Cutting quality scionwood

    Even though it's freezing cold outside today, it won't be too long before we will need to go out into the orchard and collect some pecan scionwood. The other day I cut down a young pecan tree (a really poor cultivar!) and it gave me the opportunity to cut off some pecan branches so I can show you how to find and select quality scions.

   Let's start by looking closely at a pecan branch. The best scions come from last year's new growth. In the photo above, you can see 2-year-old wood on the left and one-year-old wood on the right. Two-year-old wood is generally more grey in color and all the primary buds are missing. The reason 2-year wood has missing primary buds is because last spring, these buds opened and produced  catkins.  Two-year wood ends in what is called the annual growth ring which is actually a ring of closely spaced bud scars. One-year wood has a more brown or reddish-brown color with primary buds still firmly attached to the stem. Note that the first few buds on the 1-year wood are small and you don't see a prominent primary bud until about two inches up the stem. When I cut scionwood from a tree, I take only 1-year wood and make the first cut just above the annual growth ring.

     The best scions are collected from one-year-old shoots that are at least 2 feet in over-all length. After I cut the shoot off the tree, I cut the wood up into individual scion sticks that are each 6 to 7 inches long and contain at least 3 buds (photo at left). I try to make sure that the upper most bud on each stick is at least one inch below the top of the scion. I always discard the terminal piece of wood (stick at far left) because it is too small in diameter for the grafting techniques I use.

   Once a graft is made, the vigor of emerging buds from a scion is largely dependent on the amount of energy stored in the wood of the scion stick. In the photo at right, I've cut into each stick pictured above to reveal the amount of wood inside. The scion cut from the base of the one-year wood has the thickest layer of wood and the greatest reservoir of stored energy. As you go up the stem, you'll note that pith seems to become more prominent and the actual woody tissue more narrow.  The base of last-year's growth is the oldest portion of the stem and has had an entire growing season to lay down wood. As a stem grows in diameter the wood also compresses the pith into a narrower band of corky tissue.
    When I'm grafting, I can always tell if a scion is going to make a successful graft based solely on the ratio of wood to pith. The scion with a lot of wood and tiny pith will always out-perform a scion that's mostly pith. In cutting scionwood I always discard the terminal piece for two reasons; the buds are too close together and the stick is too pithy. In looking at the scions above, I'd choose to graft with the two sticks on the right. The second stick from the left is marginal and I'd use it only if I've run out of other scion choices.
   Remember, when you are cutting scions, you don't need to slice into each piece to check the wood to pith ratio. Simply look at the cut surface at the top of each scion and note the diameter of the pith as compared to the overall diameter of the stem. The pith diameter should be no larger than 1/3 the diameter of the entire stick.

Notes on Jayhawk pecan

    Jayhawk originated as a seedling of Giles planted by Lewis Harris on his farm near Wichita, Kansas.  This seedling cultivar first came to light when entered into the Annual Nut Evaluation of the Kansas Nut Growers Association back in 1989.
    Jayhawk has been under test at the Pecan Experiment Field for several years and we have a pretty good feel for how this cultivar performs. On the plus side, Jayhawk is precocious, productive, scab resistent and produces a medium-sized, thin-shelled nut. This cultivar has a protogynous flowering habit and ripens nuts 10 days after Pawnee and 6 days before its parent, Giles. Jayhawk trees have good tree structure and are easy to train.

    Back in 2011, I noted a single negative trait that seemed bad enough to keep Jayhawk off my top ten list. Jayhawk kernels appeared mottled with darker brown patches giving the nut meats an unappealing appearance. At that time, I blamed the blotchiness on the 2011 drought. So this year, I was curious to see what Jayhawk kernels would look like  following a cool summer with ample rainfall (photo at right). In comparison to 2011, the 2013 Jayhawk kernels had much better color but were still far from perfect. The upper side of the kernel halves had only a few minor brown patches but the underside displayed a mottling pattern that makes the kernel look "dirty". Although the patches of kernel discoloration seem to have zero effect on kernel flavor, it will be hard to convince consumers to place "dirty" looking pecans in their mouth.
   Jayhawk is a great example of a pecan cultivar that looks almost perfect but probably shouldn't be propagated.  A single serious defect (blotchy kernels) is enough for me to discard Jayhawk as a potential recommended cultivar. 

Pecan oddities from the cleaning table

Twins!

   This week we've been looking at thousands upon thousands of pecans streaming across the inspection table as we clean the 2013 pecan crop. As we look to remove  rocks, stick-tights and damaged nuts, we will come across a few genetic mishaps.
   What might look like one big pecan split in two is actually two fully formed nuts joined at the base (photo above). These twin pecans had their genesis all the way back during pistillate flower formation when a genetic miscue led to the creation of a double flower. A double flower has two stigmas, two ovaries but a fused shuck. At harvest, a twin nut falls free from its shared husk revealing  a pair of nuts with shells fused only at the very base. Crack open the nuts in the twin and you will find two kernel halves in each pecan just like a normal pecan.

   Harder to spot on the cleaning table are nuts that don't have the normal two kernel halves inside. The other day we spotted a nut with three cotyledons inside (photo at left). Viewed on its side the nut looks quite normal. However, look at the nut's apex and you can see that the shell has three distinct faces signalling the fact the kernel inside is divided into 3 pieces instead of the normal two. Over the years, we have also come across pecans with a single cotyledon and even nuts with four kernel pieces. 

Misshaped pecans

     This year, we also found a couple examples of pecans that look like their growth was simply pinched off. We found a nut with an extremely narrow, pointed apex as well as a nut with a pinched of base (photo at right). Obviously something went wrong with these nuts during nut expansion but what that something was I haven't got a clue. Its just a good thing that we found only these two deformed nuts in the tens of thousands pounds of pecans we have cleaned.

Mid-winter pecan harvest

    It looks like mid-January will represent the longest stretch of harvesting weather we've going to get to pick up the 2013 pecan crop. This past week the Neosho River bottom was humming with the sound of pecan harvesters (photo above). At the Pecan Experiment Field we finally finished picking the entire grove and have now started on our second picking.
   You would think that we could get the majority of nuts picked up on the first pass across the orchard, but several trees have required a second shake to bring all the nuts down. And frankly, mechanical harvesters always leave nuts behind during the first harvest. How much do we harvest on the second pass? The chart below provides some numbers.

 
    At the Experiment Field, we have 6 native pecan plots that we record annual yield. These plots are labeled A through F and we record the weight of clean, harvested nuts from both the first and second harvests. In 2013, the plots averaged 1640 lbs/acre in total harvest. A little over 20% of that yield was collected from the second harvest.