Stalk borers in corn have always challenged farmers, but management has seemed especially troublesome in recent years. In cornfields where grass or broadleaf weed control was poor the previous summer, stalk borers flourish and fieldwide stand losses are possible the following spring. Stalk borers also infest corn rows that are adjacent to grass terraces, fence lines, or grass waterways. Stalk borers lay their eggs during late summer and early fall on leaves and stems of grasses and broadleaf weeds. Grassy areas surrounding cornfields are ideal egg-laying sites.
Fire can be a successful management tool to kill stalk borers.
Burning grass and weeds where eggs are laid greatly reduces damage from larvae in adjacent corn. George Decker, an ISU entomologist during the 1920s and 1930s, reported that stalk borer populations could be reduced 82-97 percent by burning fence lines. Recent burning experiments I conducted in central Iowa resulted in yield increases up to 68 percent in corn adjacent to burned grass terraces. Burning grass to kill stalk borer eggs. Burning grassy areas to kill stalk borer eggs should be done in early March in southern Iowa to very early April in northern Iowa, for several reasons.