Released June 4, 2009
AMES, Iowa — This is a very good time to walk corn fields and check the plant stand. Estimating your plant stand will help you know what plant population actually emerged compared to what you thought you planted. And it will help you scout for early-season insects and disease.
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. 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.
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, http://www.extension.iastate.edu/CropNews/2009/052109pope.htm. 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, http://www.extension.iastate.edu/CropNews/2009/0527hodgson.htm.
To scout and control armyworms, read the ICM News article on armyworms, http://www.ipm.iastate.edu/ipm/icm/2001/6-11-2001/armysouth.html. The recent stalk bore article will help you prepare to watch for stalk borer if they begin to move into your field, http://www.extension.iastate.edu/CropNews/2009/060209hodgsonpope.htm.
Update on wireworm presence in Iowa An unexpected event with the wireworm in Iowa and surrounding states is that they have caused stand loss in fields of corn where the seed had been treated with Poncho 250. If you have planted seed with a Poncho treatment, don’t ignore it. If there is stand loss from wireworms in those fields you might consider going to the higher rate (Poncho 1250) next year or to treat the fields with a granular insecticide instead.
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http://www.extension.iastate.edu/CropNews/2009/0604tollyhodgson.htm
Sources: Jon Tollefson, (515) 294-8044, tolly@iastate.edu
Erin Hodgson, (515) 294-2847, ewh@iastate.edu
