Westfield, Indiana, USA
January 30, 2025
When Randy Dowdy hit the scene with 500-bushel-an-acre corn yields, agronomists like AgriGold’s Josh Johnston took note. Dowdy’s emphasis on even emergence caught his attention.
Johnston decided to test Dowdy’s methods and launched his own flag trials. His conclusion? Even emergence is seemingly one of the best predictors of a corn crop’s yield potential.
Four key timeframes
With corn, there are four windows where farmers can influence the final yield — at emergence (VE), V5 (ear girth), from V10 to V16 (ear length) and from R5 to R6 (kernel flex).
According to Johnston, the significance of the emergence stage isn’t emphasized enough. “You cannot overcome uneven emergence.”
How to do a flag trial
“My No. 1 tip is to be out there crawling on your hands and knees, looking for that first little spike to come out of the soil,” Johnston says. “If your first bout of flagging is when corn plants are half an inch tall, you’re too late. You’ve missed the opportunity.”
Most hybrids emerge when they’ve collected between 100 and 125 growing degree units (GDUs). Therefore, farmers should visit the flag trial fields every 12 hours beginning around 80 GDUs. “On your first visit to the field, nothing should be coming out of the ground,” Johnston emphasizes.
When you see that first spikelet, put a flag in and measure off 17.5 feet (1/1000th of an acre with 30-inch rows). Then, crawl down that stretch of row, inserting a flag by each plant that’s up. “That’s Wave 1,” he says. “At your next check 12 hours later, mark newly emerged plants with a different flag color for Wave 2. Keep flagging every 12 hours until all plants have emerged.”
Measuring the results
A couple weeks prior to harvest, Johnston goes back to the field, finds his flags and hand-harvests each wave of emergence, storing them in separate sacks. Then he starts crunching numbers.
“This is where the rubber meets the road,” Johnston says, noting there’s a massive difference in ear size with each passing emergence wave. Using one representative field, he notes that the second, third and fourth wave of emergence drops 34 bushels, 67 bushels and 161 bushels, respectively, compared to the first wave.
Moisture and test weight are also negatively impacted with each passing wave.
Applying the results
The numbers drive home the importance of moving the second-wave emergers into the first wave, or the third wave into the second wave.
“There are a lot of ways to do that,” Johnston says. “But our first focus should be on what the planter is doing.”
Small variances in planting depth can lead to massive changes in emergence, Johnston details. Farmers should thoroughly check all the planter’s key components and replace them as needed, from double disc openers to gauge wheels to the row-closing system. It’s worth considering an investment in hydraulic down pressure to aid in consistent seed depth, especially in no-till environments.
“The planter pass is the most critical, laying the foundation for the course of the season. Don’t pinch pennies when it comes to planting equipment,” Johnston says. “Make sure you’re doing all you can to create consistent seed placement and good seed-to-soil contact.”
Plant into a warming trend for a uniform stand
One of the worst things you could do for even corn emergence is to plant into a cooling trend, according to Johnston. Once the soil is dry enough and the forecast calls for steadily warming temperatures, Johnston urges farmers to plant.
“It’s much better to plant when it’s a little cold but the forecast is favorable than to wait and hammer down at the end of a warming trend when temperatures are ideal but a cool rain is on the way,” Johnston says. “The first 24 hours of seed placement is the most crucial. Temperature and soil condition need to be consistent.”
“Be proactive and let soil conditions be your guide.” Johnston says. “Use a warming trend as your cue to start planting rather than current air temperatures.”
Control weeds and consider fertility
Next up is soil prep. “Whether you’re working ground or no-tilling, you have to think about soil conditions,” Johnston says. Weed pressure can wreak havoc on seed depth, he says, noting bluegrass can cause major problems in his Kentucky territory.
He also advises removing the no-till coulter from the planter. It takes about 100psi to push in a fluted no-till coulter, Johnston explains. “There are many instances when we don’t have that extra weight.”
If a no-till farmer is concerned about managing residue, especially in the seed trench, Johnston says there are many row-cleaner options that do a good job.
In-furrow fertility and micronutrients can also foster even emergence, especially if a farmer is facing an inclement emergence window. But Johnston cautions against overdoing any such applications. Too much can do more harm than good.
Other options that can help include use of an appropriate plant growth regulator.
Consistent seed size
Another must for even emergence is consistent corn seed size. “I don’t care if I have a mixture of rounds and flats, as long as they’re the same weight,” Johnston says. “But if I have large rounds mixed in with small flats, there’s no way I’ll get even emergence.”
He encourages farmers to make sure their supplier is grading the seed with enough scrutiny that the seeds in the bag are the same weight. “AgriGold does a great job of working to ensure the seed in the bag is the same size.”
Prioritize emergence to drive corn yields higher
Flag trials have really driven home what’s at stake during VE. “As you go through waves of emergence, yield potential declines faster than most realize,” Johnston says.
“If you want to bring in stellar yields, do all that you can to make sure as much of that crop comes up within a 12-hour window as possible.” For support making that a reality on your farm, reach out to your local AgriGold agronomist.
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