Wednesday, August 16, 2017

Marking successful grafts

     By the first part of August, scions I grafted last spring using a bark graft have grown 5 feet in height (photo at right). Over the summer months I've pruned the scion down to one shoot, trimmed off trunk sprouts, and removed grafting tape to prevent girdling. Now its time to remove all graft wraps and paint the graft union to make field identification of successful grafts easy.
   At this point in the growing season, my bark grafts are still covered with aluminum foil and a plastic bag. To remove these wraps I take my knife and make a vertical cut through plastic, foil, and grafting tape. After making the cut, I simply peel off all the graft wraps together at one time.

   Once uncovered, you can see how moist the tree is under the wraps (photo at right). By mid August, the graft union is fully formed and is beginning to slow its growth rate.  The reason I like to unwrap the grafts at this time is because ants and dogwood borers like to make a home in the moist environment under the wraps. Since both insects can damage tree cambial growth, exposing the graft union to the air helps prevent this kind of insect damage.

   Unfortunately unwrapping a graft union in mid summer can cause sun burn to recently exposed bark and cambial tissues. I use latex house paint to prevent sun scald and to mark successful grafts (photo at left).

    One advantage of painting the graft union is that I can now easily see which trees have been successfully grafted from a distance (photo at right). I also use different color paints to identify the cultivar grafted. On my farm, Kanza trees are white, Lakota yellow, Hark green, and USDA 61-1-X is red. Once painted, I don't need to worry about missing ID tags or trying to draw an accurate map of an orchard created from a field of randomly spaced volunteer pecan seedlings.

    We are rapidly approaching the season of the year when buck deer begin rubbing young trees. So after marking my new graft with paint, I replace the deer cage over the tree to protect this fine young Kanza graft (photo at left).