In 1932, on account of the difficulties in outdoor grafting of the
walnut, the author became interested in bench grafting of walnuts in the
greenhouse as a means of supplementing outdoor grafting. However, like
many other so-called new methods, it was discovered when we looked up
the literature in 1937 that William P. Corsa[3] had used methods that
were similar about 1896. He cut off the seedling above the crown instead
of below the crown as we did. The completed graft was packed in layers
of sphagnum and placed in an incubator instead of using a greenhouse.
Notwithstanding all that has been done in black walnut grafting, the
straight grained and brittle wood, the heavy sap flow, the almost
instant oxidation of cut tissues, the liability to frost injury in the
North in short seasons lowering vitality of scions, all combine to make
walnut grafting with best methods available, a seasonal gamble.