The rule to plant the Persian walnut where peaches and sweet cherries do
well is a good one; but not infallible and certainly can't be too
closely relied upon here in southwestern Michigan. Since 1933, I have
placed several hundred grafts of the Persian walnut upon black stocks.
Many of these are top worked trees, but there were 68 grafted seedlings
in nursery rows, grafted in 1936. These were planted out two years
later. Some are now about ten feet tall with a well branched head. Of
this lot I have only harvested one ripe nut and that was four years ago.
Two of these same trees were planted near some buildings and shrubbery
at a neighbor's home, and they are now bearing well.
Before going further I must say that Persian walnut trees and peach
trees are quite different. First, the Persian walnut cannot stand having
its female flowers frosted when they are out or nearly so. Second, the
peach can stand frost at, or shortly after, full bloom, and they will
set a bumper crop of peaches. We have had two years of late spring
frosts at the time nut trees were in bloom, and we have had bumper crops
of peaches each year. Apples were badly hit, so many have failed to
bear. Lilac blossoms failed to come out and be showy because of these
severe frosts. However, I know of a peach tree heavily loaded right now
growing between two Persian walnuts that haven't had a single nut either
year, though they have borne nuts previously. Thus, peaches will bear in
frosty springs when Persian walnuts are damaged. Further, good-air
drainage, such as a high hill, with a deep valley below will save the
Persian nut crop in a frosty spring. I have a small Persian walnut
grafted in such a location, and it is the heaviest loaded nut tree I
have. It has so many large nuts on its limbs that its lower limbs are
actually resting upon the ground. This was grafted upon an established
black seedling four years ago.
What I have so far told would lead one to think that there is no nut
crop on my Persian grafts this year. This is not so, for I have one of
the largest crops in the 13 years I have had grafted Persian walnuts.
These are on top-worked trees high above the ground! Most of the
top-worked trees are over 12 feet at the graft, or higher, and it is
best to have them this high, because almost all lower limbs are simply
minus nuts, due to our unfavorable spring. As for proof, I noticed that
the lower limbs had blackened leaves, while the entire tops were
undamaged a few days after the frosty weather. The lower branches leaved
out the second time in late May. It seems as if the Persian walnut
produces two nuts to every one that a grafted black walnut will on a top
of equal size. We are troubled with walnut curculio as well as
considerably by squirrels, and by a leaf disorder that often blackens
the leaves and causes them to fall in early September, followed by
premature dropping of the nuts. Even then, there should be a good crop
this year.
Now, comes the question, should we graft the Persian walnut high, here
in Michigan? It certainly saves time, because a middle-aged walnut tree
produces, in terms of pecks and bushels, in eight to 15 years. Being
well established it saves patience and disappointment. And I know it is
far more profitable.
This writing of my experience is not intended to hurt the established
nut tree nurseryman in any way. Any of you who may live in Michigan are
certainly devoted to your hobby and have doubtless learned the skills
and pleasures of top-working a good sized seedling black walnut. You
will surely find it profitable. First, purchase the grafted Persian tree
from your nurseryman, and later, from this, work your established
seedling blacks at your convenience. Graft them at least 12 feet up and
see if what I say isn't quite true.