By Andi Anderson
Black cutworm is a pest that many farmers may overlook today. Advances in hybrid traits and seed treatments have greatly reduced its impact. However, under certain conditions, this pest can still damage young corn and deserves attention during early growth stages.
Black cutworm does not survive winter conditions in Illinois or nearby regions. Instead, adult moths overwinter in warmer areas along the Gulf Coast. Each spring, storm systems carry these moths northward. Once they arrive, moths lay eggs that hatch into larvae capable of harming corn seedlings.
Adult moths are active at night and prefer to lay eggs on broadleaf weeds such as chickweed and curly dock. After hatching, the larvae also feed at night and hide during the day just below the soil surface. Their feeding behavior makes early damage difficult to detect without careful field scouting.
The most serious injury occurs when larvae chew through young corn plants below the growing point. This cutting action can reduce plant populations and, in severe cases, may force farmers to consider replanting affected areas.
Certain field conditions increase the likelihood of black cutworm damage. Late planted fields often have higher weed pressure, which attracts egg laying moths. Fields with reduced tillage, broadleaf weeds, or corn planted after soybeans also offer favorable environments. When larvae feed first on weeds, they may grow large enough to damage corn plants before seed treatments and traits take effect.
Although the overall threat has declined significantly over the past 25 years, black cutworms have not disappeared. Occasional outbreaks continue to occur, making vigilance important.
Monitoring adult moths with traps can indicate regional risk but cannot predict field level damage. Regular scouting remains essential. Farmers are encouraged to inspect seedlings weekly during the first month after emergence. Once corn plants grow larger, they typically outgrow the pest’s ability to reduce stand.
Rescue treatments may be justified when approximately three percent of seedlings have been cut. Correct identification is critical, as similar insects may appear but do not cause yield reducing injury. Consulting an agronomist can help ensure proper and cost effective decisions.
Photo Credit: gettyimages-dszc
Categories: Illinois, Crops, Corn