Cold Temperatures: Decision Tools and Recommendations - May 14, 2010

Encyclopedia Article

Hard Freezes and Emerged Corn

Roger Elmore

Recent cold temperatures and a hard freeze across central and northern areas of Iowa have resulted in some foliar damage to emerged corn seedlings. On the positive side, most of Iowa’s emerged corn has less than two fully developed leaves. The growing point remains below-ground until the sixth leaf stage. Under normal conditions, corn survival is expected following a frost this time of year. The prolonged period of cool, wet weather does increase the likelihood of plant death. Read on »

Replant Decision-Making

Roger Elmore & Lori Abendroth

Think you might have replant decisions to make? Determine yield potential for a problematic field by using our Replant checklist. Images are also available in our Image Gallery to aid in diagnosing fields. For example, the V2 plant below was frozen 5 days ago; the growing point should look like this if recovery is to occur.


Postemergence Herbicides on Frost-Damaged Corn

Bob Hartzler

There are many things to consider with the recent weather, including temperature effects on corn emergence, hard freeze effects on emerged corn, and corn tolerance to herbicides. Another issue involves determining the correct growth stage of corn that was damaged by the May 9 frost event. Read on »

Temperature Fluctuations Have and May Continue to Inhibit Corn Emergence

Roger Elmore and Lori Abendroth

Cooler soil temperatures slow the germination process and predispose seedlings to fungal infection. There are instances across Iowa though of seedling growth problems related to imbibitional chilling damage and soil crusting which is causing "leafing out" underground, variable plant emergence, and reduced plant populations. Read on »

Heat Unit AccumulationMap of Iowa

Due to abnormally cold temperatures during the first part of May, Growing Degree Units (GDUs) are currently behind normal across the state. Click here to get up-to-date local GDU totals in your area.

Early-Season Diagnostics Photo of corn

Be ready to identify early season stresses affecting your corn by checking out our image gallery.

Iowa State University Agronomy Extension Corn Production