The following spring, we planted the nuts and trees and grafted the scions on black walnut and butternut stocks. The mortality of these grafts was the greatest I have ever known. Of about four thousand English walnut grafts, representing some twenty varieties, only one hundred twenty-five took well enough to produce a good union with the stock and to grow. Some of them grew too fast and in spite of my precautions, were blown out; others died from winter injury the first year. By the following spring, there were only ten varieties which had withstood the rigor of the climate. Of the five hundred trees, only a few dozen survived. Fortunately, this was not one of our severe, "test" winters, or probably none of these plants would have withstood it.
The walnuts which were planted showed a fairly high degree of hardiness. Of 12,000 seedling trees, our nursery is testing more than 800 for varietal classification. These have been set out in test orchard formation on two locations, both high on the slope of a ravine, one group on the north side, one on the south. It has been suggested that from the remaining seedlings, which number thousands, we select 500 to 1000 representative specimens and propagate them on black walnut stocks in some warmer climate, either in Oregon, Missouri or New York. This would determine their value as semi-hardy trees worthy of propagation in such localities. Such an experiment will probably be made eventually.
The same year, 1937, in which I obtained the Polish nuts, I also bought one hundred pounds of Austrian walnuts, to serve as a check. Eighty pounds of these consisted of the common, commercial type of walnut, while the remainder was of more expensive nuts having cream-colored shells and recommended by the Austrian seed firm as particularly hardy. Altogether these nuts included approximately one hundred varieties, twenty of which were so distinctive that their nuts could be separated from the others by size and shape.
About two thousand seedlings grew from this planting, most of which proved to be too tender for our winter conditions. The seedlings grown from the light-colored nuts show about the same degree of hardiness as the Carpathian plants. Many of them have been set out in experimental orchards to be brought into bearing.
After the first year, the English walnuts progressed fairly well. Large trees, which had not been entirely worked over at first, were trimmed so that nothing remained of the original top, but only the grafted branches. The winter of 1938-39 was not especially severe and mortality was low, although it was apparent that all of the varieties were not equally hardy. Even a few of the scions grafted on butternut stocks were growing successfully. I had made these grafts realizing that the stock was not a very satisfactory one, to learn if it could be used to produce scionwood. As the results were encouraging, I decided it would be worthwhile to give them good care and gradually to remove all of the butternut top.
Each fall, the first two years after I had grafted all these walnuts, I cut and stored enough scionwood from each variety to maintain it if the winter should be so severe as to destroy the grafts. Unfortunately, the grafts had developed so well, even to the actual bearing of nuts by three varieties, that in 1940 I did not think this precaution was necessary. Then came our catastrophic Armistice Day blizzard, the most severe test of hardiness and adaptability ever to occur in the north. Many of our hardiest trees suffered great injury from it, such trees, for instance, as Colorado blue spruce, limber pine, arborvitae; cultured varieties of hickories, hiccans, heartnuts; fruit trees, including apples, plums and apricots, which bore almost no fruit the next summer.
Although not one variety of English walnut was entirely killed, all, except one, suffered to some degree, and it was not until late the following summer that several varieties began to produce new wood. The variety which showed the greatest degree of hardiness is "Firstling," originally known as Letter F. Although the primary buds on the Firstling were nearly all killed, very few of the small branches were affected and the union itself suffered no injury. Second in hardiness is Kremenetz, much of its top being killed, but its union being only slightly affected. No. 64 was affected in about the same amount as Kremenetz. Increasing degrees of tenderness and, of course, decreasing degrees of hardiness, were shown by the many other varieties, some of which may never recover completely from the shock of that blizzard. The seedling trees suffered only slight damage so that I expect that they are hardy enough to produce fruit here.
I cannot conclude this chapter without mentioning certain observations I have made regarding hardiness, which, although they require more specific study, I wish to describe as a suggestion for further experimentation by either amateur or professional horticulturists. My theory is that a determination of the hardiness factor of an English walnut tree can be made according to the color of its bark. I have seen that a tree having thin bark which remains bright green late into the fall is very likely to be of a tender variety. Conversely, among these Carpathian walnuts, I have found that varieties whose bark becomes tan or brown early in autumn show much more hardiness than those whose bark remains green. One variety, Wolhynie, whose bark is chocolate brown, is very resistant to winter injury. Another, whose green bark is heavily dotted with lenticels, shows itself hardier than those having none or only a trace of them. In testing almonds, I have found that trees whose bark turns red early in the fall are definitely more hardy than those whose bark remains green or tan. In observing apricots, I have learned that young twigs with red bark are more resistant to cold than those with brown. Of course, these findings cannot be considered as facts until further studies have been made. I hope that others will find the idea of investigating this more-than-possibility as interesting as I do.
As the years increased, however, the growth of the seedling walnuts decreased and some having made a nice tree-like form, with a trunk of approximately an inch in diameter, within a succession of years were reduced in size through the combination of winter injury and attacks by the butternut curculio as well as a bacterial blight until by 1952 only a fraction of the 12,000 seedlings remained, certainly less than 1,000. All of the originally grafted specimens are dead with the exception of one variety which has been kept alive by constantly re-grafting it on black walnut. We have not named this variety as yet, although it has borne both staminate and pistillate bloom, it has never borne any ripe nuts. Some of the seedlings, however, still show persistent traits of hardiness and of insect resistance and we still have hopes that after 15 years these trees will yet overcome the adversities of this uncongenial climate for this species.