Saturday, November 26, 2016

Pecan harvest rolls on

   For many Americans, the Thanksgiving holiday weekend means four days of over-eating, shopping for Christmas presents and watching football. However, for area pecan growers, the holiday weekend has been a great time to harvest pecans. The ground is dry and nuts are easily shaken from the trees. Today, we harvested nuts from our native pecan plots (photo above). Judging from the sound of nuts hitting the roof of the shaking tractor, we will probably harvest an average sized native crop in 2016.    

Monday, November 21, 2016

Stick-tights: When a pecan kernel doesn't develop inside

    We were shaking some Kanza trees today, when I noticed a few bright green shucks still up in the tree. Most often its just one nut in a cluster of 3 to 4 nuts (photo at right). If you look closely at the still-green nut, you'll note that the shuck hasn't even split open. The fact is, this nut will never split open and will become what we call a stick-tight.
     I pulled some nuts off of our pecan cleaner's inspection table to find out what going on inside the nuts that remain stick-tights. In the photo at left, two stick-tights are shown next to two normal Kanza nuts. I cut each of the nuts in half to reveal what is inside the shell. The normal pecans had nicely filled kernels while the stick-tights had kernels that never fully formed.
     It is the maturing seed inside the shell that triggers normal shuck opening. Without a fulled developed kernel inside, the shuck will never open.
    What causes kernels not to fill out? In this case it is not clear. Stinkbug feeding can cause a similar lack of kernel development but the interior portion on the nut would be jet black in color. Disease is not the cause because the nut appears perfectly healthy. This lack of kernel fill is most likely due to a miscue in tree physiology. For some reason the kernel filling process was switched off  during the water stage of kernel development.

    The appearance of these kind of stick-tights at harvest is not exclusive to the Kanza cultivar. When we cleaned our Pawnee pecans, I found stick-tights  with a similar lack of kernel development (photo at right). Thankfully, the number of stick-tights we harvest is only a small fraction of the total number of nuts we collect each Fall. It just drives me crazy to pull stick-tights off the cleaning table and think--what did I do wrong? The answer is probably, nothing. I guess our pecan trees are just not perfect when it comes to filling out every kernel on the tree.   

Friday, November 11, 2016

Fungicides help reduce alternate bearing of pecans

   The photo above is a perfect illustration of the impact fungicide applications have on pecan leaf retention. This morning, I drove into the Pecan Experiment Field and noticed a stark difference between our trees (left of the lane) and our neighbors trees (right of the lane and across the fence). Our trees still had leaves on them.
    The difference in leaf retention wasn't due a difference between grafted trees and native trees. Trees on both sides of the lane are grafted. On the left are Posey and Pawnee trees while the neighbors trees are primarily grafted to Mohawk. The difference in fall leaf retention pictured above is entirely due to the application of fungicides made last summer to control scab. Our neighbor did not use any fungicides in 2016.
   Even though our primary goal in making fungicide applications was to control nut scab, fungicide sprays have the secondary benefit of keeping leaf diseases under control. It was the cumulative impact of several foliar diseases that caused early leaf drop in our neighbors orchard. 
    Long before the leaves drop from the trees, foliar diseases reduce the tree's ability to capture the sun's energy and convert that energy into carbohydrates. This usually happens in late summer, exactly at the same time pecan trees need the carbohydrates to fill out nut kernels.  The result is an exaggeration of fruiting stress during the current season and a weak return bloom the next.
   Over the many years of managing our pecans at the Experiment Field we have found that preserving leaf health with fungicide applications help reduce the intensity of alternate bearing. But remember, all the fungicides applied were aimed at controlling pecan scab. Improving leaf health and reducing alternate bearing is a welcomed bonus.     

Friday, November 4, 2016

Kernel appearance matters

   Even though I get great joy from watching young pecan trees grow and then set their first crop of nuts, the real reason I invested time and money in a pecan orchard is to produce pecan kernels for sale to the public. And the public has high expectations for pecan kernel quality. One of the reasons I've come to appreciate the Kanza pecan cultivar is that it always seems to produce a plump, light-colored, kernel (photo at right).     However, there are pecan cultivars that produce such unattractive kernels it makes selling those nuts difficult. Let me show you a few examples.
   Witte ripens very early and produces a good sized nut. What looks to be an outstanding northern pecan cultivar on paper is nearly impossible to sell to the pecan consuming public. Witte kernels are always deeply wrinkled giving the nut a shriveled appearance. The kernel also darkens quickly (not shown here). If a pecan kernel is unattractive, the consumer will never place a nut in his mouth. Flavor, no matter how outstanding, will always be a secondary cultivar attribute to most consumers.
    Mandan, a cultivar released in 2009, is a pecan that was promoted as early ripening and having high nut quality kernels. Mandan produces pecans with high percent kernel but those kernels are ugly. The nuts appear wrinkled with the underside of the kernel half sunken and hollow-looking (photo at right, blue arrow). On the tip of the kernel, an extra flap of skin looks unsightly (red arrow). For a cultivar that produces nearly 60% kernel, Mandan nut meats always look shriveled and unappealing.

  A different kind of ugly kernel comes in the form of mottled or blotchy kernels (photo at left). The degree of blotching  seems to vary with the year. Pawnee, Faith, Gardner, Jayhawk and Giles are most prone to develop a mottled kernel color. Even though Pawnee has become one of our most desirable cultivars because of its large nut size and early ripening, I'm starting to limit its propagation on my farm. Between scab susceptibility and blotchy kernels, the risks associated with growing additional Pawnee trees have become too great for me.