Monday, October 14, 2013

Nut development: 14 Oct. 2013

Kanza, 14 Oct 2013
   It been a couple of weeks since I posted an update on the development of the three pecan cultivars that I have been following this season: Osage, Kanza, and Maramec. Osage completed nut development back in late September. Since that time, I've been waiting for Kanza to show the first signs of shuck split.  Today, I found a few nuts in every cluster of Kanza nuts with open sutures (photo at right). In fact, if I pressed on shucks that were not obviously split open, I could cause the shuck to pop open along the sutures. This brings up an interesting point about the development of normal shell color as it relates to shuck dehiscence.


     The  photo at left shows the normal progression in shell color development. When the shuck first separates from the shell the sutures are still tightly closed. At this point, the shell is mostly white but marked with the characteristic black speckles and streaks. The first indication of shuck split occurs when a small opening develops at the apex of the nut. As fresh air reaches the shell it oxidizes and begin to turn brown in color (2nd and 3rd nuts in the progression pictured above). As the shucks split downward, from apex  to nut base, more air surrounds the shell causing the development of natural shell color.  Finally, when shucks are split wide open and the nut inside becomes fully colored.

Maramec, 14 Oct. 2013
     Maramec has completed kernel fill in spite of the scab infection that covers the shucks (photo at right). It will be interesting to see if this cultivar will shuck split before first frost.
    Kanza seems to be about 10 days later than normal. If Maramec is also 10 days late we'll need freeze-free weather into early November to see shuck split.

        I cut into the shuck of a Maramec nut and found no trace of shuck separation at this time (photo at left). The amount of scab on this nut should not impact normal shuck dehiscence so, if and when, Maramec splits open we should be able to record that date.