Drought induced stick-tights

    After harvesting for a couple of weeks we have finally started to clean some of the 2012 pecan crop. Today, I walked over to the piles of rejected nuts that came out of the cleaning plant and grabbed two handfuls of stick-tights. The first handful came from the pile that was blown out of the cleaner by the air leg (photo at right). As you can see, the cleaner blew out stick-tights that had wafer-like kernels and nuts that fell out of the shuck normally but had shriveled or no kernel. These are the type of pecans we definitely want to keep out of our final product.

    I took a second sample from the the rejects that had been pulled off the inspection table by hand. These were all stick-tights but unfortunately, these nuts contained edible kernel (photo at left). The summer-long drought we experienced in 2012 has caused the shucks of some nuts not to open properly. This type of incomplete ripening seems more prevalent on trees with heavy crop loads. It's a terrible shame to waste these perfectly good kernels but if the shucks stay firmly attached the nut, the nut is  unmarketable.  Fortunately, stick-tights with good kernel inside are far fewer in number than the numerous stick-tights we are seeing being blown out of the cleaner (nuts with little or no kernel).

Incomplete shucksplit on native pecans

    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.

Bird's-eye view of pecan harvest

    A few days ago I was out in a hydraulic lift making nut counts and couldn't resist talking a photo of pecan harvest from a bird's-eye view (photo above). From 25 feet up into the canopy of our trees,  the harvester looks so small.

Giles ripening effected by crop load

    Thirty years ago, Giles was one of the most popular cultivars to propagate in Kansas. Selected from a native grove outside of Chetopa, Giles seemed like the perfect pecan for our growing under our conditions. But grow any cultivar long enough and you'll discover you still haven't found the perfect pecan cultivar.
    Giles has a tendency to over-produce. This leads to all the typical problems associated with alternate bearing including poor kernel quality during "on" years and next to zero crop during "off" years.  However, this year we've seen a new problem with our Giles trees--incomplete ripening.  A quick survey of Giles nuts still hanging from the tree reveals that some nuts have split shuck normally while others have not opened at all (photo above, right). At this point in the season, the nuts have have failed to split, will never open.
     I peeled out some of the "stick-tight" nuts  and cracked open the shells to see if poor kernel development was the reason for lack of proper ripening (like we saw with Posey). In every case, the kernel in the sticktight nuts were just as well filled out as nuts that ripened properly.  Something else was causing sticktights.

   
    Earlier this summer we recorded the amount of fruiting shoots produced by 20 of our Giles trees. These counts revealed a wide variation in crop load. We had Giles trees with as low as 16% fruiting shoots to as high as 70% fruiting shoots.  To see if crop load influenced the amount of incomplete ripening found on a Giles tree, I decided to climb into the hydraulic lift and make some nut counts.  My results can be seen in the graph above. The heavier the crop load (greater % fruiting shoots) the more incomplete ripening or stick-tights we found in the trees.
    Incomplete ripening due to fruiting stress may occur in other cultivars but it is most pronounced with Giles. The drought we experienced this past summer may have also contributed to making the problem worse in 2012.