Q&A on Black Cutworm Thresholds - UNL CropWatch, May 26, 2011
May 26, 2011
Q: With $7 corn, what's the threshold for treating black cutworms in corn?
A: Bob Wright, extension entomologist: The Iowa State University newsletter had an article on black cutworms earlier this month that made the following suggestion:
If larvae found in the field are smaller than ¾ inch, then a threshold of 2 to 3 percent wilted or cut plants indicates an insecticide application is warranted. If larvae are longer than ¾ inch, the threshold increases to 5 percent cut plants. Remember to take into consideration the plant population in a particular field and adjust threshold numbers accordingly. However, with corn price and input fluctuations, a dynamic threshold may be more useful.
An ISU Excel spreadsheet allows you to input your scouting data and use their calculations to aid management decisions regarding black cutworm.