Early spring tree thinning

     With warm sunshine overhead, today was a good day to cut some pecan trees down (photo at right). We removed six more trees from our Kanza block according to our pre-determined tree thinning plan.

  The trees in this block are growing at an incredible rate. Just look at the cross section of one of the trees we cut down today. Over the past 4 growing seasons, the annual growth rings of this tree averaged more than 1/2 inch per year (photo at left).  However, not all trees in this block are growing at the same rate. Generally speaking, the trees on north end of this planting are growing faster than the trees farther south.  This variation in tree growth rate is largely due to a gradual change in soil conditions.
   Every winter I walk through the planting to measure trunk diameter and look up at tree canopies to see if they are starting to get too close. Looking up is the best way I know of determining when to thin out trees.

    Here's a series of maps that tells the story of our the thinning efforts over the past three years. In looking at these maps, each green circle represents a tree and the relative diameter of each tree is depicted by the size of the circle. The red lines cut through all the trees that will be removed once the entire field is thinned. I placed a black circle over the trees that are to be removed during each particular thinning year. As you look at the maps, you'll note that the trees slated for removal one year disappear off the map of the next year's tree removal plan.

     Thinning an orchard over several years has many advantages over thinning the entire block at one time.
     1. Trees are removed in time to prevent sections of the block from becoming overcrowded.
     2. The number of trees removed per year is minimized allowing yield for the entire block to remain at a high level.
     3. The work of thinning a block of trees is spread out over several years.

        When established in 1995,  there were 144 seedling trees planted in this block. These trees were then grafted to Kanza during 1998-2000. Starting at tree age 17, we began our planned tree thinning operation. We removed 7 trees in 2012, 5 in 2013, and 6 in 2014. At this point, we have removed only one-quarter of the trees that will eventually be cut to complete the thinning plan. I'm sure more trees will need thinning a year from now.   

Judging kernels

   Over the past couple of weeks, I've been looking at a lot of pecan samples. We collected nuts from 216 trees in our pecan breeding plot and cracked 10 nuts from each tree. We evaluated those nuts for size, percent kernel, and kernel appearance. Nut weight and percent kernel are easy measurements to determine with the aid of a gram scale and calculator. However, when it comes down to kernel appearance things get a little more difficult to quantify.
   A smooth, golden kernel color is most desirable for pecan. Light-colored kernels are described by the official USDA pecan grading system as "Fancy". However, in evaluating hundreds of nut samples, my eye detects subtle color differences even among kernels that would be graded as Fancy. The photo at right demonstrates these subtle color differences. At the top are the lightest colored kernels I found among our breeding plot nuts. In the middle are kernels with a beautiful golden pecan color. The kernels at the bottom are ever so slightly darker than the ones above but still have a pleasing sandy coloration. Which looks best to you?

    Not all the nut samples we cracked had beautiful even-colored kernels. It is so disappointing to crack open a large, thin-shelled nut only to find an ugly pecan kernel inside. I found two types of kernel defects (photo at left). The first was the appearance of dark veins that cross the surface of the nut. The second was a mottling of the kernel surface with dark patches. I even found a tree that produced nuts with both veins and mottling. These kernel discolorations do not effect kernel taste but the lack of "eye-appeal" would make selling these types of kernels very difficult. 
    All nut samples from our breeding project will be on display during the KNGA annual meeting. Click on the event tab above for details.
 

Wheel bug egg mass

    The sun shine felt good today after last weekend's winter cold snap. In fact, all the snow has melted and we could get back to collecting pecan scionwood. While we were cutting scions we discovered a large egg mass (photo at right) on a pecan branch. The eggs are lined up in neat rows, are black in color, and topped with a white cap. Later this spring, these eggs will hatch and dozens of wheel bugs will emerge to start searching of other insects to feed on.

     The wheel bug is one of the most common insect predators found in pecan tree canopies. These insects will grow quite large and are easily recognized by the red antennae and  prominent cogged "wheel" on their backs (photo at left).  So if you are out pruning pecan trees make sure to leave the egg masses of these beneficial insects in place.  

Let your trees tell you when to fertilize

 

    Winter returned over the weekend covering area pecan groves with a blanket of new snow (photo above). The temperature dropped down to 2 F this morning in the Neosho River flood plain outside of Chetopa, KS. At this time of year, pecan growers are supposed to be thinking about making their Spring fertilizer application, not shoveling snow and hauling firewood.
     In timing the spring fertilizer application, it is important to remember that soil nutrients are most readily adsorbed by actively growing pecan roots. With all the cold weather we've had this winter, pecan roots are still laying dormant it the cold ground. New root growth will not start until soil temperature begin to rise with the coming of spring.  

    Because roots are buried in the soil, it is not easy to see when their growth begins in the Spring. However, watching for the earliest sign of bud swell is a good indicator that a pecan tree is coming out of dormancy and spring root growth has begun. I carefully watch lateral buds on one-year-old shoots. The first sign of bud swell will be the splitting of the outer bud scale (photo at left). When this happens, I know that root growth has started and it is a good time to spread fertilizer under my trees.