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Delayed planting may extend window for black cutworm

An integrated pest management specialist says planting delays in parts of the Midwest have extended the window for black cutworm problems.

Bruce Potter with the University of Minnesota tells Brownfield while cutworm moths are susceptible to cold temperatures, their eggs are quite tolerant.

“What these moths are looking for when they’re laying eggs (are) early-season weed growth and particularly unworked soybean stubble.  And as the season progresses it’s kind of a race between how fast the cutworms develop versus how fast the corn gets big enough to not be at risk for cutting anymore.”

He says cutworm moths fly north from the Gulf of Mexico and disperse through weather systems, making flights difficult to track.

Potter emphasizes the importance of scouting this time of year.

“Black cutworms are pretty aggressive cutworms.  One of the reasons they’re more damaging to corn than some of the other species is that they have a tendency to cut the plants below ground, particularly if it’s drier.  In the case of corn, if (the cutworm) is below ground and hitting that growing point they’ll actually kill the plant.”

Potter uses pheromone traps to monitor migration and says a localized but significant flight was detected earlier this month in south-central Minnesota.

Potter adds black cutworm problems tend to be infrequent and damage to plants is easy to identify.

He says farmers can control larvae with common insecticides.