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Extension Entomology

Corn Update – Corn Rootworms and “Ragworms”

–by Dr. Jeff Whitworth and Dr. Holly Davis

Corn rootworm larvae continue to be very active in fields of continuous corn that have been planted to susceptible varieties.

Corn earworms have been feeding in north central Kansas corn for about a week now and signs of this feeding are now becoming visible as the leave start growing out of the whorl.  The small larvae may consist of corn earworms, fall armyworms, and/or armyworms, but all may cause the same type of ragged looking leaves, earning them the name “ragworms”.

 

 

This type of leaf feeding can be highly visible, and many plants can be impacted, but the data has always indicated there is little to no effect on yield.  In addition, the larvae are well sheltered within the whorl and thus insecticides only impact them when they exit the whorls to pupate in the soil.  And, by that time, all the feeding is completed anyway.

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