Black cutworm moths flock to Indiana in record numbers

May 10, 2011

Cornfields full of purple henbit are among those at the highest risk of black cutworm damage. (Purdue Agriculture photo/John Obermeyer)

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WEST LAFAYETTE, Ind. - Black cutworm moth presence has never been greater in Indiana, said one Purdue Extension entomologist. 

Pheromone trap cooperators throughout the state have captured an abnormally large number of the moths over the last few weeks, said Christian Krupke.

"The key question is whether or not the egg-laden moths arriving in the state will find fields attractive to lay eggs in," he said.

While barren fields are not appealing places to lay eggs, the black cutworm has a broad range of hosts, so fields showing green, yellow and purple weeds are still at the highest risk. The moths are particularly attracted to winter annuals, such as chickweed and mustards.

"Remember, corn is one of the black cutworm's least favorite foods," Krupke said. "It just so happens it is the only plant remaining by the time larvae have emerged and weeds have been killed."

Typically, cutworm larvae will starve if weeds are treated with tillage or herbicide two to three weeks before corn emerges, but with the wet Indiana spring, Krupke said it is already too late for that.

He also suggested farmers pay attention to seed-applied insecticide and Bt corn labels to determine management strategies.

"We don't want producers to have a false sense of security with seed-applied insecticides and some varieties of Bt-traited corn, where the label provides only suppression and not control," Krupke said. "Growers need to check the fine print on the trait they are using. Suppression is fine under ideal environmental conditions and moderate infestation levels, however, under environmental stress and/or heavy pressure, the efficacy of these products labeled for suppression may not be sufficient."

Reduced control efficacy causes struggling seedlings to become more vulnerable to attacks from both above- and below-ground insect pests.

With so little of the state's corn crop in the ground right now, Krupke said it would be awhile before growers start to see black cutworm damage. He encouraged scouting fields once crops are planted and determining control strategies as the season progresses.

"We will continue to work with pheromone trap cooperators and to update producers in the coming weeks," he said.

For up-to-date black cutworm scouting and treatment guidelines, watch future issues of the Purdue Pest and Crop Newsletter at http://extension.entm.purdue.edu/pestcrop/index.html

Writer: Jennifer Stewart, 765-494-6682, jsstewar@purdue.edu 

Source: Christian Krupke, 765-494-4912, ckrupke@purdue.edu

Ag Communications: (765) 494-2722;
Keith Robinson, robins89@purdue.edu
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