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EVALUATION OF INSECTICIDES ON COTTON APHIDS, 2002.

EVALUATION OF INSECTICIDES ON COTTON APHIDS, 2002. (F69) COTTON: Gossypium hirsutum L., 'DPL 458BG/RR' Roy D. Parker Texas Cooperative Extension 10345 Agnes Corpus Christi, TX 78406 Tel: 361-265-9203 Fax: 361-265-9434 r-parker1@tamu.edu Cotton aphid (CA): Aphis gossypii (Glover) Furadan has been the preferred insecticide choice for Cotton aphid (CA) control in South Texas due to effectiveness and cost. However, use of Furadan has required special state and federal approval, and label restrictions make the product somewhat difficult to use. The study was conducted to evaluate selected insecticides for effectiveness on CA. Cotton was planted on 26 Apr into an irrigated Victoria clay soil at the Texas Agricultural Experiment Station near Corpus Christi. Plots were 4 rows x 40 ft with four replications arranged in a RCB design. To encourage CA increase, the test was oversprayed two times with a pyrethroid insecticide. CA on six infested leaves on separate plants in the center 2 rows (3 leaves/row) were counted on 24 Jun and these leaves were tagged. Immediately thereafter, foliar insecticide treatments were applied to the center 2 rows of each plot with a self-propelled Lee Company Spider Trac, equipped with a CO pressurized sprayer (2 TX-4 spray system nozzles/row) at 40 psi traveling at 3.5 mph, and calibrated to deliver 7 gpa. Silwet surfactant was included in each spray mixture at 8.0 oz/100 gal. Treatments were assessed by: (1) counting the number of CA on tagged leaves beginning with pretreatment counts on 24 Jun and thereafter on 3, 6, 9, 12, 15 and 20 DAT, (2) counting the number of CA on expanded terminal leaves on the same plants with tagged leaves beginning 6 DAT, (3) rating plots for damage [1 = excellent fruit load, good plant growth up to 5 = low fruit load, irregular plant growth] at 10, 18 and 26 DAT, and (5) harvesting the center 2 rows in each plot on 19 Aug with a 2-row John Deere 9900 model spindle picker. Seed cotton was weighed and a sample was obtained for ginning. The seed cotton samples were processed on a 10-saw Eagle laboratory gin to determine percentage lint in order to calculate lint weights. Data were analyzed by ANOVA and means were separated according to LSD (P = 0.05) using Agriculture Research Manager, revision 6.1.6 (4th edition) dated Aug 31, 2000 from Gylling Data Management, Inc. Tagged leaves averaged 193 CA/leaf before treatment (Table 1). Insecticides, except for Bidrin 9 and 12 DAT, significantly reduced CA numbers on the tagged leaves. Likewise, terminal leaf data were similar until 12 DAT (Table 2). Beginning at 12 DAT only F1785, Intruder and Centric treated cotton consistently had terminal leaf CA numbers statistically lower than the number in untreated cotton. Combined tagged and terminal leaf data (Table3) indicated that for all insecticide treatments except Bidrin, CA numbers were significantly lower on all inspection dates compared to the untreated cotton. Plant damage ratings generally aligned with the CA count data (Table 4). However, only Intruder and Centric (2 oz/acre rate) consistently had damage ratings significantly lower than untreated cotton. The season average damage ratings showed that all insecticide treatments, except Bidrin, had significantly lower damage rating values than the untreated cotton. Lint production (Table 4) followed almost the same numerical ranking as season CA counts and damage ratings arranged from low to high. It was anticipated before harvest that the LSD value would be large (189.2 lb/acre) due to variables at the cotton test site not associated with treatments. In spite of that problem, significant differences did occur in lint yields. Intruder and Centric (2.0 oz/acre rate) treated cotton produced significantly more lint than the untreated cotton. Numerical increases in lint yield should not be discounted in light of the other data and the acknowledged field variation. Likewise, the lower yield in Furadan treated cotton did not seem to fit with overall data obtained. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

EVALUATION OF INSECTICIDES ON COTTON APHIDS, 2002.

Parker, Roy D.
Arthropod Management Tests , Volume 28 (1) – Jan 1, 2003
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Oxford University Press
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© Published by Oxford University Press.
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2155-9856
DOI
10.1093/amt/28.1.F69
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Abstract

(F69) COTTON: Gossypium hirsutum L., 'DPL 458BG/RR' Roy D. Parker Texas Cooperative Extension 10345 Agnes Corpus Christi, TX 78406 Tel: 361-265-9203 Fax: 361-265-9434 r-parker1@tamu.edu Cotton aphid (CA): Aphis gossypii (Glover) Furadan has been the preferred insecticide choice for Cotton aphid (CA) control in South Texas due to effectiveness and cost. However, use of Furadan has required special state and federal approval, and label restrictions make the product somewhat difficult to use. The study was conducted to evaluate selected insecticides for effectiveness on CA. Cotton was planted on 26 Apr into an irrigated Victoria clay soil at the Texas Agricultural Experiment Station near Corpus Christi. Plots were 4 rows x 40 ft with four replications arranged in a RCB design. To encourage CA increase, the test was oversprayed two times with a pyrethroid insecticide. CA on six infested leaves on separate plants in the center 2 rows (3 leaves/row) were counted on 24 Jun and these leaves were tagged. Immediately thereafter, foliar insecticide treatments were applied to the center 2 rows of each plot with a self-propelled Lee Company Spider Trac, equipped with a CO pressurized sprayer (2 TX-4 spray system nozzles/row) at 40 psi traveling at 3.5 mph, and calibrated to deliver 7 gpa. Silwet surfactant was included in each spray mixture at 8.0 oz/100 gal. Treatments were assessed by: (1) counting the number of CA on tagged leaves beginning with pretreatment counts on 24 Jun and thereafter on 3, 6, 9, 12, 15 and 20 DAT, (2) counting the number of CA on expanded terminal leaves on the same plants with tagged leaves beginning 6 DAT, (3) rating plots for damage [1 = excellent fruit load, good plant growth up to 5 = low fruit load, irregular plant growth] at 10, 18 and 26 DAT, and (5) harvesting the center 2 rows in each plot on 19 Aug with a 2-row John Deere 9900 model spindle picker. Seed cotton was weighed and a sample was obtained for ginning. The seed cotton samples were processed on a 10-saw Eagle laboratory gin to determine percentage lint in order to calculate lint weights. Data were analyzed by ANOVA and means were separated according to LSD (P = 0.05) using Agriculture Research Manager, revision 6.1.6 (4th edition) dated Aug 31, 2000 from Gylling Data Management, Inc. Tagged leaves averaged 193 CA/leaf before treatment (Table 1). Insecticides, except for Bidrin 9 and 12 DAT, significantly reduced CA numbers on the tagged leaves. Likewise, terminal leaf data were similar until 12 DAT (Table 2). Beginning at 12 DAT only F1785, Intruder and Centric treated cotton consistently had terminal leaf CA numbers statistically lower than the number in untreated cotton. Combined tagged and terminal leaf data (Table3) indicated that for all insecticide treatments except Bidrin, CA numbers were significantly lower on all inspection dates compared to the untreated cotton. Plant damage ratings generally aligned with the CA count data (Table 4). However, only Intruder and Centric (2 oz/acre rate) consistently had damage ratings significantly lower than untreated cotton. The season average damage ratings showed that all insecticide treatments, except Bidrin, had significantly lower damage rating values than the untreated cotton. Lint production (Table 4) followed almost the same numerical ranking as season CA counts and damage ratings arranged from low to high. It was anticipated before harvest that the LSD value would be large (189.2 lb/acre) due to variables at the cotton test site not associated with treatments. In spite of that problem, significant differences did occur in lint yields. Intruder and Centric (2.0 oz/acre rate) treated cotton produced significantly more lint than the untreated cotton. Numerical increases in lint yield should not be discounted in light of the other data and the acknowledged field variation. Likewise, the lower yield in Furadan treated cotton did not seem to fit with overall data obtained.

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Arthropod Management Tests – Oxford University Press

Published: Jan 1, 2003

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