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ALFALFA WEEVIL & APHIDS INSECTICIDE EFFICACY IN ALFALFA, 2010

ALFALFA WEEVIL & APHIDS INSECTICIDE EFFICACY IN ALFALFA, 2010 Arthropod Management Tests 2012, Vol. 37 doi: 10.4182/amt.2012.F1 (F1) ALFALFA: Medicago sativa L. ‘CUF-101’ 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 Martin I. Lopez E-mail: marlopez@ucdavis.edu Egyptian alfalfa weevil (EAW): Hypera brunnipennis (Boheman) Blue alfalfa aphid (BAA): Acyrthosiphon kondoi Shinji Pea aphid (PA): Acyrosiphon pisum (Harris) The objective of the study was to evaluate the efficacy of the new and old insecticidal compounds used against EAW larvae and aphids PA and BAA on alfalfa grown for hay production under Spring desert growing conditions. A field study was conducted during the spring of 2010 at the UC Desert Research and Extension Center. A stand of alfalfa, “CUF 101”, was used for the experiment. Plots were arranged in a RCBD with four replications. Plots measured 33.3 ft by 50 ft. and insecticide treatments were applied on 24 Feb 2010, using a broadcast application with a tractor mounted boom. The applications were made with a Lee Spider Spray Trac operated at 50 psi delivering 54 gpa. A broadcast application was delivered through 19 TJ-60 11003VS nozzles. An adjuvant, Induce (Helena Chemical Co.), was applied at 0.25% v/v in a tank mixture with all insecticide treatments. Egyptian alfalfa weevil larvae (EAW) and an aphid complex of blue alfalfa aphid (BAA) and pea aphid (PA) were assessed in each plot with a standard 15-inch diameter insect net consisting of ten, 180 sweeps. Plots were sampled on 24 Feb pre-treatment (PT) and on 1, 3, 10 and 17 Mar or 5- days after treatment (DAT), 7DAT, 14DAT, 21DAT, respectively. Sweep samples were bagged, labeled, and frozen for later counting of EAW larvae and aphids by species (Tables 1 - 3). Data sets were analyzed using a 2-way ANOVA and means separated by a protected LSD (P≤0.05). All insecticide treatments had means for EAW larvae that were significantly lower than the means for the untreated check on all post- treatment sampling dates (Table 1). Mustang and Stallion provided the highest level of EAW control over all of the post treatment sample dates. Pretreatment aphid levels were high and there were no differences among the means for BAA, and PA for sweep samples (Tables 2-3). All insecticide treatments except Avaunt + Dimethoate 267 had means for PA that were significantly lower than the means for the untreated check for the post-treatment average, but there were no differences among the treatments means on any of the individual post-treatment sampling dates (Table 2). The sweep sample means for BAA for all insecticide treatments were significantly lower than the check means on all sampling dates with the exception of Avaunt + Dimethoate 14-DAT (Table 3). In conclusion, all insecticide treatments had good efficacy and long residual control of EAW, BAA and PA. None of the insecticide treatments showed any injury to the alfalfa plants. This research was supported by industry gift(s) of pesticide and/or research funding. Table 1. EAW larvae per 10 sweeps Treatment/ Rate/oz w xv v v v vz formulation acre PT 5 DAT 7 DAT 14 DAT 21 DAT PTA Check -- 152.00a 93.75a 33.00a 12.25a 19.25a 39.56a Lorsban 4E 32.0 222.00a 42.75b 7.50b 1.75b 5.75b 14.44b Mustang 1.5 EC 4.3 205.50a 0.50d 0.50cd 0.50bc 0.50c 0.50d Stallion 3EC 9.25 229.25a 2.50c 1.75c 0.25bc 1.50c 1.50c Stallion 3EC 11.75 156.25a 0.50d 0.00d 0.00c 0.75c 0.31d Steward 1.25 SC + Dimethoate 2.67 EC 10.0 + 121.00a 1.25cd 0.00d 0.00c 1.50c 0.69cd 16.0 Warrior II Z 2.08CS 1.5 198.25a 0.75d 1.25cd 0.00c 0.75c 0.69cd Means within columns followed by the same letter are not significantly different ( LSD; P= 0.05). Log (X+1) transformed data used for analysis;actual means reported. Pre-treatment on 24 Feb. Days after treatment. Post treatment average. 1 Arthropod Management Tests 2012, Vol. 37 doi: 10.4182/amt.2012.F1 Table 2. PA per 10 sweeps Treatment/ Rate/oz w x vz formulation acre PT 5 DAT 7 DAT 14 DAT 21 DAT PTA Check -- 3.00a 7.75a 6.00a 1.25a 11.25a 6.56a Lorsban 4E 32.0 8.00a 1.00a 0.75a 0.75a 7.50a 2.50bc Mustang 1.5EC 4.3 1.75a 0.00a 0.00a 0.75a 0.50a 0.31d Stallion 3EC 9.25 8.25a 0.00a 1.50a 1.25a 1.00a 0.94cd Stallion 3EC 11.75 2.25a 0.00a 0.75a 0.75a 4.25a 1.44bcd Steward 1.25SC 10.0 + + Dimethoate 2.67EC 16.0 6.75a 1.50a 2.25a 1.25a 5.50a 2.63ab Warrior II Z 2.08CS 1.5 7.50a 0.25a 0.25a 0.25a 4.75a 1.34bcd Means within columns followed by the same letter are not significantly different (LSD; P= 0.05). Log (X+1) transformed data used for analysis; actual mean reported Pre-treatment on 24 Feb. Days after treatment. Post treatment average. Table 3. BAA per 10 sweeps Treatment/ Rate/oz w xv v v vz formulation acre PT 5 DAT 7 DAT 14 DAT 21 DAT PTA Check -- 67.00a 125.25a 36.00a 6.00a 106.50a 68.44a Lorsban 4E 32.0 70.00a 12.50b 5.75b 0.50c 27.25b 11.50b Mustang 1.5EC 4.3 80.25a 8.00b 3.25b 0.75c 27.25b 9.81bc Stallion 3EC 9.25 97.75a 10.75b 6.25b 0.50c 19.25b 9.19bc Stallion 3EC 11.75 81.50a 5.25b 4.25b 0.00c 26.75b 9.06bc Steward 1.25 SC 10.0 + 115.00a 9.75b 4.00b 4.00ab 23.50b 10.31bc + Dimethoate 2.67EC 16.0 Warrior II Z 2.08CS 1.5 67.00a 5.75b 2.75b 1.25bc 15.25b 6.25c Means within columns followed by the same letter are not significantly different (LSD; P= 0.05). Log (X+1) transformed data used for analysis; actual means reported. Pre-treatment on 24 Feb. Days after treatment. Post treatment average. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

ALFALFA WEEVIL & APHIDS INSECTICIDE EFFICACY IN ALFALFA, 2010

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Abstract

Arthropod Management Tests 2012, Vol. 37 doi: 10.4182/amt.2012.F1 (F1) ALFALFA: Medicago sativa L. ‘CUF-101’ 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 Martin I. Lopez E-mail: marlopez@ucdavis.edu Egyptian alfalfa weevil (EAW): Hypera brunnipennis (Boheman) Blue alfalfa aphid (BAA): Acyrthosiphon kondoi Shinji Pea aphid (PA): Acyrosiphon pisum (Harris) The objective of the study was to evaluate the efficacy of the new and old insecticidal compounds used against EAW larvae and aphids PA and BAA on alfalfa grown for hay production under Spring desert growing conditions. A field study was conducted during the spring of 2010 at the UC Desert Research and Extension Center. A stand of alfalfa, “CUF 101”, was used for the experiment. Plots were arranged in a RCBD with four replications. Plots measured 33.3 ft by 50 ft. and insecticide treatments were applied on 24 Feb 2010, using a broadcast application with a tractor mounted boom. The applications were made with a Lee Spider Spray Trac operated at 50 psi delivering 54 gpa. A broadcast application was delivered through 19 TJ-60 11003VS nozzles. An adjuvant, Induce (Helena Chemical Co.), was applied at 0.25% v/v in a tank mixture with all insecticide treatments. Egyptian alfalfa weevil larvae (EAW) and an aphid complex of blue alfalfa aphid (BAA) and pea aphid (PA) were assessed in each plot with a standard 15-inch diameter insect net consisting of ten, 180 sweeps. Plots were sampled on 24 Feb pre-treatment (PT) and on 1, 3, 10 and 17 Mar or 5- days after treatment (DAT), 7DAT, 14DAT, 21DAT, respectively. Sweep samples were bagged, labeled, and frozen for later counting of EAW larvae and aphids by species (Tables 1 - 3). Data sets were analyzed using a 2-way ANOVA and means separated by a protected LSD (P≤0.05). All insecticide treatments had means for EAW larvae that were significantly lower than the means for the untreated check on all post- treatment sampling dates (Table 1). Mustang and Stallion provided the highest level of EAW control over all of the post treatment sample dates. Pretreatment aphid levels were high and there were no differences among the means for BAA, and PA for sweep samples (Tables 2-3). All insecticide treatments except Avaunt + Dimethoate 267 had means for PA that were significantly lower than the means for the untreated check for the post-treatment average, but there were no differences among the treatments means on any of the individual post-treatment sampling dates (Table 2). The sweep sample means for BAA for all insecticide treatments were significantly lower than the check means on all sampling dates with the exception of Avaunt + Dimethoate 14-DAT (Table 3). In conclusion, all insecticide treatments had good efficacy and long residual control of EAW, BAA and PA. None of the insecticide treatments showed any injury to the alfalfa plants. This research was supported by industry gift(s) of pesticide and/or research funding. Table 1. EAW larvae per 10 sweeps Treatment/ Rate/oz w xv v v v vz formulation acre PT 5 DAT 7 DAT 14 DAT 21 DAT PTA Check -- 152.00a 93.75a 33.00a 12.25a 19.25a 39.56a Lorsban 4E 32.0 222.00a 42.75b 7.50b 1.75b 5.75b 14.44b Mustang 1.5 EC 4.3 205.50a 0.50d 0.50cd 0.50bc 0.50c 0.50d Stallion 3EC 9.25 229.25a 2.50c 1.75c 0.25bc 1.50c 1.50c Stallion 3EC 11.75 156.25a 0.50d 0.00d 0.00c 0.75c 0.31d Steward 1.25 SC + Dimethoate 2.67 EC 10.0 + 121.00a 1.25cd 0.00d 0.00c 1.50c 0.69cd 16.0 Warrior II Z 2.08CS 1.5 198.25a 0.75d 1.25cd 0.00c 0.75c 0.69cd Means within columns followed by the same letter are not significantly different ( LSD; P= 0.05). Log (X+1) transformed data used for analysis;actual means reported. Pre-treatment on 24 Feb. Days after treatment. Post treatment average. 1 Arthropod Management Tests 2012, Vol. 37 doi: 10.4182/amt.2012.F1 Table 2. PA per 10 sweeps Treatment/ Rate/oz w x vz formulation acre PT 5 DAT 7 DAT 14 DAT 21 DAT PTA Check -- 3.00a 7.75a 6.00a 1.25a 11.25a 6.56a Lorsban 4E 32.0 8.00a 1.00a 0.75a 0.75a 7.50a 2.50bc Mustang 1.5EC 4.3 1.75a 0.00a 0.00a 0.75a 0.50a 0.31d Stallion 3EC 9.25 8.25a 0.00a 1.50a 1.25a 1.00a 0.94cd Stallion 3EC 11.75 2.25a 0.00a 0.75a 0.75a 4.25a 1.44bcd Steward 1.25SC 10.0 + + Dimethoate 2.67EC 16.0 6.75a 1.50a 2.25a 1.25a 5.50a 2.63ab Warrior II Z 2.08CS 1.5 7.50a 0.25a 0.25a 0.25a 4.75a 1.34bcd Means within columns followed by the same letter are not significantly different (LSD; P= 0.05). Log (X+1) transformed data used for analysis; actual mean reported Pre-treatment on 24 Feb. Days after treatment. Post treatment average. Table 3. BAA per 10 sweeps Treatment/ Rate/oz w xv v v vz formulation acre PT 5 DAT 7 DAT 14 DAT 21 DAT PTA Check -- 67.00a 125.25a 36.00a 6.00a 106.50a 68.44a Lorsban 4E 32.0 70.00a 12.50b 5.75b 0.50c 27.25b 11.50b Mustang 1.5EC 4.3 80.25a 8.00b 3.25b 0.75c 27.25b 9.81bc Stallion 3EC 9.25 97.75a 10.75b 6.25b 0.50c 19.25b 9.19bc Stallion 3EC 11.75 81.50a 5.25b 4.25b 0.00c 26.75b 9.06bc Steward 1.25 SC 10.0 + 115.00a 9.75b 4.00b 4.00ab 23.50b 10.31bc + Dimethoate 2.67EC 16.0 Warrior II Z 2.08CS 1.5 67.00a 5.75b 2.75b 1.25bc 15.25b 6.25c Means within columns followed by the same letter are not significantly different (LSD; P= 0.05). Log (X+1) transformed data used for analysis; actual means reported. Pre-treatment on 24 Feb. Days after treatment. Post treatment average.

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Arthropod Management TestsOxford University Press

Published: Jan 1, 2012

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