Stalk borer eggs have hatched and many larvae are now in brome or other grasses bordering corn. Some stalk borers already may be in corn because they hatched from eggs that were laid on grass or giant ragweed out in the field last fall, or they moved directly into border row corn instead of the grass when they hatched. Most stalk borers that hatch in grass stay there until they grow to a size that is too big for the grass stem. Then they migrate in search of larger diameter plants, which often is corn. As of May 31, there were two reports of stalk borer migration in southwest Iowa. This article discusses management for stalk borers only in grass adjacent to corn, but occasionally stalk borer damage may extend through fields when there are suitable host weeds present in the field for early larval development.
Rice, Marlin E. and Pope, Rich, "Stalk borer migration set to begin" (2005). Integrated Crop Management News. 2371.
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