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. [Illustration: _Best in the World, Oregon Walnuts_] [Illustration: _Drying the Nuts_] THE HARVEST The harvest comes in October, a convenient season where there are fruit crops to be taken care of. The process is extremely simple, being little more than an old-fashioned "nut gathering." When ripe, the nuts fall to the ground, shedding their hulls on the way. They are picked up by boys, girls, men and women. During the harvest three or four rounds must be made through the grove, perhaps a week elapsing between trips, each time slightly shaking the trees to make the ripe nuts fall. On the last round, a padded mallet with a long handle is used to dislodge the remaining nuts. The expense of harvesting is slight, five or six people being sufficient to care for a fifty-acre grove. WASHING AND DRYING