True Armyworms in Wheat

Author: Scott Stewart, IPM Extension Specialist Comments Off on True Armyworms in Wheat

This is a repeat of an older article … as a reminder.  There have been a couple of reports of armyworms in wheat. Nothing crazy but much of the wheat is still in the milk stage and would be susceptible to excessive defoliation. Occasionally, armyworms may even cut the heads, typically when populations are high.  Yield loss is most likley if defoliation occurs during the milk stages, with little yield loss likely during the dough stage even if severe defoliation occurs. The picture below was sent to me a couple of years ago by a private consultant showing substantial defoliation under a pivot where the field was not treated.

Click to enlarge
Click to enlarge

For true armyworm, use a treatment threshold of 6-8 larvae per square foot if wheat is in the milk stage. Once past the milk stage, wheat can tolerate higher populations and treatment is not usually recommended unless larvae are cutting wheat heads. Remember that larvae often fall to the ground when disturbed and hide under debris during the day, so you’ll need to look close. Synthetic pyrethroids at mid rates such Baythroid XL, Declare, Karate/Warrior, and Mustang Max are typically used with good effect.

True armyworm – click to enlarge
Armyworm (click to enlarge)
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