Several beetles including Japanes beetles will clip the silk off. You can put pollen on the stubs to help fill the ear up.
https://www.ca.uky.edu/agc/pubs/id/id48/id48.htm
Stress can make organisms do strange things. Remember the frog DNA from Jurassic Park?TZ -OH6 wrote:Native corns do that stuff all the time, so it might be a trait of that heirloom if it had a lot of those short season varieties in its background. The frequency could be increased by inbreeding (seed repeatedly taken from a small plot) assuming that the variety generally doesn't do it very much. It took a lot of work to breed it out of the modern hybrid sweet and dent corns. That being said I got some kernels on a tassel of Burpees Delectable hybrid a couple of years ago. I suppose odd conditions could make it show up. My Painted Mountain, which is a mixed genepool of dozens of western native corns, does all kinds of freeky things.