FLEA BEETLE AND APHID CONTROL ON FLUE-CURED TOBACCO WITH FOLIAR SPRAYS, 2001

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This experiment was conducted at the Virginia Tech Southern Piedmont AREC, Blackstone, VA, to evaluate various foliar insecticides for GPA and TFB control and to assess the resulting effects on the value of fluecured tobacco. Tobacco 'K 326' was transplanted into experimental plots on 2 May. Plots, 4 by 40 ft (1 row by 24 plants), were separated by single untreated guard rows. Normal production practices were followed for weed and disease control, fertilization and topping, and sucker control. Nine treatments and an untreated check were established in a RCB design with 4 replications (Table 1). Treatments for TFB control were applied as foliar sprays using a CO2-pressurized backpack sprayer that delivered 15.5 gpa at 50 psi through a TX-18 nozzle (1 per row) on 25 May. The sprayer was also used to deliver 30 gpa at 50 psi through TX10 nozzles (3 per row) for the second applications on 29 Jun. The 3rd application was applied on 3 Aug with a CO2-pressurized DeCloet high clearance sprayer operated at 40 psi and delivering 24 gpa through TX-12 tips (3 nozzlses/row) at 3.5 mph. After the 25 May application, 0.05 and 1.32 inches of rainfall fell at 0 and 1 DAT. No significant rainfall occurred within the first wk after the 29-Jun application, and 0.94 inch of rain fell 1 d after the 3-Aug treatments. Temperatures on the application dates ranged from 78-82 oF on 25 May, 86-90 oF on 29 Jun, and 85-88 oF on 3 Aug. TFB and TFB feeding holes were counted on 10 plants/plot at 2, 10, and 20 d after the 25-May applications. GPA counts were made on the upper 4 leaves of 10 plants/plot 3 d before treatment at 3, 7, 14, and 20 DAT after the 29-Jun application, and 1 d before treatment at 3, 7, and 19 DAT the 3-Aug application. On 29 Aug, GPA damage was rated on a scale of 0 to 10 where 0 = no damage and 10 = extensive damage from sooty mold, honeydew, necrotic tissue, and caste skins. Tracer 4L was applied at 2 fl oz/acre to the entire test for control of tobacco hornworm Manduca sexta L. on 29 Aug. Tobacco was harvested as it ripened. It was cured, weighed, and graded by a USDA/AMS inspector and gross economic value in /acre was calculated based on market prices for the assigned market grades in 2001. Data were analyzed by ANOVA and significantly different means were separated by WD (k-ratio = 100). Data for GPA and TFB feeding hole counts were transformed to Log10(x+1) before analysis. Actual means are presented in the tables.