Chemical control of Heliothis armiger (Hubner) in sweet corn

Four trials were conducted at Griffith, New South Wales for the control of the corn ear worm, Heliothis armiger, in sweet corn. A screening trial, where sprays were applied at 50% silking and 7 days later, showed that the pyrethroids permethrin and fenvalerate were the most effective chemicals. The insecticides used (g active ingredient ha-1) and the percentage of cobs damaged in each treatment were as follows: permethrin 100- 15%; fenvalerate 100- 17%; methomyl 450-22%; sulprophos 720-25%; methomyl 340-30%; monocrotophos 800-33%; CGA 15324 750-34%; endosulfan 740-39%; acephate 750-39%; chlorpyrifos 750-55%. Permethrin and fenvalerate were also found to be effective at rates of 50 and 75 g a.i. ha-1. Applications during the tasselling and early silking stages were more effective than sprays during the later silking stages.