EFFICACY OF SPIROTETRAMAT AGAINST APHIDS AND MEALYBUGS ON RED GINGER, 2009

The efficacy of spirotetramat as a foliar or drench application to control mealybugs and aphids on red ginger flowers was conducted at the University of Hawaii at Manoa, Waiakea Research Station near Hilo, Hawaii from 11 Aug to 16 Nov 2009 in an established 0.25 acre field of ornamental red ginger. Treatments were laid out in a CRD with four replicates, each replicate consisting of three adjacent 16-20 ft beds of flowering ginger. Four treatments included: 1) Kontos (spirotetramat) applied as a drench (12 ml per ft of plant height); 2) Kontos applied as a foliar spray (1.7 fl oz/ 100 gal); 3) Kontos applied at a higher foliar rate spray (3.4 fl oz/100 gal); and 4) an untreated check. Both foliar treatments consisted of two applications (11 August and 11 September) to all flowers and foliage until runoff using CO2 compressed air spray equipment (40 psi) fitted with an adjustable nozzle (Teejet 800 4VS). Silwet L-77 was added to the foliar sprays as a surfactant. The drench treatment was applied once (11 Aug) to the root zone of the plants. Insect counts were conducted prior to treatment, then at 2 wk intervals for eight weeks following the initial treatment, then at 3 wk intervals up to 14 WAT due to reduced seasonal flower production. Evaluations consisted of counting the number of live and dead insects on a minimum of six ginger flowers harvested at least 1/4 open from within each replicate. A dissecting microscope was used to aid in counting and determining insect species. Adult mealybugs were turned over to expose and count nymphs. Mortality was determined by probing insects lightly with a needle and observing for movement. Two species of aphids (BA and CA) and two species of mealybugs (CM and LM) were present in pretreatment evaluations of red ginger flowers. Adults and nymphs of both mealybug and aphid species were pooled for data analysis. Live insect counts were converted to a 1 to 10 rating system based on pretreatment means with “1” signifying 0 live insects. Each consecutive rating step corresponded to increased aphid counts in increments of 50, and mealybug counts in increments of 10. Live insect ratings were arcsine transformed prior to analysis. Data were subjected to ANOVA and mean separation using Tukey’s (P< 0.05 and P< 0.01).