Greg Roth
Associate Professor
Penn State
January, 2003

Background

     On May 22, 2002 we visited one of our field experiments after three nights of a hard frost. The corn had been in the V2-V3 (two to three fully emerged leaves) stage of growth prior to the frost. This field had been no-tilled into wheat stubble on May 4 and we had achieved an excellent stand. Low temperatures had reached 28 degrees F for three consecutive nights. The corn was uniformly frosted to the ground. All above ground green tissue was water soaked and limp. This field was especially hard hit because it was in a low-lying area in the landscape. Fields on hillsides had less uniform frost damage. (Click on the image to the right for a larger view)

     Normally corn in the V2 - V3 stage can recover well from this type of frost but due to the low temperatures and the multiple frosts, we were unsure. The standard recommendation for assessing damage to frost damaged fields is to come back 3-4 days later and assess the survival and then decide on replanting options.

Diagnosis

     We marked a section of the damaged plants in the field on May 22 with a flag and then returned a week later on the 29th of May to assess the damage. As is often the case, the recovery was dramatic. Stand loss in this field was minimal and the plants had recovered well from the frost. (Click on the image to the right for a larger view)

     Despite the three nights of successive frost, the plants were able to recover well. Hourly frost data indicated that the temperatures each night reached a minimum of 28 degrees but not for an extended period. Some have suggested that a period of 4 hours below 28 degrees is necessary to kill young corn plants. Hourly observations of weather data can be accessed for Rock Springs and many other locations at the Pennsylvania State Climatologist site on the internet: http://pasc.met.psu.edu/PA_Climatologist/cityform.html

     In general other producers reported similar experiences as we found in this field. Some fields where corn was more advanced in the V4 to V5 experienced more mortality, with some requiring replanting. Other, very early-planted fields that experienced one or two previous frost damage episodes also experienced stand loss.

     This experience confirmed our recommendation that once frost damage occurs, wait several days before considering replanting, then assess the damage and make a replant decision accordingly. A Purdue University worksheet (http://www.agry.purdue.edu/ext/pubs/AY-264-W.pdf) can provide some help in assessing the returns from replanting fields with reduced stands.