Some Factors Determining Corn Borer Damage

Abstract

This paper reports the results of observations and experiments conducted on the European Corn Borer, Pyrausta nubilalis, near Sandusky, Ohio, during the summers of 1927 and 1928. In experiments with six varieties of corn planted on five different dates, a high positive correlation was found between the height of com and the number of egg clusters laid, indicating that the fields of sweet com, usually planted earlier than field corn, and the earliest plantings of all com fields usually bear more egg clusters because of the greater height of such corn. One year's results indicate that the corn borer moth shows a preference for com of very early maturity and of about average height or taller. Next in preference is the variety or type that is tallest throughout the oviposition period of the moth. altho such variety is rather late in maturing. Short varieties, altho early in maturing, and varieties late in maturing and that are relatively short during the early part of the oviposition period receive the fewest egg clusters. Borers hatching on corn planted on June 1 have as good a chance to survive and reach maturity as those hatching on com planted earlier. Significant differences were found between the survival of the borer on the large dent corn varieties Red Cob Ensilage and Learning, with survivals of 25.6 and 28.4 per cent, and the survival occurring on the sweet com varieties Red Evergreen and Golden Bantam, on the early maturing variety Northwestern Dent, and on the Flint type of corn, with survivals of from 35.3 to 44.7 per cent. The average percentages of survival on all the varieties were 35.6 and 34.0 for 1928 and 1927. Such high survivals give a new appreciation of the reproductive powers of the corn borer.