J. Franklin Collins, Washington, D. C.
I presume some of you know as much about certain features of this chestnut disease as I do myself; for I have only worked over certain sides of the whole question. I also presume that you are all acquainted with the fact that this disease, which is known as chestnut blight or the chestnut bark disease, is without doubt the most serious disease of any forest tree which we have had in this country at any time, that is, so far as its inroads at present appear to suggest.
I want to call your attention to certain general historical facts in connection with the disease, facts which are familiar to some of you, but unfamiliar possibly to others. The Forester of the Bronx Zoological Park, Dr. Merkel, discovered in the fall of 1904, or had his attention particularly called in 1904 to the fact, that a good many chestnut trees were dying in his vicinity, a number sufficient to have attracted especial attention. He looked at the matter carefully, and decided that there was a definite disease on these trees. He handed specimens over to Doctor Murrill of the New York Botanical Garden; who worked out the disease, and decided that it was a new fungus which was causing the trouble. He named it Diaporthe parasitica, the name under which it is generally known today, although there is some question as to whether that is the one which should be applied to it. This, you remember, was in 1904—in the fall.
The first publication which appeared on the disease was in 1906, as I recall it. The publication which then appeared was Doctor Murrill's upon his investigations. The disease has spread very rapidly since then, so that today we know the disease in a general area indicated by the red color on this map. The green area indicates in a general way the natural distribution of the common chestnut. Since 1904 investigations upon the geographical range of the disease have been carried on so far as to show that the disease is now known over approximately the area indicated in red on that map. The northern limits of the disease are perhaps in New York State. Further east, it is known as far north as northern Massachusetts, mainly in the western part, and it is also known in Boston. There have been two or three cases of the disease found in the Arnold Arboretum. On the west, we have two cases in West Virginia, and the most southern station which I know of is in Bedford County, Virginia. But those are isolated stations beyond the area which is indicated here. I shall have a little more to say in regard to the distribution.
Before speaking of that, I want to call your attention to a few points in regard to fungi in general, points of common knowledge to all who have studied fungi or mycology. A fungus is a kind of plant which does not, on account of the absence of the green coloring matter, manufacture its own food. It is a plant which has, in other words, no green foliage, and as it has no green foliage, it must obtain its organic or elaborated food from some other source. The fungi have very aptly been termed the tramps of the vegetable kingdom, that is, they live on food prepared by somebody else. They can take certain organic substances and change them apparently into other organic matter which can be used by the plant. In the case of this chestnut fungus, we have a fairly typical fungus in certain respects. We have a vegetative stage of the fungus which is nothing more or less than a lot of threadlike structures penetrating the bark of the chestnut, the inner bark or the middle bark, and there drawing the organic matter from the bark of the chestnut and appropriating it to its own use. Fungi, like practically all other plants, have two stages of existence, one the vegetative or growing stage, the other the reproductive stage. Sooner or later the fungus will produce the fruiting bodies, after it has obtained a sufficient amount of food to justify the formation of these more highly organized structures. In the case of the fruiting body of the chestnut fungus, we have very small, pinhead-like structures, which come out to the surface of the bark, the vegetative portion developing through the interior of the bark. On smooth bark we find that these fruiting pustules are apt to appear all over the surface. With bark that is sufficiently old to have ridges and crevices, we find these fruiting bodies only in the crevices.
These fruiting pustules which you will see on this bark are the structures which produce the reproductive bodies, these latter being known as the spores. There are two types of spores which are produced by this fungus. One is the type which is commonly spoken of as the summer spore, the other the type which is spoken of as the winter spore. The winter spore is known from the point of view of the mycologist as the perfect stage of the fungus, that is, it is the more characteristic of this particular fungus. If we should make a cross section of the bark, we should find that the vegetative stage is running through the middle bark, and commonly the inner bark, sometimes in one place only, sometimes in the other only, sometimes in both. This vegetative stage later sends up in various ways a mass of tissue which results in the formation of pustules. These appear on the surface, sometimes more or less regularly rounded, sometimes rather irregular. In the case of the summer spore stage, we have inside the pustules a mass of tissue which is formed into spores. The interior of the spore mass, or at least portions of it, is somewhat mucilaginous, so that when moisture is applied a swelling of the interior mass is produced at a certain stage and something has to break. As a result, we have a mucilaginous mass pressed out through the break in the shape of a twisted thread, much the same as if you take a collapsible tube of paste and pinch it.
Now, one of those summer spore threads may contain anywhere from one to five million spores. I have tried to estimate the number in a thread of this sort which was about an eighth of an inch long, and by taking a certain portion of that thread, mounting it in a drop of water, and then counting over a certain measured area under the microscope, I have estimated, by multiplying, that there were 2,400,000 spores in that one thread. So you can imagine how many of these spores may be produced by a single diseased area which has produced perhaps four or five hundred of those pustules, each pustule containing anywhere from one to twenty threads. Each one of those spores may develop a new diseased area, provided it is transported to a fresh break in the bark of a chestnut tree. Fortunately, only a very small fraction of one per cent ever reaches the proper place for growth.
This last is what I alluded to as the summer spore stage. There is a winter spore stage, or technically, the ascospore stage, which comes, as a rule, later in the development of the fungus. In this same pustule, later in the season, certain sacs are formed. These have long necks which extend to the top of the pustule. These sacs are sufficiently large to be seen with the naked eye. They are dark colored. Inside these, we have a lot of smaller transparent sacs or cases in each of which we get eight spores, sometimes in one row, sometimes in two rows. Each spore can propagate the fungus.
We have, then, two types of spores, either one of which can reproduce the fungus under suitable conditions. There is still another way by which the disease may be kept going. The vegetative stage can survive the winter and continue growing the following year.
I will say right here that I am planning to give you merely an outline of this disease, and have time afterwards for questions which I think in a meeting of this sort are one of the most productive sources of information.
In regard to the rapidity of spread of this disease, I will merely call your attention to two cases as illustrations, or to certain facts, rather. One is that the disease, so far as our attention has been directed to it, has developed over the area indicated on the map since the fall of 1904. Another case is one which has occurred in Rhode Island, where I have had a chance to watch its development a little more closely than in other places, that is, more constantly. In the fall of 1908, after I had made over thirty excursions around Rhode Island, I was unable to find a single trace of this disease, and no one else was able to find a single case of the disease in Rhode Island. In May, 1909, I happened to be about five miles west of the city of Providence, and I found two or three cases, all in one rather restricted spot. Later, it was discovered a little farther south, and soon, a little to the north, so that at the end of the season of 1909 we knew of about ten cases in Rhode Island. At the end of 1910, a season in which very few trips were made with the special object of surveying for the disease, we had more than doubled the number of infections found. That led to putting someone into the field in 1910 to make a survey of Rhode Island. A man was also put into the state of Massachusetts for the same purpose. Mr. Rankin, in cooperation with the United States Department of Agriculture, made a survey of New York State, which has resulted in this map. A man was put into Pennsylvania and one into Maryland for the same purpose. As a result of the survey in Rhode Island, where at the end of 1910 we knew of less than fifty cases at the outside, we now know of very nearly 4000 cases. It has been much the same story in Massachusetts. At the beginning of this year, there were four towns in which the disease was known; now there are seventy-one. At present in Connecticut, the disease is known in one hundred thirty-two towns of the one hundred sixty-eight in the state, and the southwestern part of Connecticut is very badly infected, just as badly as the adjoining portions of New York.[A]
So much for illustrations of the rapidity with which the disease develops. I am not going to say at this time anything special about the origin of the disease, simply because we haven't yet decided what was the probable origin. I will merely say there are some different theories in regard to the origin. One is that it was imported from the Orient, another, that it is a saprophyte, a fungus which has lived normally upon dead organic matter, but which has taken on the parasitic form, which develops on living organisms.
In connection with any disease of this sort, one naturally inquires, how are we going to recognize this disease? This past summer Pennsylvania has put into the field thirty or more men who have been trained to recognize this disease, with the idea of locating the infections in Pennsylvania. As perhaps all of you know, the legislature of Pennsylvania has passed a law relating to this particular disease, and has appropriated $275,000 to see if the disease can be controlled. Their idea is that they have perhaps fifty million dollars' worth of chestnuts, and if $275,000 can show whether or not this disease can be controlled, it is economy to try it.
So far as Pennsylvania is concerned, it means possibly the saving of the chestnuts in the middle and western parts of the state; but it also means that if they can check it there, it is likely to save the great area of chestnut growth along the southern Appalachians. I don't want to make any prophecy as to how that experiment is likely to come out, but, however it comes out, it will be a very great object lesson as to what can be done on a large scale with a disease of this sort.
One of the first things which had to be considered in Pennsylvania was to train a number of men to recognize the disease, so as to go over the country and locate the diseased spots. The method of recognizing the disease I will briefly outline. Of course, over a large country, many hundreds of square miles, it is a long, and laborious operation to look over every tree. It is perhaps impossible without a very much larger force than $275,000 could put into the field. But there are certain clues to the location of the disease which can be seen a long distance, a quarter of a mile, at any rate. The means of recognition is by what I commonly call danger signals. This fungus, when growing through the bark, starts from the common point of infection and grows in all directions, up the stem, down the stem, and around the stem. Wherever this vegetative stage, technically known as mycelium, penetrates, the bark is killed; and of course, you all know what that means. When this has succeeded in reaching around a twig, branch, or trunk, everything beyond that girdled area dies, not immediately, perhaps, but sooner or later it dies; and it dies in such a way that the leaves change color during the summer. The first obvious change which can be noted is a slight wilting of the leaf; then the leaf assumes a pale green color, and from the pale green it takes on a yellow stage; from this a reddish yellow stage, and then a brown, till the leaf is the ordinary dark dull brown of the dead leaves. This coloration which takes place is conspicuous. There is your guide, your danger signal. If the disease has worked very long, half a season, in one locality, you are almost sure of getting some of these danger signals. Where one is present, you can go and look up the cause of that danger signal. It may be a broken twig, but the point is to find out if it is this disease which has caused the danger signal. We start by looking at the danger signal, then at the base of the dead area. If we find here some of the reddish pustules which have been shown on this bark we are quite sure that the disease is present. Then by cutting into the bark a little, instead of the normal buff or yellowish tint of the fresh clean bark, we get, when the disease is present, a rather mottled effect, varying from a brownish to lighter or even darker. There is a peculiar fan-like effect to this mycelium which penetrates the bark, so that by shaving off the surface of the bark, you get this mottled appearance, which gives you another means of identifying the disease. So we look for the danger signals, and then look for the meaning of the danger signals. If we find those two things, the pustules and the mottled mycelium, we can very safely say that this disease is present.
There are a few fungi which closely resemble this chestnut disease in general appearance, but they are not very common, and are not confused with the disease, as a rule, when you get the lens on them.
In regard to the experiments for the control of the disease. I want to say a few words. As far back as 1907, the United States Department of Agriculture began experiments on certain experimental plots, particularly in Long Island near the region where the earliest cases of this disease were known, to see if it could be controlled on individual trees after they had become infected. Later, experiments were undertaken along the same line in Lancaster County, Pennsylvania. Spraying was tried, although there was no idea that it would be of any use, because the vegetative stage of this fungus is running through the interior of the bark, where no spray could reach it. Thus spraying was found to be of no use whatever. Then the operation of cutting out the disease was tried. Where the diseased spot appeared, it was cut out with a gouge. Then the exposed area was covered in various ways with antiseptics.
This gave, for a year or two, very promising results, but about the third year the disease appeared to get over on to the margin, where it had been cut. This led to the later discovery that the disease had been running in the wood, as we had previously suspected. So the cutting out of the bark alone is not sufficient. This year cutting has been done so as to include a portion of the sap wood.
There is just one other topic which I want to allude to. That is in regard to the immunity question. It has been found that this disease attacks the common native chestnut, the chinquapin, the various cultivated European chestnuts, but very rarely the Japanese. In regard to this point. I hope that Doctor Morris will tell us something about his experiments on the breeding of chestnuts with the idea of producing a new and immune variety.
You will understand that I have just made an outline of this disease, and I hope that, if there are any questions to be asked, you will make them easy, so that I can answer them.
President Morris: This very interesting paper is now open for discussion, and I hope that we can get some points which will allow us to know how to control the disease. With the wind-borne spores that are carried miles and miles by a single sharp gust of wind, this disease is a difficult matter to control. We must, I believe, find some natural enemies, if we can. I don't know where to look for these. I will have to ask the mycologists what we may anticipate along the line of natural enemies. I would like to ask if it is common for a weak species to become a devastating species. Have we many parallels in the field of mycology? The point relating to raising immune kinds is one for discussion. Are we to raise immune chestnuts? The history of most plants, I think, has been this, that where they have met their enemies in their natural environment, the fittest survive; and it seems to me that this is a case in which we perhaps have survival of the fittest in North Asia; for the North Asian chestnuts certainly resist the disease better than any others, but the chestnuts of southern Asia are quite vulnerable to it. In my own orchards, I have twenty-six kinds of chestnuts, and have followed them along, for the purpose of determining which ones would resist the blight best. I cut out last year 5000 old American chestnut trees on my property. There is not a tree in all that part of Connecticut, the vicinity of Stamford, that is not blighted, and very few that are not dead. Now, in the midst of this disaster, what was the behavior of my experimental chestnuts of various kinds? It was this. I had about one thousand Koreans that lived up to five years of age, growing in the midst of blighted chestnuts, and none of these blighted. It occurred to me that it might be well to graft these on the stumps of American chestnut, because these Koreans resisted the blight; but when I grafted them on the sprouts of American stumps, at least fifty per cent of the Koreans blighted, showing that the pabulum wanted by the Diaporthe seemed to be furnished by the American chestnut. I had some chestnuts from North Japan that resisted the blight, and yet these grafted on the sprouts from American chestnuts blighted. I had some Chinese chestnuts, and none of those have blighted as yet; and in grafting them, two or three have not been blighted. I have perhaps twenty-four chinquapins, both the western form and the eastern, and only one branch of one tree has blighted. Of the southern Japanese chestnuts, very many are blighted. They are not as resistant as the northern. I have a good many chestnuts of European descent, and among these some resist the blight pretty well; and some of the American progeny, like the Hannum and Ridgely, seem to resist well enough, so that now I am grafting these upon many different sprouts. This should be worked out, and I wish to know what men have tried experiments along this line. I would like to ask Professor Reddick to discuss this question.
Professor Reddick: I have very little that I can add at the present time. The points the talk has raised here are of the greatest importance, and there is certainly room for a great many people to work, though here in this state we have only one man who is devoting his attention particularly to this disease. I find in connection with the work that Professor Collins is doing, and in connection with the Pennsylvania work, that there are some people engaged on these very vital and important problems. They are not giving any particular attention to field work, but are working on these special problems. I think you all appreciate that progress of investigations on this kind of subjects is rather slow, and in the meantime the man who has his trees and his nurseries blighting is surely up against it.
I have only one thing in mind, a thing which I suggested to Mr. Rankin when he first started on this work, and it is a thing which Doctor Peck, our state botanist, suggested at the chestnut bark conference that was held in Albany not long since. Doctor Peck says that he has lived a good while, and he has seen epidemics come and go. Certain plants, certain varieties were threatened with extermination, yet at the present time they are still with us. I suggested to Mr. Rankin that, while it looked as if chestnut blight was going to be with us indefinitely, the chances were it would all be gone before he had a chance to find out all the things he thought he was going to. Our friend Doctor Clinton of Connecticut would have us think it is only a matter of a few years to have conditions come around so that the chestnut blight will not be a thing of serious importance. In other words, Doctor Clinton stoutly maintains that, while this fungus is doing so much now, it is largely due to the condition to which our trees have come, owing to a succession of very unfavorable summers and winters; and as soon as the conditions get around to normal, the disease will be no more. Some of us are not inclined to agree with him entirely.
Professor Craig: Perhaps you can tell us what Mr. Rankin has been doing this year.
Professor Reddick: At the beginning of the past summer, from the surveys and observations that had been made almost entirely by the United States Department of Agriculture authorities, it was known that the chestnut disease had extended up the Hudson River perhaps as far as Poughkeepsie. It was our idea that he would probably find the border line of healthy and diseased trees somewhere in the vicinity of Poughkeepsie, so Mr. Rankin located it opposite Poughkeepsie at Highlands. During the course of the summer, the assistance of the State Survey Commission and the State Department of Agriculture was enlisted, and there were six or eight men who spent part of July and all of August surveying the portion which now appears on this map in red. The results of this survey show that the entire Hudson River Valley, with the exception of a small part in the vicinity of Albany, is now infected. In fact, it is the general opinion that there is no use whatever to attempt in any way to save the trees in this locality. Very fortunately there is a strip of territory which is almost solid spruce forest, and in which there are almost absolutely no chestnut trees. We have already, then, abandoned the Hudson River Valley, but with this great natural barrier, you see that it is going to be relatively easy, so far as the State of New York is concerned, to put some sort of an artificial barrier across the little neck there. This all depends on what can be done in Pennsylvania. This cross-hatching of red along the Delaware River represents an area in which the infection is only partial, and the few dots of red shown about Binghamton represent localities in which the blight has now been exterminated. The diseased trees have been taken out, stumps killed, and bark burned. We are in hopes the disease will not reappear there. I don't believe things have been definitely settled at Albany in the Department of Agriculture, where the control work naturally lies, but Commissioner Pearson is very anxious that something be done to try to control or prevent the further spread of the disease in our state. Plans are being made so that a large number of men will be located in this territory next summer, making very careful inspection, removing the occasional diseased trees, killing stumps, and burning bark; and a forester will be connected with the work, for the purpose of advising with regard to the use of the diseased timber. I might call attention to the fact that our state agricultural law, as it now reads, empowers our Commissioner of Agriculture to quarantine against this or any other dangerous fungous disease,—a very broad step from what it was before that time, when the only fungous disease he had any power to act against was the black knot of plums.
Mr. Reed: From the chart, it appears that the disease is more common in the vicinity of streams and bodies of water.
Professor Reddick: That is an observation that has often been recorded.
Mr. Reed: How is it elsewhere than in New York?
Professor Collins? The question has been asked more often than otherwise, why do we find the disease on the tops of hills away from the water? I think there isn't a sufficient amount of evidence or observation on that point to say whether it is more common near or away from bodies of water.
I will call your attention to one experiment that can be performed by anybody with the microscope. Take a piece of one of those spore horns or threads, put it in a drop of water on a microscope slide. Inside of two minutes, it will disappear entirely. It is dissipated in the water, and the spores are so small you cannot see them with the naked eye. If you let the water dry on the slide, then put that slide under the microscope and try to blow those spores off, you can do it just about as easily as you can blow the shellac off a door. You can brush that film under the microscope, and you can't see that a single spore has been disturbed. The explanation, I think, lies in the fact that these spores are of a mucilaginous nature, and when they dry, they stick to whatever they come in contact with. That does not mean that these spores cannot be blown, because they may lie on fragments of leaves and be blown about by the wind. Again, some of the spores may be detached in a mechanical way and thus blown by the wind. But I am quite convinced that the spores are not blown broadcast, simply because they are of a sticky nature.
Now, those spore threads are forced out under certain conditions, moisture conditions, as a rule. It has been shown after repeated observation that these spore threads are pushed out a day or two after a rain. Of course, in the springtime, the atmosphere is much more moist than later in the season. Consequently, we find more of these spore threads in the spring than at any other time. You will recall that the last week of August this year was a week of almost continuous rain. Two days after that ceased, I saw as many of these spore threads as I had seen at any one time all summer. So that, although conditions are best in the spring for greater abundance of these spores, they may occur at any time. If a bird alights on these spore masses, there is no reason that I see why they should not be carried. We know the rain water running down the trunk dissolves these spore masses, and they are carried down, there to reinfect the tree when insects crawl around.
President Morris: My brother has some Japanese chestnuts twenty-five or thirty years of age. By cutting off one branch at a time as fast as they blighted, he has saved those trees.
Professor Collins: You spoke, Doctor Morris, of grafting Japanese on to American stock. I have seen repeated cases where the Japanese has been grafted on to American stock. The whole Japanese tree has been killed, and we find the disease has killed the tree by girdling the American stock below the graft.
President Morris: Yes, I find this over and over again. In one case where I had a very choice variety of Burley's chestnut, the Diaporthe attacked the American stock underneath this, and had practically girdled it when I saw it. There remained a fraction of an inch of good bark. I cut off all except that, and put tar over it, and grafting wax over that, and this year the graft has grown a foot or more. So by giving a great deal of attention to some one little injury, we can overcome the effect of it.
Mr. Jensen: In your grafting, what was the relationship of the rapidity of the growth of top after grafting, compared with the old stock?
President Morris: When these grafts are put on the stock, on rapidly growing shoots from a large root, they grow enormously, and sometimes we have had nearly one hundred feet of growth in one year. That, however, would be a chestnut like the Scott or the Ridgely. We frequently get thirty, forty, or fifty feet growth in one year.
Mr. Jensen: Does the plant grow more rapidly when it is grafted than on its own stock?
President Morris: I have not grafted Japanese on Japanese stock, but the Japanese and Korean grafted on American stock does grow more rapidly than it does on its own roots.
Professor Craig: Mr. Hall has another interesting instance of chestnut blight.
Mr. Hall: On the ground where the blight appeared, there were four chestnuts set by a nurseryman, two Japanese and two European chestnuts. Of the European chestnuts, one has succumbed to the blight, and the other has been continually attacked for the past four or five years, twice in a period of four years, and it is still alive and recently appears to be in a more healthy condition than for the past four or five years. During that time it has never borne any chestnuts. The companion tree of the same kind was girdled in two or three years.
President Morris: There is comparative resistance. Some of my trees went down instantly, and went all to pieces, while others stood up for four or five years. Chestnuts of the Paragon type I hoped were going to be fairly immune, but they are going pretty fast. I have advised people who have asked about Paragon chestnuts to buy them, but be prepared to have to cut out blighted branches as they appeared. It is a question whether I can advise even buying them much longer, because I have lost nearly all my Paragons, but they have not gone as fast as the Americans.
Doctor Deming: Ought we not before we leave this subject either to appoint a committee, or to pass resolutions urging action on the part of the state similar to the action taken by Pennsylvania in attempts to limit this disease? I would make such a motion, that the Northern Nut Growers' Association urge legislative action similar to that already taken by the State of Pennsylvania to limit the spread of the chestnut bark disease.
Mr. Littlepage: I second the motion. (Carried.)
Professor Craig: Should not the Secretary be empowered to send a copy of those resolutions to the Commissioner of Agriculture? I think the motion includes that.
Mr. Reed: It seems to me that this disease is of as much importance to other states as it is to New York and Pennsylvania, and that this sentiment, as this action can only be a sentiment of the Association, should be sent to the Commissioner of Agriculture in other states, as well as in New York. This is not the New York Nut Growers' Association. I would make that as a motion, that the sentiment of this Association in favor of state action similar to that of Pennsylvania be pressed upon the Commissioner of Agriculture in each state where that disease is prevalent.
President Morris: Shall we make Mr. Reed's motion take the place of Doctor Deming's?
Doctor Deming: I would accept that as an amended motion. (Carried.)
Professor Craig: Inasmuch as we have gone that far, should we not take another step, and that is, fearing lest the United States Secretary of Agriculture should feel slighted, should we not as the Northern Nut Growers' Association draw his attention to the fact that here is a serious disease sweeping over the whole northern part of the country, representing a very considerable portion of his domain, and ask his aid and cooperation with the various states which are attempting to do such good work?
President Morris: Will that have to go as another motion or as an amendment to Doctor Deming's?
Professor Craig: I move that a resolution of a similar type be passed, and forwarded to the Secretary of Agriculture of the United States. (Carried.)
Mr. Wilcox: May I ask some of the gentlemen who have experience along this line if we may look for any cure or help for it in the future, and if so, along what lines will it be possible, along the lines of isolation, of natural enemies, or some other preventive or cure?
President Morris: Yes, I would like to ask if anyone has a definite proposition beyond the one that has been proposed, restricting it by cutting out the advance agents of the blight. I believe that has been the only proposition so far. We certainly can't kill off the birds that will carry off blight on their feet. We don't know if a fungous enemy is likely to follow it up, or if it is a weak species, brought into activity by certain conditions, which will be brought back to its normal mode of life again. I don't know that anything definite could be stated till we know more about it.
Professor Craig: Perhaps Mr. Collins or Professor Reddick might offer something in the way of suggestions on that.
Mr. Collins: I don't think that I have anything to propose beyond the points suggested by the President. I think there are a good many points which should be kept watch of, and I don't know any one that looks any more promising than the other, except perhaps this of cutting out the disease. But this is an expensive method.
Mr. Reed: Have you ever found any individual trees in infested districts that were immune?
Mr. Collins: Only the Japanese, but I think Doctor Morris has found the Korean even more immune. I shouldn't use the word "immune," perhaps, but "highly resistant" to the disease. I have watched quite a number of trees, in the midst of disease, which seemed to be resisting the disease. I explained it in some cases by the fact that the bark was very free from injury—maybe that was the reason why they did not take the disease so easily as they might otherwise.
President Morris: The next paper will be that of Mr. C. A. Reed of the United States Department of Agriculture on "The Present Status of Nut Growing in the Northern States."