Managing insect pests in Eucalyptus globulus (Labill.) plantations in Victoria using insecticide tablets at establishment

Abstract

Summary We studied the effects of fertiliser and insecticide delivered by tablets on defoliation and growth of Eucalyptus globulus in plantations near Meredith in west-central Victoria to determine whether improved foliage retention and growth were conferred by the insecticide and/or fertiliser components of the tablet. Trees at the study site were variably defoliated by three species of insect from March 2004 to September 2005. In the first year of the study, treatments containing imidacloprid insecticide had significantly less defoliation in both the upper and lower crowns than did treatments containing no insecticide. Treatments containing both insecticide and fertiliser showed increased height growth, most likely as a result of a combination of increased levels of available nutrients and protection from defoliating insects provided by the tablets leading to increased overall vigour. The tablets appear to provide adequate protection to trees for about 1 y after planting, although some protection seems to have remained until the 1.7 y assessment. Further observation is required to determine how long this protection lasts. The implications of the study are significant for eucalypt plantation managers. The application of insecticide and fertiliser in tablets at the time of planting potentially provides a more effective and environmentally safer method of insect control than traditional broadscale insecticide applications during the establishment phase. This could potentially lead to improved growth, yield and general health in the longer term.