Common Stalk Borer Activity Update: May 30, 2019

Jun 03, 2019

By Adam Varenhorst

Another cool, wet week has led to a limited accumulation of degree days. Based on our calculations, common stalk borer activity still doesn’t warrant any scouting, but spraying field edges should be avoided around Hot Springs, Winner and Vermillion. We will continue to monitor the degree days and provide updates.

Predicting Common Stalk Borer Migration Into Corn Fields With Degree Days

The hatching and movement of common stalk borer caterpillars can be estimated by using degree days with a developmental threshold of 41°F. Common stalk borer eggs typically begin to hatch at 575 degree days. The caterpillars finish hatching and begin development on weeds and grasses at 750 degree days. At 1300 degree days, 10% of the caterpillars will begin moving to corn. At this point corn should begin to be scouted. At 1400 degree days, 50% of the caterpillars will or have moved into corn.

As a reminder, the equation for degree days is:

(Maximum Daily Temperature - Minimum Daily Temperature) ÷ 2 - The Developmental Threshold

In South Dakota, most of the state is still between conditions approaching egg hatch and egg hatch occurring. No scouting is necessary for common stalk borer at this time. We will continue to update this information.

Table 1. Common stalk borer caterpillar activity based on accumulated degree days.

Accumulated Degree Days	Common Stalk Borer Caterpillar Activity	Recommendation
0-574	Conditions favorable for egg hatch.	No scouting necessary.
575-749	Eggs begin to hatch.	No scouting necessary.
750-1299	Young caterpillars begin boring into grass and weeds.	No scouting necessary. Avoid spraying grass and weeds along field edges.
1300-1399	10% of caterpillars begin moving into adjacent corn.	Begin scouting field edges for defoliation.
1400-1700	50% of caterpillars moving into adjacent corn.	Continue scouting for defoliation along field edges. Spray if necessary.

Table 2. Common stalk borer activity based on degree day accumulation for South Dakota. Location Accumulated Degree Days Since January 1, 2019.

Location	Accumulated Degree Days Since January 1, 2019	Recommendation
Buffalo	596	No scouting necessary
Newell	622	No scouting necessary
Rapid City	627	No scouting necessary
Hot Springs	767	No scouting necessary. Avoid spraying field edges.
Lemmon	564	No scouting necessary
Faith	476	No scouting necessary
Cottonwood	601	No scouting necessary
Mission	622	No scouting necessary
Selby	515	No scouting necessary
Gettysburg	487	No scouting necessary
Pierre	639	No scouting necessary
Winner	789	No scouting necessary. Avoid spraying field edges.
Aberdeen	564	No scouting necessary
Huron	638	No scouting necessary
Mitchell	734	No scouting necessary
Tyndall	749	No scouting necessary
Sisseton	515	No scouting necessary
Brookings	536	No scouting necessary
Vermillion	824	No scouting necessary. Avoid spraying field edges.

Source:sdstate.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.”