Fertilizing pecan trees in the spring

    Today we made our springtime fertilizer application (photo at right). Every spring, we rent a fertilizer spreader and carpet the entire orchard floor with nitrogen and potassium fertilizers. We applied 150 lbs. /acre urea fertilizer which contains 69 lbs./acre nitrogen. Mixed in with the nitrogen, we applied 100 lbs./acre potash (=60 lbs./acre potassium).  The applied cost of the nitrogen was $27.56/acre and the potassium was $17.75/acre. This spring we invested $45.31/acre in our pecan crop.
    For pecan growers with just a few trees you can calculate your springtime fertilizer needs by measuring the diameter of your trees. Apply 1/2 lb. of urea fertilizer for each inch of trunk diameter. In other words a 10 inch diameter tree should have 5 lbs. of urea spread over the tree's entire rooting zone. When it come to potash, apply 1/3 lb. of fertilizer per inch of trunk diameter.
    Many backyard pecan growers buy their fertilizer in bags containing a 10-10-10 mix of N, P and K. To apply the recommended levels nitrogen, 2.5 lbs. of 10-10-10 should be applied per inch of trunk diameter. Again, the fertilizer should be applied over the entire root zone.

The first signs of pecan tree bud growth

Surecrop, 17 March 2106

    This year we've been experiencing a warm and early spring. Over the past week, I've been watching pecan buds carefully to detect the first signs of bud expansion and growth. At this point only some trees are showing signs of bud swell while other are quite dormant.
   This morning I collected some terminal branches from several cultivars which will help me illustrate the first event in pecan bud development -- outer scale split. The twig I collected from a Surecrop tree (photo at right) had buds that were fully dormant. Each primary bud appears to be encased in a smooth, hard shell offically known as the outer scale.

Kanza, 17 March 2016

    The Kanza twig pictured at right shows the very first sign of bud swell. The outer bud scale on the upper-most bud has cracked open. (The shriveled stem above this bud is last years pedicle that held a cluster of nuts).

Peruque, 17 March 2016

  


  Once the outer scale cracks open, the scale drops off to reveal an expanding pecan bud covered by an inner scale. The photo of the Peruque terminal (at right) demonstrates that the outer scale split process begins with the terminal bud and continues sequentially down the stem.

Greenriver, 17 March 2016

   The photo at right of a Greenriver terminal shows what is revealed when the outer scale separates from the bud. Each bud contains a primary vegetative bud in the center surrounded on each side by smaller axillary buds containing catkins. The vegetative bud will eventually grow out into a new shoot that terminates in a cluster of pistillate flowers.
  

Fire damage on young pecan tree

      The other day a grower called to see if he should burn off the pasture under his pecan trees. Early spring burning might be a tried and true method for invigorating Kansas grasslands but fire and pecan trees don't mix.
   Earlier this year I removed a fire damaged pecan tree from my farm. This gave me the opportunity to cut a cross section of the trunk to reveal the fire damage and how the tree responded to that damage (photo at right).
   The tree was located in a field of tall native grasses. When a grass fire moved through this field, it was pushed along by a strong southern wind. The south side of the trunk was exposed to such intensely high temperatures that the bark was singed and the cambium underneath was killed. The red arrow in the photo points to the burned portion of the trunk.
   In response to fire damage, the tree attempted to grow over the wounded area. Note how wide the wood growth rings are in the areas that are attempting to grow over the wound (marked A and B). This tree was moving quickly to seal over the wound. If this tree was left standing, it would have taken just a couple more years before these two fingers of wood growth to meet and grow together to completely seal over the burned portion if the trunk.
    Young pecan trees, with their relatively thin bark, are especially prone to fire damage. Older, mature trees with decades of bark thickness are more resistant to fire, however, these tree can also be severely damaged by fire. Keeping the pecan orchard mowed, thus minimizing the potential for a run-away grass fire, is the best method for preventing fire damage to you pecan orchard.    

Pecan seedlings heading for advanced testing

    Twenty years ago I made some controlled crosses between several pecan cultivars. Over the past three years we have been evaluating the nuts produced by the seedling trees that grew from those crosses (photo at right). This year, I have collected scions from a select group of trees from our breeding project to be grafted into advanced trials. The advanced trials should give us a better idea of how these selections perform in terms of yield, precocity, alternate bearing and tree growth habit.
   Yesterday, I photographed the nuts from trees that will be entering advanced trials this year. When you look at each photo, be aware that the two inshell nuts were placed on different sides to give you a feel for overall nut shape. A table of the 2015 average nut weights and percent kernel for these selections is given at the bottom of this post.

KT 114

    This first group of selections all resulted from crosses made between Pawnee and Greenriver (photos at left).

KT 116

KT 156

KT169

KT 342

KT378

KT 129

    The next group of selection are the results of crosses made between Pawnee and Major.

KT 143

KT 149

KT 201

KT 178

 

   The last seedling to enter into advanced trials this year will be an open pollinated Kanza seedling.














Nut weight and percent kernel data for the 2015 crop season is given below.