Ear shoot initiation and silk emergence occurs when a hybrid has reached its appropriate heat unit accumulation for reproduction.A cool backward year like 2009 favours early silking hybrids as they will start their grain fill period sooner and have more opportunity to reach physiological maturity before a killing frost occurs.They offer a much greater chance for growers to achieve better yields and higher test weight corn in a low heat unit year.The above shots were taken of the same corn plant.As you can see Silk elongation is occurring before pollen shed has started.This is exactly what breeders prefer.They have strived for years to develop hybrids with better silking - pollen shed synchrony.Breeders want a hybrid to shed its silks before its pollen as this will improve a hybrids overall yield stability.