Sunday, September 1, 2013

Notes on planting pecan trees: Reality vs. expectations

   A couple of years ago when record prices were paid for pecans, growers got very excited about planting new trees. The thinking at the time was, "If I can move the large seedling trees I already have growing in fence rows, I can fill in some orchard gaps and increase production in no time at all."  Over the winters of 2011 and 2012, hundreds of 1 to 2.5 inch diameter trees were moved with a truck-mounted tree spade in the Chetopa, KS area.
    Unfortunately, many of these transplanted trees have suffered serious dieback (photo at left). Two summers of drought (2011 & 2012), the total lack of weed control, and no irrigation has caused most of these transplanted trees to die back to the ground. These tree are not completely dead, you can spot a few new pecan shoots sprouting up from the base of the tree.
     In the photo at left, a red arrow points to the basal sprouts that have emerged this summer (A response to this year's much needed summer rains).  This tree is struggling to get back to a sustainable balance between roots and shoots. Initially, the tree spade cut off a large amount of the tree's lateral root system. Then the drought caused even more root loss. Without an adequate water supply supplied by the roots, the top of the tree simply burned up. Two years later, the surviving roots are trying to re-establish leaves and stems to provide  the photosynthetic energy necessary for tree survival.
   A lot of time and money was spent to move big trees in an effort obtain quicker nut production. Now two years later, the transplanted trees are just barely surviving. The moral for this story is: If you spend a lot of money to transplant large trees, expect to spend even more time and money in keeping them alive. Weed control and water, lots of water, are essential.

    At the Pecan Field, we decided to transplant one-year-old container-grown trees out into the gaps of our orchard (photo at right). I have always felt that the younger a tree is when transplanted, the better that tree will handle transplant shock.
    We learned a valuable lesson last year, when transplanting container grown trees out into the field. The deer seem to love destroying nursery grown trees. So, now we cage each tree right after transplanting.
    We have watered these trees during dry periods and tried our best to suppress the weeds (looks like some crab grass is coming in). Despite all of our best efforts to minimize transplant shock, I notice that most of these seedling trees have sprouted basal shoots--an indication that the tree is readjusting itself to a new growing environment. In our heavy clay soil, its not until the third year after transplanting that these seedling trees start to take off.

    The best way to avoid transplant shock is to never move a pecan tree in the first place. On my farm, I've gotten very good at spotting pecan seedlings amongst the weeds and grass from the seat of a tractor while brush-hogging. I carefully mow around the seedling then come back with a weed-eater to release the young tree from surrounding vegetation (photo at left). Once the tree is standing tall above the closely mowed grass, I carefully use a herbicide to kill all weeds in a seven foot circle around the tree.
   Letting nature plant your trees has the advantage of avoiding transplant shock but results in a completely random distribution of trees across the field. Since I've spent most of my career around native pecan groves, weaving around randomly positioned trees to mow, spray, and fertilize seems only natural. However, the total lack of straight rows would drive others completely crazy.
   When mowing around naturally occurring seedlings, I leave the most vigorous growing seedlings I find. These trees will make good rootstocks for my grafting efforts. I allow 30 to 40 feet between trees using my 10 foot brush-hog as a rough guide.  I allow the trees to grow to about 1.5 to 2.5 inches in diameter before applying a bark graft.