Winter Drag - Chestnut Grafting

Although the long, drawn out winter continues here in the Louisville area, that doesn't mean that American chestnut restoration efforts are at rest.  What is happening right now? Well, for one, chestnut seeds (nuts) either in the wild or in cold storage are getting ready to start sending a tap root out.  This happens every spring!  Sometimes early, sometimes late.  My guess is for this year - late.

What else is happening?  Well, for me, I am experimenting with nut grafting!  What is nut grafting, you might ask?  It is a way of grafting living/growing materials (from trees/stump sprouts/etc) onto a live seed.  The nut provides the energy for bonding a twig onto a nut and producing roots to feed the twig.  Basically, it provides the ability to clone an existing tree by using a nut to "nurse" the twig along.  It sounds more difficult than it is.  A great resource for learning more about this can be found at Nut Grafting and this is what I used as a guide, for the most part.  Photo guidance is always good!

So, I am seeing some results from my early February nut grafting attempts.  Here is a grafted twig with not much bud activity:

The bud appears dormant (or dead) even after a month of having been grafted.

However, look at this bud.  See a difference?

The bud is expanding/swelling as it should be, which indicates a successful graft!  You might note that something is coming up at the base of this grafted twig, as well.  This sprout is the epicotyl coming up from the nut.  This will have to be cut back, as it does not have the genetics of the graft, but genetics of the nut.

Here is a closer look of the sprouting from the nut next to the grafted twig:

This sprout will have to be removed, as will this lower bud if it sprouts out and attempts dominance over the bud above it.

Here is the same sprout 10 days after the other photos were taken.  Slowly, the bud continues to grow!

And a few days later, it is still expanding.  Slow going, but it IS growing!  Note that I removed the lower bud.  I want all of the energy to go into the growth of this shoot.

The resulting grafted seedling will be a genetic mirror of the tree that it was removed from this winter.

Why would anyone want to go to the effort of doing this?  Well, think about genetics.  If we were to find an overtopped stump sprout in the woods, say in a woods that cannot be manipulated by management activities (timber harvest, removal of surrounding trees, etc), we can take part of the stump sprout with the simple tool of pruning shears and graft it as I have done here.  If successful, the grafted seedling can be outplanted into a mother tree orchard where it can serve as a "mother" for receiving pollen from other trees or it can be used as a "father" by collecting pollen from it, once it matures to the point of producing flowers (about 3 - 5 years).   The genetics from this "lost" tree can now be carried forward within the Kentucky State TACF breeding program rather than being lost completely or never being utilized within the breeding program.  The more genetic variation within the breeding program, the better off it will be (within our regional area).

Grafting can also be used for carrying forward "selected" trees from backcross orchards.  If a particular tree shows high resistance, it could be cloned (ie, grafted) to make "more of it" in order to produce more nuts/offspring from it.  Rather than having 1 or a few trees, we can create multiple trees with the identical genetics via grafting.

This is the same process used for much of our commercially nut bearing trees, as well as fruit trees.  I'm sure you have heard of a particular apple strain or pear strain.  These are produced by grafting, for the most part, and not from cross-breeding with other varieties.

Same with wine.  In order to produce a particular flavor in wine, it is important to have consistency in the grapes.  This is done by grafting.

Okay, I might have the technique down.  Now, I need to find some stump sprouts, gather scion wood and graft them onto nuts so that I can provide some new genetic sources to the KY-TACF breeding program!  Shoot, if the weather would ever cooperate, maybe I could do this, but things are not looking good for this winter!  I might have to practice on bud grafting this summer!

Happy March!