Lessons in Grafting

Grafting has been practiced for millennia, most likely in imitation of the natural unions that occur in trees of many sorts.  But the science of grafting has been much slower in its development.  In Downing’s Fruits and Fruit Trees of America, for example, the Van Mons theory re grafted sorts is put forth:  “There is always a tendency in our varieties of fruit trees to return by their seeds towards a wild state”–so far so good, but then Downing lets fly this whopper:  “This tendency is most strongly shown in the seeds borne by old fruit trees.  And the older the tree is of any cultivated variety…the nearer will the seedlings raised from it approach a wild state.”

Again, Downing notes that in cutting scions, “straight, thrifty shoots of last years growth” should be selected–which is solid advice.  But then he adds that “scions taken from…lower bearing branches will produce fruit soonest, but…will not afford trees of so handsome a shape, or so vigorous a growth , as those taken from the thrifty upright shoots near the centre or top of [a] trees.”

That is to say, experience has a way of overturning myths.  As Downing himself notes, “The ancients boasted of Vines and Apples grafted on Poplars and Elms; but repeated experiments, by the most skilful cultivators of modern times, have clearly proved that although we may once in a thousand trials succeed in effecting these ill assorted unions, yet the graft invariably dies after a few months’ growth.”

Likewise, our successes and failures in the nursery this grafting season have yielded a number of observations:

  1. Rootstock is best obtained early.  Our stocks this year were not shipped until near mid-March because of the threat of cold weather, and then when they arrived, summer attempted to over-run spring, causing both our stocks and scions to break dormancy.
  2. Grafts that were completed by the end of March have grown out best.
  3. It is possible to graft onto stocks that have broken dormancy, but those that have put out significant growth appear to fail to significantly, “drowning the graft” as it were.  This fact, combined with a shortened callusing period (and hot weather following) has caused significant loss in our grafting beds this year.
  4. Rootstock that has broken dormancy is best  replanted and grown another season, or used for stooling.
  5. Scion wood that is breaking bud, even in part of the stick, is best discarded.
Plate of Green Gage Plum from Forsythe's Culture and Management

Plate of Green Gage Plum from Forsythe’s Culture and Management

In short, graft as early as you can in late winter.  Callus your trees a month or so in a cold, shaded pit, or in refrigeration.  And pass over stocks and scions that have largely broken dormancy.   As William Forsythe notes in A Treatise on the Culture and Management of Fruit Trees (1803):  “By strictly observing [these] rules.  we shall seldom miscarry, provided the operation be rightly performed, and at a proper season, unless the weather should prove very bad, as it sometimes happens, whereby whole quarters of fruit-trees miscarry. “

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