Effect of imidacloprid on the growth of Eucalyptus nitens seedlings

Imidacloprid is currently being investigated, as a control mechanism to prevent seedling defoliation by endemic Melolonthine scarab beetles in Tasmania. A trial to test any phytotoxic effects found a significant reduction in growth of Eucalyptus nitens seedlings following the application of imidacloprid as a root drench at medium and high concentrations. Compared to untreated seedlings, those treated with 50 mL L -1 suffered a 13% reduction in growth and at 15 mL L -1 the reduction was 8%. As eucalypt seedlings are particularly vulnerable to damage by insects and mammals within 12 months of planting, the cost of reducing their growth by use of imidacloprid should be considered when developing a strategy for pest control.