Stalk Borers are Migrating to Corn
Stalk borer is an occasional pest of corn, but it can be persistent in some fields, especially those fields near perennial grasses that serve as overwintering sites (fence rows, terraces, and waterways are typical sources). Tracking degree days is a useful way 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.