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Illinois corn farmers encouraged to scout for black cutworms in coming weeks

A field crop entomologist says black cutworm pressure has increased in parts of Illinois this season and the pest could begin feeding this week.

Kelly Estes with the University of Illinois tells Brownfield several storms allowed moths to migrate this spring and based on trapping dates, larvae could start causing injury to corn plants anytime.  

“Earlier flights were in late April and early May so projected cutting dates start right around the 18th of May and a lot here in the upcoming week, particularly through the North Central part of Illinois as well as Northern Illinois.”

She says later planted fields and areas with grassy weeds are at higher risk for black cutworm feeding and plants are most susceptible from early emergence through V5.

“They do cut off plants at the base, right near the soil. However, smaller larvae are going to cause smaller injuries, so we look for things like pinhole feeding on the leaves, maybe some feeding on the leaf margins. They’re mostly active in cooler temperatures, so earlier morning and later in the afternoon or early evening.”

She says growers should consider a rescue treatment if 3% or more of plants are injured and there are still larvae present in the field.