AgEBB-MU CAFNR Extension

David Burton
Civic Communications Specialist
2400 S. Scenic Ave.
Springfield, MO 65807

September 8, 2017

Field Crop Scouting Report
Threshold Level Podworms Found in Soybeans

LAMAR, Mo. — Jill Scheidt, agronomy specialist with University of Missouri Extension, scouted fields west of Golden City for the August 23 crop scouting update.

Printed reports are sent out one week after the report to allow subscribers to phoned reports the full benefit of their subscriptions. Barton County MU Extension sponsors the field scouting report. For more information on the scouting report, or to learn how to receive the information earlier by telephone, contact the Barton County Extension Center at (417) 682-3579.


Ear rot diseases were in later planted fields. Ear disease are expected with late-planted corn and a wet summer.

"Once corn is past the soft dough stage corn earworm are no longer a concern. Soybean fields nearby should be scouted to see if the larvae have moved into those fields," said Scheidt.


Soybeans ranged from bloom to beginning seed stage.

Scheidt observed threshold level podworm feeding in all soybeans. Threshold level for podworms, also known as corn earworm, are one per foot of row or when five percent or more pods are damaged.

Pest pressure ranged from one to three podworms per foot of row and one to seven percent pod feeding.

"Podworms were about one inch long, which means they are close to the end of the larval stage. But, late plantings, cool weather and matured corn are all conditions that can lead to podworms moving into soybeans and being present to cause damage longer than normal, justifies an insecticide application to protect against more hatchings this season," said Scheidt.

Scheidt observed grasshopper, bean leaf beetle and green stinkbugs, also pod feeders.

"Differentiate podworms from other larvae in the field by looking for four prolegs located in the middle of the body. Podworms range in color from yellow to brown to green," said Scheidt.

Scheidt recommends reading the label for harvest restrictions when selecting an insecticide. Warrior has a 30-day harvest interval; Hero and Mustang have 21-day harvest intervals and Lorsban has a 28-day harvest interval. Use a higher rating for larger larvae or heavy infestations.

"Choose an insecticide with a longer residual due to current crop and weather conditions," said Scheidt.

Source: Jill Scheidt, (417) 682-3579

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