As corn pokes through the soil it’s susceptible to a wide variety of attacks. From insects to disease, attacking organisms see young corn as easy prey—and an attack could be detrimental to yield. “Try to be proactive, by getting in the field to scout on a seven to 10 day basis to get into fields and watch for insects, disease and weeds,” says Brandon Bruce, DeKalb technical agronomist. “Evaluate stand establishment by the second or third collar.” Every ear lost on 1/1,000 of an acre—if uniform across the field—represents 5 bu. to 7 bu. lost yield. Catch pests early to salvage yield.
Control insect pests “Scouting for insects can be a little hit and miss,” Bruce says. “Black cutworm is the first that comes to mind, we see feeding and stand loss every year but damage is often random. Damage can still occur with traited products.” For cutworms specifically, start scouting in no-till or weedy fields that are at higher risk of the pest. Corn is most susceptible to this pest at 15” or shorter, but can recover from damage if the growing point is not damaged. When corn is young, cutworms cut plants below or above the soil surface at the base—it looks almost like someone cut the plant with scissors. However, cutworm isn’t the only pest that could be targeting your corn. If you see wilted plants or skips you could have wireworm; stunted or dead plants could be white grubs, if the plant didn’t emerge it could be seedcorn maggots; and if you see root feeding you could have Japanese beetle larvae. Make sure you’re thorough and don’t forget your trowel to figure out what pest is plaguing your field. Once you identify the pest you can understand your treatment options. Manage diseases Hot or cold, wet or dry, diseases can sneak in. Check corn just after emergence to see what could be inching into your fields. “Pythium and fusarium root rot are the two most common,” says Jason Welker, Mycogen commercial agronomist. “Pythium overwinters in residue and causes stand issues, and fusarium is a soil bacterium that stunts plants and generally turns roots brown.” If you’re seeing an uneven stand with inconsistent color this could be a sign of disease and means you should dig up plants. Even if you have a decent stand, dig up plants to evaluate early root development and check for any root rots that could be detrimental to yield down the road. If you’ve had cool, wet weather, you’re at a greater risk for Pythium and fusarium. If you’re seeing those diseases, it’s too late to make changes for this year—aside from replant. Take note of where you’re seeing problems because they could show up again next year and plan seed or in-furrow treatments to salvage stand next year. “Seed has an inherent genetic yield potential, and as soon as you put it in the soil it faces a myriad of stresses that attack that seed,” says Dale Ireland, Syngenta seedcare technical product manager, U.S. corn and soybeans. “Early season is critical because the first 30 days the plant grows as much below ground as it does above.” Minimize weed competition You want to start clean—if weeds get a jump on corn they’ll easily overtake the crop and steal sunlight, water and nutrients. Watch for weeds popping up around corn emergence, too. Every additional weed steals from yield potential. If you sprayed a preemergent herbicide with residual and are seeing weeds pop up that could be telling you there was an application error or possible resistance—use this info to plan for next year. If you meet a weed threshold consider an over-the-top herbicide application. As you scout early this season watch out for insects, disease and weeds that steal yield. This article first appeared in April 2017.