Posted: 09.16.2011

With scattered frost reports popping up around the state, UW-Extension Corn Specialist, Dr. Joe Lauer, has some suggestions growers can keep in mind for the harvest.

In Lauer's daily blog - he notes that for many growers in northern Wisconsin the growing season is over.

"Corn in many areas had not reached physiological maturity and was killed prematurely (in Wednesday nights frost event).  Corn is killed when temperatures are near 32 F for a few hours, and when temperatures are near 28 F for a few minutes.  A damaging frost can occur when temperatures are slightly about 32 F and conditions are optimum for rapid heat loss from the leaves to the atmosphere, i.e. clear skies, low humidity, no wind.  At temperatures between 32 to 40 F, damage may be quite variable and strongly influenced by small variations in slope or terrain that affect air drainage and thermal radiation, creating small frost pockets.  Field edges, low lying areas, and the top leaves on the plant are at greatest risk.  Greener corn has more frost resistance than yellowing corn.

Symptoms of frost damage will start to show up about 1 to 2 days after a frost.  Frost symptoms are water soaked leaves that eventually turn brow.  Because it is difficult to distinguish living from dead tissue immediately after a frost event, the assessment should be delayed 5-7 days.

For fields that only had light frost damage, it is too early to harvest.  Growing conditions may improve during September allowing the crop to mature and produce reasonable grain and silage yields.

For fields that were harder hit by frost, farmers will need to manage frost damaged corn silage and grain."

You can read more of Lauer's management suggestions on his agronomy page blog:  http://wiscorn.blogspot.com/2011/09/handling-immature-corn-after-early.html?spref=tw

Lauer also advises growers to go to their agronomy field web page for updates. http://corn.agronomy.wisc.edu/Management/L041.aspx.

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