SOME PERSIAN WALNUT OBSERVATIONS, EXPERIMENTS AND RESULTS FOR 1912

E. R. Lake, Washington, D. C.

The Arlington work for 1912 in the propagation of the Persian walnut consisted in top-grafting three and four year old nursery stock by several methods, as ordinary cleft, side cleft, bark cleft, prong, whip and modified forms of these. For wrapping we tried bicycle tape, waxed cord and cloth, with wax and plasticine for covering.

The work was done during the latter part of April and first part of May. The stocks averaged from ¾ to 1¼ inches diameter, and were cut off from 16 to 30 inches above the surface of the ground. In a few cases bark grafting by modified whip form was performed upon the branches at a height of about 4 feet.

Later in the season from June 12th to August 25th buds were placed by varying methods. In the earlier instances the buds were taken from left-over grafting stock. Of the scion wood received last year all the wood from Eastern growers was frost bitten and wholly failed to take with one or two exceptions.

The Pacific Coast wood was received in excellent condition and operations with it were gratifying, especially with the ordinary cleft graft, and patch bud.

Next year's work in grafting will be confined to the cleft, and the bark-whip processes. This latter is very simple and under careful treatment promises to be a convenient and successful process.

In the budding operations we resorted to a number of methods largely for the benefit of the information obtained from the practice, and not so much for the returns in propagated trees.

However, for 1913 in the work of propagating for stock results we shall confine our practice to the patch method, though we may find from later tests that the hinge method so favorably looked upon by Oregon is better suited to the work.

Various experiments with tying material were tried. Raffia, cotton cord, waxed cloth and bicycle tape were used. The raffia and cord gave best results. A tight tie is needed.

June-budding from the left-over graft-wood gave a very low percentage of "takes." Most of the buds appeared to be drowned. Buds from the current year's growth inserted from early to middle of August are at present apparently in good dormant condition.

Some July buds from the left-over graft-wood placed in the younger branches of a twelve year old American black took well and made from three to six inches growth. The branches were cut back as soon as the buds appeared to be set, a course that would not be advocated if one were doing the work for re-topping. The young wood from these buds is delicate and soft and in order to insure their living through the winter, so far as our efforts may avail, they have been enclosed in strong paper bags. In our budding and grafting operations we had no success with the Japanese or Chinese stocks. We expect to try them further as their rapid growth makes them much to be desired if a permanent union can be effected. So far as we have been able to learn from the southern propagators who have worked along this line, no difficulty has been encountered in effecting a short-life union,—four to six years on an average, though a few have kept alive for twelve years.

The growth of the successful grafts has been very variable. In several instances in which both scions upon a stock grew, the growth was from two to three feet. In other cases the young wood was scarcely a foot long.

The fact that the stocks and scion-wood varied widely in size and vigor and the further fact that the scions were from several varieties of western stock are quite sufficient causes for no uniform results in this respect.

The wood of all successful grafts appears to be in excellent condition for the winter season and we are looking forward to an interesting further growth of these next year, though the trees have just been transplanted. In order to doubly insure ourselves against loss of the varieties now growing one half, or even more in a few instances, of the young wood has been removed and placed in a cold room so that further grafting or budding of these varieties may be made next year.

Nursery trees of the Franquette, Pomeroy, Parisienne and unidentified others, on their own roots are making a pitiable effort at successful growth, while all wood on the black stock is making excellent growth.

In one instance the wood of Mayquette a cross between Mayette and Franquette formed two nutlets. Lack of pollen was all that prevented the fruiting of one-year-old grafted trees. A splendid point for the unit orchard booster, but a point of no value to the real walnut grower.

CROSS FERTILIZATION

Owing to the very vigorous weather of the past winter the catkins on the older Persians at Arlington Farm were killed. In order to study the conduct and product of these trees we sought pollen elsewhere to fertilize their liberal display of pistils. We were successful in obtaining some from the trees of Messrs. Killen and Rosa, and Miss Lea, but though this and some pollen of black, butternut and the Japanese was used no pollenation was successful.

In the case of sieboldiana, however, we succeeded in securing what appears to be fruit of certain definite cross-fertilization, as sieboldiana x nigra; sieboldiana x cinerea and possibly sieboldiana x regia.

Only in one instance did the nuts appear to have other than the usual characters of sieboldiana.

The nuts of the cinerea cross were longer, more tubular and somewhat deeper furrowed and darker.

Unfortunately some conflicting results in the fruiting of the sieboldiana places the possible cross-fruits under a cloud.

A peculiarity of the blossoming of the sieboldiana at Arlington this year was that the stamens and pistils of an individual tree opened at dates of six to ten days apart, and with the tree used for crossing the catkins were all off before the pistils opened. As no two trees are near together, perhaps two to three hundred feet being the closest, natural cross-pollenating was not expected. However, after the cross-pollenations by hand were made and fruits set, and even matured, it was found that some clusters had from one to three more nuts than were hand treated. Many of the clusters had less nuts than the number of pistils treated, which was to be expected.

But how to account for the extra sets is a problem not clear for it is possible that pollenation might have occurred in one of two ways—by stray pollen grains from the hand operations by wind-carried grains from the trees. In any event only the fruiting of the trees from the nuts under consideration will settle it, and as these have been planted we are on the way to the solution.