Minimum Number of Insecticide Applications for the Control of the European Corn Borer on Sweet Corn in Quebec1

Field experiments were conducted at St. Luc, Quebec, from 1963 to 1965, to determine the relative effectiveness of 1, 2, 3, or 4 applications of DDT or carbaryl (Sevin®) in 2 commercial sweet corn fields. In all cases, the 1st application was made 5 days after the beginning of egg laying period and the others at weekly intervals, except for the single application of DDT or carbaryl, which was made 15 days after the 1st eggs were observed. In general, results were similar for the 3 years: the early variety was more infested than the late variety, DDT was slightly superior to carbaryl, the peak of egg laying always occurred between the 2nd and 3rd insecticide applications, and the date on which the single application was made varied each year from only 2 to 4 days from the date of maximum oviposition. The results of this 3-year study indicate that under the conditions of heavy infestations of the European corn borer, Ostrinia nubilalis (Hubner), in southwestern Quebec, 3 applications of either DDT or carbaryl would be recommendable for an early variety of sweet corn and 1 application for a late variety to obtain economical commercial control.