Friday, January 28, 2011

What's wrong with my pecans?

   I often receive pecan samples from home owners that have a pecan tree or two in their yard with a note simply saying--"Whats wrong with these pecans?". So I thought it might be a good idea to describe how I determine the problems associated with these type of samples. The sample pictured above came from a gentleman from the Wichita, KS area. The note that came with the sample stated that the pecans produced by his tree rarely fill well and some nuts have an "off" flavor.
    The first step to determine the cause of poor pecan performance is to determine if the nut comes from a grafted tree. These nuts were smaller than most cultivars and the thick shell confirmed the nut to be a seedling. Before cracking the nut open, I noticed that the shell markings that are normally dark black on a pecan were lighter and reddish on the submitted sample. This told me this pecan did not receive a long enough growing season to complete normal nut development. I cracked open the nut and found more evidence that this pecan is not adapted to the Kansas growing season.  Three kernel defects were present--hollow kernels, kernels that don't extend the full length of the shell, and brown fuzz adhering to the kernels. All 3 of these defects indicate that this tree ran out of time (length of growing season) to fill the kernel properly.
   The "off" flavor of some kernels were caused by stinkbug feeding. This problem shows up as darkened areas on the kernels. A full explanation of this malady can be found in a previous post call "black spots on kernels".
  So now its time to make recommendations. There are no remedies for poor genetics. The tree that produced the pecan pictured above likely originated from a seedling tree (or nut) collected in Texas and moved to the Wichita area. During years when we experience a longer-than-normal growing season the nuts will fill better. Stink bugs can be controlled in the commercial pecan orchard setting but the chemicals used are not compatible with application  within suburban neighborhoods.
   This nut sample provides yet another example of why proper cultivar selection is critical for successful pecan production in the North.