Farmers heading into a cold, wet stretch of weather with high‑yield “racehorse” type corn hybrids should be ready to scout aggressively and treat early for disease, advises Dan Bjorklund, technical agronomist with Landus Cooperative.
Bjorklund says the combination of water-saturated soils and below‑normal temperatures in parts of Iowa and some other Corn Belt states could be setting the stage for stand and yield losses, especially in hybrids with traits that are more offensive than defensive.
He says those hybrids with offensive genetics may excel in warmer, “friendlier” springs but they can stumble when early‑season stresses ramp up.
“We know from past experience that when we have an extended period of cold temperatures and rain after planting that emergence will be impacted,” Bjorklund says. “We won’t get those hybrids up and out of the ground maybe as uniformly as we would like, and that has yield impact. We might possibly lose some seedlings due to diseases out there.”
Bjorklund points to current forecasts in parts of Iowa calling for temperature highs in the 60s and lows in the 40s following heavy rainfall as a red flag for early disease pressure in both corn and soybeans.
Bjorklund references environmental swings in recent years that have triggered major disease outbreaks. He ties cold, wet conditions and certain genetics to fusarium-related crown and stalk rot issues.
Scout Corn At V5, Evaluate Stalks
While seed treatments offer a good line of defense, Bjorklund notes that environment and genetics can still impact hybrids depending on how long the seed sat in the ground prior to emergence. He points out that many high-yielding “racehorse” hybrids are ill-equipped to deal with saturated soils.
Bjorklund recommends making a scouting pass in corn at the V5 growth stage – when corn plants have five leaves with visible collars – and digging up some plants and splitting stalks open for evaluation.
“Look at the crown… if it’s nice and white and clean and doesn’t show a lot of damage, OK. But if you see a little bit of discoloration, then I would say you need to be concerned about potential crown and stalk rots,” he says.
Bjorklund recommends making a fungicide application when early‑season conditions are stacked against the crop, especially if stalks reveal any discoloration.
“Try to get that fungicide on when you know that plant is at V5, when it’s making the rows around and the length. So that’s when ear determination is occurring. We don’t want to have the corn to have a bad day at that point in time,” he says.
He acknowledges there is debate over how well fungicide applications penetrate the plant, but says the yield data in cold, wet scenarios are hard to ignore.
“The data shows that V5 applications, in situations where we had cold days and over three inches of precipitation, we had a really nice yield response. We do know that the data is supportive,” he says.
As forecasts in some parts of the Corn Belt continue to point to cool, wet stretches, proactive scouting and timely treatment may be the difference between a racehorse hybrid that finishes strong — and one that doesn’t get a strong start out of the gate.
You can hear all of Bjorklund’s recommendations in his latest video here.
