Thursday, August 3, 2017

Pecan development and summer shaking

    Many orchards in northern pecan states are blessed with excellent pecan crops this year. Some cultivars have even set excessive crop loads increasing the likelihood of poor kernel quality this fall and  increased risk of cold injury this winter. Using a trunk shaker to remove a portion of the crop in mid summer is the best way to avoid kernel quality issues this year and increase return bloom next year.  However, for summer trunk shaking to be effective growers must time their nut thinning operations by carefully monitoring nut development.
    Trunk shaking to thin the crop works best when pecans have reached full size and the kernel is in the water stage. This means that growers must monitor their crop to check on kernel development. Yesterday, I collected nuts from four pecan cultivars (photo above). Let's see what inside.

    To check kernel development, hold the nut so you can see the attachment scar on the bottom of the nut (photo at left). Note that the attachment scar is oval in shape. The long axis of the oval was aligned with the stem of the pecan shoot.
   To reveal both sides of the kernel and the progress of kernel development, I cut the nut in half perpendicular to the long axil of the oval attachment scar (photo at left). If you find the mid point perfectly, your knife will split the shell on the suture. 

      The nuts I cut open yesterday, revealed that kernels have not yet reached full water stage (photo at left). Currently, Pawnee is at 1/2 water stage and Giles 1/4 water stage.  Nut development can move quickly at this time of year so be prepared to monitor nuts about every 5 days or so. From past experience, we have thinned Pawnee about a week before Kanza and about 10 days before Giles and Lakota.