Preparing a pecan sample for evaluation

     Each year, the Kansas Nut Growers Association evaluates nut samples, submitted by producers, for shell-out percentage and kernel quality. The results of these evaluations are exhibited at our annual meeting in March with the results published in the Kansas Nut Growers newsletter. We are currently right in the middle of pecan harvest so it is a good time to think about collecting your samples the evaluation.
    When I collect samples for evaluation I start by pulling a random sample of a singe cultivar out of a sack of cleaned nuts. The photo above shows a sample I pulled from our Kanza crop. They are all Kanza nuts but they still vary in size and shape.

     In the photo at left, I sorted through my random sample and pulled out the small, squaty, miss-shaped, or shell fractured nuts (nuts in the top row). This left me with a more uniform, and more representative sample of the Kanza nuts produced on our farm (bottom two rows).
    For evaluation purposes, we require a 30 sample. Place your sample in a paper bag that is marked with your name and the name of the cultivar. Samples should be sent to: Pecan Experiment Field, 8960 SW 90th Str., Chetopa, KS 67336. We are also interested in evaluating outstanding nuts produced by seedling trees.

Kanza: Long term productivity

    Back in 1965 the USDA pecan breeding station set some scions of the pecan clone 55-11-11 to Kansas for advanced testing. Pictured at right is the tree grafted with that wood. In 1996, 55-11-11 was named Kanza and released as a new, scab-resistant pecan cultivar for northern pecan growers.
   One of the greatest challenges facing pecan breeders is predicting how a new cultivar will perform over the long run. And by long run, I mean 30 years and more. History is full of pecan cultivar that looked great as young trees only to fall apart in a mature orchard. Shoshoni, Chickasaw, Mohawk, and Maramec are a few examples that come to mind.
    So every year I watch this old original Kanza tree for signs of weakness. So far, this single Kanza tree has been extremely reliable, producing nuts every year with no sign of production problems. This year's crop was no different (photo above) and provides more evidence that Kanza is a cultivar for the long run.

Importance of a vigorous rootstock

    We were harvesting pecans today and couldn't help but notice the graft unions of two of our older trees. As I clamped the shaker onto the trunks,  I asked myself, "What happens when the scion cultivar out grows its rootstock?"
    In the photo at right, a Major scion was grafted about 4 feet up into a native pecan tree. Note the slight bulge at the graft union and the fact that the  Major top has a larger diameter than the native rootstock. This tree was originally grafted way back in the late 1950's and is currently about 2 feet in diameter. This is also the only Major tree on the research station that has out grown its rootstock.
    Major trees tend to grow more vigorously that other northern pecan cultivars. Major trees that we grafted on to Giles seedling rootstock back in 1983 are nearly the same size as the Major tree pictured here. It became obvious to me, that the Major tree in the photo, was being dwarfed by a inferior rootstock.
    I shook the tree and found its nut production to be similar to other Major trees of equal trunk size. The problem is, at 55 years old, this Major should be closer to 30 inches in diameter.  As far as I can tell, the inferior rootstock has had only one effect on the scion cultivar--it has slowed tree growth. However, slower tree growth means the tree is slower to come into bearing age and has less cumulative nut production over time.

     The Major tree is not the only tree that has shown scion over growth. In the photo at left, a Peruque scion was grafted into a native tree also sometime in the late 1950's. This tree is even smaller in diameter than the Major tree pictured above. If you take a close look at the photo of the Major tree, you can see the Peruque tree just to the left of the Major trunk in the background. Since these two trees are only 100 yards apart, it is likely that the seed parent for both inferior native rootstock trees could be the same.
     On my farm, I have hundreds of volunteer pecan seedlings that could be grafted. But which ones should I use? Will I be condemning certain scions to a life of perpetual slow growth if I choose the wrong seedling? How can I tell?
     I only graft seedlings that have demonstrated a strong growth rate--2 feet of new growth in a single year. If a tree seems to be struggling to grow as a sapling, it is a pretty sure sign that tree will not provide a vigorous enough rootstock for any scion cultivar.
         

Pawnee kernel defects caused by drought

    I was cracking some Pawnee pecans and noticed that this past summer's drought didn't effect nut fill as much as it created  kernel color defects. In the photo at right the upper two kernel halves are plump and exhibit normal kernel color for Pawnee. The lower two kernel halves have dark blotches and prominent veins. Look carefully at the lower two kernels and you will see that they are also not as plump as the upper kernels. The area between the dorsal groves looks shrunken and the meats are not fully expanded all the way to the tip of the kernel.
     You can find both types of kernels produced by the same tree. Without enough available water this past summer,  the tree was unable to completely fill out the kernels of all nuts produced. 
    I've tasted both normal and darkened kernels and found little difference in flavor. However, the dark blotches can be a big "turn-off" to consumers. If  Pawnee had just produced some kernels with less than perfect kernel fill and no color changes, no one would probably notice. Blotchy kernel darkening associated with incomplete nut fill seems to be unique to this year's Pawnee crop.