Choose hybrids that withstand high winds July 8, 1993, is a date that many Nebraskans will never forget. "It's one of those dates where everyone remembers where they were and what they were doing," says University of Nebraska scientist Roger Elmore.
That day a huge storm moved across the state with wind speeds of up to 100 mph. In its wake the storm left millions of dollars of damage to cornfields. Everyone suddenly became familiar with the term brittle snap.
"It broke as many as 90% of the plants in some fields," Elmore says. "In most cases, the stalk snapped below the ear. But in other fields in the same area, the damage was as little as 5%."
While brittle snap damage is more prevalent in the western Corn Belt, farmers across Minnesota, Iowa and Illinois have suffered significant losses in subsequent years. In some ways it's like corn borer damage. You know somebody is going to have a problem, you just can't predict where.
Years of research since that devastating storm have reinforced two pieces of evidence it left behind. Brittle snap, or green snap, is largely a function of genetics. While all hybrids are susceptible to the phenomenon at some point in their growth cycle, some are more susceptible than others. And because corn plants tend to break at the node just below the ear, the loss is 100%.
Better growing conditions increase the odds that you'll find brittle snap in your field. "High-organic-matter soils that are tilled and have pre-plant fertilizer applications are more likely to have damage," Elmore says. "Sidedressing and no-till tend to decrease the risk."
Row direction also affects the amount of brittle snap damage a field suffers, according to Elmore. "You can reduce your risk of brittle snap by not planting all your rows in one direction," he says. "Winds perpendicular to the rows do the most damage."
Other environmental conditions are factors also, according to Leroy Svec, research manager for Pioneer Hi-Bred International. "When you've got nighttime temperatures in the 55-60 range and dew on the plants, you're more likely to see brittle snap," he says. Dew is a factor because it indicates that there's plentiful moisture and the plants are turgid and full of water.
The most vulnerable time for corn plants is roughly seven to 10 days before tassels emerge, Svec says. That's usually the last week in June and the first week of July - when most farmers are hoping for rain to carry their crop through pollination and the oncoming summer heat.
The best way to minimize the risk of brittle snap is to choose a hybrid that's proved capable of standing up to high-velocity winds.
Seed companies have developed similar scoring systems for their hybrids, but there is no industry standard, Svec says.
"We use a 1-9 scale, with 9 being the best," he says. "In the Western states, our salespeople say they will work with a 4 and a 5 is fine. They don't want to see a 3 because farmers in that area can't field that kind of risk. A hybrid with a 3 rating that's well-adapted for the eastern Corn Belt, where the risk of brittle snap is less, might find a market there."