In the 1930's, when the Wisconsin Horticultural Society distributed seeds of the Carpathian Walnut from Poland, my brother secured some and we planted them. From these nuts we now have four trees, one of which has been bearing for the last four years.
Lubec, Maine is located at the extreme eastern tip of the United States just a few miles south of the 45th parallel. The site where the trees are planted is on a peninsula extending out into the Bay of Fundy which gives very low summer temperatures and moderate winter temperatures. The night temperature in the summer is usually in the 50°s F. with day temperatures rarely reaching 80° F. Winter temperatures seldom go to -10° F. and only lower than this about once in ten years. During the early summer, fogs are usually heavy and continuous. Day length is, of course, longer in the summer than in most of the United States but it is similar to that of the Northern tier of States from the Great Lakes West.
The trees have grown well being about 18 feet tall and even more in spread. They are multiple trunked having never been pruned. The foliage is remarkably clean and glossy and has not been bothered by insects or disease and it ripens and turns yellow in the late fall before killing frosts at the end of October. Excessive late terminal growth is usually winter-killed but this sort of growth has not been as great since bearing started. The staminate flower buds are more likely to be winter killed than the pistillate but the whole of them have never been entirely killed.
The trees do not leaf out until mid-June, after the danger of killing frosts is over. They have not been frost injured at any time in the spring. The nuts ripen and are shed from the husks in late September and early October while the tree is in full foliage. The nuts are shed perfectly clean with husk either falling separately or remaining on the tree. The nuts will germinate and seedlings have been raised. In 1953, one tree bore 315 nuts. This number represents just a fraction of the pistillate bloom, for while this tree is self fertile, the catkins bloom for a much shorter period than the pistillate blossoms, the latter extending over nearly a month.
In the same year that the above Carpathian variety of Juglans regia was planted, my brother and I also planted some Juglans mandshurica secured from F. L. Skinner of Dropmore, Manitoba which had originated in Harbin, Manchuria. The resulting trees agree well with many of the specimens in the Herbarium of the Arnold Arboretum at Boston labelled Juglans mandshurica. These trees have done remarkably well in Lubec, the trunks being 8-9 inches in diameter, while the height is 15 feet or more and the spread 20 feet. They have borne annually since 1939. They are planted less than 1000 feet from the ocean exposed to the summer storms, winter gales and salt spray. These trees leaf-out a month earlier than the Carpathians yet the foliage has only been partially frost injured once. Wind whipping sometimes injures the leaves in early summer while they are still tender but this sort of injury has never been serious.
The nuts are borne in clusters of up to six and the shells are hard and thick. The flavor of the kernels is excellent having more character than the butternut yet not as strong as the black walnut. Cracking is easy with the Hershey nut cracker. The kernels resemble our American butternut in shape which may account for the fact that J. mandshurica is sometimes called the Oriental butternut.
The nuts germinate well and make trees quickly. In one case, I had mature nuts five years after planting the seed. This particular tree was unusually vigorous having leaves 36 inches long and 23 inches wide.
In my experience, J. regia and J. mandshurica do not hybridize easily if at all, at least with the individuals and under the conditions with which I have been working. After several attempts I now have two progenies of reciprocal crosses of which a few seedlings seem to show hybridity in the vegetative parts. However, there is such a range of characters in the herbarium specimens labelled J. mandshurica that there will be a doubt in my mind until I see the mature trees, or it may be possible that some of the herbarium specimens may have been collected from naturally occurring hybrids, as the two species overlap in their distribution in Manchuria. If the best vegetative and fruiting characters from these two species can be combined the result should be good for our northern sections.
My Thirty Years Experience With Nut Trees
CARL WESCHCKE, St. Paul, Minn.