Thursday, November 17, 2011

Why won't some pecan shucks split open?

    We've been harvesting pecans this week and I've noticed quite a few green nuts still up in the trees. With this mornings low temperature registering 24 degrees F, all those green shucks were frozen and are quickly turning black. But long before last night's freeze, there was a reason those nuts where green and still stuck in the shuck (Photo above shows sticktights vs normal nut).
    In a previous post,  I described how pecan weevils can cause pecan shucks to remain green long after normal nuts have split shuck and started to dry. But the nuts pictured above remained green until last night's freeze and failed to open correctly because the kernel inside failed to develop.
    Here is a photo of a well developed Kanza nut vs. a Kanza sticktight (photo at left). You can plainly see that the sticktight nut developed a seed coat but never filled it with kernel (read about kernel filling here). Since the seed coat is a normal tan color, we can assume that the lack of kernel filling was related to this past summer's drought.  Under drought conditions, pecan trees often abort part of their nut crop to be able to fill the nuts that remain.
     If the seed coat had been dark black inside, stinkbug feeding in early August would have been the cause for the lack of kernel development. In any case, it looks like we will have a lot of sticktights to pick off the cleaning table this fall.