The official first day of Fall is just around the corner so, today, I thought it would be a good idea to check on the progress of pecan shuck-split among the trees in our breeding program. To find out if the shuck is beginning to separate from the shell of a pecan, I use my pocket knife to slice down through the shuck until I hit shell. I give the knife a quick twist to see if I can easily pop off a portion of the shuck. Separation between shuck and shell begins at the apex of the nut and works downwards toward the base. So my first cut is always about 1/4 of the way down the nut. If the shuck pops off, I make a second cut about 1/2 the way down the nut. In the photo at right, you can see that the shuck separated from the shell at the 1/4 cut line. Note the beginnings of the shell markings near the tip of the nut. Then with my next cut the shuck stayed firmly attached to the shell. This pecan was only starting the journey towards shuck split.
Moving on to another tree, I found pecans that were further along in the shuck-split process. I used the same process of cutting through the shuck 1/4 of the way down the nut then repeating at 1/2 and 3/4 of the way down. The photo at left shows a nut after I made the 3/4 cut. Here I found that the shuck was completely separated from the shell but the shuck had not yet split open. I then decided to peel off all the shuck to take a good look at the nut within.
The nut was easily extracted from the shuck but had yet to develop the even brown shell color we usually associate with mature pecans (photo at right). To develop normal shell color, the nut needs to be exposed to the air and begin the drying process. This will start when the shucks split open.
The splitting open of shucks is another process that occurs over time. Each pecan cultivar seems to split shuck just a little differently. In the photo at right, the shuck has begun to open along the suture right in the middle of the nut.
In the more common case, the shuck opens at the tip of the nut and works towards the base (photo at right). The nuts pictured here are from our earliest ripening clone. Last year I recorded shuck-split for this tree on Sept. 20. This photo was taken today (17 Sept. 2018).
One other observation I have made when recording shuck-split data. With many cultivars, shucks open uniformly over the entire tree. While other trees seem ripen over a couple of weeks. The nut cluster pictured at left shows a pecan clone that splits shuck one nut at a time over a 7-10 day period. In a cluster of 3 nuts, one is fully open while the others are still held firmly inside the shuck. Looking over the entire tree, I noticed just a few open shucks randomly within the canopy. Most nut were still tight in the shuck.
Over the next month, I'll be watching for shuck-split among tree in the breeding project and the trees I've grafted on the farm. As of today, I found no movement towards shuck-split on my Kanza, Hark, Gardner, and Faith trees. (Gardner and Faith ripen the same time as Pawnee).
The photo at right is from another tree in the breeding project. This nut may be early ripening but it is not a very impressive pecan.
