Monday, June 6, 2016

Trimming up the "pasture" pecan graft

   A few weeks, back I showed how I converted a multi-stemmed "pasture" pecan tree into a single-stemmed grafted tree. Yesterday, I came back to this tree and found that the scion had budded out (green buds) but the graft-union was surrounded by vigorously growing shoots growing from the rootstock (reddish colored leaves) (photo at right). Like most bark grafts, the trunk below the scion developed numerous trunk sprouts. In addition, all the stems I previously pruned off at the ground level had begun to resprout, creating a forest of new shoots adjacent to the stem I had selected for grafting. All of these red-colored shoots will need to be pruned off in order to force the growth of the scion.

   Once the rootstock sucker growth was removed I was left with a single trunk and a budding scion (photo at left). However, I'm sure that I'll need to visit this tree often because the large root system under this "pasture" pecan tree will continue to push up new shoots from just below the soil surface.
   I call this tree a "pasture" pecan tree because this tree had been mowed down year after year during hay harvest. Even though the top of the tree was removed annually, the root system continued to grow in size. Once all haying stopped, the tree burst forth with multiple stems and rapid growth.
  Because this tree has the potential to send up numerous root sprouts, I'll need to be extra careful in using herbicides to control weeds around this tree. Systemic herbicides like Roundup, Liberty, and Remedy could easily enter the tree via hardly-visible new root sprouts and cause tree damage or even tree death.
    However, the benefits of weed control around young pecan trees is well known. Grasses can be controlled safely with a grass specific post-emergent herbicide like Select. To suppress broad leaf weeds and any new rootsuckers,  I plan to use the non-systemic, burned-down herbicide, Gramoxone.  Since Gramoxone works by desiccating live tissue, I will need to be careful not to get this herbicide on the trunk of my tree.
    Eventually, the scion will grow to dominate and will start to inhibit the growth of additional root sprouts. Once that happens, tree maintenance and weed control will be much easier.