Crop & Pest Report


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Scout for European Corn Borer Moths (07/09/20)

Traps catches increased this past week for the univoltine Z-race ECB moth (see map below).

Traps catches increased this past week for the univoltine Z-race ECB moth (see map below). Crop stages were V8 to V12. Weekly maps of the trapping results for European corn borer moths are posted on the IPM website.

The degree days for ECB also have increased to 1000-1187 accumulated degree days (ADD) compared to 800-980 ADD last week (see map on next page). This indicates that the univoltine ECB moths are 50-75% emerged, so now is a good time to start scouting for ECB in non-Bt field corn.

Corn should be monitored weekly for corn borers at least five weeks once plants exceed an extended leaf height of 17 inches. Inspect plants for the presence of egg masses, whorl feeding, and active larvae.



See Table for the Economic Threshold for corn borer per plant based on crop value and control costs. If we use an expected yield of 150 bu per acre and the current price of corn at U.S. $3.26 per bu, we would have U.S. $489 per acre for the value of corn crop. The yellow highlighted box indicates the E.T. or the number of corn borer larvae per plant, depending on the control costs.


Janet J. Knodel

Extension Entomologist

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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