WEST LAFAYETTE, Ind. - Stalk health is poor in many Midwestern cornfields, meaning growers might need to take a "triage" approach when deciding which fields to harvest first, says Purdue Extension agronomist Bob Nielsen.
Drought conditions during corn grain fill caused much of the affected corn crop to "cannibalize" itself, or pull carbohydrate reserves from the stalk to meet the needs of developing grain. The remobilization not only weakened stalks, but it also made them susceptible to stalk rots. Weak and rotten stalks are prone to lodging, which can make picking up grain with a combine difficult and ultimately lead to yield loss.
"There are a lot of fields vulnerable to storms, so growers need to prioritize the health of their fields for harvest," Nielsen said. "When we start harvesting corn in earnest, we need to get the weakest fields out the earliest."
While stalk breakage is easily seen when scouting fields, identifying stalks prone to lodging can be harder. The best way to identify compromised stalks is to pinch the lower stalk internodes to see if they collapse from the pressure.
In some instances, Nielsen said pushing stalks out of the way when scouting is enough to make weak stalks fall over.
"Fields and hybrids at high risk of stalk breakage should be harvested as early as possible to minimize the risk of significant mechanical harvest losses," he said. "Recognize that hybrids can vary greatly for late-season stalk quality, even if grown in the same field, due to inherent differences for late-season plant health or resistance against carbohydrate remobilization when stressed during grainfill."
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Stalk rots can get bad enough in some fields to spread to the ear shank, where the ear connects to the stalk, and on into the cob. Shank and cob rots can cause plants to start dropping their ears either spontaneously or when bumped by a combine head.
Part of prioritizing the least healthy fields for earliest harvest also means growers might not want to wait until grain dries down to 18 percent - the desired moisture percentage for harvest.
"This is not the year to let corn dry down further in the field," Nielsen said. "Get it out of the fields. Don't be greedy about waiting to get this corn down from 22 percent to 18 percent. You're rolling the dice on some of these fields.
"If a storm comes along, we're not talking about leaning corn. We're talking about corn flat on its face."