planted close together is the
safe rule to plant by.

I know of one planting of ten grafted trees of one variety of Persian
walnuts, now twenty years old, that has never produced any nuts even
though they are planted so that cross-pollination would be expected. In
1950 only a few catkins developed. These produced pollen early and were
on the ground before the pistilate bloom opened and was receptive. I
never saw a nicer pistillate bloom on any Persian walnuts than these
trees had, yet not a single nut set. They are in the center of a
fifty-five acre black walnut orchard, and when the pistillate bloom was
at its peak, the black walnuts surrounding were shedding pollen. Do not
try to tell me that native black walnuts will satisfactorily pollinate
the Persian walnut. After this demonstration, I know different. Were all
the Persian walnut trees of Pennsylvania properly pollinated, the crop
of nuts, in my estimation, would be increased a hundredfold over what it
is normally. Lack of pollination is probably the greatest factor causing
non-production in our Persian walnuts. It is far more important that the
fertility factor which is so important in production of the common black
walnut. (2)

Fayette Etter and Milo Paden both feel that the Broadview variety is
self-pollinating, but even this variety may prove to be benefited by
cross pollination.

The Persian walnut has developed in Pennsylvania and Ohio in a rather
interesting pattern. Trees planted fifty to a hundred and fifty years
ago managed to live and produce nuts. From these trees, seedlings were
grown and planted by neighbors and friends. These trees and their
seedlings in turn have now grown to producing age. Some few that produce
good crops of nuts you hear about, but the vast majority are just
non-producing shade trees. Until you look for them you little realize
how numerous they are.

At Linglestown, Dauphin County, however, we find a striking exception to
this. Here all the trees are productive. The question there is not why
don't my trees produce, but is quite spirited as to who harvests the
largest crop and best nuts.

About seventy-five years ago Alfred Kleopfer planted some Persian
walnuts of unknown origin, but probably from Germany. He grew three
trees which were planted, one beside the village blacksmith shop, one
across the street, and the third at a neighbor's. One tree lived for
only a short time. The blacksmith shop has been replaced by a modern