heavy rain in September saved our drought stricken pecan crop this year by promoting kernel fill. At that time, I warned that we might find that the pressure of an expanding kernel might actually crack the shell on nuts that had sized during the drought. By late September, I found one early maturing cultivar that was split open by the kernel. Now that we are in the middle of harvest and are cleaning pecans, we have noticed several cracked shells crossing the inspection table (photo at right).
The cracks we've observed in the shell have appeared both along the suture (middle nut above right) and 90 degrees to the suture (top nut above right). We even found a pecan cracked both ways (bottom nut above right). All of these cracks were created by a sudden expansion of kernel following the September down pour.
Cracks in the shell allow pathogens and insects easy access to pecan kernel. When we see these nuts on the cleaning table we discard them in order to maintain top quality in our final product.