Late Season Nitrogen Deficiency

Jul 22, 2015

By Douglas Beegle

With all of the rain we have had since June, there are a lot of questions about nitrogen (N) deficiency.

Two common scenarios are: it was too wet to sidedress, so the corn did not get the necessary N and the other problem was loss of applied N with the excessive rain. Both of these are potential serious limitations for corn this year. Up until tasseling, N application will be beneficial, especially if the crop did not receive adequate N because it was too wet to sidedress. It is more difficult to predict if the crop will respond to additional N if a normally adequate amount of N was applied but may have been lost. Especially if there is a significant amount of organic N in the system, the N level may rebound when the soil dries out.

However, if the crop is showing serious N deficiency symptoms (inverted yellow V, starting at the tip of leaf and going back the midrib on the lower leaves), a late application of N prior to tasseling may be beneficial. Unfortunately, after pollination, there are not a lot of good options. Corn uptake of N declines sharply after pollination. After pollination, corn is mainly redistributing N that it took up during the grand growth period. Therefore, even though applications to corn after tasseling with high clearance equipment are sometimes possible, generally they are not very effective. There have been reports from the Midwest of benefits from modest applications (30-60 lb N/A) within a couple of weeks after tasseling on severely deficient corn. This will probably not make up completely for the lack of N uptake by the corn earlier, but may provide some benefit. Application of a small amount of foliar N, will not likely provide any sustained benefit. This may green it up for a day or so, but the amount of N taken up by the crop will be so small from such an application, that it will have minimal overall impact.

Source: psu.edu

Video: Why Your Food Future Could be Trapped in a Seed Morgue

In a world of PowerPoint overload, Rex Bernardo stands out. No bullet points. No charts. No jargon. Just stories and photographs. At this year’s National Association for Plant Breeding conference on the Big Island of Hawaii, he stood before a room of peers — all experts in the science of seeds — and did something radical: he showed them images. He told them stories. And he asked them to remember not what they saw, but how they felt.

Bernardo, recipient of the 2025 Lifetime Achievement Award, has spent his career searching for the genetic treasures tucked inside what plant breeders call exotic germplasm — ancient, often wild genetic lines that hold secrets to resilience, taste, and traits we've forgotten to value.

But Bernardo didn’t always think this way.

“I worked in private industry for nearly a decade,” he recalls. “I remember one breeder saying, ‘We’re making new hybrids, but they’re basically the same genetics.’ That stuck with me. Where is the new diversity going to come from?”

For Bernardo, part of the answer lies in the world’s gene banks — vast vaults of seed samples collected from every corner of the globe. Yet, he says, many of these vaults have quietly become “seed morgues.” “Something goes in, but it never comes out,” he explains. “We need to start treating these collections like living investments, not museums of dead potential.”

That potential — and the barriers to unlocking it — are deeply personal for Bernardo. He’s wrestled with international policies that prevent access to valuable lines (like North Korean corn) and with the slow, painstaking science of transferring useful traits from wild relatives into elite lines that farmers can actually grow. Sometimes it works. Sometimes it doesn’t. But he’s convinced that success starts not in the lab, but in the way we communicate.

“The fact sheet model isn’t cutting it anymore,” he says. “We hand out a paper about a new variety and think that’s enough. But stories? Plants you can see and touch? That’s what stays with people.”

Bernardo practices what he preaches. At the University of Minnesota, he helped launch a student-led breeding program that’s working to adapt leafy African vegetables for the Twin Cities’ African diaspora. The goal? Culturally relevant crops that mature in Minnesota’s shorter growing season — and can be regrown year after year.

“That’s real impact,” he says. “Helping people grow food that’s meaningful to them, not just what's commercially viable.”

He’s also brewed plant breeding into something more relatable — literally. Coffee and beer have become unexpected tools in his mission to make science accessible. His undergraduate course on coffee, for instance, connects the dots between genetics, geography, and culture. “Everyone drinks coffee,” he says. “It’s a conversation starter. It’s a gateway into plant science.”