Pollination

Every fruit and nut grower should know the simple theory of pollination.

When a tree appears thrifty but fails to produce, nine times in ten the

trouble is with the pollination. The walnut is bi-sexual and

self-fertile; the staminate catkins appear first, at the end of the

year's growth (see Fig. 1), and the female blossoms, or pistillates,

from one to three weeks later at the end of the new growth (see Fig. 2).

Thus the staminate catkins sometimes fall before the pistillates form,

and naturally there is no pollination and no crop. This should not

discourage the grower or cause him to uproot his trees. Often by waiting

a few seasons--if the tree is of the correct variety--the trouble may

right itself. Many growers have gotten a crop from single trees where

there was trouble with the pollination by artificially fertilizing, that

is, shaking the pollen from fertile trees, even black walnut, over the

barren pistillates. Birds, insects, and the breezes carry pollen from

one tree to another. Therefore, if nuts for seed are desired, keep each

grove of pure strain separate that there may be no deterioration owing

to cross-fertilization. But the mixed orchard may bear best. Some

varieties of walnut trees--notably the Los Angeles--are suitable only

for shade in Oregon and should not be planted with any other thought in

mind. The staminate blossoms of this variety appear six weeks ahead of

the pistillates and, there being no pollination, naturally there are no

nuts.