Control of Sweetpotato Whitefly and Leafminers on Staked Tomato with Insecticide, Soap, and Oil Sprays

Abstract

Abstract FALL, 1990: Raised beds 36" wide on 6 ft centers were prepared 3 wks before planting in sandy soil at the Southwest Florida Research and Education Center in Immokalee. Fertilizer was applied as a bottom mix before beds were formed (508 lbs/acre of 5-16-8) and as a top mix (952 lbs/acre of 19-0-30) at bed formation in two bands 9" from center. Beds were fumigated at formation with Vapam (37% metham-sodium) at a rate of 30 gal/acre. The Vapam was mixed at a ratio of 3:2 with water and applied with injectors spaced 5" apart across the bed. Immediately after fumigation the beds were covered with whiteface black polyethylene film. Tomato transplants were set 20" apart on 4 Sep. The experimental design was a randomized complete block with 12 treatments and 4 replications. Plots were 3 rows wide, 20 ft long and separated by 40". Treatment applications began 9 Oct and continued weekly until harvest using a tractor mounted boom sprayer with 4 drop lines holding a maximum of 24 nozzles fitted with Albuz ceramic hollow cone tips (ATR brown delivering ca. 0.26 gal/min @ 400 psi). Manzate 200 (1.5 lb/acre) and Tri-Basic Copper (3 lb/acre) were applied weekly for disease control with the same sprayer at 150 psi except that T-Jet hollow cone nozzles with TLX-3 80° tips were used. Whitefly immatures were counted at two week intervals on the terminal trifoliate of the 6th or 7th leaf from the top of 3 randomly selected plants per plot. The number of leafminer stings and mines and the numbers of dead and parasitized leafminers on the trifoliate were also noted. Adult whiteflies were sampled on alternate weeks by counting the number found after carefully inverting the 3rd leaf from the top of 3 randomly chosen plants per plot. Plants affected by geminivirus were marked as symptoms appeared. All fruit of marketable size were picked and graded from 10 randomly selected healthy plants per plot on 27 Nov and 17 Dec. Culls were removed and the remaining fruit separated into medium, large, and extra-large categories with a mechanical grader. Dollar value was estimated on the basis of $5.00/25 lb box for medium fruit, $6.00 for large fruit, and $8.00 for extra-large fruit. A split plot analysis of variance was used with treatments as whole plots and sample dates as subplots.