Originally published in the Chat 'n Chew Café (16 March 1998)
Also published in the Purdue Pest Management & Crop Production Newsletter (20 March 1998)

Differences in Stalk Decomposition During the Off-Season

R.L. (Bob) Nielsen , Agronomy Department , Purdue University, West Lafayette, IN 47907-1150
Internet address: rnielsen@purdue.edu

The Information Superhighway has a new exit down at the Chat 'n Chew Café. Charlene purchased and set up one of these new $800 desktop computers with a dialup connection to the Internet via the "Just URL and Me" Internet service provider located uptown at the old Hardware Hank store. So now, from time to time, I receive an Email direct from one Charlene's patrons with a trivia question that has come up for discussion around the coffee and donuts.

Last week, the question had to do with differences in stalk rotting and stalk color over the winter among and within fields of corn. It seems that someone had been out in an untilled corn field recently and noticed that the stalks in part of the field were blacker than other parts of the field, even though the whole field was the same hybrid. What is the reason for this?

Well, the stalks that are blacker are stalks that are rotting more quickly or thoroughly. My opinion (based partly on fact, partly on guess) derives from the concept that corn under stress during grain fill is more likely to "cannabilize" itself to fulfill the demands of the developing ears. Such remobilization of stored carbohydrates from the stalks and roots increases the susceptibility to root and stalk rots in the latter stages of grain fill. Such depleted stalk tissue is also more susceptible to other "opportunistic" fungi that invade the tissue and begin the normal decomposition process after harvest.

Bottom Line: Normal stalk decomposition will occur more easily and quickly in 1) areas of fields that endured stress during grain fill, and also 2) in hybrids that are genetically more prone to remobilizing stored carbohydrates during grain fill. The latter case is illustrated by hybrids that are not considered to be 'stay-green' types. If you are using the new Bt corn hybrids, you will likely also notice that their stalks will not begin decomposing as rapidly as non-Bt hybrids, especially in years where corn borer pressure is heavy, simply because the Bt hybrid stalks will remain healthier longer.

For more information on stalk lodging and rotting, see AY-262, Stalk Lodging in Corn: Guidelines for Preventive Management, available on-line at http://www.agcom.purdue.edu/AgCom/Pubs/AY/AY-262.html or from your local Purdue University Cooperative Extension Service office.

Corn Growers Guidebook

For other information about corn, take a look at the Corn Growers Guidebook on the World Wide Web at http://www.agry.purdue.edu/ext/corn/

End of Document