 0.83 d 0.98c 0.69 d Untreated Check --- 1.10a 5.05a 1.30a 6.88a 3.80b 4.26a Means within columns followed by the same letter are not significantly different (P>0.05). Post treatment average. Table 2. SWF eggs per 16.5 cm of melon leaf Treatment/ formulation Rate/acre 30 Apr 7 May 14 May 21 May 29 May PTAz GF-2860 1.78 oz 5.50a 2.25a 0.75a 1.50a 2.75a 1.81abc GF-2860 3.57 oz 2.00a 2.25a 2.25a 0.75a 3.00a 2.06ab GF-2860 5.35 oz 7.25a 4.25a 1.75a 1.25a 3.50a 2.69a GF-2860 7.14 oz 2.25a 3.00a 0.50a 1.00a 0.25a 1.19bc Closer SC 5.7 fl oz 2.75a 1.75a 0.00a 0.75a 0.00a 0.63c Radiant 1SC 5.7 fl oz 4.25a 3.00a 0.75a 0.50a 2.25a 1.63abc Sivanto 200SL 14.0 fl oz 2.75a 0.50a 0.25a 1.00a 1.00a 0.69c Untreated Check --- 2.50a 2.50a 2.75a 2.75a 3.75a 2.94a Means within columns followed by the same letter are not significantly different (P>0.05). Post treatment average. Table 3. SWF nymphs per 16.5 cm of melon leaf Treatment/ x x z formulation Rate/acre 30 Apr 7 May 14 May 21 May 29 May PTA GF-2860 1.78 oz 14.75a 43.25a 22.25b 0.92b 0.87ab 20.69ab GF-2860 3.57 oz 18.25a 30.25a 23.00b 0.96b 1.02ab 18.44ab GF-2860 5.35 oz 20.25a 27.25a 22.25b 1.06ab 1.08ab 18.75ab GF-2860 7.14 oz 19.75a 23.25a 21.50b 0.72bc 0.88ab 15.38bc Closer SC 5.7 fl oz 15.00a 49.50a 16.00bc 0.85bc 0.78bc 19.75ab Radiant 1SC 5.7 fl oz 10.25a 35.75a 39.00a 0.95b 0.99ab 23.19a Sivanto 200SL 14.0 fl oz 14.00a 21.75a 9.50c 0.57c 0.46c 9.13c Untreated Check --- 13.25a 26.75a 34.25a 1.34a 1.17a 25.06a Means within columns followed by the same letter are not significantly different (P>0.05). Log transformed data used for analysis. Post treatment average. Table 4. Kg of fruit and numbers of fruit by size per 0.002 acre Treatment/ Total of formulation Rate/acre Kg Fruit 9's 12’s 15’s 18’s 23’s 30’s all fruit % brix GF-2860 1.78 oz 19.03 0.50 2.75 7.25 2.25b 2.50 2.25 17.50c 10.38 GF-2860 3.57 oz 24.45 0.25 2.00 5.00 9.25a 3.25 0.25 20.00abc 9.83 GF-2860 5.35 oz 25.79 0.50 5.25 7.75 6.25a 2.50 0.75 23.00abc 9.38 GF-2860 7.14 oz 22.33 1.00 2.75 5.75 6.25a 1.75 1.25 18.50bc 9.94 Closer SC 5.7 fl oz 21.59 0.75 0.25 7.00 8.50a 5.50 0.50 22.50ab 9.79 Radiant 1SC 5.7 fl oz 21.19 1.50 3.50 3.00 5.50a 4.00 0.75 18.25c 9.56 Sivanto 200SL 14.0 fl oz 26.02 0.50 2.75 5.75 6.75a 5.00 2.00 22.75a 10.27 Untreated Check --- 21.11 0.50 4.50 5.75 4.75a 2.00 1.00 18.50bc 10.17 Means within columns not followed by any letters are not significantly different (P>0.05). Means within columns followed by the same letter are not significantly different (P>0.05).

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Arthropod Management TestsOxford University Press

Published: Jan 1, 2013

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