Efficacy of Insecticides Against Thrips on Dendrobium, Hi, 1994

Abstract

Abstract Tests were conducted from 14 Jul through 8 Sep 1994 on 8 year old orchid plants at a commercial dendrobium farm in Kailua-Kona. Plants were growing in 1.3 cm crushed basaltic rock under 30% polypropylene shade using standard cultural practices. Experimental plots measured 40 ft2 with 58 plants per plot arranged in a RCB with four blocks. Four weekly applications of insecticides were applied beginning 14 Jul and ending 4 Aug. A spreader-sticker (Ad-here, J. R. Simplot, Lanthrop, CA) was added to all foliar treatments, including the control, at a rate of 0.5 ml per liter solution. Insecticides were applied at 1,345 liters/ha using a backpack sprayer (Solo Inc., Newport News, VA) equipped with an 8004 Teejet nozzle (Spraying systems Co. Wheaton, IL) at 276 KPa. The control was sprayed with water. Treatment efficacy was evaluated by randomly harvesting 5 inflorescences weekly from each block. Blossoms were removed from the inflorescences, counted, and placed in Berlese funnels heated with a 60 watt incandescent light bulb. Thrips were collected in an 8:2:1:1 solution of ethanol, distilled H20, acetic acid and glycerin, and the number of nymphs and adults counted. Because the number of blossoms per inflorescences varied, thrips counts were adjusted to the number of thrips per blossom by dividing the total number of thrips recovered by the total number of blossoms. Data were transformed to log,0(x + 1) and analyzed by ANOVA.