Yield Threats For Later Planted Corn

09:53PM Apr 27, 2018
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Planters are rolling—quickly—across many of the corn and soybean growing states in an effort to get caught up. But do you really need to work quite so furiously? Planting seems behind compared to the past few springs, but is it as bad as what many believe?

“It’s too early to call this late planting,” says Kevin Scholl, Syngenta agronomist in northern Illinois. “Over the past few years we’ve had exceptionally early planting, which makes it feel late even though we’re not late yet. The last week of April and first week of May is really the optimum time for Illinois. We’re in good shape for now—but I know things can change in a hurry,” he adds.

Don’t get too worried about yield loss by planting dates just yet—those losses could come from other agronomic causes instead.

“We don’t start losing much corn yield potential until the middle of May [in Illinois],” says Lance Tarochione, Dekalb/Asgrow technical agronomist. “Yield decline starts slow after that, but once you get into June, losses become steep. Weather in July is what determines corn yield, not when you planted it.”

By all counts, it looks like farmers are about two weeks behind the new “normal” for planting. Two weeks might not cause major changes throughout the growing season, but it could mean that diseases take hold earlier in growth stages and pollination gets pushed back to potentially hotter weeks.

Diseases could have a harsher effect on younger corn. Northern corn leaf blight (NCLB) and gray leaf spot (GLS) typically attack corn right at or before it reaches reproductive stage—a two week planting delay could push that timing to earlier, more vulnerable stages.

“Diseases develop more on a calendar basis,” Tarochione says. “GLS shows up the same time every year, but the crop is better at defending itself when it’s further along. GLS hitting at pollinations hurts yield less than when corn is waist high—so there’s more potential to reduce yield.”

Scouting isn’t optional—get out into fields and monitor potential disease outbreaks and take action early to save yield potential. GLS, NCLB and rust are the most common diseases, but talk to your local agronomist for area-specific disease information, too. Catching these diseases early and employing a timely fungicide application could make a difference come harvest.

“It all adds up—seed, herbicide, fungicide, insecticides—all of this is designed to maximize a good environment or make the best of a bad one,” Tarochione adds.

Pollination success is in Mother Nature’s hands. High yields are still very much within reach across much of the Corn Belt.

“When pollination is pushed back later into the growing season, say mid- to late-July and August, you often expect hotter, drier weather,” Scholl says. “But, as long as we don’t get into the 90s and stay there for a long time we shouldn’t have too much trouble with pollination.”

“This is a concern every year [high temps at pollination], but this year’s risk might just be a little higher,” Scholl adds. “Like so much with farming, it’s all up to the weather.”

You can’t control the weather, but you can set your crops up for success with actions you take now for pollination and grain fill. Don’t rush planting and cause compaction or other issues, for example. Mind soil conditions, fertility and disease and insect pressure to make sure corn never has a bad day and top-end yields are achieved.