Evaluation of new systemic insecticides for elm insect pest control.
The use of systemic insecticides that can be injected either into the root system or trunk of woody plants provides several potential advantages, notably in control of drift during application. Recently, new classes of insecticides with systemic activity have been developed, which may supplant the organophosphate and carbamate systemic insecticides that have previously been available. To evaluate their potential to control insects affecting shade trees, studies were conducted using imidacloprid and abamectin on Ulmus americana and U. pumila. Soil injections of imidacloprid appeared particularly effective, controlling all of the target pest species in this study (Xanthogaleruca luteola [Pyrrhalta luteola], Gossyparia spuria and Tinocallis ulmifolii). Both imidacloprid and abamectin also were effective against at least some insects when injected into trunks. Persistence of imidacloprid was unusually long, providing second season control of all Ulmus insect pests, although root uptake following soil injections was slow.