Wednesday, September 14, 2011

Drought effects nut fill

     A hot dry summer has played havoc with this year's pecan crop. The dry weather during the 1st half of the summer decreased nut size dramatically. Back in early August, we received some welcomed rains that seemed to perk up our trees. But unfortunately, the rain turned off again and the 100 degree plus temperatures returned. Hot, dry weather in late August through early September has had a major impact on nut fill.
     This morning, I cut open some nuts to check on the progress of nut filling and made some interesting observations.  The first cultivar I checked was Pawnee.  I had expected Pawnee to have nut filling problems this year because of its large nut size but was pleasantly surprised when I found a fairly well packed kernel. However, our Pawnee nuts will not be perfect. In an earlier post, I mentioned that kernel filling starts at the seed coat and works inward. Note that the top of each kernel half has grown much thicker than underside of the kernel. This will mean that, at harvest, our Pawnee nuts will have a concave appearance on the bottom of each kernel half.

    Next, I cut open a Osage nut, thinking that a super, early-maturing nut may be better filled. You can see in the photo that kernel deposition was similar on both upper and lower portions of each kernel half. At this point in the season, Osage has already started the process of shuck separation from the shell and kernel deposition is effectively complete. Note that there are still obvious voids in the kernel. This type of drought damage translates into a dry, crumbly kernel at harvest.
     Lakota ripens almost 2 weeks later than Pawnee and you can see that the nut filling process is still underway. If you zoom in on the photo, you can see translucent areas where kernel is still being developed. Amazingly, we are getting some rain today, with more forecast later in the week. Will these rains help Lakota fill out their kernels? Time will tell, but I think most of our cultivars and all of our native pecans will produce nuts with much lower percent kernel than in normal years.