Stalk strength and stalk rot

​There have been numerous studies comparing inbreds and hybrids for the fiber strength of stalks.  Perhaps these results are somewhat helpful to predicting standing corn at the end of a season but I suspect that it ignores the biggest factors affecting standability at harvest time.  When the stalk collapses in the lower internodes preharvest, the pith tissue has pulled away from the rind of the stalk.  This reduced the structural strength by 1/3 as what was once a rod now becomes a tube. This happened because the root died earlier, reducing water uptake followed by wilting of the plant.  This dessication of pith cells caused withdrawal from the rind. The dead cells, now having limited resistance to fungi readily invading the tissue and digesting the cell walls, further weakening the strength of the stalk.
 
The time between black layer and harvest level grain moisture is the best time to evaluate stalk quality.  A simple push test of several plants in many areas of a field can give one a good idea the crop’s vulnerability to lodging.  Basically those that are strong, soon after black layer,  will not decrease in strength during the rest of the season.  One should never forget, however, the stalk rot of 2016 in one field is not necessarily an indication of the behavior of the same genetics in the same field next year.  Evaluations across several environments is critical to predictions of yield and stalk quality.