True Armyworms Showing Up In MS Wheat Ahead of Schedule

In the last couple of  days there have been calls coming in about armyworms in wheat.  It is not unusual for us to get armyworms in wheat in MS but this at least 2-3 weeks ahead of schedule compared to years past.  There is no doubt this is an early spring and insects are taking advangtage of it.

Mississippi has always used a threshold of 5-6 larvae per square foot through the milk stage.  Once past the milk stage armyworms should be treated if they begin to clip heads.

Most calls to date have been smaller larvae down in the canopy feeding on lower leaves; however, in at least one field they had moved up and started feeding on the flag leaf during the boot stage.

If wheat is not headed and armyworms reach the flag leaf, treat. Data from Arkansas in the early 2000’s suggested that once wheat reached the milk stage that very little yield loss was associated with foliage feeding. This was true even when they defoliated all plant foliage including the flag leaf. We do not have a sweep net threshold on armyworms.  Armyworms are generally sampled by folding back the canopy and shaking plants on the ground.  Armyworm infestations will likely be highest where bluegrass is mixed in the wheat.

True armyworms are not difficult to control as long as you can get the material down to them.  Look for birds in a field.  If you see birds working a field, that is a good sign it has armyworms.

Armyworm Treatment Options:  Click Here go to page 71

Armyworm larvae on wheat heads, 2001 (photo courtesy of Robert Bellm, University of Illinois Extension).