Summary:
Efficacy of a horticultural oil + insect growth regulator mix (SuffOil-X + Molt-X) and two imidacloprid formulations (Bayer Tree and Shrub; Fertilome Tree & Shrub Systemic Insect Drench) were tested for control of bark scale (Eriococcus lagerostroemia) on crapemyrtles at LeTourneau University. There was a trend towards decreasing alive scales and decreasing alive:dead scale ratio with time, especially by the fifth week in all treatments (including the control). The systemic insecticides (imidacloprid) demonstrated a decrease in alive:dead scale ratio two weeks after treatment, whereas contact treatments showed a decrease one week after treatment (horticultural oil + insect growth regulator). Since the control also showed decrease in scale populations, in some cases before other treatments, the efficacy of the insecticides studied here are inconclusive.