Abstract

Two species of entomopathogenic nematodes, Steinernema carpocapsae and Heterorhabditis bacteriophora, and two synthetic chemicals, Dimetheoate and Imidachloprid, were evaluated for suppression of the iris borer, Macronoctua onusta, on bearded iris. Field trials were conducted in prepared planting beds of bearded iris established at the Central Maryland Research and Education Center in Ellicott City, MD. Examination of larval galleries in the rhizome and number of live larvae found were used to evaluate the effectiveness of each treatment. The applications of all rates of entomopathogenic nematodes and the systemic insecticide, Imidachloprid, gave control equal to that of Dimethoate. All treatments gave significant control of iris borer compared to the control. Imidachloprid reduced borer larvae by 87% reduction; S. carpocapsae (all rates and aerated and none aerated) provided 100% control; H. bacteriophora provided 87% control; as did Dimetheoate.