Control of Silverleaf Whitefly on Tomato with Sucrose Esters, Insect Growth Regulators, and a Synthetic Pyrethroid/Organo-Phosphate Tank Mix, 1995

Field: Agricultural and Biological Sciences (Life Sciences)

Abstract Commercially grown greenhouse seedings exposed to a greenhouse colony of SLW for 5 days were planted 27 Feb 1995 in single rows at 18-inch spacing on 12 black sided plastic mulched beds 32 inches wide and 240 ft long on 6-ft centers. Beds had been fumigated with a 67/33% mixture methyl bromide and chloropicrin at a rate of 2201b/acre and were subsurface irri-gated. Four blocks, 3 rows wide, were divided into 10 plots 24 ft in length to accommodate an RCB with 4 replications and 10 treatments. Plants were sprayed weekly for disease control with an alternating combination of Maneb 80 WPat 1.5 lb/acre plus Kocide 101 at 2 lb/acre and Bravo 720 at 2pt/acre. Biobit (Bacillus thuringiensis kurstaki) was added to the disease control sprays weekly at the rate of 1 lb/acre to control the southern armyworm, Spodoptera eridania. Weekly treatments commenced on 23 Mar and terminated on 8 May with the exceptions of CGA-215944 + fenoxycarb which was sprayed twice on 23 and 31 Mar and V-71639 which was sprayed every 14 days for a total of 4 applications. Latron CS-7 was tank-mixed at 16 oz/100 gallon spray as a sticker spreader for all treatments. Spray mixtures of synthetic and natural sugar isolates were made by dissolving 23 grams of ester in 100 ml of ace-tone and 100 ml of methanol, then adding 28 ml of Latron CS-7 adjuvant before mixing with water to make a 3% sugar ester spray mixture. [Spray was delivered using a high-clearance sprayer through “ATR yellow” Albuz® hollow-cone nozzles at 200 psi pump pressure. Four nozzles per row were used through 5 Apr calibrated at 33 gpa, increasing to 6 nozzles and 61 gpa on 12 Apr. and then to 8 nozzles and 81 gpa for the duration.] Sugar ester (SE) treatments were put out at 0.3% w/v throughout the trials whereas concentration of other treatments was adjusted according to gallonage to achieve the required rate per acre. Plants were evaluated weekly for the presence of whitefly adults, nymphs, pupa, and parasitized pupae. Adult whiteflies were sampled with a beat pan made from 9.5" X 13" pie pan painted black and covered with an oil/detergent mixture. The center six plants in each row of each 3-row plot were sampled and the numbers recorded as a total for each row. Nymphs and pupae were sampled by removing a trifoliate leaf from around the 6th node of four until 4 April when two randomly selected plants per row for a total of 12 and then 6 leaflets per plot. Counts were made under a stereoscopic microscope within a 0.5-cm2 template and later a 1-cm2 template on each side of the midvein of each leaflet for a total of 12 cm2 per row or 36 cm2 per plot. Sprays were commenced when pre-treatment counts reached 4 nymphs per 36 cm2 and 1 adult per beat (17 March). Plants were inspected weekly for symptoms of tomato mottle geminivirus (ToMoV). All fruit of marketable size on 10 plants per plot was harvested on 9 May 95 and fruit of marketable quality graded for size on a commercial-type line. Unmarketable fruit was inspected for damage by pinworm, southern armyworm or other causes.