(F50) COTTON: Gossypium hirsutum L., ‘Stoneville 4793R’ EVALUATION OF INSECTICIDES AGAINST TARNISHED PLANT BUGS IN COTTON, 2004 J. H. Temple LSU Agricultural Center Department of Entomology 404 Life Sciences Bldg. Baton Rouge, LA 70803 Phone: (225) 578-1839 Fax: (225) 578-1643 E-mail:
[email protected] R.H. Gable LSU Agricultural Center Macon Ridge Research Station 212A Macon Ridge Rd. Winnsboro, LA 71295 B.R. Leonard Tarnished plant bug (TPB): Lygus Lineolaris (Palisot de Beauvois) Selected insecticides were evaluated for control of tarnished plant bugs (TPB) in two tests at the Macon Ridge Research Station (Franklin Parish). Cotton seed were planted into a Gigger silt loam soil on 19 Apr for Test one and on 3 Jun for Test two. Plot size was eight rows (centered on 40-inches) × 50 ft. Treatments were placed in a RCB design with four replications. Insecticides were applied on 6, 14 Jul in Test one and 26 Aug in Test two with a John Deere high clearance sprayer and CO2 charged system calibrated to deliver 4.8 gpa through Teejet TX-8 hollow cone nozzles (2 per row) at 42 psi. Treatment efficacy against TPB adults and nymphs was determined at 6 DAT (app 1), 8 DAT (app 1), and 8 DAT (app 2) in Test one and at 3 DAT (app 1), 7 DAT (app 1) and 14 DAT (app 1) in Test two. TPB were sampled with a standard 3 ft shake sheet. In Test one and Test two samples were taken on 24 row ft and 12 row ft, respectively. Cotton squares (25/plot) were examined in Test one for TPB injury. Data were subjected to ANOVA and means separated according to DMRT (P ≤ 0.05). Between the initial application and final evaluation, rainfall of 1.03 inches occurred during Test one and 1.4 inches occurred during Test two. In Test one, there were no significant differences among treatments for TPB adults at 6 DAT (app 1), 8 DAT (app 1), and 8 DAT (app 2) (Table 1). All treatments except Diamond + Orthene and Orthene had significantly fewer TPB nymphs compared to the untreated check at 6 DAT (app 1). All insecticide treatments had significantly fewer TPB nymphs at 8 DAT (app 1) and 8 DAT (app 2) compared to the untreated check. All insecticide treatments except Diamond (0.039 lb (AI)/acre) and Diamond (0.058 lb (AI)/acre with and without crop oil concentrate) had significantly fewer damaged squares than the untreated check. The addition of crop oil to Diamond (0.058 lb (AI)/acre) significantly reduced damaged squares below that in the plots treated with Diamond without crop oil. In Test two, there was no significant difference among treatments for numbers of TPB adults at 3 DAT (app 1) (Table 2). Plots treated with Orthene, Centric, Regent, Leverage, and Vydate had significantly fewer TPB nymphs at 3 DAT (app 1) compared to that in the untreated check. All insecticides except Leverage significantly reduced TPB adults compared to the untreated check at 7 DAT (app 1). All insecticides significantly
reduced TPB nymphs at 7 DAT (app 1) compared to the untreated check. There were no significant differences among treatments for TPB adults or nymphs at 14 DAT (app 1). No phytotoxicity was observed with any of the insecticide treatments in these tests. Table 1. No. tarnished plant bugs per 24 row ft 6 DAT (app 1) Treatment/ formulation
Rate lb (AI)/acre
Diamond 0.83EC Diamond 0.83ECa a Diamond 0.83EC Diamond 0.83ECa a Diamond 0.83EC +Karate-Z 2.08SC Diamond 0.83ECa +Orthene 90S Orthene 90S Untreated check
0.058 0.039 0.058 0.078 0.039 0.025 0.039 0.25 0.5 ---
P>F
8 DAT (app 1)
8 DAT (app 2)
8 DAT (app 2)
Adult
Nymph
Adult
Nymph
Adult
Nymph
0.5a 1.3a 0.5a 0.8a
0.8bc 1.3bc 0.8bc 0.3c
0.5a 1.0a 0.8a 1.0a
1.0b 0.5b 1.0b 0.8b
0.8a 1.0a 1.0a 0.8a
0.3b 0.5b 0.0b 0.0b
34.3a 33.0ab 21.3bc 10.8c
0.0a
0.5c
0.8a
0.8b
0.3a
0.3b
11.8c
0.3a 0.8a 1.5a
2.5ab 2.0abc 3.3a
1.5a 0.5a 1.8a
1.0b 0.3b 3.3a
0.3a 0.0a 1.0a
0.5b 0.0b 2.3a
20.8bc 12.5c 40.8a
0.43
