Detecting an insect threshold begins with scouting early in the season. Farm Journal’s Associate Field Agronomist Missy Bauer discusses the need for early scouting the black cutworms in Episode 6 of Corn College TV Season 3.
Bauer says that it is important to put traps out in the field as soon as the weather starts to warm up. She says to record the number of moths in the trap every few days to determine when peak flight is occurring. Then, check to see if the number of heat units has been met for those larvae to hatch.
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When scouting, look for plants that have a wilted look. These have likely been totally cut off by the black cutworm larvae. Look through the soil for larvae and, if you find any at the 3-5% threshold, it is probably time to start spraying.
"If you’re getting that 3-5% cut plus you’re finding the actual larvae themselves and identifying the stage of the larvae, that will give you a good indication of how much longer they’ll be feeding."
Watch Episode 6 below for more info on the black cutworm and insect thresholds. Click here to register for 2013 Corn College events happening throughout the summer.