Efficacy of Selected Insecticides for Control of Cotton Aphid (Aphis ...

Efficacy of Selected Insecticides for Control of Cotton Aphid (Aphis gossypii) and Bandedwinged Whitefly (Trialeurodes Abutilonea) in Cotton — 2005 Jarrod T. Hardke, Gus M. Lorenz, Kyle Colwell, Craig Shelton, and Wes Kirkpatrick1 RESEARCH PROBLEM The widespread implementation of transgenic Bt cotton has led to pests that were once considered “secondary” now being more serious (Greene and Capps, 2002). The high reproductive rate and rapid life cycle of the cotton aphid have provided the insect with an increased ability to develop resistance to insecticides (Robertson, 2004). The bandedwinged whitefly, another pest, is usually present in cotton at low populations, rarely achieving damaging levels (Hendrix et al., 2002). When these pests reach population levels that require treatment, current data on available products are needed to determine appropriate management decisions. These studies utilized selected rates of various insecticides currently recommended for control of these pests, as well as selected rates of several insecticides not presently recommended for their control (Greene and Capps, 2002). The aphid test consisted of the following treatments: Currently recommended – Intruder® (acetamiprid), Centric® (thiamthoxam), Trimax® (imidacloprid), and Bidrin® (dicrotophos); and Not currently recommended – Carbine® (flonicamid) and Mustang Max® (zeta-cypermethrin). The whitefly test consisted of the following treatments: Currently recommended – Intruder (acetamiprid), Capture® (bifenthrin), Orthene® (acephate), and Centric (thiamethoxam); and Not currently recommended – Experimental 1 and Experimental 2. BACKGROUND INFORMATION The cotton aphid, Aphis gossypii, has recently become a major pest in the U.S. Cotton Belt. Early-season infestations can result in plant discoloration and disfigurement, and late-season infestations can cause “sticky cotton” and sooty mold (Wells et Seasonal agricultural technician, extension entomologist, seasonal agricultural technician, and graduate assistant, Cooperative Extension Service, Little Rock; and cooperative extension agent - agriculture, Desha County, McGehee, respectively. 1

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Summaries of Arkansas Cotton Research 2005 al., 1998). During the 2003 growing season, an estimated 600,000 acres were infested with aphids, of which 200,000 acres were treated. There was no loss attributed to aphid infestation (Williams, 2003). The current threshold for aphids in Arkansas is to treat “when populations are building and aphid colonies are present on approximately 50% of the plants” (Greene et al., 2005). The bandedwinged whitefly, Trialeurodes abutilonea (Haldeman), is found in most of the US Cotton Belt but is only rarely an economically significat pest in cotton (Hendrix et al., 2002). During the 2003 growing season, an estimated 350,000 acres were infested with whiteflies, of which 12,000 acres were treated. There was no loss attributed to whitefly infestation (Williams, 2004). The current threshold for whiteflies in Arkansas is to “treat infested areas when 50% of the plants are infested” (Greene, 2005). RESEARCH DESCRIPTION The aphid test was conducted at Desha County, Ark., in 2005. The field was planted on 27 April using the variety Stoneville 5599 and afterwards subdivided into plots of 4 rows on 38-inch spacing and 50-feet long. Plots were set up in a randomized complete block with four replications. Treatments were made according to statewide threshold recommendations. Treatments were applied with a CO2 backpack applicator using a 4row boom with 19-inch nozzle spacing. The nozzles used for application were Tee-Jet TXVS 6. Operating pressure was 40 psi and 10 gal/acre of volume. The single treatment was made on 10 June. Treatments included were: an untreated control, Intruder® at 0.0175 lb ai/acre + Dyne-amic® (non-ionic spray adjuvant) at 1 pt/acre, Intruder at 0.025 lb ai/acre + Dyne-amic at 1 pt/acre, Carbine® at 0.06 lb ai/acre, Carbine at 0.04 lb ai/acre, Centric® at 0.031 lb ai/acre, Centric at 0.025 lb ai/acre, Trimax® at 0.047 lb ai/acre, Trimax at 0.031 lb ai/acre, Bidrin® at 0.33 lb ai/acre, Carbine at 0.06 lb ai/acre + Mustang Max® at 0.02 lb ai/acre, and Mustang Max at 0.02 lb ai/acre. Observations were conducted on 13 June [3 days after treatment (DAT)], 20 June (10 DAT), and 23 June (13 DAT). In each plot, aphids were counted on five leaves using a 1-square-inch hand lens. Each time, the third unfurled leaf was counted, with the hand lens positioned at the base of the petiole. Data were analyzed using Agricultural Research Manager Version 7 using Analysis of Variance and LSD (P=0.10). The whitefly test was conducted at Lonoke County, Ark., in 2005. The field was planted and afterwards subdivided into plots of 4 rows on 38-inch spacing and 50-feet long. Plots were set up in a randomized complete block with four replications. Treatments were made according to statewide threshold recommendations. Treatments were applied with a CO2 backpack applicator using a 4-row boom with 19-inch nozzle spacing. The nozzles used for application were Tee-Jet TXVS 6. Operating pressure was 40 psi and 10 gal/acre of volume. The single treatment was made on 19 August. Treatments included were: an untreated control, Intruder at 0.04375 lb ai/acre, Experimental 1, Experimental 2, Capture at 0.0782 lb ai/acre, Orthene at 1 lb ai/acre, and Centric at 0.05 lb ai/acre. Observations were conducted on 22 August (3 DAT) and 25 August (6 DAT). In each plot, total whiteflies were counted on five leaves. Data were analyzed using Agricultural Research Manage Version 7 using Analysis of Variance and LSD (P=0.10). 203

AAES Research Series 543 RESULTS AND DISCUSSION In the aphid test, observing total aphids per square inch on 5 leaves per plot at 3 DAT, Intruder at 0.0175 lb ai/acre + Dyne-amic at 1 pt/acre, Intruder at 0.025 lb ai/acre + Dyne-amic at 1 pt/acre, Centric at 0.031 lb ai/acre, Trimax at 0.047 lb ai/acre and at 0.031 lb ai/acre, and Carbine at 0.06 lb ai/acre + Mustang Max at 0.02 lb ai/acre all significantly differed from the untreated control. The two rates of Intruder + Dyne-amic were numerically the best treatments in the study, however, they were only significantly better than the untreated control, Centric at 0.025 lb ai/acre, and Mustang Max at 0.02 lb ai/acre. At 10 DAT, no treatment was significantly better than the untreated control, however, Carbine at 0.06 lb ai/acre + Mustang Max at 0.02 lb ai/acre and Mustang Max-alone at 0.02 lb ai/acre were statistically worse than all other treatments. It should be noted that at 10 DAT, the overall aphid population was considerably less than at 3 DAT. At 13 DAT, no treatments significantly differed from one another. It should also be noted that the overall aphid population was considerably less than at 3 DAT and 10 DAT. In addition, a large population of lady beetles was seen in the field at both 10 DAT and 13 DAT. In the whitefly test, observing total whiteflies per leaf on 5 leaves per plot at 3 DAT, Intruder at 0.04375 lb ai/acre, Experimental 1, Experimental 2, Orthene at 1 lb ai/acre, and Centric at 0.05 lb ai/acre all performed significantly better than the untreated control. Capture at 0.0782 lb ai/acre performed statistically equal to the untreated control. At 7 DAT, no treatments significantly differed from one another. In regard to season totals of whiteflies, Intruder at 0.04375 lb ai/acre, Experimental 1, Experimental 2, Orthene at 1 lb ai/acre, and Centric at 0.05 lb ai/acre all performed significantly better than the untreated control and Capture at 0.0782 lb ai/acre. Orthene at 1 lb ai/acre performed significantly better than all treatments except Intruder at 0.04375 lb ai/acre, in regard to season totals. PRACTICAL APPLICATION Intruder tank-mixed with Dyne-amic, Carbine, Centric at 0.031 lb ai/acre, and Trimax have shown to be highly effective in controlling aphids. Mustang Max alone has shown to be ineffective in controlling aphids. Intruder, Experimental 1, Experimental 2, Orthene, and Centric have shown to be highly effective in controlling whiteflies. Capture has shown to be ineffective in controlling whiteflies. ACKNOWLEDGMENTS We thank Ken Holt for providing a test location for the aphid trial and Laudis Brantley for providing a test location for the whitefly trial.

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Summaries of Arkansas Cotton Research 2005 LITERATURE CITED Greene, J.K. and C.D. Capps. 2002. Management of secondary pests in transgenic Bt cotton. In: Proc. Beltwide Cotton Conferences. National Cotton Council of America, Memphis, Tenn. http://www.cotton.org/beltwide/proceedings/getPDF. cfm?year=2002&paper=H129.pdf Greene, J.K. (ed). 2005. Insecticide recommendations for Arkansas, MP-144, 2005. University of Arkansas Cooperative Extension Service, Little Rock, Ark. Hendrix, D.L., J. Henneberry, J.E. Slosser, and M.N. Parajulee. 2002. Bandedwinged whitefly honeydew: Another possible source of cotton stickiness. In: Proc. Beltwide Cotton Conferences. National Cotton Council of America, Memphis, Tenn. http://www.cotton.org/beltwide/proceedings/getPDF. cfm?year=2002&paper=H113.pdf Robertson, W.H., D.R. Johnson, G.M. Lorenz, III, P.R. Smith, J. Greene, C. Capps, D. Plunkett, and R. Edmund. 2004. Efficacy of selected insecticides for control of aphids, Aphis gossypii (Glover), in Arkansas, 2003. In: Proc. Beltwide Cotton Conferences. National Cotton Council of America, Memphis, Tenn. pp. 1779-1781. Wells, L., R.M. McPherson, J.R. Ruberson, and G.A. Herzog. 1998. Integrating biological control with selective insecticides for environmentally sound management of cotton aphids. In: Proc. Beltwide Cotton Conferences. National Cotton Council of America, Memphis, Tenn. pp. 1058-1061. Williams, M.R. 2004. Cotton insect loss estimates – 2003. In: Proc. Beltwide Cotton Conferences. National Cotton Council of America, Memphis, Tenn. pp. 1258-1312.

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AAES Research Series 543 Table 1. Efficacy of selected insecticides for control of cotton aphid (Aphis gossypii).

Aphidsy

Treatment

Rate

3 DAT

(lb ai/acre)



z



Untreated control Intruder (Acetamiprid) + Dyne-amic (non-ionic spray adjuvant) Intruder (Acetamiprid) + Dyne-amic (non-ionic spray adjuvant) Carbine (Flonicamid) Carbine (Flonicamid) Centric (Thiamethoxam) Centric (Thiamethoxam) Trimax (Imidachloprid) Trimax (Imidachloprid) Bidrin (Dicrotophos) Carbine (Flonicamid) + Mustang Max (Zeta-cypermethrin) Mustang Max (Zeta-cypermethrin)

N/A 0.0175 1 pt/acre 0.025 1 pt/acre 0.06 0.04 0.031 0.025 0.047 0.031 0.33 0.06 0.02 0.02

10 DAT

13 DAT



182 abx 2 d 2 d 99 bcd 93 bcd 59 cd 138 abc 38 cd 33 cd 93 bcd 67 cd 222 a

36 2 3 5 14 12 21 5 8 40 87 90

b b b b b b b b b b a a

19 a 2 a 1 a 6 a 5 a 4 a 9 a 2 a 8 a 15 a 19 a 18 a

Application date: 10 June. Evaluation date: 13 June (3 DAT), 20 June (10 DAT), and 23 June (13 DAT). x Means followed by same letter do not significantly differ (P=0.10, Student-Newman-Keuls). z y

Table 2. Efficacy of selected insecticides for control of bandedwinged whitefly (Trialeurodes abutilonea). Treatmentz Untreated control Intruder (Acetamiprid) Experimental 1 Experimental 2 Capture (Bifenthrin) Orthene (Acephate) Centric (Thiamethoxam)

Whitefliesy Rate (lb ai/acre) N/A 0.04375 N/A N/A 0.0782 1.0 0.05

3 DAT 615 aw 102 bc 283 b 237 bc 573 a 17 c 146 bc

6 DAT

Season totals

374 272 336 304 404 201 456

989 a 374 bc 618 b 541 b 978 a 217 c 602 b

a a a a a a a

Application date: 19 August. Evaluation date: 22 August (3 DAT), and 25 August (6 DAT). x Means followed by same letter do not significantly differ (P=0.05, Student-Newman-Keuls). z y

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