Friday, May 27, 2016

Forcing scion growth on new grafts

    Its been a month since I started grafting pecan (and hickory) trees.  So far, it looks like I have a perfect success rate with many grafts already pushing out new shoots (photo at right).  One of the most overlooked keys to preserving graft success is taking the time to come back to each grafted tree and trimming off the trunk sprouts that emerge below the graft union. So yesterday, I started inspecting each graft armed with my trusty pruning shears.

     In the photo at left, you can see that I have a successful bark graft growing on a fairly large seedling tree. Below the graft union, numerous trunk sprouts have also started to grow. Note that the leaves of these sprouts are reddish in color. Red pigmentation on new leaves is a common characteristic of a juvenile pecan tree. The sprouts growing from the scion are pure green indicating that these shoots are growing from sexually mature tissues (ready to bear nuts). To make sure the tree focuses its energy on growing scion shoots, I used my clippers to remove all trunk sprouts. I also pruned off any upward growing shoots sprouting on side limbs that I left on the tree to provide photosynthetic energy to the root system.

     A month ago, I placed a hickory scion on a small hican rootstock using and arrowhead graft (photo at right). The hickory scion has sprouted nicely but the rootstock has already sprouted extremely vigorous shoots that are growing at a rate that would soon engulf the scion.  That's the problem with not getting back to inspect grafts several times during the summer. Some trees try to grow around a scion rather than invest tree energy into growing a "foreign" shoot (the scion). The quicker you get competing trunk sprouts pruned off,  the more tree energy will be forced into the growing scion shoots and more wood with be formed to grow over the graft union.