In this schedule the crackability of the sample is measured by the weight of first crack and the number of halves. The yield of kernels is measured by the total weight of kernels in the sample. The first crack includes only those kernels that either fall out or can be removed easily with the fingers. The remaining kernels are rescued with a pick or by recracking. In my judgment, the score accurately measures the merit of the samples. In the Mandeville, the large size is measured by the weight of kernels which in part offsets poor cracking quality. Poor cracking is usually caused by the edges of the halves being curved so as to be bound in the shell. Much more testing should be done to determine the value of the schedule.
Opinions regarding the ease of propagation of the butternut differ, but mostly it is considered difficult to propagate, with often complete failure. This merely means that the matter is not well understood. In my own experience I have had just about as many failures as successes, and must confess that I do not have much idea of what has been responsible for either success or failure. Best results have been secured by using inlay or bark slot grafts on stubs about 2 inches in diameter. This agrees with the experience of Mr. Burgart, of Michigan, and Mr. Weshcke, of Minnesota, who report that grafts must be made several feet from the ground and not at the crown.
Shield budding has apparently not been satisfactory. Mr. D. C. Snyder writes that chip budding is more successful. It is recommended by others and I agree that grafting should be done early, just as growth starts rather than later when trees are in leaf. Special care must be used in tying the new shoots of the graft to braces to prevent breakage by wind or birds. The butternut wood is very brittle and the grafts are often lost by breakage. The whole matter of butternut propagation merits further careful study.
Butternut varieties may be grafted on black walnut, butternut, or J. Sieboldiana stocks. Mr. Burgart, Mr. Weschcke, and Mr. D. C. Snyder consider black walnut to be better than the others, giving a more vigorous long lived tree. Varieties on butternut stocks are apparently relatively short lived and J. Sieboldiana stocks have a different growth rate and are not hardy. Mr. Burgart uses bark slot grafts on black walnut seedling stocks, 2-3 years old.
Butternut trees on their own roots transplant relatively easily because there is no taproot as with the black walnut and the hickory, and there are many fibrous surface roots that can be lifted when the tree is dug. Black walnut stocks are not difficult to manage, particularly if the taproots are cut on the seedlings. Culture is no special problem. Mulching and supplying nitrogenous fertilizer is good practice.
The butternut has the reputation of being susceptible to disease and hence being short lived as a tree. Whether or not this is actually the case is perhaps questionable. Many butternut trees, particularly those in favorable situations of soil and moisture, live to be of large size and old age. Trees on poorer, thinner soils apparently die off earlier than those under better conditions. In any case, it is well recognized that the butternut has a shorter life span on the average than the black walnut, which frequently lives to a large size and old age. There are two common diseases of the butternut. One is leaf spot caused by the fungus Marsonia, which defoliates the trees fairly early in the season and probably predisposes them to injury from other fungous attack. This is the same leaf spot that attacks the black walnut leaves. The other disease, which may cause trouble, is a fungous walnut blight known more specifically as Melanconis blight. It has not been established that this disease is an active parasite. The evidence indicates rather that it attacks trees that are already somewhat weakened by defoliation or other injury. It is a fact that many of the dead limbs on butternut trees are found to be affected with the disease. It is a matter of observation that trees growing under favorable conditions are less damaged by the disease than those growing under poor conditions of soil and water, therefore, keeping trees vigorous is good practice.
As with other nut tree species, there are troublesome insects. One of these, the butternut snout beetle or curculio, attacks both the butternut and the Japanese walnut. Control has apparently been secured by dusting foliage with DDT. Sometimes the leaves of butternuts are badly distorted with galls caused by mites. The bunchy top or witches'-broom caused by a virus, that is serious on the Japanese walnut, Juglans Sieboldiana, does not appear to be so virulent on butternut. This, however, is a matter of personal observation and is not based on a thorough study.
In conclusion, let me say that in my judgment, the butternut is worthy of more attention than it has had so far received, particularly by home owners in the northern states who would like to have trees in their yards that will bear nuts under conditions that are unfavorable for most other kinds. If it were publicized that varieties are available that will crack out in halves with relatively little effort, the chances are that with these facts in mind those interested in nut trees would give the butternut much more attention. The difficulty at the present time seems to be related to a lack of knowledge as to the relative merit of different varieties and a scarcity of trees because of difficulty of propagation. If we have time and the chairman will permit, I would welcome comments on the propagation problem and would also like to obtain any information on the merit of the named varieties. Let me also state that if any of you have a sample of 30 nuts of any named variety in this or last fall's crop that you can spare, I would be much pleased to have you send it to me for testing.
Discussion
MR. STOKE: It grows in New Brunswick, and I have had specimens from north of Lake of the Woods.