The Midwest has experienced some stretches of below-normal temperatures, with cold, rainy conditions this spring. Research shows that the opportune time to plant corn is somewhere between the last two weeks of April and the first few days of May. However, Mother Nature isn’t necessarily on that same schedule. Fields that have been recently planted or those that will be planted in the next couple days may be subject to seedling injury.
SIGNS OF INJURY
Corn that has been recently planted in the Midwest has experienced less-than-ideal overall conditions, especially when it comes to temperature. In many locations, the weather pattern of cold rain and low temperatures has potential to promote a problem for young seedlings called “Imbibitional Chilling Injury.” Some basic visual symptoms may be corkscrewing of the young germinating plant or leafing out below ground level. Consider digging up a few seedlings and checking them for signs of corkscrewing, leafing out underground or damping off.
WHY WOULD SEEDLINGS REACT LIKE THIS?
A possible issue that cause less than optimum stands and poor emergence is chilling injury to the mesocotyl or coleoptile plant tissue caused by sub-lethal cold temperatures (less than 50 degrees) during the period very soon after planting when seeds begin to imbibe water. The seed will not begin to germinate until the soil temp approaches 50 degrees, however, the seed will allow water to enter regardless of temperature. This chilling injury basically equates to cells rupturing which results in the corkscrewing of the mesocotyl. This delays the emergence of the coleoptile prior to the usual emergence of leaves from the coleoptile.
In addition to slowing the germination process, cold temperatures, snow and cold rains may cause irreparable harm to the delicate structures of an emerging corn seedling. When dry corn seed absorbs cold water, Imbibitional Chilling Injury is not uncommon. Such injury in corn seeds ruptures cell membranes and results in aborted radicles, proliferation of seminal roots, delayed seedling growth and potential for diseases pathogens to attack the young seedling. When temperatures remain at or below 50 degrees Fahrenheit after planting or fall below 50 degrees within 24-48 after planting, damage to germinating seed can be particularly severe as they imbibe water. This should be considered as there is risk associated with the temperature and moisture roller coaster we have experienced so far this planting season.
If you have any questions, contact your local Hoegemeyer agronomist or District Sales Manager.