FIELD SPRAYS AND INSECTICIDAL DIPS AFTER HARVEST FOR PEST-MANAGEMENT OF FRANKLINIELLA-OCCIDENTALIS AND THRIPS-PALMI (THYSANOPTERA, THRIPIDAE) ON ORCHIDS

Insecticidal double dips applied after harvest reduced >95% of a mixed infestation of Frankliniella occidentalis (Pergande) (90%) and Thrips palmi Karny (10%) infesting Dendrobium 'Uniwai Princess' blossoms compared with untreated controls. Double dipping consisted of immersing an inflorescence for 3 min in insecticide with agitation followed by a 2-h waiting period and a second 3-min immersion in insecticide. Single insecticidal dips were not as effective as double insecticidal dips. In addition, double insecticidal dips were more effective against nymphs emerging from eggs laid before treatment than single insecticidal dips. Four weekly field applications of abamectin 0.15EC reduced the number of thrips per blossom less-than-or-equal-to 90.8%. There were no significant differences in the number of thrips per blossom between inflorescences that received four weekly field applications of abamectin 0.15EC and inflorescences that received no field treatment and only a single dip in chlorpyrifos 4EC. Phytotoxic response to the insecticide double dips was a loss of vase life ranging from 1.2 to 3.6 d. Response varied among cultivars.