Seeing Northern Corn Leaf Blight?

Jun 14, 2016

By Rebecca Vittetoe

It seems too early in the growing season yet to be seeing corn diseases like Northern Corn Leaf Blight (NCLB), but I happened to spot a few corn plants with NCLB lesions on them in an isolated area in a corn field in southeast Iowa.

Northern corn leaf blight lesion (cigar-shaped and pale gray to tan in color) found on corn (V7 - V8) in SE Iowa on June 13, 2016.

This disease was widespread in Iowa in 2014 and again last year in 2015, and it was severe on susceptible hybrids. Since the fungus (Exserohilum turcicum) survives the winter in corn residue, we likely have above normal inoculum present this year.

Why are we seeing NCLB so early?

That goes back to the disease triangle, which describes the three necessary factors for disease development: 1) pathogen presence, 2) a susceptible host, and 3) the favorable environmental conditions (aka weather).

With NCLB, favorable environmental conditions for fungus and disease development are cool weather (65 to 80°F) with frequent precipitation. Warm and dry conditions will slow or halt disease development until favorable conditions return.

With the warm and dry weather we experienced last week, I am thinking that this corn was infected prior to the warmer and dryer weather, and that the weather actually halted the NCLB from spreading more. Although we have chances of rain this week, temperatures look like they will remain on the warm side, providing less than ideal conditions for NCLB.

Agronomists and farmers are encouraged to scout fields, especially at-risk fields (susceptible hybrids, corn-on-corn fields), for NCLB. Keep an eye out for NCLB by looking for the cigar-shaped lesions that are pale gray to tan in color.

If the disease is present on 50% or more of the plants in the field, the hybrid is scored susceptible, and cool, wet weather is in the forecast, a foliar fungicide application may be required.

Source: iastate.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.”