Part 6

"Our ultimate aim, of course, is to establish a race of chestnut trees which shall replace our now practically extinct American chestnut. The loss in money value from this timber tree has amounted to millions of dollars in comparison with which the value of its nut crops is very small indeed.

"However, we are interested in the nut problem, and whenever any particularly fine nuts appear we note the fact. We have now a strain of Chinese chestnut which has not yet come into bearing which we believe will have nuts as sweet as the old American chestnut, but much larger."

With this forward-looking note we close our report. We have a foundation upon which to build that is substantial and tried. The pioneering work of a patient, far-sighted, and distinguished group of workers has shown us much of what to do and what not to do. It is now up to us, the farmers, the planters, to multiply their work and continue it.

Side-lights on the 1943-4 Survey

Very many interesting bits of information have been included in the survey reports; so many that the committee has regretfully omitted some that hardly seemed properly to belong with the material of a survey, which after all must have some limits. One such item is from J. C. McDaniel, of Haines City, Fla., and has a special interest for members of this Association. He says:

"Perhaps you will be interested in data on one of America's largest Chinese chestnut trees, even if it does grow in Florida, at Monticello. It stands adjacent to a lot in which the late J. F. Jones had a nursery for a short time in the early years of this century, and apparently was planted at that time, around forty years ago. The trunk is now more than 25 inches in diameter below where it divides 6 feet above the ground. From this level, the tree branches profusely and has a symmetrical, rounded crown. It is healthy, not having a sign of the bark disease, although a native chinkapin 100 feet away is badly infested. It has abundant bloom and sets heavy crops of burrs but, lacking another variety for pollination, the number of nuts matured is small. Nuts are about average size for the species, of typical sweet flavor, and separate readily from the pellicle. Many of them become infested, before ripening, with a fungus which rots the kernel, apparently the same one which infests chestnuts and chinkapins at Savannah and Albany, Georgia. Mr. Paul Goldberg, of Monticello, the present owner, states that the tree has been bearing annually during the twenty years his family has owned it."

This nut-rot among the oriental chestnuts is one of the diseases that have become troublesome elsewhere. It is being studied and efforts are being made to combat it. Thus far, so far as we know, no effective cure has been found. A report upon present progress would be worth while.

Oscar E. Swan, Jr., Tulsa, Okla., reports an enviable situation. He says: "My nut trees are growing on a farm where more than 30 years of cultivation have failed to kill the native pecan sprouts. They come up year after year from the top roots. Since acquiring the place in 1936, I have allowed the pecan sprouts and the few native walnuts to grow unchecked except where necessary to cut them out to avoid crowding. The growth of these sprouts is quite vigorous, and they are ideal for top-working. I have top-worked a few trees every spring and now have about 300 grafted trees all the way from 6 to 30 feet tall. Many are too close together for full grown trees and I plan to thin them. My problems, so far, are the mechanical ones of top-working. I have settled upon a modification of the Biederman bark graft, which gives very good results. After the grafts are well established, the trees get very little attention except for cutting out the crowding trees. They are literally growing 'wild', yet the growth has been better than transplanted trees would have made with the best of care, because the root systems are well established in a situation which suits them.

"This system of neglect probably explains why I have failed with some species and varieties such as the butternut and some of the hickories. Occasionally I am pleasantly surprised, as in the case of some seedling Carpathian walnuts which, grafted upon some established black walnut sprouts, came through the severe 1943 drouth in fine shape without benefit of mulch, cultivation, fertilizer, or watering. The same applies to the Helmick hybrid. (A two year old tree, a hybrid walnut, grafted and growing well on black walnut stock, and which Mr. Swan says will bloom next year.) I have pampered my Chinese chestnut trees with cultivation, mulch and manure, as they are located in poorer, drier soil. They were badly hit by the drouth. Some died in spite of the attention.

"As to varieties, I am far enough south to grow all the standard southern pecan varieties, although several do not have a long enough season to mature their nuts. I am trying the northern varieties and, so far, am well pleased with their growth as compared with the southern kinds. It will be a few years before I can report on the size and quality of their nuts."

J. C. McDaniel again: "Source and variety of seed in Chinese chestnuts have a great influence on the performance of seedlings. Numerous seedlings from the original Hobson tree began fruiting in their second season of growth, and half of the ones I have are fruiting during their fourth season. On the other hand, I have a tree from imported seed which grew nine seasons before setting and ripening its first burr. The above data refer to my planting near Hartselle, Morgan County, Ala., and that vicinity. I have several black walnut trees under observation, native trees, on which data are not yet complete enough for evaluation."

If any man deserves a bright N. N. G. A. medal, it is A. L. Young, of Brooks, Alberta. Lowest temperature expected in winter, 45° below; lowest known, 62° below. Highest expected in summer, 101°. Frequent drouths? Yes. Hot, dry winds? Yes. Native nuts found plentifully? None. Sparingly? None. Yet Mr. Young plants nut trees. It is men like that who have made Canada what it is. It takes more than mere weather to stop them. The never-say-die spirit of pioneers speaks throughout his report:

"Black walnuts, butternuts, some oaks, hazels and American chestnuts (Ohio buckeyes) all came through last winter well. However, late frosts reduced the nut crop. Of these species, filberts are not getting anywhere. Winkler, I believe, will eventually make a go of it. Heartnuts got a rough deal last winter, and European buckeye chestnuts were hurt a little by late spring frosts. Some Manchurian walnuts also got a setback with spring frosts, and some did not. Carpathian walnuts killed back quite a lot, so did most of my hybrid walnuts. Hybrid hazels seem perfectly hardy. Pecans, beechnuts and sweet chestnuts almost passed out of the picture last winter. Giant hickory from Ontario seems hardy but particular about the kind of soil and conditions. When irrigated, too much water will kill them. And this is true also of walnut and butternut seedlings. I have no acreage of nut trees. I grow seedlings and plant them wherever I find a place protected from the stock and within reach of moisture from the irrigation ditch, as this is a desert, cactus country.

"I always have a stock of seedling trees on hand, and whenever visitors show any interest, I give or send them fruit or nut trees and a few perennial flowers. So there are sure to be a few nut trees, some day, growing successfully throughout Alberta.

"There is more benefit from this northern seed, especially as I am using a commercial pollen with the hope of getting a hardy white walnut with possibly a coarse bark like the black to ward off sun-scald in this climate. They are on their way. I don't know when we'll be eating these imaginary nuts. However, it is not so long ago that fruit growing on the cattle range was a dream. I grew the first pears in Alberta, so far as we know. Now we are insulted if there is not a crop of fruit every year. I have many seedlings of standard apples, unnamed, that are really choice fruit, and, of course, a few named varieties that are doing fairly well. Minnesota has done great work in apple and plum breeding for the north. We are enjoying some of them right here.

"I am sorry that I have no data on husking, cracking, etc. Really even the hardiest, best trees bear nuts that, while of fair size, do not have fleshy kernels, and some have three sections instead of two. Butternuts are very sweet with fair size kernels. I was surprised, after a long hard winter, to find the Ginkgo trees still alive and gaining growth. Credit some or all this result to J. U. Gellatly and Paul Crath for supplying me with seed, seedlings, and pollen to carry on with. I am greatly obliged to them and also to George Corsan of Echo Valley, Islington, who has a wealth of nut interest.

"We have had a mighty dry year here, so, between irrigating and tending the largest herd of Ayrshire cattle in the prairie provinces, I have been busy. The town of Brooks is probably the only town in Canada on straight Ayrshire milk; and the change in Brooks from a box-car on a siding years ago to the Brooks of today, with its hundreds of healthy children now on the streets, is the marvel of a man's lifetime."

George H. Corsan, Echo Valley, Islington, Ont.: "Last winter, 1942-43, was by far the coldest ever recorded. No damage to filberts. A few inches of twigs were hurt on certain English walnuts. The Stranger heartnut, a tender variety, passed through unscathed. Persimmons and pawpaws passed without a bud killed. These are perfectly hardy varieties. Jujubes passed O. K., but that may be due to the very deep snows."

Dr. Oliver D. Diller, Associate Forester, Ohio Experiment Sta., Wooster, Ohio: "You will be glad to know that the experiment station has set aside some land for improved varieties of nut trees. If you find some promising walnuts which might be tested in this part of the state, we should be glad to have you keep us in mind." This is indeed welcome news and will be appreciated by all growers in this area.

J. G. Duis, Shattuc, Ill.: "A chicken yard is one of the best places to grow nut trees."

J. U. Gellatly: "I do not believe in selling nuts for seed purposes except on a very large scale."

J. C. McDaniel: "A neighbor lost some 5 year old Chinese chestnut trees following a summer drouth on silty loam soil, rather shallow to hard-pan. It is my observation that deeper, sandier soils (not too extremely sandy) are best for chestnuts in the coastal plain and other regions subject to summer drouths. In the mountains where summer rainfall is more uniform, they thrive also in clay soils."

G. H. Corsan: "Best success in grafting (hickories) has been in juicy, wet springs. Heartnuts must not be budded until late August (in Islington, Ontario). Heartnuts must not be pruned."

A. L. Young, Alberta: "There is a demand for young walnuts for pickling." (Does anyone know the details--when to pick, how to pickle?) (Note by Ed. Several recipes and methods in Am. Nut Journal now out of print but indexed by Ed. Copies of this index in his hands and those of Mr. C. A. Reed at Washington. Also recipes in 33rd Ann. Report p. 95).

Sterling A. Smith, Vermillon, O.: "With me, summer budding is the most successful means of propagating black walnuts."

J. Russell Smith: "Chinese chestnuts will blight some if under-nourished." Which includes the wrong kinds of soil, if uncorrected.

"Does anyone know for sure how to get pawpaw seed to germinate?" Several have asked this question. The chairman has had the same trouble, so can not answer. (Note by Ed. See "Nut Puttering in an Offyear" in this report.)

So far as the correspondence shows, no state or federal department buys seed on a large scale (with the exception, now, of chestnut seed) from trees of the better named varieties with which to grow seedlings for distribution by state nurseries for forest planting. All nut seed seems to be gathered haphazardly.

W. G. Tatum, Lebanon, Ky.: "A nut tree with plenty of root, top cut back one third, promptly set, roots protected, stem wrapped, 4 inches, mulch applied, set either spring or fall, grows for me 99% of the time. Failures are not worth mentioning if the above conditions are met."

Carl Weschcke, St. Paul, has a dozen or so extra hardy Persian walnuts by selection from some 12,000 seedlings. Also is introducing the hardy "Hazelbert," result of crosses between wild varieties and filberts.

"Dip wire screen guards in red lead and they will be good for twenty years."

Thomas and Stambaugh, among the black walnuts, are, with justice, entrenched leaders, but it will be well to watch Patterson, Mintle, Elmer Myers, Eureka, Creitz, Todd, and other promising new ones less well known. Thomas is more prolific in the south (generally) than in the north, which indicates that its bloom may possibly be out nearly enough to suffer in the north from late frosts.

Among chestnuts, the weight of evidence favors Hobson, Carr and Reliable, though J. Russell Smith says he has something he likes better than the first two.

Among pecans, Major, Greenriver, Pleas; among filberts and hazels, Winkler, Jones hybrid, Cosford, Gellatly, Brixnut; among Persian walnuts, Broadview, one or two Crath varieties, Payne, Breslau; among hickories, Stratford, Fairbanks, Barnes, Glover, Weschcke. These seem, so far as the returns show, to have outstanding points of superiority. In any such survey, injustice is bound to be done to some not fully reported.

Outside of filberts in the northwest, no northern grown nut can yet be said to have reached the status of a profitable commercial crop. (Exception: The narrow pecan belt along the southern terminus of the Ohio river valley; mostly wild trees.) Dr. A. S. Colby, University of Illinois says, "The report from the State Statistician at Springfield indicated a crop of 575,000 pounds of pecans for Illinois in 1943. I don't know just where they came from." Short crops were reported in Calhoun and Gallatin, leading nut producing counties. No reports have been received as to the size of pecan crops in the Kentucky and southern Indiana portions of the same belt.

The search for better varieties must continue, but it is also altogether likely that with an orchardist's attention, with cultivation, mulching, fertilizing, spraying one to three times yearly with Bordeaux and lead sprays, we might approach the commercial goal more closely with what we have today. Is anyone treating a bearing nut orchard as well as he would treat an apple orchard? That's the test.

S. H. Graham of Ithaca, N.Y. says: "The Ohio is commonly regarded as hard to hull. With a chained tire husker it hulls as well as any." He rates it for hardiness and a percentage of 90 to 100 for filled nuts, while Thomas yields only 0 to 90%.

[Illustration: Seasonal Zones Compiled from the U.S. Department of Agriculture Records, Based on the Average Date of the Last Killing Frost in Spring]

Juglone--The Active Agent in Walnut Toxicity

_By GEORGE A. GRIES, Connecticut Agricultural Experiment Station_

The problem of walnut toxicity dates back at least to the writings of Pliny. In his "Natural History," this Roman philosopher stated that "the shadow of walnut trees is poison to all plants within its compass" and that it kills whatever it touches.

The first rebuttal to the existence of such a toxicity was forwarded by Evelyn in the 17th century. This author discussed the high regard in which walnuts were held in Burgundy as field trees. The roots of these trees were below the plow sole and thus did not affect either cultivation nor the growth, of grasses and cereals beneath them.

The pros and cons of the problem have been reviewed several times in the recent proceedings of the Northern Nut Growers Association. (Greene, 1930; MacDaniels and Muenscher, 1942; Brown, 1943.) That the roots of walnut trees are toxic to the roots of certain crop plants in direct contact with them is widely accepted. In nature this toxicity seems to be limited to plants with tap root systems such as tomato and alfalfa (Davis, 1923) and those with other types of deep root systems such as apple trees (Schneiderhan, 1927), rhododendrons (Pirone, 1938), and privet. This toxicity is exhibited only when there is a direct contact between the roots of the two plants involved. (Jones, 1903; Massey, 1925). That the wilting observed under walnuts is due to a toxic product from the bark of the walnut, and does not result from a lack of water, is substantiated by the fact that the vascular or water conducting system is discolored for several inches above the point of contact with the walnut root. This symptom is very similar to that produced by vascular disease fungi. No such discoloration results from wilting due to competition for water. This symptom of toxicity has been overlooked by many workers in the field.

Massey (1925) suggested that the toxic component of walnuts might be juglone. This idea was further supported by Davis (1928). Today this concept is widely held. Chemically this substance is known as 5, hydroxy-1, 4, naphtho-quinone and belongs to a group of strong oxidizing agents with commercial uses, including tanning agents, medicinals, poisons, etc.

A knowledge of the physiology of juglone in the walnut is essential to an understanding of the divergent results obtained by various experimenters. Juglone, as such, occurs probably only in minute quantities in the inner root bark, and in the green husks of the nuts. These regions are, however, rich in a substance known as hydrojuglone. This compound, the colorless, non-toxic, reduced form of juglone is immediately oxidized to its toxic form upon exposure to the air or some oxidizing substance from the roots of other plants. Upon standing in the air juglone again disappears, being either changed back to hydrojuglone or broken down into other non-toxic substances.

This sequence of events may be noted in a fresh green husk of a black walnut. When the fresh husk is cut, the interior is white but immediately turns yellow as the colorless hydrojuglone is transformed into the yellow juglone. Upon standing or drying the husk becomes black as further chemical changes occur. It is impossible to extract juglone from these dried husks without first reoxidizing them.

It now becomes possible for us to understand some of the discrepancies in the studies on walnut toxicity. If walnut bark or other plant parts are allowed to become desiccated, no toxicity may be found. If the roots of plants do not contact plant parts containing juglone or hydrojuglone, their oxidizing ability can not produce the toxin. Further the relative amounts of juglone in various species of _Juglans_ has not been completely investigated. It does occur definitely in _J. nigra_ and _J. cinerea_ and has been reported as being in _J. regia_. Other species need investigation before being included as sources of juglone.

It is known that many plants are not adversely affected when grown under or near walnut trees. Some of these have root systems too shallow to contact the roots of the walnuts, especially in plowed ground. Some plants may send out sufficient surface roots to keep the plant alive in spite of injury to the deeper roots. The possibility that the roots of some plants are capable of withstanding the oxidizing power of the juglone is currently under study.

In early American folklore, the inner bark and the husks of the nuts were used as a source of a yellow dye for cloth. This yellow dye is juglone. The ancients also used this method of dying both cloth and hair.

Another property of juglone is its toxicity to fish. A few years ago it was a common practice in the South to cut the husks from young nuts and throw them immediately into a still pond of water. The fish, stunned by the juglone, would rise to the surface and were collected and eaten. No one seemed to worry about the effects of such poisoned food on the consumers.

Juglone is toxic to fungi and bacteria. Of all the medicinal powers attributed to walnuts by the Greeks and Romans, its use in curing certain skin diseases including ringworm has held up through the ages until many today can recall the use of the green husks for control of ringworms. Brissemoret and Michaud (1917) reported the use of juglone in clinical cases for the cure of eczema, psoriasis, impetigo and other skin diseases and concluded that juglone deserves extensive use in dermatology. To our knowledge the medical profession has not followed up the possibilities which this substance offers. The author is familiar with one case in which pure juglone was applied to a persistent ringworm infection. The infection disappeared within a month after treatment was begun. Though conclusions can not be drawn on a single case, certainly this observation lends credence to the medicinal lore of the ancients and the American pioneers.

During the fall and winter of 1942-43, investigations on juglone were started at the Connecticut Agricultural Experiment Station in conjunction with studies of the effect of other plant toxins on the roots of higher plants. When the toxicity of this oxidizing compound was established, it was produced in some quantity both by extraction from walnuts after the method of Combes (1907) and by synthesis after the method of Bernthsen and Semper (1887). Working on the assumption that the killing of germinating fungus spores and root hairs are similar phenomena, juglone was subjected to standardized laboratory tests for fungicidal value. In a series of experiments, this compound proved to be equally toxic with the copper in Bordeaux mixture. Such a high degree of toxicity was deemed worth further investigation, so juglone was tested as a seed protectant and as a spray in field trials for the control of black spot of roses.

As a seed protectant, juglone failed miserably. It's toxicity to the noncutinized surfaces of root tissues was so great that germination was abnormal and greatly impaired. The injury noted here was apparently the same as that discussed by Brown (1943) and that which occurs normally in the field.

In field tests on the control of black spot of roses juglone stood up well. No phytotoxic activity could be noted on the cutinized stem and leaf surfaces. On the variety George Ahrens, juglone gave equal control with 2-1/2 times as much 325 mesh sulfur, the standard control for this disease.

SUMMARY

1. Under certain conditions walnut trees exhibit toxicity to those plants whose roots are in intimate contact with the roots of the walnut.

2. This toxicity is due to the action of juglone, the oxidized form of hydrojuglone, a non-toxic substance occurring in the inner bark and green husk of walnuts.

3. Juglone has been used in dermatology to cure various skin disorders including both bacterial and fungus diseases.

4. As a seed protectant, juglone is unsuitable because of its inherent toxicity to the non-cutinzed root surfaces.

5. Laboratory and field tests have shown juglone to be an excellent fungicide

LITERATURE CITED

1. Bernthsen, A. and A. Semper Ueber die Constitution des Juglons und seine Synthese aus Naphtalin. Ber. d. deutsch. Chem. Gesellsch. 20: 934-941. 1887.