|First generation European corn borer moth emerging|
|Written by Assefa Gebre-Amlak|
Colorado State University Extension is seeing the first generation European corn borer moth at Eckley (one of their pest monitoring sites in northeastern Colorado). First generation moths prefer taller and early planted fields for laying eggs; non-Bt cornfields should be scouted the next 2-3 weeks.
Some hybrids have useful resistance to the first brood of European corn borer, which feeds in the whorls and later enters the stalk. Control can be expected with Bt corn hybrids, except those containing only events that target corn rootworms.
European corn borer usually goes through two generations each year. The young larvae feed first on the leaf near where they hatched. As the larvae grow, they move to the whorl or leaf sheath area and feed.
When leaves emerge, the “shot hole” feeding signs in the leaves can be seen. Most of the mature larvae will bore into the stalks, feed and finish development there.
Second generation larvae cause ear damage, tunneling in the shank and feeding on silks, kernels and cobs. Signs of infestation include: dropped ears, broken shanks, stalk breakage, sawdust-like castings on leaves and holes in the stalks.
To determine infestation levels of first generation and make management decisions, 25 plants in four locations in a cornfield should be checked for leaf infestations. Larval damage is noticed as feeding scars and shot holes in plant leaves.
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