Wednesday, July 6, 2011

Training young pecan trees: When to start training

    Many pecan growers start to prune young pecan trees too soon after transplanting. I my experience, a recently transplanted pecan tree seems to just sit there, growing only 4-5 inches of new shoot growth in the first year (photo at left). What you don't see is the rapid growth that is taking place under the soil surface. Newly transplanted trees grow roots, regenerating a strong tap root (or tap roots) and developing a network of lateral roots. To support active root growth,  trees need plenty of leaves to capture the sun's energy and create the carbohydrates needed to build root tissue.
     During the root regeneration phase that follows transplanting a young tree, do not prune the top of the tree. Pruning at this point only serves to remove leave area and slow down root growth.  A pecan trees will tell you when they are ready to be trained.  Two to three years after transplanting,  the top of the tree will suddenly explode with new shoot growth (especially with proper weed control and adequate soil nutrition). This is the tree's signal that the root system has become well established and the tree is ready to be trained.
     That brings us to the next 2 foot rule. When a tree grows at least 2 feet of new shoot the previous season it is time to either graft a seedling tree or train a grafted tree. The tree pictured at right is ready for grafting, Several of the shoots grew over 3 feet the previous year and even sprouted some lateral shoots from stalked buds. Note that this tree looks like a training disaster--limbs growing every-which-way and no strong central leader. This is a seedling tree that will be grafting soon after bud break. So we will cut the tree off, right under the 1st whorl of branches and set a bark graft at that point.
    Training young trees starts by applying the 2 foot rule right on the growing graft. In the photo at left, you can see that a vigorously growing seedling tree will push both the scion and stump sprouts to grow rapidly. Find the strongest growth shoot growing from the scion and prune all other out. This shoot will be the new central leader. Prune off all the stump sprouts unless your central leader has already grown 2 feet in height. Following the 2 foot rule, you can leave a lateral shoot on below the graft  to help provide leaf area to support the root system (photo below).
    Use a stake to train you central leader (I use bamboo). The stake also provides a place for birds to perch so they don't land on the tender new growth of the central leader and damage the growing point.
    Training a young tree that grows rapidly is relatively easy using the 2 foot rule. It just requires paying attention to details and a monthly inspection (and pruning when necessary) of your trees from May thru July.

   The last post in the training young trees series is Summing up