There have been reports armyworm and wireworm attacking some fields in southern Iowa the past few days. Some cutworm activity is going on in central and southern Iowa. Northern Iowa cornfields need to be watched too.

Now is a very good time to walk your cornfields and check your plant stand. Estimating your plant stand will help you know what plant population actually emerged compared to what you thought you planted. Also, getting out into the fields will help you scout for early-season insects. That advice comes from Iowa State University Extension entomologists Jon Tollefson and Erin Hodgson.

There are several insects that might be decreasing your plant stand right now. “We have had reports of dingy cutworms, black cutworms, wireworms, and armyworms,” says Hodgson. “You can still take action against the black cutworms and armyworms. Even though it is too late to treat for wireworms now, finding them in corn fields can help you be prepared for them next year.”

Also watch fields for black cutworm activity

Cutting of corn by black cutworms was in progress by the end of last week and should now be happening in central and northern Iowa, as reported in the ICM article Predicted black cutworm cutting dates in corn . This insect can be stopped with foliar insecticide sprays. A recent ICM Newsletter article, Dynamic BCW Action Threshold , provides calculation aids for the treatment thresholds that should be used.

To scout and control armyworms, read the ICM News article on armyworms.  The recent stalk borer article will help you prepare to watch for stalk borer if they begin to move into your field.

Update on wireworm presence in Iowa

An unexpected event with the wireworm in Iowa and surrounding states this spring is that they are causing stand loss in fields of corn--even in fields where the seed corn had been treated with Poncho 250—a seed-applied insecticide.

“If you have planted corn seed with a Poncho treatment this spring, don’t ignore those corn fields,” advises Tollefson. “You need to all of scout your cornfields now and watch for signs of this very destructive insect pest. If there is stand loss from wireworms in those fields, you might consider going to the higher rate of which is Poncho 1250—for a seed-applied insecticide next year. Or you may want to treat your corn fields with a granular insecticide next spring instead of using the insecticide seed treatment.