Today we switched from harvesting pecan cultivars to picking some of our natives. While shaking the trees I noticed about %5 of the trees had nuts with green shucks. I climbed out of the tractor and collected some of the green hulled pecans (photo at right). I noted that some of the nuts had split their shucks normally while others were not split at all.
Taking my knife, I cut into the shuck of a pecan that had not opened properly and popped off the shuck (photo at left). The pecan inside was fully colored and loose in the shuck but the shuck had not split along the four suture lines. This called for futher investigation.
I collected 3 pecans that had normal shucksplit and compared them to 3 pecans that I had to cut out of the shuck. I then cracked open each of the nuts to reveal the kernel inside (photo above, right). The 3 pecans on the right had shucks that opened normally. The pecans with shriveled kernels on the left were cut out from closed shucks.
During a drought, some heavily bearing trees "choose" to fill only a portion of their crop. Those pecans that do not fill their kernels do not shuck-split properly. We saw the same phenomenon when we harvested our "Posey" crop.