By Dan Davidson
DTN Contributing Agronomist
Editor's note: A version of this article appeared in 2011 when spring planting conditions resembled those being experienced this year across much of the Midwest. We've revived and republished it at the request of readers concerned about cold, wet growing conditions.
OMAHA (DTN) -- Growers are anxious to plant corn. Some have already started, but the threat of cool and wet weather has prompted many to postpone planting for now, and for good reason: Corn can't handle a cold drink.
Early planting is a common practice across the Corn Belt as growers plant more acres of corn and want to finish before the optimal window closes. Combine this "get in early" trend with no-till and other low-disturbance situations, and more corn after corn, and the resulting high-residue conditions can create an emergence risk, particularly during the first two-thirds of April when we can get cold rain that can hang around for a week.
The threat isn't cold temperatures or saturated soil; rather it's the combination of the two. Protected with seed treatments, today's seed can handle cold soils and still emerge up to 20 days later as long as the soils don't become saturated.
Corn is a tropical crop and relishes warm temperatures, but we have adapted it to tolerate early spring planting under cold soil conditions of 50 degrees Fahrenheit or even 45 degrees. At those cold temperatures, the seed is naturally predisposed to stress.
Corn seed imbibes most of its water in the first 30 minutes in the soil, and a shot of water colder than 40 degrees shocks the seed and literally stops the germination process, or at least slows it down considerably, while damaging the seed.
Of all the plant stages, seed is the least tolerant of an extended wet spell. Seedlings are moderately tolerant, and emerged plants exhibit good tolerance as long as air temperatures are above freezing and the soils aren't saturated for an extended period of time.
When planted dry corn seed absorbs cold water as a result of a cold rain or melting snow, the seed experiences imbibitional chilling injury. The cold water damages and ruptures cell membranes in the embryo, radicle or coleoptile.
When temperatures remain wet and below 50 degrees after planting, damage to germinating seed is severe, resulting in soft or rotted seed or stunted or aborted radicles or coleoptiles.
Prolonged exposure to cold delays the germination, which causes seed deterioration. Damaged seeds are more likely to be attacked by insects and diseases, and surviving seedlings are more likely to emerge late and become runts.
Growers have been monitoring the near-term forecast and many have delayed planting. Still, if you find yourself in this situation and can't wait, plant well-drained and low-residue fields first, and plant seed that has good saturated cold tolerance and can best handle imbibitional chilling.
For more information on how corn management in a delayed planting season, see this Ohio State University article: http://goo.gl/…
For more information on early season cold stress, see this Iowa State guide: http://goo.gl/…
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