P&PDL Picture of the Week for
December 10, 2007

Frosted Volunteer Corn

Bob Nielsen, Extension Agronomist, Purdue University

A combination of an early fall harvest and unusually warm conditions throughout September and early October resulted in an unusual "flush" of volunteer corn germination and growth prior to later-occurring killing freezes. The growth of volunteer corn in many fields was so noticeable (thick and as large as leaf stage V6) that many believed that mechanical harvest loss this past fall was surely greater than usual. The volunteer corn indeed resulted from the shattering that occurred this past harvest season at the combine head or out the back of the thresher. A couple of factors contributed to the harvest loss this past fall: 1. Grain dried very quickly during the warmer than usual September and kernels exploded off the cobs very easily once they hit the snapping rolls. 2. Some combine operators simply drive too fast for the volume of grain they are pushing through the machine and I suspect the machines simply cannot separate the grain effectively enough. I stopped at several fields that were dramatically visual from the road and did some harvest loss estimations. These were some of the worst-looking (most dense lush growth of volunteer corn) fields, yet the harvest loss only ranged from 1 to 2 bu/ac. While maybe not acceptable loss rates, such losses were also not exceptionally bad considering how green the fields looked from the field. It's just that 1 to 2 bu/ac translates to 90,000 to 180,000 kernels or plants per acre; substantially more than a typical intended planting rate of 30,000 seeds per acre.

Click image to enlarge

Frost injury to volunteer corn at approximately the V6 stage of development.

Frosted volunteer corn in field with loss rates equal to 1 to 2 bu/ac (90,000 to 180,000 kernels per acre)

Frosted volunteer corn in field with loss rates equal to 1 to 2 bu/ac (90,000 to 180,000 kernels per acre).

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service