Control of Silverleaf Whitefly (Swf) on Tomato Using Sanmite Applied with Hydraulic and Airboom Sprayers, 1996

Abstract

Abstract Tomato seedlings “Agriset” from a commercial plant house were transplanted on 7 Mar 96, 18 in between plants, into raised beds 32 in wide and 250 ft long on 6-ft centers. They were covered with black polyethylene film mulch. A dry bottom mix of 50 lbs N, 160 lbs P and 80 lbs K per acre was placed at the bottom of the beds and an additional 3.25 lbs per acre N and K was fertigated 3 times a week by drip irrigation. The plants were sprayed weekly with an alternating combination of Maneb 80 WP at 1.5 lb/acre plus Kocide 101 at 2 lb/acre and Bravo 720 at 2 pt/acre for disease control. Dipel was added to the disease control sprays when needed at a rate of 1 lb product/acre. Each of the 4 beds was used as a replication divided into 5 plots separated by 2-ft buffers, with each 48-ft plot randomly assigned to 5 treatments. Applications were initiated 16 May when whitefly population was established and continued weekly for 3 weeks. Spray was delivered using two different types of spray equipment: a high clearance sprayer utilizing an hydraulic pump operating at 200 psi, delivering spray through 6 Yellow Albuz hollow cone nozzles, 3 per drop boom at a volume of 69 gpa at 2.5 mph, and a Berthoud airboom sprayer delivering spray material at 50 psi through 6 Brown Albuz nozzles, atomized by an airblast 172 mph and dispensing at a volume of 35 gpa. Spray coverage was evaluated on 8 May by using water sensitive papers and spectophotmetric analysis of FD&C#1 blue dye deposited on paper targets. Plants were evaluated weekly for the presence of whitefly adults, eggs, nymphs, pupa and parasitized pupae on a trifoliate from the 6th node of 8 randomly selected plants per plot. Counts were made using stereoscopic microscope by placing a 1 cm sq template twice on each side of the midvein of each leaflet (4 cm2/leaflet = 12 cm2/trifoliate = 96 cm2 per plot). Adult whitefiies were evaluated by striking plants 5 times with a 9.5" X 13" pie pan painted black and covered with a 9:1 oil/detergent mixture (N = 6/plots). Fruit was not harvested for evaluation because a heavy infestation of pin worm and high incidence of disease on many of the plots would have rendered the data of little value.