Stalk borer is an occasional pest of corn, but it can be persistent in some fields, especially those fields near fence rows, terraces, and waterways that serve as overwintering sites. Tracking degree days is a useful tool to estimate when common stalk borer larvae begin moving into cornfields from their overwintering hosts. Foliar insecticide applications are only effective when larvae are migrating and exposed to the insecticide. Start scouting corn for larvae when 1,300-1,400 degree days (base 41°F) have accumulated. Much of Iowa has reached this important benchmark (Figure 1); therefore, scouting for migrating larvae should begin now to make timely treatment decisions.
Iowa State University
Dean, Ashley and Hodgson, Erin W., "Stalk Borers are on the Move Across Iowa" (2021). Integrated Crop Management News. 2698.
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