(F26) COTTON: Gossypium hirsutum (L.) 'Stoneville 4792BR' EVALUATION OF INSECTICIDES AGAINST TARNISHED PLANT BUGS IN COTTON, 2005 P. Price LSU AgCenter Macon Ridge Research Station 212 Macon Ridge Rd. Winnsboro, LA 71295 Phone: (318) 435-2157 Fax: (318) 435-2133 E-mail:
[email protected] J. Temple K. Emfinger B. R. Leonard Tarnished plant bug (TPB): Lygus lineolaris (Palisot de Beauvois) An insecticide efficacy trial was conducted at the Macon Ridge Research Station near Winnsboro, LA (Franklin Parish). Cottonseed was planted into a Gigger-Gilbert silt loam soil on 23 May. Plots consisted of eight rows (centered on 40 inches) by 50 ft . Treatments were arranged in a CR design with four replications. Insecticides were applied to cotton at NAWF (nodes above white flower) 8, 7, and 6 with plant height averaging 36, 42, and 42 inches, respectively. All treatments were applied with a high-clearance sprayer and CO2 charged system calibrated to deliver 9.5 gpa through TX-8 hollow cone nozzles (2 per row) at 48 psi. Insecticide efficacy was evaluated against tarnished plant bug by recording the number of damaged flower buds (squares) in a sample of 50 squares/plot, and nymphs per four shake (3 × 3 ft) samples/plot on 04 (2 DAT1), 10 (2 DAT2), 18 (1 DAT3), and 22 Aug (5 DAT3). Data were analyzed with ANOVA and means separated according to DMRT (P = 0.05). The test area received 1.21 inches of rain on 16 Aug. Pre-treatment TPB infestations exceeded action thresholds for Louisiana cotton. TPB nymphs were significantly lower in treated plots at 2 DAT1 and 5 DAT2 for those treated with Diamond at 2 DAT1. All treatments significantly reduced TPB nymphs below that in the non-treated control based on the season mean. There were no significant differences among treatments observed in damaged squares at 2 DAT1. All treatments significantly reduced the number of damaged squares below that in the non-treated control in samples at 2 DAT2, 5 DAT3, and for the season mean. In the one 1 DAT3 sample, only plots treated with Carbine and Orthene had fewer damaged squares than that in the non-treated plots. No phytotoxicity was observed with any treatment during the test. TPB nymphs (no./12 row ft) Treatment/ formulation Diamond 0.83EC Carbine 50WG Orthene 90SP Untreated check (P > F)
Rate lb (AI)/acre 0.058 0.072 0.75 --
2 DAT1 2 DAT2
TPB damaged squares (no./50)
5 DAT3
Season mean
2 DAT1
2 DAT2
1 DAT3
5 DAT3
Season mean 9.4bc 6.9c 5.5c 15.2a
7.8ab 6.3b 3.5b 11.0a
4.8a 3.5a 3.3a 8.0a
1.8b 2.0b 0.8b 4.8a
4.6b 3.9b 2.5b 7.9a
24.8a 21.5a 21.5a 25.3a
11.5b 9.0b 8.0b 18.0a
10.5abc 7.8bc 4.8c 16.3a
6.3b 4.0b 3.8b 11.3a
0.03
0.06
< 0.01
0.04
0.81
< 0.01
0.04
< 0.01
Column means followed by the same letter are not significantly different (DMRT, P > 0.05).
< 0.01
