Tobacco Insect Control with Insecticides Applied in the Transplant Water, 1996

Abstract

Abstract Various insecticides applied as transplant water treatments were compared with foliar and soil treatments for TA and TFB control and for their effects on the yield of flue-cured to bacco. Tests were conducted on a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agricultural Agric. Res. and Ext. Cntr., Black-stone, VA. Eleven treatments and an untreated check were established in a RCB design with 4 replications. Plots, 4 X 40 ft (1 row X 24 plants), were separated by single untreated guard rows. The Temik treatment was applied in a 14-inch band using a tractor mounted-Gandy granular applicator and immediately covered with 6 inches of soil at bed formation on 21 May (soil temperature 75 °F ambient temperature, 88 °F, soil pH, 5.6; weather, sunny; soil moisture, good). The Admire drench treatment was applied to tobacco seedlings in 288-cell float trays 24 hrs before transplanting. The treatment was applied with a CO2-pressurized backpack sprayer that delivered 1 fl oz of Admire 240 FS in 1.84 gal of water/1,000 plants through 8003LP tips at 20 psi. Treatments were watered in with an additional 1 gal of water immediately after application. ‘Coker 371 Gold’ flue-cured tobacco was transplanted and the transplant water (TPW) treatments were applied in 204 gal solution/acre with a Holland plunger-type transplanter on 21 May. The weather was sunny, and soil and ambient temperature was 75 °F and 88-91 °F, respectively. Foliar applications of Orthene were applied on 3 Jul and 8 Aug with a CO2-pressurized backpack sprayer that delivered 28 gpa at 60 psi through TX-12 nozzles (3 per row. The weather was clear, wind speed was less than 5 mph, and ambient temperature was 84-86°F at each application. Except for insect control, tobacco production followed Virginia Cooperative Extension recommendations. Dipel 4 L (Bacillus thuringiensis) was applied for tobacco hornworm control on 3 Jul. TA were counted on the upper 4 leaves of 10 plants/plot about once a week from 6 to 10 wks after transplanting. On 22 Aug, TA damage was rated for each plot on a scale of 0 to 10: 0 = no signs of aphid feeding; 10 = all leaves showing severe damage resulting from TA infestations including honeydew, sooty mold, necrotic leaf tissue, and exuviae. TFB feeding holes were counted on 5 plants/plot on 2 and 26 Jun, 2 and 5 wks after transplanting. Tobacco was harvested and cured and yield was determined. Data was analyzed by ANOVA and significantly different means were separated by Waller-Duncan K-ratio t-test (K = 100). TA count data were transformed to log10 (x + 1) before analysis.